WIRELESS LANDSCAPES: MAKING THE INVISIBLE …footage/ART_on_BART.pdfsimply as white noise. Others...

WIRELESS LANDSCAPES 1

WIRELESS LANDSCAPES: MAKING THE INVISIBLE INTELLIGIBLE A practical guide for wavespotters An Inspiration "There are some kinds of knowledge too that cannot be obtained from books, but must be gathered by actual observation. The inspection of a formation in nature, which is pointed out to you, will teach you more in regard to it in a few minutes that you could learn from lectures or from reading books in as many hours, and the lesson so received will be better remembered. "How lonely would be a journey on which you would see not a single face that you know, and how different it would be if every one you meet were an old friend. So to the tourist new charms must be given to scenery, however attractive it may already be, if he knows something about its geology. The rocks, mountains, valleys and plains, although he sees them for the first time, are old friends in perhaps new and interesting forms. He meets them with a certain pleasure, for he understands what he sees and he is given the materials for many a happy hour of quiet and profitable reflection at home, on what he has seen on his railway journey." From An American Geological Railway Guide, by James R. MacFarlane, Ph.D., New York: D. Appleton and Company, 2nd edition, 1890, pp. 3-4. Rick Prelinger Made for the "ART on BART" Tour San Francisco, October 1, 2005 http://www.prelinger.com


Introduction Though BART leaves a conspicuous footprint over much of the Bay Area, it retreats into tunnels, jumps onto aerial right-of-ways, and hides behind tall fences. It inflicts a measure of sensory deprivation on its passengers, distancing the landscapes it penetrates through thick, sound-dampening windows. But one environmental attribute is harder to shut out: the wireless landscape. Imagine a totally sensory-deprived spectator, unable to sense sight, sound, smell, touch, taste or movement, but able to receive and demodulate radio-frequency (RF) emissions. What would this spectator perceive? And, as BART passed by, what would RF sniffing reveal about the people, their activities and the infrastructure supporting them? This tour will mark, identify and interpret the rich quilt of wireless transmissions through which our BART journey passes. It will describe the characteristics of this invisible landscape and relate it to the human activities occurring around the places we pass by and through. It will also propose "wirelessness" as a sixth sense that we can mobilize as a way to navigate and understand our emerging environments. This guide follows the order of the ART on BART itinerary. It is intended to be an introductory guide to the wireless landscapes that the BART system penetrates and is neighbor to. It avoids overly technical information, and certain specific details of some communications systems have purposely been omitted. For specific information on two-way radio communications systems operated by federal, state, county, municipal and other government agencies throughout California, I recommend the Government Radio Systems guides published by Mobile Radio Resources, 1224 Madrona Avenue, San Jose, Calif. 95125-3547; 408 269-5814 (no website). The BART official station designators are used in official communications between BART employees, and are included here to add coherence to these communications when we or others listen.


Civic Center (BART official designator: M40) We begin our observations at the BART station closest to San Francisco's city, state and federal government buildings. Great rewards await careful and patient observers in this area, where a rich RF environment prevails. Immediately above the station is United Nations Plaza, commemorating the founding (in S.F.) and further achievements of the United Nations, supporting farmers' markets and crafts vendors on various days of the week, and serving as a resting place and agora for working-class and poor people at other times. The plaza is also frequently populated by San Francisco police (SFPD) enforcing quality-of-life offenses and the Mobile Assistance Patrol (MAP), whose members pick up homeless and distressed people often under the influence and transport them to various public facilities. The SFPD is a major user of the Emergency Communications Department trunked radio system (see below), and MAP operations may be heard on the Public Works Department trunked radio system. At the intersection of Grove, Hyde, Market and 8th streets is the Orpheum Theater, patrolled by security guards whose walkie-talkie transmissions are easy to monitor yet devoid of much interest. Inside the theatre, stagehands and ushers use other radios, and wireless microphones are often in use. It’s reported that concert bootleggers have sometimes smuggled radios into venues and recorded the high-fidelity output of wireless mics worn by performers, then later remixed these tracks with field recordings to obtain a higher-quality bootleg. Wireless mic frequencies are generally standardized and well-known, but this method of obtaining high-quality audio seems difficult, and the transmitters are quite low in power. It is unlikely that transmissions from the Orpheum's stage penetrate the foundation and issue into the BART station. Across Hyde from the Orpheum is the San Francisco Public Library, which recently installed a free wireless computer network for its patrons. Such networks, commonly known as "Wi-Fi" or 802.11 networks, provide high-bandwidth, high-speed Internet access to anyone with 802.11 compatible equipment. These networks operate on unlicensed spectrum in the 2400 Mhz range (most microwave ovens use a frequency in this range, 2450 Mhz, for cooking by heating up water molecules in food) and, though very low in power,

can be received for many miles. Setting up a computer in United Nations Plaza to "stumble" wireless networks will reveal dozens, and conceivably hundreds. Prominent networks receivable in the vicinity include that of the Public Library, many networks at nearby Hastings College of the Law, and the network operated by a commercial contractor within the Superior Court building at 400 McAllister street, intended for the use of attorneys and jurors waiting to be called for trial. Nearby is also the Federal Office Building bounded by Hyde, Turk, Golden Gate and Larkin. As far as we know, no Wi-Fi networks operate within this building, as the ease of intercepting traffic on these networks constitutes a security vulnerability for the agencies in the building, including the FBI, DEA and various divisions of the Department of Homeland Security. A look at this building's roof, though, reveals a generous number of transmitting antennas, many of which operate in the two exclusive government frequency bands of 162-174 and 406-420 Mhz. Shortwave networks also exist to back up other communications nets in case of disaster, and some antennas for this may be located atop the FOB. Many transmissions in these bands are now digitally encrypted and will appear to the civilian listener lacking the proper equipment simply as white noise. Others may be picked up by anyone with the proper equipment. For many years, the San Francisco FBI field office operated a complex radio network that was easily monitored, presenting a fascinating and often cryptic panorama of surveillance activities. In the early 1980s, this network was updated to support digital encryption, and now only occasional plain-language transmissions can be heard. This and other federal facilities are protected by the Federal Protective Service Police, continually present in and around this building. Their primary dispatch channel on 417.200 Mhz may be heard throughout the Bay Area and is interesting listening, especially when demonstrators convene to disrupt the normal flow of government business or to petition for redress of grievances. Nine blocks from the BART station is the five-year-old building housing the San Francisco Emergency Communications Division, at 1001 Turk street. This modern building houses the city's 911 call and dispatch center for police, fire and other public safety activities. It is a high-security, seismically-hardened environment. Microwave links and telephone lines connect this building to approximately 13 city radio transmitter sites, said


to be atop 555 California street, Bernal Heights, California Pacific Medical Center, Clay and Jones, Twin Peaks, Embarcadero Center, Sunset Heights, Fort Miley, the Hall of Justice, McLaren Park, South Hill (Daly City), Sutro Tower, and within the underground Muni tunnels along Market street. The public safety trunked system occupies 23 channels in the 800 Mhz band. Transmissions emanating from this building are a major portion of total RF activity occurring in the city at any one time, and carry information often of great urgency and importance. In addition to their immediate pertinence, messages from the ECD dispatch site reveal many patterns and structures of life and social interaction in San Francisco. The city also operates a separate trunked radio system for Public Works and other city departments. Five blocks south of Civic Center station is San Francisco's Hall of Justice, a courthouse and detention facility administered by the San Francisco Sheriff's Department, who operate a 16-talkgroup system on the city's trunked radio system. The traffic on this system is one measure of the city's pulse and degree of distress. Entering the station takes you from a rich RF environment into a subterranean gallery also rich with RF signals. The BART station platforms and tunnels run one level below the "Muni Metro" level, used by light-rail cars operated by the San Francisco Municipal Railway. The Muni uses radio for operations and security, and operates an automatic polling system by which streetcars and buses communicate automatically with base stations. In order for these radio systems to work underground, a "leaky cable" relays signals from above into the tunnels and stations. These cables can be easily seen on the Muni level. This system also relays police and fire radio from the surface. On the BART level, a similar system relays transmissions on the BART trunked radio system, a complex area-wide system that serves the BART system fairly well but is difficult to hear as the distance from the actual tracks increases. About 50 miles of RADIAX "leaky-cable" relays signals from 75 local nodes into tunnels and stations. Between Civic Center and 16th Street Mission, BART passes under the US 101 freeway reconstruction project, which was completed on September 9th, 2005. During the lengthy construction period, Caltrans and its contractors deployed many portable radios to coordinate this complex project. Though the FCC allocates

particular frequencies for the use of state transportation agencies and private construction companies, it is now often the case that construction crews use cheap, unlicensed Family Radio walkie-talkies available for as little as $15 apiece in chain stores. These radios typically use 14 frequencies in the 462 and 467 Mhz range, and most models can be used to scan all channels in the group. Many millions of these radios are now in use for every imaginable purpose, from child's play to the coordination of combat operations in Iraq. (Special models using government-only frequencies in the 380 and 390 Mhz range are manufactured for the Department of Defense.) Those interested in a fast and inexpensive means of monitoring the nearby wireless environment, as well as a continuous source of informal commentary on nearby happenings and events, and not fearful of the vernacular, quotidian or banal, might well acquire one of these radios for listening purposes. Since they are often sold in packs of two, it is easily possible to combine the roles of observer and participant.


16th Street Mission (BART official designator: M50) Above and east of the station is the Redstone Building (at 2926-2948 16th Street), home of the Lab performance and exhibition space and many community and political organizations. One is Enemy Combatant Radio (ECR), currently webcasting news, talk, music and events. At one time, ECR operated an unlicensed over-the-air radio station from various sites in the Bay Area, and served an avid audience with news and updates of political and community actions motivated by the U.S. invasion of Iraq in 2003. Many demonstrations, include recent antiwar marches, begin or end in this area or in nearby Dolores Park. March coordinators often use generic Family Radio walkie-talkies, while tactical police commanders and squads use police talkgroups A9, A10 and A11. Other information relating to large demonstrations is often transmitted over the Golden Gate Traffic air frequency on 124.300. Audio recordings of tactical police radio transmissions played a significant role in Whispered Media's videotape We Interrupt This Empire (2003), which documented antiwar demonstrations and activities in San Francisco after the U.S. attack on Iraq. The Bay Area has been home to a large number of unlicensed or "pirate" radio stations for many years. Some, like Free Radio Berkeley (check) can easily be received from the BART system while traveling aboveground, as long as headphones are used. The 16th street area is a busy part of the city with a rich RF environment. Much of it is generated by cellphones and other personal communications devices, which have become ubiquitous in recent years, especially among people of post-college age who form a large part of the crowds in this area. Many who have recently taken up residence in the US also use cellphones as a primary means of personal communication, as is evidenced by the large number of cellphone stores targeting non-English speaking customers. Many of these stores emphasize prepaid services, which carry a higher per-minute calling cost. The Mission district is particularly rich in Wi-Fi networks. In early 2004, a Wall Street Journal reporter "wardriving" (navigating a vehicle equipped with a computer, wireless card, antenna and wireless "stumbling" software) reported finding over 10,000 networks in the immediate Mission area.


24th Street Mission (BART official designator: M60) Like 16th street, 24th street is a rich personal communications environment. In addition to the decentralized RF traffic created by hundreds or thousands of portable transmitters, the 24th street area is overshadowed by two hilltop transmitter sites: Twin Peaks, altitude approx. 920 feet, home of the city's Central Radio Station; and Mount Sutro, altitude 834 feet, on whose summit a stinger-shaped tower, 977 feet from base to top of mast, has been built. This tower hosts transmitting antennas for many radio and television services, including commercial and government two-way networks and analog and digital transmitters for most Bay Area television stations (most located between 657 and 977 feet above the base). Lower on the tower, at approximately 187 feet above ground level, reside standby antennas for the area's TV and a few FM stations, which would be used in case of failure or damage to the primary antennas. Mount Sutro, operated by a corporation known as Sutro Tower, Inc., reflects great design and engineering ingenuity. Many of its immediate neighbors take exception to the presence of such a high-power RF emitter in their vicinity, and have expressed concern about the biomedical effects of high-density RF fields. The research in this area is complex and often specific to individual situations, and many of the investigators in this field have close ties to the communications industry. There have also been concerns that Sutro Tower, Inc. has not closely observed regulations or obtained proper city permits for all of the transmitters on the tower. Even at some distance from the tower, the high-power transmitters affect radio reception throughout the city, throwing out interference and spurious signals that affect the ability to receive certain services clearly. In addition, Sutro's central location and high power combine to raise the RF "floor" level throughout San Francisco, making it difficult to use RF sniffers and "near field" receivers, equipment that can enable hobbyists and artists to pursue many engaging and instructive projects. South and slightly east of 24th Street station and less than a mile away is Bernal Heights Park, where offleash dogs run freely and American Kestrels, our smallest raptors, hunt small mammals. Atop the hill is what appears to be an abandoned AT&T Long Lines microwave relay site, one example of the nationwide network that carried long distance telephone calls until the widespread deployment of fiber optic lines and satellite networks. These sites are easily distinguished by the presence of large

horn-shaped antennas (known as the TD-2 relay system). Otherwise, the site is in active use by the city of San Francisco, various federal government agencies, and a number of private users. There is a proposal to build a 30th Street Mission BART station, but construction has not yet begun.


Glen Park (BART official designator: M70) At Glen Park, our route begins to leave the tunnels; sunlight is visible at the south end of the station. BART then parallels I-280 (also known as the Southern and Foran Freeway) until south of the Daly City station. Freeways are hotbeds of RF activity. In addition to transmitters in vehicles, such as two-way radios, cellular phones, two-way pagers and Blackberry wireless data devices, freeways utilize radio networks extensively for police and patrol, maintenance, the transmission of traffic information, and polling vehicles to manage traffic more effectively. I-280 is patrolled by the California Highway Patrol, which utilizes a combination of car radios, hilltop transmitters and relay stations, most operating in the 42 and 39 Mhz range. These "lowband" frequencies can be received at great distances, providing the receiver and transmitter are within line of sight. In addition, when sunspot activity (which peaks on 9-year cycles) is at high levels, lowband frequencies are subject to a phenomenon known as "skip," and can be received at great distances. I have received CHP transmissions (and SFPD dispatches, when that agency was on lowband) in Connecticut. Caltrans provides construction, maintenance, repair and other services to this and other state highways, using mountaintop transmitters, which in this immediate area are located on San Bruno Mountain (see below). Television cameras are mounted at many freeway locations to transmit pictures of strategic spots to traffic management centers (TMCs) and the CHP. While some of these cameras may transmit wirelessly, others use landlines. There is a growing tendency in the U.S. to use unlicensed spectrum, sometimes Wi-Fi or Wi-Fi-like radios, to transmit surveillance camera pictures. At many points along Bay Area freeways, small Yagi (fishbone-style) antennas "ping" FastTrak transponders located in private vehicles, polling them for information which is then channeled to TMCs and used to compile aggregate data on traffic congestion. These can, for instance, be seen on US 101 northbound at the Waldo Grade, just north of the Golden Gate Bridge, and on I-80 eastbound in San Francisco, just before the entrance to the Bay Bridge. It is apparent that data on individual transponders, and thus on individual cars and

drivers, is being gathered at such points, as frequent commuters sometimes receive traffic survey questionnaires asking them about their travel patterns. Balboa Park (BART official designator: M80) This station, whose platforms are illuminated by natural light, is close to the San Francisco Municipal Railway car shops (the Curtis E. Green Light Rail Center) and to San Francisco City College. After Balboa Park, the route wends back underground, surfacing with the vast panorama of the Excelsior district and the slopes of San Bruno Mountain to the east. On the west is the outer Mission district and Bernal Heights. BART follows a long, languid curve in a generally southwestern direction until it curves further southwards just before the San Francisco/San Mateo county boundary. Just before the city line, BART passes a 7-11 convenience store sporting a satellite dish and 2400 Mhz Wi-Fi vertical antenna on its roof. These Wi-Fi antennas are typically seen on many California 7-11 stores. 7-11 stores and other locations that sell California state lottery tickets are connected by local wireless networks whose hub is a 7-11 or other business which aggregates transactions on the ticket terminals and transmits them to a central computer, perhaps via satellite. This arrangement saves connectivity costs, since only one location within the cluster of sales agents is actually connected to the central computer at all times.


Daly City (BART official designator: M90) Daly City station, just a block south of the San Francisco city/county line, is just southeast of I-280. At the north end of the station, a tall tower holds antennas for the BART communications system and for one or more cellphone providers, an example of colocation (when a tower is shared by more than one user). By the station is Pacific Plaza, an office complex with several restaurants and a movie theater, which is also the home of DigiDesign, the developer of the well-known ProTools audio editing software. Theater employees communicate via low-power walkie-talkies, probably in the UHF range, and servers in the restaurants receive reminders via short-range unlicensed tone-only pagers when dishes are ready to be picked up at the kitchen and brought to tables. Colma (BART official designator: W10) Lying southwest of San Bruno Mountain, Colma is a town of 1.9 square miles. It is home to approximately 1,200 living and an estimated two million dead, with 17 cemeteries dedicated to the needs of deceased humans and those who remember them, and one for pets, well worth a visit. Besides its quieter districts, Colma is also home to two shopping malls (280 Metro Center and Serra Center) and just across I-280 from a larger mall, Serramonte Center, technically located in Daly City. The presence of so many stores and the proximity of San Bruno Mountain, whose ridge is topped by ten large towers with hundreds of transmitters, including many for local FM and TV stations, makes for a rich and often chaotic RF environment. Big-box stores such as Target, Mervyn's and Bed, Bath and Beyond, all in the area, use low-power two-way radios extensively for security, inventory control/replenishment and maintenance. Many fast-food outlets in the area also have drive-through windows, where cashiers speak to drivers via a two-frequency radio link, usually on frequencies reserved for low-power use or wireless mics. Many newer scanners feature search capability for these low-power frequencies, and a search in the Colma area will immediately turn up quite a number of conversations about what seem to be highly ephemeral concerns. Members of the public using portable Family Radios are also highly present on air in this vicinity. South of Colma BART enters another tunnel.

South San Francisco (BART official designator: W20) BART serves the east end of South San Francisco, known to many as "The Industrial City" from the whitewashed lettering on the side of Sign Hill Park. The station, though underground, receives natural light through skylights, and, like the other recently constructed San Mateo County stations, is filled with public artworks. South San Francisco is a working-class town that seems in many places to belong to an earlier era. Its west side is residential, and its east side contains many support businesses for the nearby San Francisco International Airport. Much radio traffic in the area is generated by hotels, car rental agencies, trucking companies, limousine services, and the frequent Caltrain passenger and freight trains along the Southern Pacific line. San Bruno (BART official designator: W30) For the first time on this leg of the tour we see blue sky above the station platforms. This station serves the modestly-sized town of San Bruno, whose downtown preserves the image of a 1960s California town. San Bruno station is located at Tanforan Park Mall, which was formerly the Tanforan Park racetrack. In the early days of World War II, Japanese Americans were concentrated into buildings built to temporarily house animals at the racetrack, prior to their relocation to and internment in remote camps throughout the rural West. Today, Tanforan Park serves working-class and middle-class shoppers from San Francisco and the northern Peninsula, with a mixture of big-box stores, a multiplex movie theater and restaurants, all of which generate the kind of RF smog we previously experienced in Colma. After the San Bruno station we dive into a tunnel, then out again to an elevated structure, and then east on one arm of the Y-shaped spur to San Francisco International Airport (SFO).


San Francisco International Airport (BART official designator: Y10) The airport spur passes through an unused tract of land that during BART construction was discovered to be habitat for the endangered blue, green and red San Francisco garter snakes. Nearby is a white dome mounted on a short tower that I surmise contains a NEXRAD automatic weather radar observation system to supply real-time weather information to aircraft and controllers. This information is available by subscription and on several websites. We then pass over busy US 101 and into the stem of the Y, then into the relatively new International Terminal, where the BART station is located. You may hear the train operator announce directions to specific airlines, a kind of announcement not often heard on American transit systems. As the train pulls into the station, aircraft parked at gates 89 through 91 may be seen being loaded and serviced. The International Terminal offers a number of interesting destinations for the nonflying visitor. On the lower level, right outside the BART paid area, is the Meditation Room. This relatively luxurious and RF-free room forbids the use of radios or cellular telephones, and is a place where the visitor or harried traveler may relax. After some meditation the visitor will realize that this is a dual-purpose room, designed both to serve the spiritual needs of visitors and as a secluded facility for relatives and survivors of airplane crashes. Upstairs is the airport museum, which currently features interesting displays of passenger air transport advertising and memorabilia. On the concourse, behind the check-in kiosks, is a free-standing exhibition space which at last visit was displaying highlights from the excellent David Rumsey map collection. Finally, there are two food courts with restaurants that serve generally better-quality food than is available at most U.S. airports. All of these facilities reside outside the sterile secure area and may be visited by anyone complying with general airport conduct regulations. A visit to the airport on a nonflying day can be delightful and free of the tension that often accompanies travel in the jet age. The radio-equipped visitor will find a great deal of interest at this busy airport. Airports are fascinating RF environments with activity in many portions of the radio spectrum, much of which can easily be heard by hobbyists. Perhaps most prominent are the various kinds of air traffic control communications. A detailed taxonomy and description of air traffic control and

its wireless manifestations is beyond the scope of this guide, but suffice it to say that arriving and departing aircraft first communicate with an ATC Center (in this case Oakland), one of 21 that handles air traffic over a sector of the United States, then are handed off to a TRACON (Terminal Radar Approach Control), which in San Francisco's case identifies as SIERRA control and handles a number of Bay Area airports. When an aircraft is 10 miles from SFO, SIERRA control hands it off to San Francisco Tower, which communicates with it as it orients itself to the runway and lands. Further communications occur on special ground control frequencies. A continuous recorded broadcast known as ATIS (Airport Terminal Information Service) repeats weather, barometric corrections and current information for aircraft in the vicinity. All of these communications occur in the VHF aircraft band (118-137 Mhz) which uses AM modulation, unlike conventional two-way radio ground communications that utilize FM. Commercial airlines speak to aircraft in flight using VHF airband frequencies, known as "company" channels. These are generally assigned by airline and the messages they carry can range from the painfully banal to the urgently pertinent. In addition, there are a number of navigation services that transmit what would appear to the ear as tones and pulses. There are also air traffic control services provided over UHF military air frequencies by the same controllers, which may or may not be repeated over the VHF control frequencies. On higher frequencies, typically in the microwave range, are a number of radar systems that provide imagery of the air traffic environment and local weather conditions. One aircraft frequency of special interest in the Bay Area is 124.300, known as "Golden Gate Traffic." Low-flying aircraft and helicopters use this frequency to self-announce their presence to one another, and as a kind of "intercom" on which to compare notes about air and ground conditions. Typically present on this frequency are the CHP helicopters (known as "Eureka" units), traffic observation aircraft working for radio and TV stations, the regular Coast Guard port and harbor security patrols, and tourist excursion helicopters. This frequency is an excellent indicator of major events and activities in the region. For example, during the antiwar demonstrations of spring 2003, much useful information about activities on the ground and the positions of demonstrators and police was exchanged between airborne members of the media and law enforcement air units, in what


was probably a common example of cooperation between the press and police. Beyond air-to-air and air-to-ground channels, the airport is a hotbed of wireless activity. An incomplete list of radio users on the ground includes: • ground personnel handling baggage, controlling the movements of passengers, and solving problems. Each airline has its own frequencies, which make interesting listening when the traffic involves your own plane • airport police and fire crews • security officers. The Transportation Security Administration (TSA) uses frequencies assigned to the FAA in the 172 Mhz range • Immigration and Customs Enforcement officials, who use radios in the federal frequency bands • San Francisco police officers and firefighters, who have special bureaus established at the airport. San Mateo County sheriffs, California Highway Patrol officers, FBI, Secret Service, and State Department Bureau of Diplomatic Security officers all percolate through the airport on various specific assignments, making it a hotbed of law enforcement, much of it invisible to the unsensitized eye • Passengers with personal voice and data wireless devices and users of the many Wi-Fi nodes at the airport. Finally, one of the most interesting wireless communications networks that operates at SFO may also be heard throughout the Bay Area and the world, provided that the listener makes a small investment in equipment and finds a sensitive antenna. It's the ACARS network, operated by Aeronautical Radio, Inc. ACARS (Aircraft Communications and Reporting Service) is a data-only service that's sometimes jokingly called "email for planes." All commercial passenger and many general aviation aircraft are equipped with ACARS terminals, which allow crew to transmit and receive text messages from ground stations. During a given flight, an airplane may send and receive many messages, some of which are completely automated (machines talking with machines about status of the aircraft systems, weather reporting and forecasts, etc.) and others of which are keyed in. Messages about health emergencies onboard, sensitive information involving passengers and crew, and other operations-related information are all

transmitted, and can easily be received with a receiver and computer equipped with free software. ACARS sounds like little "burrs" of audio, each a burst of data, and uses a few nationwide frequencies, especially 131.550.


Millbrae (BART official designator: W40) After an all-too-brief visit to SFO, we proceed along the other leg of the Y in a southeasterly direction to Millbrae station. This station lies adjacent to the Caltrain right-of-way, formerly the Southern Pacific Railroad's commuter and freight line along the Peninsula. Direct platform-to-platform transfers between BART and commuter rail are possible here. Caltrain, like most railroad operations, is a heavy radio user (there are 96 weekday trains), and many railroad buffs carry scanners to monitor railroad operations, similar to many railroad workers who carry handie-talkies. Voice communications concern movement and safety issues, and can be very interesting when you are a passenger caught in the midst of a service disruption. Private telephone communications (PBX) are also carried on these channels, all in the 160 Mhz region. Trains communicate internally (from engines to end of trains, and between engines and helper engines) using data-only telemetry networks at 452 and 457 Mhz, which humans perceive as short bursts of noise. The Bay Area's busy freight railroad system also uses an automated data system operating in the 900 Mhz region. This system tracks movement of trains, status of signals and switches, and the location of equipment over many thousands of square miles. Hobbyist software is available to track trains and build a real-time representation of rail operations, and the advanced rail buffs who have experimented with this system find it remarkable. The Union Pacific and other railroads also use microwave "backbone" networks that link their operating regions with central dispatch centers, in the UP's case located in Omaha, Nebraska. These elaborate systems, operating at 6.6 Ghz, permit workers in the field to speak with dispatch thousands of miles distant. At the north end of the Millbrae BART platform, we see a high tower bearing antennas for BART's own trunked system and various cellular providers. Our return train will carry us to Pittsburg/Bay Point, and the next station not previously described is:

Powell (BART official designator: M30) BART's four downtown stations occupy a region filled with dense electromagnetic energy, which some critics of wireless network expansion have called "RF smog." Without the "leaky-cable" system that distributes public safety and BART operational communications throughout the Market street tunnels, the underground stations would be radio quiet zones, but on the street an observer would find busy and chaotic activity on most frequency bands. In past years much of the traffic was voice: "loss prevention" officers in the nearby stores, taxi dispatchers, security and housekeeping workers at the hotels in and around Union Square, and more. The 1990s ushered in a wide switch to digital communications, and though some of these voices can still be heard, powerful digital signals from cab dispatch systems, paging networks, digital cellular transmitters, telemetry from Muni buses and trolley coaches and other wireless data services beep, buzz and burr continuously, creating an agreeable cacophony that's unintelligible without the proper decoding software. Older buildings with unused radio transmission masts can be seen up Powell and the other hilly Nob Hill streets. These masts held antennas for early AM, possibly some FM stations and shortwave transmitters before AM transmitters were located outside city centers. Montgomery (BART official designator: M20) Serving the heart of San Francisco's once-preeminent financial district, Montgomery is another communications nexus. Atop many highrises in this area are microwave dishes transmitting highspeed data communications to data centers and satellite corporate facilities located outside the city. Many data links that were once point-to-point terrestrial microwave now use satellite dishes or fiber networks, which has relieved congestion in the microwave bands to some degree. The wardriver will note that a high percentage of the wireless networks in this area use encryption. North and slightly west of Montgomery station is the first large Chinatown in San Francisco, another RF-rich area, whose merchants make heavy use of Family Radio walkie-talkies to conduct business.


Embarcadero (BART official designator: M16) Embarcadero is San Francisco's last station before our train enters the 3.6 mile transbay tube. The station lies below the Hyatt Regency Hotel and close to the Embarcadero Center and Golden Gateway building projects, both of which generate substantial radio traffic for security and maintenance purposes. At the end of Market street, several blocks beyond the station, is the newly remodeled Ferry Building, where ferries arrive from and depart for various destinations. BART's transbay tube (construction commenced 1965, opened September 16, 1974) joined other infrastructure built to span the Bay. In addition to the tube, which lies 135 feet below the surface at its deepest, there's the San Francisco-Oakland Bay Bridge (opened 1937, currently being seismically upgraded and in part replaced) and various underground communications cables. While in the tube, BART passes under and adjacent to a number of interesting radio transmitters and networks. Though San Francisco's port handles only a fraction of the passengers and cargo it did in the past (most of the freight traffic is now handled through the Port of Oakland), there is considerable marine traffic inside and outside of the Golden Gate, and marine radio channels at 156-157 Mhz are still very busy. The Vessel Traffic System (VTS), dispatched from a high-security center atop Yerba Buena Island in the middle of the Bay, controls the movements of large vessels, and they can be heard checking in with VTS outside the Golden Gate and as they enter the Bay. The Coast Guard's stations are quite active with rescue traffic and notices to mariners, as well as law enforcement and security operations (many of which are coordinated via encrypted radio channels). Coast Guard HH-65 helicopters in telltale orange regularly patrol the ports and Bay shoreline, and can be seen and heard flying throughout the Bay Area every day. Their operations are easily heard on 124.300 ("Golden Gate Traffic"), on the military air frequency 345.000, and others. Commercial fishing vessels and pleasure boats also chat heavily on marine channels. Caltrans maintains the Bay Bridge and operates a busy trunked radio system with several subsystems audible throughout the Bay Area. The California Highway Patrol patrols the bridge and reports delays, accidents and incidents occurring there. On Yerba Buena Island, much of which has been closed to public exploration even before 9/11/2001,

small Yagi-style antennas point eastward and upward. These antennas, part of a UC Berkeley geophysical monitoring network, are connected to seismic sensors on the island and transmit signals indicating ground movements in the area. At the Bay Bridge toll plaza, hundreds of short wireless transmissions occur every minute as vehicles equipped with FastTrak devices pass through the tollgates. The FastTrak transponders are not active transmitters, but passive devices that are "pinged" by transmitters at tollgates and other locations. When pinged, they each transmit a unique code, which when sent to a central computer indicates whose toll account is to be charged.


Oakland West (BART official designator: M10) The Oakland West station, which in the 1970s primarily served a small local population and workers in the neighborhood, has become a busy transfer station in recent years. West Oakland is a historically African American working-class and working-poor neighborhood that is now experiencing gentrification and a population increase as artists and middle-class people move into new or remodeled buildings, many of industrial origin. Like many neighborhoods near manufacturing areas and transportation facilities, West Oakland is traversed by a high density of wireless communications. In the 1960s, African American activists discussed the theoretical possibility of gaining funding for unmet community needs by charging tolls to suburbanites passing through their neighborhoods on the way to the central city. Today, the extreme gap between the value of the communications services physically located in poor and working-class communities and the low wealth held in these communities suggests that residents might take a look at the invisible services that their neighborhoods provide without compensation. The Oakland Army Terminal, commissioned as the “Oakland Sub-Port of the San Francisco Port of Embarkation" on December 8, 1941 and closed in 1999, was probably the largest generator of wireless communications in West Oakland during its time of operation, especially during the Vietnam war. This facility, plus the Naval Supply Center Oakland and several other facilities, lie largely unused, waiting for political consensus and economic development to converge so as to support new uses. Some nonprofit organizations such as the Alameda County Food Bank and a few commercial tenants use the facility, but it is largely a quiet spot on the wireless map. Near the station are many railroad yards, whose wireless communications are described under Millbrae, and the U.S. Postal Service's large Oakland Processing and Distribution Center, where international mail that is to be sent by sea and other bulk mail is processed. The Postal Service uses radio extensively for trucking and loading operations. A large cellular telephone tower is located on the south side of the BART line between Oakland West and the downtown Oakland tunnel.

Oakland City Center – 12th Street (BART official designator: K10) BART passes under downtown Oakland, stopping first at the 12th Street Station. Downtown Oakland, home of a few corporate headquarters, a major hotel, a large Chinese American community, a city and regional museum of art, culture and science, an antiquarian bookstore, numerous interesting art exhibition and performance venues and the location of Philip K. Dick's disturbing realistic novel Humpty Dumpty in Oakland, presents a wireless profile much less congested than downtown San Francisco's but still interesting. Amtrak passenger and freight trains pass through downtown Oakland in the Jack London Square area, generating interesting traffic on the radio and traffic jams on the streets. The city of Oakland operates an EDACS-type trunked public safety radio system that is engineered so as to be extremely difficult to hear outside the Oakland city limits. Because of budget constraints that have limited the city's ability to employ workers, the system is often much quieter than municipal communications systems in cities of similar size. Family Radios are very active in the Chinese American community, located just east of the downtown core. And since residences and businesses are located close to one another, cordless telephone signals and Wi-Fi networks mix with business radios.


19th Street Oakland (BART official designator: K20) 19th Street is close to the southern end of Oakland's "Auto Row," a twenty-block stretch of automobile dealers and services. Automobiles are becoming wireless transmission platforms in their own right. Consider a new car: it is possibly equipped with Bluetooth short-range wireless technology, so that the occupants can talk "hands-off" on their cellular phones; the driver may be using a wireless transmitter on an iPod or similar device so that the unit can play through the dashboard stereo; the vehicle may be equipped with OnStar, a system that integrates car sensors, an onboard cellphone and satellite technology so that a driver in distress (or a stolen car) can "talk" directly to a central dispatch center; or it may be LoJack equipped. LoJack, a technology operating on 173.075 Mhz, is activated when a car is stolen; the hidden LoJack transmitter sends out signals that can be received by any police patrol car with a telltale array of four vertical antennas on its roof, enabling the car to determine the direction and strength of the signal. It is claimed that LoJack-equipped cars are almost always discovered. In addition to contributing to congestion and pollution, therefore, cars also add to radio spectrum congestion. The radio spectrum, fortunately, is not a limited resource. MacArthur (BART official designator: K30) MacArthur station, a busy transfer point, is located in the middle of a freeway, CA 24, which generates a great deal of wireless traffic as described earlier. Close to the station is the Oakland office of the California Highway Patrol (CHP), transmitting regular dispatches on 42 Mhz, links to tower sites on 72 Mhz and in the microwave range. The CHP operates a complex radio system stretching the length and breadth of California. Most communications to and from the familiar black-and-white (and occasionally all-white) vehicles take place in the low VHF band on 39 and 42 Mhz. Listening to the CHP provides a detailed picture of the pulse of transport, weather and law enforcement activity throughout California, and is recommended for the long-distance highway traveler not contented with music and news. The lowband channels, which are color-coded (Oakland operates on "Green," San Francisco on "Pink" and Hayward on "Aqua") may be heard at great distances. Individual CHP officers also carry walkie-talkies that operate on 154.905 and other frequencies, communicating directly with mobile extenders in the patrol cars that repeat handheld

transmissions through the car radios and into the dispatch centers. Most CHP cars continuously repeat transmissions over a mile radius, sometimes more, on this channel, and so continuously monitoring 154.905 will indicate when one is near a CHP vehicle. At accident and disaster scenes, the traffic on this channel is often quite informative. Near MacArthur is a complex of hospitals, in the district sometimes known as "Pill Hill." Hospitals are hotbeds of radio activity, with traffic ranging from cardiac telemetry (in which ambulatory patients carry small transmitters relaying their heart activity to remote receivers so that their vital signs can be observed by nurses), to the special cordless phones that are approved for in-hospital use, to security and maintenance networks, to communications with air ambulances and Life Flight helicopters transporting in trauma victims and to the interesting ambulance-to-hospital channels, ubiquitous throughout the U.S. These channels permit paramedics to communicate directly with emergency room physicians and staff, to provide initial exam and triage data before arrival, and to send EKG data to the hospital. So as to comply with recent health privacy (HIPAA) regulations, these channels are encrypted in some cities so as to prevent the public from hearing patient names and details of their physical and mental condition. Rockridge (BART official designator: C10) BART proceeds from MacArthur to Rockridge along the center of CA 24. The University of California Berkeley campus is visible on the left (North) side of the line, about two miles north. Rockridge is an increasingly affluent residential neighborhood and many homes are equipped with broadband Internet access. Many use wireless routers that emit the characteristic Wi-Fi signals. Leaving Rockridge, we near the Berkeley Hills. Along the ridgeline are several hilltops that host major communications sites, including Grizzly Peak, Vollmer Peak (where the Berkeley Police radio system primary site is located) and KPFA Hill, transmitter site of the often-contested and contentious Pacifica FM station. We enter the 3.5-mile long Berkeley Hills tunnel, passing into Contra Costa County along the way.


Orinda (BART official designator: C20) Orinda, a bedroom community of 17,599 people, is protected from many of the diverse RF emitters of the San Francisco Bay basin. Its topography is characterized by rolling hills and thus is well suited for the VHF radio systems used by the Contra Costa police, fire and local government agencies. BART follows the freeway median until Walnut Creek, serving (and in many cases sustaining) the narrow spine of commercial and higher-density development that surrounds the freeway and transit line. On the south (right) side of the line between Orinda and Lafayette, the house of an amateur radio operator (ham) with the characteristic array of antennas can be seen. A cross-yagi antenna for satellite operation is pointed towards the sky. Lafayette (BART official designator: C30) BART continues to follow the freeway median. Between Lafayette and Walnut Creek on the North (lefthand) side of the line, a hilltop radio site stands with many masts, towers and antennas, all enveloped and partly hidden by a eucalyptus grove. This effect is similar to that sought by cellular system operators when they camouflage their towers to look like trees, except that in this case the camouflage is actually planted. Walnut Creek (BART official designator: C40) BART crosses over twelve freeway lanes and enters downtown Walnut Creek, which has become a regional office and corporate center and nightlife hub for Contra Costa County. The downtown area is filled with self-contained office "plazas", new buildings designed to look historic, and some relics of the area's agricultural past, including old farm buildings. The office buildings generate the usual radio traffic, as do the freeways, especially the busy intersection of I-680 and CA 24. On the east and south lies Mount Diablo, one of the two high mountain transmitter sites in the area (the other being Mount Hamilton, east of San Jose). Diablo is a major site used by federal and state government agencies, and transmissions from the 3900-foot peak can be heard throughout Central and much of Northern California. From Diablo, there is a line-of-sight view to the snow-capped peaks of the Sierra Nevada, weather and smog permitting, and radio reception is equally great,

encompassing the northern Central Valley, the Sacramento Valley and the Sierras, though interference from nearby transmitters can be a problem. Pleasant Hill (BART official designator: C50) Along I-680, which parallels BART as we approach Pleasant Hill, we can see traffic cameras. Some, though not all, of these cameras transmit pictures to Traffic Management Centers and CHP dispatch centers via wireless links. Others are hardwired. By Pleasant Hill station is a large Embassy Suites hotel equipped with highspeed Internet access. Hotel wireless networks are extremely active. Though the content of transmissions is generally uninteresting and their privacy should in any case be respected, their density characteristics can reveal a great deal about the guests and their activities. Idle hotel guests having a moderate level of technical awareness and some freely available software can monitor network activity (though usually not the content of computer-to-computer transmissions) and gain insight into the intangible networks that exist in these singular places. Along the line between Pleasant Hill and Concord, many relatively new homes can be seen in a landscape one might describe as "generically Californian." These houses are built out of mass-produced, often inexpensive materials and are quite RF-permeable. Wardrivers and those interested in cordless telephone communications (monitoring cordless telephones is prohibited by state and federal law) will find these houses to be quite forthcoming with details about the interests and activities of those inside.


Concord (BART official designator: C60) Entering Concord, we pass by BART's Concord yards, where much maintenance, repair, switching and train assembly activity takes place, with accompanying radio chatter. By Concord station the Concord police headquarters is visible, sporting a tall radio tower in support of its 11-channel radio system. Nearby is the Bank of America Center, a large backoffice processing complex that relies on a four-channel UHF system for operations, security, and engineering. If the wireless observer hears evidence of mall operations, it is likely to emanate from the nearby Sun Valley Mall. We are just east of Buchanan Field, a large airport serving mostly general aviation, whose air traffic control activities can be heard in the conventional airband. Leaving Concord, we proceed along an extension of the original BART system. North Concord-Martinez (BART official designator: C70) Passing through another fairly generic suburban area, the BART line proceeds at grade past houses that are walled off from the street, past the Olivera Crossing shopping mall and into the newish station. This portion of the line is unusual in that it is visually integrated with the area it passes through rather than on an elevated structure or in a subway. A wireless observer along this part of the system would experience the quotidian traffic of home life and the mall. North Concord-Martinez is the closest station to the Naval Weapons Station (WPNSTA) Concord (also known as Naval Weapons Station Seal Beach Detachment, Concord), a 12,800-acre site. WPNSTA Concord is comprised of two geographically separate units, the Inland (5,170 acres) and Tidal (7,630 acres) Areas. The Department of Defense (DoD) announced in May that it had included the Inland Area of the Concord Naval Weapons Station (CNWS) on its list of recommended bases to be closed by the Base Realignment and Closure (BRAC) Commission. The station houses conventional explosive ammunition and munitions and is reputed, though not officially acknowledged, to house nuclear weapons as well. From BART, the typical gray and white railroad cars used for munitions transport can be seen on the numerous rail spurs within the base. Base

operations and security can be heard in the military VHF band (138-144 Mhz) and elsewhere; much of this traffic is encrypted for security. On September 1, 1987, S. Brian Wilson, who had served as a U.S. Air Force officer in Vietnam and whose uncle had served as a young officer on the U.S. prosecution team at the Nuremberg trials, chose to commit nonviolent civil disobedience in protest of U.S. military actions in Central America by engaging in a 40-day water-only fast while sitting on the railroad tracks outside the Weapons Station, where the tracks crossed the public highway. He was struck by a train and lost both of his legs, among other injuries. Various unofficial markers placed by peace activists and other traces recall this event. Martinez, county seat of Contra Costa County, is also home to the Shell and Tosco refineries, both of which operate busy trunked radio systems. Eastern Contra Costa County also is home to other refineries and chemical companies, and residents have major environmental and epidemiological concerns. There are frequent alerts and shelter-in-place alarms, which can be heard audibly via sirens (controlled via a VHF lowband network) and via county radio and state EDIS (Emergency Digital Information Service) bulletins.


Pittsburg/Bay Point (BART official designator: C80) BART now passes through golden hills that are currently unbuilt but may not long remain so. This "natural" gap between two heavily built-up sectors of the Bay Area is quite striking. We pass under CA Highway 4, then into its median. The Naval Weapons Station may be seen on the right (south) side, with the telltale white cars used for munitions transport and the lumps in the ground that represent underground ammunition bunkers. Mount Diablo is also visible in this direction, standing alone in the landscape. Turkey vultures and other raptors populate this area and are easily seen from the train. North of the BART line, before arriving at Bay Point station, is the Calvary Temple, a large church. Churches frequently use wireless microphones to amplify pastors and principal singers, and these can often be heard at some range from the buildings. There have been many cases where passing vehicles, notably taxis, interfere with the mics and spurious transmissions are heard over church public address system. South of the line, new homebuilding was in progress (as of August 2005). The traditional sounds of homebuilding, such as hammers and saws, are now augmented by Family Radio traffic and the Nextel wireless handsets favored by workers in the building trades, which emit the well-known chirping when announcing transmissions in "Direct Connect" (walkie-talkie) mode. On the South side, a hillside has been burned, the fire almost but not quite reaching a cellular transmission tower. Also on the North (left) side of the line is San Pablo Bay. On a clear day, the view from the train encompasses a great deal of the Bay and surrounding land. Northeast of the station, wind turbine power generators can be seen. The Bay Point area is an industrial community with a large African American and Spanish-speaking population, many of whom trace their family heritage to ancestors who worked in the US Steel-Posco finishing mill (which operates a complex radio sytstem) and shipyards. It is a current example of a post-industrial landscape that's rapidly converting to residential use, where it is safe to construct houses. Motorcyclists along the freeway can frequently be seen wearing wireless headsets to speak with other riders or even persons riding on the same bike.

These handsets are voice-activated and generally operate on unlicensed 49 Mhz frequencies. We return along this line to MacArthur and then transfer to the Richmond line.


Ashby (BART official designator: R10) The line between MacArthur and Ashby runs on an elevated structure above Martin Luther King Jr. way, formerly known as Grove street. On the right (North) side of the line, we pass by the former site of Merritt College, later Grove street College, a site of significant political organizing and activism, especially involving peoples of color, in the late 1960s and early 1970s. In January 1967, the first Black Panther Party office was established at 5624 Grove street. Ashby station, the southernmost station within the city limits of Berkeley, is perhaps more interesting for its wireless past than its present. Throughout the 1960s and 1970s, radio communications and radio interception played a key role in radical social and political movements. This story is not well known, and it is not clear whether documentation survives. Beginning in 1967, members of the Black Panther Party followed Oakland police cars to observe interaction between police and members of the community, and confronted police officers when they witnessed incidents of police brutality. BPP members used tunable radios and later scanners to monitor Oakland police operations. Some of these encounters ended violently. Law enforcement agents at all levels closely monitored BPP activities, coordinating surveillance by two-way radio. They also paid much attention to antiwar activities and activists, putting many of them under surveillance. After Patricia Hearst's kidnapping in February 1974, FBI agents blanketed the area in search of the mysterious Symbionese Liberation Army. North Oakland and Berkeley together were the site of a massive and longterm surveillance and information collection effort on the part of many government agencies. The traces of this effort can be seen in declassified documents and in accounts by activists of the era. Thousands of hours of radio conversation once occurred, most of it unmonitored by hobbyists or activists due to the lack of equipment at the the time, and it isn't easy to determine whether it was taped at the FBI dispatch console or at other control points. Since radio waves weaken but don't stop vibrating until they vanish into the RF noise floor, though, we may playfully imagine that the evidence of this massive taxpayer-funded surveillance effort is still bouncing around the cities, available for reception and reconstruction if only the means could be found to do so.

Berkeley (BART official designator: R20) A university town that has morphed into an affluent suburb with the issues we commonly associate with large cities, Berkeley supports a remarkably high volume of upscale restaurants and shops, especially on its north side and in the Fourth street area. It runs from the hills down to the bay, and is economically dominated by the University of California campus. The campus is a rich generator of wireless traffic, with its own 800 Mhz trunked radio system and a number of Federal systems (operated by the Department of Energy and possibly other agencies) located at the Lawrence Berkeley Laboratory uphill from campus. The Berkeley Police use a standard UHF radio repeater system on three channels, which can easily be heard throughout the Bay Area. Several other low-power channels are used for surveillance and narcotics squad activity, especially around Telegraph and San Pablo avenues. There are a number of community Wi-Fi networks in the area, as well as many thousands of private wireless networks. For five years, Free Radio Berkeley operated from a number of temporary sites in the city and hills, at 104.1 FM. Around the city, especially at its entry points, are handmade signs on which are painted only "104.1 FM," a cryptic allusion to the station. This micropower station was pulled off the air by court injunction in June 1998. Berkeley Liberation Radio, another organization, has succeeded in its place, but I don't know whether it is still broadcasting. The city of Berkeley operates its own "emergency radio station" at the top end of the AM dial on 1610 Khz. It generally transmits a taped loop of city information, but could be used to transmit live emergency messages if needed. Signs at the city limits alert those entering the city to its existence.


North Berkeley (BART official designator: R30) The northernmost underground station in Berkeley lies in a residential neighborhood favored by families. Many families with young children employ baby monitors as a means of benevolent surveillance. A transmitter in the child's bedroom relays sounds (hopefully of normal snoring and breathing) to a small portable receiver. These generally operate in the unlicensed 49 Mhz range. Though FCC regulations limit the power of unlicensed devices, baby monitors can often be monitored at quite some distance from the baby's room, including outside the house, and can make interesting listening, especially because they are never powered down. A drive through areas in which families with children predominate with a scanner programmed to sample common baby monitor frequencies can yield some interesting ambient sounds, especially if the parents sleep in the same room with the child. BART exits the Berkeley tunnel at the city line and passes along an aerial structure in the town of Albany, adjacent to Key Route boulevard, named after the Key System interurban trains that once served Alameda County and San Francisco. On the West (left) side of BART is the Bay, and beyond the bay in Marin county, Mount Tamalpais, at some 2,500 feet the tallest peak in Marin County and a site for state, county and federal radio transmitters. A semi-classified Air Force radar station is situated below the top of the mountain. Many of the antennas at the station are hidden within plastic or fiberglas radomes. El Cerrito Plaza (BART official designator: R40) The Plaza station is situated adjacent to a shopping center of the same name, which appeared to have come upon hard times in the early 2000s, but now seems to be thriving once again. The neighborhood consists of a mall on the west side and densely arranged small houses on the east, and the wireless environment is the mix of domestic and retail use that's quite typical in the Bay Area.

El Cerrito del Norte (BART official designator: R50) The neighborhood continues along similar lines, with a similar RF signature. A big-box Target store, a hotbed of RF activity, sits by the track. Family Radio walkie-talkies may be obtained very inexpensively there. West of the line between del Norte and Richmond, a large cellular tower rises into the sky. The United States has a large number of such towers, and many communities have actively opposed their construction and proliferation. One reason we have built so many towers in the US is that the major cellular carriers (in the Bay Area Verizon, T-Mobile, Cingular, Sprint/Nextel and Metro PCS) are reluctant to colocate (share towers) unless they are forced to. This is why, for instance, a drive along I-5 will reveal three or four separate proximal cell towers, and why carriers resort to ever more sophisticated means to camouflage their antenna sites in cities and suburbs.


Richmond (BART official designator: R60) Richmond, "The City of Pride and Purpose," is an industrial city that expanded rapidly during World War II. Its population jumped from 23,000 in 1940 to over 100,000 by the end of World War II. Most migrants worked in the city's four shipyards, built from scratch by Henry J. Kaiser's company, employing 90,000 and building 747 ships in less than four years. During World War II, some 46,000 African Americans moved to the Bay Area, many settling near the shipyards that employed them in Richmond, Vallejo, Hunters Point and elsewhere. The urban infrastructure strained with this extreme migration, and many workers lived in squalid trailers and later in industrial housing that was rapidly and poorly built. World War II still affects the community of Richmond. Many working class and poor African Americans still reside in communities built to be temporary, especially in the unincorporated North Richmond area, where streets remained unpaved for over thirty years and urban amenities were nonexistent. The legacy of World War II migration and displacement also troubles the city, which has been the venue for many tragic youth-on-youth killings in recent years. The Richmond Police Department's radio frequently reveals current police response to these and other incidents. Richmond's industrial heritage is also a matter of pride; it is one of the last true working-class cities in the Bay Area, home to foundries and oil refineries. It is well served by a number of freight and passenger railroads, many of which run along BART and are very active users of railroad radio, stretches into the hills and northeast towards its suburban-style shopping center, the Hilltop Mall, which may one day be a further terminus for the BART system. The present BART station is an intermodal transfer point between BART, buses, and Amtrak. Between Richmond and San Rafael (Marin County) runs the deteriorating and frequently-under-construction Richmond-San Rafael Bridge, crossing the north reaches of San Francisco Bay and meeting the Marin County mainland at San Quentin, where the famous California state prison is situated. Like other California Department of Corrections facilities, San Quentin operates a three-channel 800 MHz trunked system on which much activity can be heard. Those wishing to dissolve the information barrier that separates prisoners from those outside the walls might well monitor prison radio systems, where some information about

prisoners and their activity (including incidents that result in disciplinary action) trickles out. We leave Richmond and proceed south on the A line towards Fremont. Lake Merritt (BART official designator: A10) Lake Merritt, on the eastern side of downtown Oakland, was once the flagship station on the BART system and the location of BART Headquarters (the original building at 800 Madison street is now being evaluated for possible demolition, and BART trains are now centrally controlled from an office building elsewhere in downtown Oakland). It is close to the Oakland Museum and to Laney College. We exit the tunnel at 6th avenue and East 8th street and proceed southeasterly with I-880 and the Oakland Estuary to our South (right). Active railroad tracks and yards are there as well. Radio traffic in this area is heavily transportation-oriented, with activity especially on marine and railroad VHF channels. To the right, off 22nd avenue, is the local Ham Radio Outlet, where fine amateur radio equipment (as well as scanners, antennas, battery packs and frequency guides) may be obtained. Fruitvale (BART official designator: A20) The Fruitvale neighborhood was known in the 1920s as Oakland's "second downtown," with its own courthouse, highrise buildings, banks and community organizations. It later deteriorated, but has seen major growth and commercial revitalization in recent years. East of the station is Fruitvale Village, a mixed-use development with many stores catering to the Mexican American consumer, and on the west is a new mall with big-box stores. Family Radios are very active here, and the listener will hear a great deal of traffic in Spanish, testifying to the demographic transitions occurring in the once traditionally African American East Oakland flatlands. Proceeding south, we pass an AC Transit bus yard near 55th avenue. The AC transit buses have long been equipped with radios and are capable of both voice and data communication. The powerful data bursts from AC buses have long interfered with other transmissions in the Bay Area.


Coliseum (BART official designator: A30) The Coliseum station serves both the Oakland-Alameda County Arena/McAfee Coliseum (built 1966), spiritual home of Raider Nation, the Oakland A's and Golden State Warriors, and connects by bus to the Oakland International Airport (OAK). Sports arenas are fascinating places for the wireless observer. The full wireless profile of each venue is different and the overall picture quite complex, but the typical arena offers the following opportunities for the careful observer: • Team operations: coaches to players via helmet-mounted radios; managers and owners to coaches via walkie-talkies; • Media production: wireless microphones, communication between anchors and commentators and production personnel, remote control of cameras and sound equipment, communications with Goodyear and other blimps in the air above the stadium; • Stadium operations: security, hospitality, food vending; • Police, security and emergency medical activities; quite extensive traffic since as many as 80,000 people may be assembled for periods of time; • Federal undercover antiterrorist patrols and activity; security for elected officials and VIPs • Parking control The nearby Oakland International Airport is a busy place and houses, among other airlines, the discount carriers Southwest and JetBlue. For a wireless profile of the airport, please see above, under San Francisco International Airport. We proceed southwards through East Oakland, entering the city of San Leandro at about 103rd avenue. Along the way, we pass by numerous factories and warehouses on both sides of the line, some housing heavy industries such as the AB&I foundry. Those who believe that the United States is a postindustrial nation would do well to monitor incidental radio traffic in this area; they'd be surprised by what they heard and whom they heard speaking. One distinctive industrial building houses a plastics recycling company whose yard is filled with a plethora of interesting raw material.

San Leandro (BART official designator: A40) Southern Alameda County is one of the most interesting regions served by BART. The landscape is a mix of suburban housing, neighborhoods that still appear to be semirural, traces of the county's agricultural past, heavy industry, shopping centers, and unconstructed areas full of wildlife and wild plants. Near San Leandro station, the high-tech company Tri-Net has constructed a new Mission-style headquarters building that sits directly across from old houses with fenced-in yards. Up the hill from the station at approximately 150th Avenue sits the county services complex, with a large radio site servicing various Alameda County agencies, the county juvenile hall, an adult detention facility, and a maintenance yard. South of the station on the east (left) side of the BART line is the base of an old windmill. Several of these, occasionally next to older houses identifiable as former farmhouses, may be seen from BART trains. Bay Fair (BART official designator: A50) Bay Fair station is located within the unincorporated area known as Ashland, a bit of post-World War II-era suburbia that (aside from individual home remodeling) looks remarkably unaltered from its original design. It is also adjacent to the Bay Fair mall, anchored by big-box stores including Target, Macy's, Kohl's, and Bed Bath & Beyond. The radio profile for malls is well-described elsewhere in this guide. Bay Fair is a transfer station for the Pleasanton line. At the junction between the lines, a Yagi antenna points up the branch line, placed there to relay BART communications. We pass another old farm site with the base of a windmill on the east side.


Hayward (BART official designator: A60) As we pull into Hayward, we pass the residence of a Citizens Band aficionado on the East side of the tracks, distinguished by its very tall ground-plane antenna, a vertical element with four poles in a cross-like pattern at its base. CB radio, which operates in the 27 Mhz range, was first authorized in the 1950s and reached the apex of its popularity in the mid-to-late 1970s. Though CB radio is restricted by law to modest power levels and local communication, many CBers employ illegal linear amplifiers and operate on unauthorized frequencies to permit communication with faraway stations. CB is also a favorite of longhaul truckers, who use the band to warn of hazards and police speed patrols, to chat and flirt with other truckers and interested members of the public, and to avert boredom and loneliness. Hayward is an ethnically diverse city of 140,000 whose official city slogans are "Heart of the Bay" and "No Room for Racism." It is home of the California State University campus that recently renamed itself "Cal State EastBay," up the hill from town with the easily-seen highrise building. Many small aircraft use the Hayward airport, west of the station, and can be heard with the ears (and with the airband receiver) at all times. As we push further south, the hills become barer and less populated and the BART right-of-way becomes bordered with flowers. The area begins to resemble an old-time ruralized suburb. South Hayward (BART official designator: A70) Just north of the station, the house of a radio amateur (ham) may be seen on the west side, where there are also some fine old houses. South of South Hayward station is BART's Hayward shop, a large rail storage yard. There is also a test track for BART cars. Yard operations are busy and generate a lot of traffic on the BART communications system. Union City (BART official designator: A80) This station serves the historically Mexican American community known as Decoto and newer suburban-style developments in the vicinity. Real estate development is occurring in this area: a 16-acre office park just south of the station on BART's East side is announced by signs, and a walled-in development is also on the same side.

On the West side of the tracks lies a large grassy tract with no buildings, providing a rare example of liminal space in the central Bay Area that seems to have escaped development. Prior to Fremont, we pass through Quarry Lakes Regional Park, where lagoons border the track on both sides. On my survey for this guide, a strong skunk smell pervaded the car for two to three minutes, a refreshing reminder that some outside sensory information can permeate the somewhat sterile environment of the BART car. Fremont (BART official designator: A90) Some 23 miles from Oakland, we reach BART's present southern terminus. An extension of BART southward past Fremont to the Warm Springs District in southern Fremont is in the planning and engineering stage by BART planning staff. A further, controversial extension towards San Jose is also proposed by the transit district south of BART, the Santa Clara Valley Transportation Authority, but preliminary engineering remains to be completed and funding to be acquired. Fremont, a city of 203,000 people, has the largest Afghan population in the United States. The area around the station is mixed residential and business, and the traveler can see many planned-unit houses, townhouses, and a few office buildings, some of which seem to serve as transmitter sites in the absence of other highrises. Fremont is also an auto production center. The NUMMI (New United Motor Manufacturing Inc.) plant at I-880 and Fremont Blvd., a joint venture between General Motors and Toyota, employs about 4,800 workers, produces the Toyota Corolla, the Toyota Tacoma truck and the Pontiac Vibe, and can build almost 400,000 cars per year. Radio is used for paging, operations and manufacturing support, and several complex radio systems exist on the site. We take a northbound train and transfer to the Dublin/Pleasanton line at Bay Fair.


Castro Valley (BART official designator: L10) The L line proceeds down the median of I-580 for its full length, as if to convince motorists on the perennially crowded freeway of the ease and convenience of mass transit. Sadly, the message doesn't seem to have taken. Castro Valley is an unincorporated residential extension of Hayward. When it gives way to hills and Dublin Canyon, there is little to see but quiet countryside. As might be expected, the wireless traffic here is predominantly automobile- and freeway-related, as described elsewhere. The West Dublin/Pleasanton station is planned and funding has been secured for its construction. Dublin/Pleasanton (BART official designator: L30) This station is located in a recognizable "edge city," a sprawling satellite city complete with regional shopping centers, many large office buildings, major hotels, a sporting grounds, entertainment facilities, and a variety of styles of relatively new housing. It is a congested area, with the city of Dublin on the north and the city of Pleasanton on the south. As an edge city, it combines many of the attributes of legacy cities and newer suburbs, and has a diverse wireless profile. If and when BART continues along this same route, it will serve the city of Livermore, home of the Lawrence Livermore Laboratory, an indispensable component of our nation's nuclear weapons program and operator of many interesting radio systems, many encrypted. In the seven minutes that we have between trains, we will use the search feature of our scanner to make a quick survey of the wireless landscape, and see what we can do to make the invisible intelligible.

Appendix: BART's Radio Communications System BART operates a ten-channel EDACS analog trunked radio system. It can be monitored on most trunktracking scanners. Frequencies: 01 866.07500 02 866.72500 03 866.88750 04 867.37500 05 867.60000 06 867.80000 07 867.85000 08 867.96250 09 868.15000 10 868.68750 867.7500 Conventional wide area 868.9875 California fire mutual aid Talkgroups (see next page) are reprinted from Government Radio Systems: Golden Gate Region, published by Mobile Radio Resources, by permission of Robert Kelty, publisher.

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