Description of document: National Bureau of Standards Report: Electromagnetic Pulse Signal Classification and Identification of Nearby Sferics in the High Altitude Nuclear Detection Studies (HANDS) Program, Volume 2, March 1968

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FEB 1 0 2012 Ref: 12-F-0370

This responds to your December 23, 2011 Freedom oflnformation Act (FOIA) request for "Electromagnetic Pulse Signal Classification and Identification ofNearby Sferics in the High Altitude Nuclear Detection Studies (HANDS) Program, Volume 2." The Defense Technical Information Center (DTIC) located one document responsive to your request. The Defense Advanced Research Projects Agency (DARPA) reviewed the enclosed document and determined that it is appropriate for release without excision. There are no assessable fees associated with this response. Accordingly, your request is now closed in this Office.

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Enclosures: As stated

NATIONA.L BUREAU OF STANDARDS REPORT

9839

F ina I Report

ELECTROIIAGNEnC PUUE SIGNAL Cl.ASSIFJCAnON AND IDENTIFICATION . OF NEARBY SFOICS IN THE

· HIGH AL nTUDE NUCLEAR DmCTION SlVDIES (IIMDS} PROGRAII

VOLUME II

----· StATFJIENT 12 UlfCLASSUIID . ........._____

This document 1s subject to speo!al export controls aaa .... tr,~sm1tta: to foreign government~n§pr~~1gn natioaale mer .. ~de only with prior approval ot ----------------------

AiJvanced Research Projects A11ency N11clear Test Detection Office

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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT 4566437 March 1968

Final Report

ELECTROMAGNETIC PULSE SIGNAL CLASSIFICATION AND IDENTIFICATION

OF NEARBY SFERICS IN THE HIGH ALTITUDE NUCLEAR DElETION

STUDIES (HANDS) PROGRAM

VOLUME II

R. T. Moore K. M. Gray

Measure111ents Automation Section lnfor111ation Processing Technology Division

Sponsored by Advanced Research Projects Agency

Nuclear Test Detection Office ARPA Order No. 183

IIIPOITNfT IIOT1CE

NBS REPORT 9839

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TABLE OF CONTENTS Page

PREFACE • • • ii ABSTRACT. .iii

I. INTRODUCTION • 1

II. REMDTE STATION EQUIPMENT CONFIGURATION 2

Siting. • 2 Equip•ent Description. 3

AWRE Aziauth Digitizer and Azimuth Display • 5 AWRE Signal Nor•alizer. 5 Digital dB Meter and Display. 5 AWRE Transient Detector 6 Control. 6 Buffer • 6 Microwave Transmitter • 7

III. TABLE MOUNTAIN EQUIPMENT CONFIGURATION. 7

7 9 9 9

Microvave Receiver. Computer Interface and Control. AWRE Normalizer. Record Decision Control • High-apeed Transient Recorder • Sferic Receiver and Waveform Analyzer Signal Claaaification Logic. Antenna Calibration Facilities. System Timing

IV. SYSTEM CALIBRATION.

Amplitude Calibration. Azimuth Calibration

V. EXPERIMENTAL RESULTS

Diacuaaion of Results.

VI. CONCLUSIONS AND RECOMMENDATIORS

APPENDIX I •

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• 14

• 14 • 18

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• 44

• 45

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PREFACE

This work is reported in two volumes. Volume I contains the description of the experimental plan which includes the rationale for the signal selection and classification criteria which were employed. Volume II contains the de­scription of the experimental equipment and system config­urat~on, the calibration procedures employed, the experimental results and conclusions.

We acknowledge the contributions of the many individuals whieh have made this project possible. The collaboration of A. Glenn Jean, and the entire.HANDS staff of the ESSA Research Laboratories is especially appreciated. Don R. Boyle, E.,. Ainsworth, W.B. Truitt, P.G. Stein, T.B. Hall and J.H. HcGra~h all contributed to the design, development. installation or operation of the experimental equipment. C.L. Albright and D.s. Grubb provided assistance in data reduction and J.R •. Pino furnished essential administrative and secretarial support.

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ABSTRACT

~lectromagnetic pulse signals from certain classes of nuclear events, in terms of height of burst and distance, have features which afford a means of recognition. Similar features are also observed in atmospherics, but these have a 3maller normalized source function amplitude. An experiment was conducted to investigate the feasibility of measuring the distance to nearby sferics using azimut~ and amplitude data observed at two sites separated by a few kilometers. Knowledge of the distance to the source and the observed amplitude would permit calculation of the normalized source function amplitude which might be used as a discriminant. Data were also collected on the frequency of simultaneous (within equipment and propagation delay) observation at both sites, of signals exceeding 10 V/m amplitude and 10 V/m/~s rate of rise which persisted for one microsecond or less. Transients from lightning would not be expected to me~t these criteria over propagation distances of more than a few kilometers.

The Ji,tanc~ ranging experiment did not yield results which were within acceptable limits in accuracy based on the locations and dispersion of fixes plotted during a period of activity from a presumably isolated thunderstorm region whose position was established by weather radar. Results from the spaced transient detectors were favorable and this technique appears sufficiently promising to warrant further investigation under the HANDS program.

111

ELECTROMAGNETIC PULSE SIGNAL CLASSIFICATION AND IDENTIFICATION

OF NEARBY SFERICS IN THE HIGH ALTITUDE NUCLEAR DETECTION

STUDIES (HANDS) PROGRAM

VOLUME If

RY

• R.T. MOO~E K.H. GRAY

I. INTRODUCTION

The ~ationale for the design of the experimental plan to collect data for the classification and identification of nearby sfertcs has been described in Volume I, UHS Report 13A-101 (SID), of this report.

This plan required the measurement of amplitude and azimuth data on individual signals at two oites with a base­line separation of 20 to 30 kilometers. Data from the remote station were relaye~ hy a high-speed digital micro­wave link to the base station at Table :tountain where they were recorde.i, together with locally obtained measurements on the same sferic signal.

Additionally, signals meeting certain preset waveform criteria were independently recorded at Table ~ountain.

A brief outline of the equip~P.nt configuration which waa employed at Campion and at Table Mountain is contained in Sections II and III. System Calibration is described in Section IV. Section V describes the experimental results, and Section VI the conclusions.

A aample of the data collected is reproduced in the Appendix.

1

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II. REMOTE STATION EQUIPMENT CONFIGURATION

Siting

In the selection of a site for the remote station. primary consideration was given to locations which were within line of siabt of the Tab!e Mountain Facility and at a distance of about 30 km. Secondary considerations included accessibility to power aud telephone lines and terrain which was geographically similar to that at Table Mountain.

Several areas to the north of Table Mountain were surveyed, and from these a site one mile west of Campion, Colorado appeared most suitable. It was 27.5 km on a true bearing of 26 degrees from Table Mountain and located just to the west of the brow of a alight elevation that provided a line-of-sight microwave path to the base station.

A small area approximately 100 feet north of the road was leased and enclosed by a rope fence to keep cattle out. A van housing the re•ote station equipment ~as positioned within the.enclosure. together with a trailer mounted motor generator and a small metal utility shack. Two meter whip antennas for the AWRE transient detectur and the Digital dB meter were mounted on small ground planes within the enclosure while the crossed l~ops and sense antenna for the azimuth digitizer equipment& were mounted on a 15-foot high wooden platform locatad about 100 feet northwest of the enclosed area. Buried plastic conduit was employed to bring th£ cables from the platfora to the van withir. the enclosed area.

The antenna for the microwave data link equipment was aounted on a six-foot tripod faatened to the roof of the equipment van and aligned with Table Mountain. The north­south loops of the azimuth digitizer equipment was also aligned in the sa•e direction, thus all bearing data was relative to the base line between the two stations.

Power for operation of the remote station was obtained froa the REA serving the area. Two power distribution systeas were employed within the van. a utility system and an instrument power system. The utility sys~~m served ~~~hts 0 air conditionin& and heating equipments and the convenience outlets on the aaintenance bench. The instrument power was obtained froa a 1.5 KVA electric motor generator nounted on a aaall trailer. The aotor generator was equipped •o~ith a large flywheel and its inertia would maintain the output voltaae to at least 105 ~olts for interruptions of ~otor

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power havina a duration of up to three seconds. The instru­mentation equipment was isolated from voltage transients and •omeotary outaaes which are frequent durin& thunderstorms by this arraoaement. Under-voltaae protection was provided by automatically disconnecting the instrumentation from the aeoerator when its output was less than lOS volts.

A leased land-line between Campion and Table ~ountain was employed for comaunicationa and remot~ monitor and control functions. Unauthorized entry, excess temperature and power status at Campion were continuously displayed on a monitor panel at Table Mountain. Primary power at Campion could be turned on and Qff from Table Mountain and a limited equipment calibration could a!so be remotely initiated. Telephone signalling could be accomplished from either station, but monitor and control functions were disabled whan the line was employed for voice communications. This capability for voice communications between the two stations was indispensable in estab!ishina and checking out the operation of th• Campion equipment.

Eguipment Description

The aeoeral configuration of the instrumentation at the Campion station is shown in Figure 11-1. With the exception of the antennas and their cable drivers, the equipment va3 mounted in two atandard 19-inch racks in the instrument van.

Incomina ciaoals excaadina a nominal threshold of O.S V/m cauaed a mast•~ triaaer to ~e generated by the AWRE Signal Noraalizsr. Thia triager initiated the timing aequaoce aaployad by the ~yatem. The Digital dB Meter and Azimuth Diaitizer operation• were atarted and the control system vaa reaat. The Diaital dB Meter was gated on for a period of 60 pa and the peak aignal amplitude (either polarity) obaerved within this period was &tored. At the end of 60 pa tha stored value waa digitized. Digitization required an additional 60 pa and the data vas then trans­ferred to the buffer and aodam interface where bits were added identifyioa it aa an aaplitude aeaaurement and indicatina whether or not a transient detector output had also occurred. The data word vas then output aerially to the aicrova•e aquipaant for tranaaiaaion at ~ ~ate of one bit each fou~ aicroseconda. The aziauth data fro• the aaiauth d1attiaer ia aYailabla no aocoer than 200 ps aft•r the aaster triaaer. It, in turn, ia transferred to che buffer for assaably with additioncl bits proYidin~ identity and •alidation inforaation and it ia then tranaaitted 4t a tlae ranaioa fro• 20 to 200 Pa after tbe aaplitude data.

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A brief functional description of the major instrumen­tation components shown in Figure Il-l follows:

AWRE Azimuth Digitizer and Azimuth Display

The Azimuth Digitizer and Display, supplied through the courtesy of AWRE, was used for receiving the sferic signals and digitizing their angle of arrival. Two crossed-loop antennas and an omnidirectional vertical antenna are used for signal pickup. The vertical antenna and its associated cable driver have a bandwidth from 1000 Hz to 150 kHz, while the crossed loops form part of a narrow-band tuned circuit centered at 11.1 kHz. The vertical antenna is used to resolve the 180-degree a•biguity associated with crossed­loop direction fiuding. The digitized azimuth, in the form of a aerial pulse train, ia counted and displayed on the Azimuth Display unit at the same time it is transferred to the buffer. The equipment was set up to accept and process sferic signals separated in time by four or more milli­seconds.

Calibration signals could b~ applied locally or remotely to the equipment. In the local calibration mode~ any of the eight quadrature azimuth directions may be simulated by a selector switch. In the remote mode, only that azimuth direction corresponding to a single position of the selector switch may be simulated.

AWRE Signal Normalizer

The signal normalizer, also supplied through the · courtesy of AWRE, ia designed to generate a master trigger

when signals exceeding a preset amplitude threshold are observed and to normalize the amplitude of these signals to provide a peak output that is constant within 10 d~ from inp~1t signals having up to 50 dB variation in peak amplitude. In the equipmen~ configuration employed at Campion, only the amplitude discrimination ancl master trigger functions were utilized.

Digital dB Meter and Display

This unit is used to measure the peak amplitude of the received signal. It operates directly from a wide-band antenna driver and produces a binary coded 9-bit number plus sian which represents the peak amplitude, in dB, of the received electromagnetic signal. The 0.1 dB frequency response is 1 kHz to 150 kHz and response is down 3.0 dB at 250 kBz. Resolution is 0.1 dB over a 51.1 dB dynamic range

5

•

and accuracy is ±0.2 dB over that range within the 1 kHz to 150 kHz frequency band. The unit is initiated by the "M~ster Trigger" pulse and digitizes the peak amplitude occurring within a 60 ps time bracket referenr.~d to that trigger. The digitized amplitude and sign ar~ ~!splayed on the display unit and at the same time a level change is produced indicating the end of conversion and causing the data to be transferred to the buffer for transmission •

AWRE Transient Detector

The AWRE transient detector provides an output pulse upon rec~ipt of a signal having a peak amplitude greater than 10 V/m. A second output is provided by signals having a rate-of-rise >10 V/m/ps which persists for one microsecond or less. A third output is provided when both of the fore­going criteria are met. Each of these outputs is employed to actuate one of three electromechanical counters incor­porated in the equipment but only the output resulting from signals meeting both amplitude and rate-of-rise criteria was relayed to Table Mountain.

Control

The control unit is activated by the Master Trigger and produces a sequence of timing signnls employed by other portions of the syste3. These include commands to transmit amplitude data and transmit azimuth data. In addition, the control unit performs certain validity tests on the ampli­tude and azimuth data and incorporates the results of these testa in the transmitted messages.

Buffer

The buffer gates the digital information, representing amplitude and azim~th, into temporary storage, and then, under the command of the Control Unit, sequentially scans the digital data, presenting it in serial form to the ~l,rowave Tr•namitter. The sequential scan rate is contrglled by a clock operating at 250 kHz. Two frames of data are sequenced. one representing peak amplitude and the other representing azimuth. Each frame of data is 14 bits in length, starting out with a double zero as the block or frame identifier, thea followed by a flag bit which is used to indicate the type of frame, i.e., amplitude or azimut~. The remaining bits are used for data. The logical ones and zeros of the data word are as follows: two transitions per bit time equal a logical one, and one transition per bit time equals a logical zero.

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Microwave Transmitter

The aicrowave transmitter provides one watt output on a carrier frequency of 1755 mHz. It is frequently modulated and provides a base-band response from 300 Hz to approxi­aately 750 kHz. The antenna is equipped with a four-foot diameter parabolic reflector providing 25 dB gain. This reflector is attached to a six-foot tripod and mounted on the roof of the van.

III. TABLE MOUNTAIN EQUIPMENT CONFIGURATION

The general configuration of the b~se station equipment employed at Table Mountain is shown in Figure III-1. The installation was made in the ARPA building and the equipment (excluding computer) occupied approximately five and one­half standard 19-inch racks.

Facilities for measuring the azimuth and amplitude of sferics and the detection of transients were identical to the equipment& use~ at Campion. These data were digitally recorded using the HANDS SDS-930 computer. It had been the intention to process these data in real time to identify nearby sferics, but it was necessary to modify this plan to accommodate only on-line data recording with the computer.

The basic facilities for measuring and recording azimuth and amplitude are supplemented by special equipment& for detecting signals meeting preset combinations of wave­form feature criteria, classifying these signals in accordance with the selected combinations of features and recording the results on a high-speed transient recorder independent of the HANDS computer.

A brief functional description of each of the major equipment components which have not already been described follows:

Microwave Receiver

The microwave receiver is the companion component of the tran•mitter used at Caapion and has compatible per!or­aance characteristics. The incoai~a signals are picked up with an antenna equipped with a four-foot parabolic reflector •ounted on the roof of the ARPA building and in "line of siaht" of the Caapion antenna. The incoming signal is deaodulated to obtain the 250 kHz data bit stream. This sianal is then input to the Coaputer Interface and Control loaic.

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The Coaputer Interfac~ and Control accepts the output of tha aicrowave receiver, r~covera the clock. decodes the bit atreaa into ones and &eros and. strobe• the data bits into the appropriate reaistcr for subsequent proceeeina and recordina. The loaic ia arranaed to detect a double aero in the.bit atreaa, indicatina the start of the data fraae. The detection of the double aero opene a aate which accept• the aezt 12 bite, under clock control, to the buffer raaieter. There the data are •••••bled with a correepoadiDI aaplitade (or asiaath) aeaearaaeat obearved by tha Table Mountain aqaipae~t. A coaputer priority interrupt ie thea aeaerated and the data ie input to the SDS-930 coapater and taaaed with the tiae, raeolved to !he neareet ceatieecond.

AWI.E Roraali&er

Thie eqaipaent ie aeed eoaewhat differently than the aoraali&ar at Caapioa iaaeaach aa, in addition to produciaa a aaater trissar.or initiation palae for the whole ayatea, it alao parforaa a acalina operation on the analoa wavefora. The aaaloa wavafora ie eiaaltaneoaaly applied to the noraaliaar and a delay line. While in the delay line, the aiaaal peak aaplitade ie aeaeared. Baaed upon thie aaaaareaent, a aeriea of "sated" 10 dl aaplifiera are eat up. One ailliaecond later the aaalos eiaaal froa the delay line i• input to the "aated" aaplifiera. The reeultina output eianala are thaa "co•r••" aoraaliaed to within 10 dl.

After the coerae (10 dl) noraali&ation of the aianal, the aoraali&ed aisnal ia asain scaled, or •••••red, to the aeareat unit of dl. The aaplitade of the eiaaal ie thea dieplayed in deciael fora to the nearest unit of dl. A farther acalins of the aaalos wavefora ie perforaed with an additi~nal delay line beiaa aeed for etoreae uf the wavefora while L~e ••in of an aaplifier ie adjaeted diaitally in one dl etepe. Thie operation yielde ~n analoa vavefora, delayed in tiae by 2 •• fro• the aaeter triaaer, and noraalised to the neareet unit of dl. Thie wavefora ie available for recordins by the hiah-apeed transient recorder if daaired.

lecord Decieion Control

The l.ecord Deciaion Control ia aaed to control the peripheral hish-epeed tranaient recorder. The control ie operated froa one or ao~• aeaae lines fro• the varioua eqaipaeate. Vhen aianale or event• aeetina preaet criteria occ•r, a record deciaioa reaalta and the hiah-apeed traaaie~ recor••r ia enabled. The criteria ••played to initiate recordias are deacribed in Sectioa v.

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Bish-apeed Transient Recorder

The high-speed transient recorder equip•ent is intended to digitize nor•alized analog vavef~r•s and record these with appropriate header infor•ation on •agnetic tape. It contains a six-bit analog-to-digital converter operating at a one mHz sa•ple rate. a 1024 word co~e •e•ory. control logic and a •agnetic tape transport. Digitized analog vavefor• samples are loaded into the core •e•ory at the sample rate. Header infor•ation consisting of a date ti•e group. identity and flag characters and other data is then input to the me•ory from buffer registers. The •e•ory contents •ay then be recirculated and output through a digital-to-analog converter to display the stored waveform ou an oscilloscope or alternatively recorded on digital •agnetic tape. Nor•ally this latter •ode of operation vas e•ployed. Haximu• rec~rding rate is approximately 30 signals per second each having a •axi•u• duration of one millisecond.

The tape unit is a standard 7-track tape recorder. Bit densities of 556 BPI and 800 BPI can be manually selected.

Sferic Receiver and Wavefor• Analyzer

This equip•ent vas built to NBS specifications and perfor•• the following functions:

A) Receives at•ospheric signals in the frequency range of 1.0 kHz to 5.0 •Hz. over a dynaaic range of from 0.1 V/m to 2500 V/•.

B) Exa•inea the signal for certain presettable wave­form features including amplitude and half-cycle duration and determinea if a processing sequence is to be initiated.

C) Measures the peak amplitude of the incoming signal and nor•alizes same to ~1 dB over the full dynamic range specified. One millisecond later the signal is available in analog for• with a constant peak amplitude of 5 volta ±1 dB.

D) Deter•inea if the signal peak amplitude exceeds 10 V/•. Sisnala having peak a•plitude greater than 10 V/• are specially classified.

In addition. twenty-eight discrete values associated with seven para•etera of vavefor• teaturea can be set up by front panel controls. A digital output is produced for each para•eter value ••t or exceeded by the analog vavefor• (all •easure•enta are perfor•ed on eith•r the first or second half-cycle of the vavefor•).

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\ The following paraaetera aay be set up and aubdivided

into aignal rangea: wavefora polarity; rate of rise; tiae to peak; peak aaplitude; aultiple peak; early peak and half­c~cle duration.

Certain other control aignala are produced. auch aa "data ready"• "aignal equality"• and "wavefora ready to record".

All of theae signals and controls are available on separate linea and can logically be combined in other equipaenta aa desired.

Signal Clasaification Logic

The aignal claaaification logic is arranged to accept up to aix digital inputs froa the sferic receiver and wave­fora analyzer in three aeparate groups. Each group is logically coabined to produce inputs to the Record Decision Control. The groups are identified by characters located within the foraat of the record to facilitate analysis of the data• In addition. the receipt of signals having peak aaplitude greater than 10 V/a by the aferic receiver and waveform analyzer or a aignal aeeting both criteria of the AWRE Transient Detector would also produce a record command.

The equipaent ia alao uaed to count the number of aignals not aeeting criteria required for recording by the transient recorder. The overflow of the event counter then cauaes a record coaaand to be produced.

Antenna Calibration Facilitiea

Facilities were incorporated at both Campion and Table Mountain to calibrate the antenna cable drivers of the AWRE nor•alizer equipaent and the Digital dB meter. Signals with known characteristic• could be injected into the ayatea and the response meaaur~d. to aaaure proper operation.

The basic tiaing diagraa of the overall ayatem ts shown in Figure 111-2. The entire tiaing cycle ia referenced to the "Maater Trigger•" produced at Table Mountain. Figure 111-3 illuatratea the tiae fraae diagraa and ahowa the tolerances or tiae spreads between the two atationa. The tia~ correlated• two-atation data. ia alway• available within one ailliaecond of the Baae Station Master Trigger. This would per•lt direct correlation of aignala with the

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600 700 I I

600

aferic receiver and vavefor• analyzer equip•ent in real ti•e, and would allow all of the signal classifications to be parfor•ed within thia ti•e period. The basic syate• resolution vaa li•ited to four •illiseconds •ini•u• between aignala by ·~• A&i•uth Digitizer. The transient recorder vaa li•ited to a recycle ti•e of about 34 •illiseconds, however, by the digital ••gnetic tape transport.

IV. SYSTEM CALIBRATION

The effects of local environ•ental factors can noraally be expected to influence the apparent value of aziauth and to a leaaer extent, the a•plitu~e of a signal as observed at a given location. The unavoidable presence of conductors, such aa power linea, antennas, fences, etc., in the vicinity of direction finding loops causes distortions in an incoming wave front-which vary as a function of azimuth. For accurate position fixing, it is necessary to determine these siting effects and to apply appropriate corrections to the observed data. In thia case, since range inforNation was desired rathe~ than position inforaation, the calibration procedures eaployed vera somewhat different than those which might be used in a position fixing network.

Amplitude Calibration

As an initial step in the amplitude calibration process, a field survey vas conducted.

~'o Type NH-lOA Field Strength Meters were calibrated by the NBS Radio Standards Laboratory. These were then set up at the Caapion and Table Mountain sites and on June 8 and 9, 1967, a aeries of aimultane~ua aeasure•ents were taken of the field strength of VLF tranaBissiona froM AnnspoliB, Pana•a, Hawaii and Seattle. Following the observations, the field strength aeters were again recalibrated and the data was reduce~.

Seventeen time coincidental observations were made at each aite. The average field strength of a given VLF signal as observed at Table ~ountain was l.63 dB greater than that observed at Ca•pion. The •ean vaa 1.70 dB and the standard deviation of the data was 2.00 dB.

Using the NH-lOA aa ~ two-ter•inal tuned volt•eter, the transfer function of the whip antenna and receiver uBed to excite the diaital dB •eter was •easured •• -20.96 dB. with a standard deviation 1.78 dB, in ter•• of V/• field strength vereua oatpat voltaae. Replacina the antenna vith ita

14

·,

L

r

calculated equivalent capacitance of 22 pf, and exciting this vitb a si1nal gP-nerator, a value of -21.76 dB vas observed at 20 kHa. The latter value vas adopted as reference •nd the operational a•plifier gain at Table Mountain vas set to provide an indicated output of 15.9 dB on the di1ital d~ •eter fro• a 20 kHa signal having a calculated ••pl~tude equal to that resultins fro• a 1.0 V/• field stren1th. The saiD at Caapion vas set 1.6 dB hi1her to offset the observed averase difference in field intensity of distant VLF stations at that site.

To test the validity of these settings, a statistical evaluation nf the observe~ a•plitude of sferic sisnals vas undertaken. Sisnals fro• relatively distant sferica arrivins froa directions n~r•al to the base line vould be expected to have the sa~e ~••rage a•plitude as observed at each station, vhile the a~plitude of sisnals arrivins fro• directions alons the base line vould be expected to be alishtly sreater at the station nearest the source.

Fisure IV-1 shovs the average differenc~ in a•plitu~e of 88,338 sferica plotted as a function of indicated ••i•uth at Ca•pioD and 79,735 sferics plotted as • function of indicated aai•uth at Table Mountain. These data vere selected fro• sianals havins indicated 4•plitudP at both stations of 0.28 V/a ~ A ~ 0.5 V/•. If a ••dian source function a•plitude of 360 ~/• at 1 k• and rando• geographic distribution is assu•ed, an average ranse of ·~proximately 900 k• ••Y be calculated. This vould result in a displace­•ent of the theoretical equi-a•plitude curve by about 0.2SdB alor~ th .. base-line (N-S) direction aa co•pared to its valut.l in directions nor•al to the base line (E-W).

~he curves in Figure IV-1 shov aa interestins correlation in for• but have an ~verase displace•ent of 3.04 dB fro• aero. The average value of both curves is ahovn in Fisure IV-2 in polar coordinate for• after aub­tractins 3.0 dB displace•ent, the ••diaD difference in ••plitude. The standard deviation of the curve fro• the ••dian value is 0.30 dB.

The 3 dB diaplace•ent of the value of the c~rve fro• aero vas a source of i••ediate conc•rn. It vaa discovered upon reduction of the first data t&pes at NBS, Gaithersburs, Md. in late October, 1967. Data co\lectioa vaa ter•inated on Rove•ber 3, 1967 an~ the ter•inal calibration check disclosed that the response of the Ca•pion ••plitude ••asurina equip•eat vas 3.0 dl l~s• than that observed at the ti•• of the !•at calibration which vaa •ade on Ausust 12, 1967 prior to tbe collection of presu•ably valid data. It vaa caaaed by a •alfunction in the cable driver.

IS

INOtCATEO AZIMUTH

.oa

.06

. ' .... 1.• iIi l.LU_i 1~ 0

I I I ;_j ,(){ ,(Iff

..ot

.ol(

I·· --

! .. !-• ,..: I -

:-= I

.........

.. 0 r . ,.

• :0

~ n I-~ g f: ~- ~

• • ;;1 n 0

r-· :,.. ~"' ,--

~ .,.. .,. . -·o

f-I'"

t-

' .. _ i·-I ~

1: 1-1 ••

1-·-I f :_ I i '. 1-=

f-=-~ _..._

I \. __

.

This alao affected ~he frequency response as shovn ln Flzure IV-3.

Aa an aid in eYaluatlna these effects and their Influence on the experiment, the data base vas ~uhjected to further pr~ceaatna. The aYeraze difference in amplitude vas co•puted aa a function of a•plitude aa observed at T~hle ~ountain for thoae sianala arrlvinz froa aziouths vlthin ts• of Eaat and ~est. The reaulta are ahovn ln Table IV-I and Fiaure JV-4.

Field Strenath

!'l.S - 1.n V/• 1.n - 2.0 V/c

2.0 - 4.0 V/m

4.0 - 8.0 V/m ~.n -16.0 V/o

Table IV-1

nos 750

151

16

1

t. Amp. dll

CA~ - T-.

-3.~1

-3.71

-3.83

-3.R7

-S.4

There appears to be a tendency for the difference !n observed amplitude til ino:reaae "ith incrParting ~t!.~;nal amplitude. Thi5 irt con5!atant with the observed impairment to the high frequency response at Campion.

Azimuth Calibration

~uring the 19~~ thunderstorm ~eaaon, efforts were nade to obtain azimuth calibration data to conpensate for aitin~ errore at Table Hountain by correlating optically obtained azi•uth data with data from the AWRE azimuth digitizer. Although some potentially useful data was obtained, the process vaa not efficient. Other meana werp employed after invalidation of this data baae occurred when the crossed­loop antenna at Table ~ountain vaa destroyed by high winds.

The process was based on evaluating the average difference in indicated azimuth, aa a function of azi~uth for a large nu•ber of m~derately distant sferics. T~e sianals selected were a aub~et of thoae e•ployed in calculatlna a•plitude differences, i.e., indicated a•plitudea between 0.28 V/• and 0.5 V/~, hut excluded certain ti•e intervale vhen the station loa records indicated that azi•uth data •1ght be invalid. 73,9~1 paira of azi•uth obaervationa were then proceaaed ty computing the average differrnce in azi•uth for the paira aaallciated with

18

100Hz

t---f -· ·-- ------.

1kHz 10kHz

100kHZ ·' &

i

.Aug.l2,1961

-10

-15

Figure mm:ber IV-3 Frequency Respom;e of Input Circuitry t.o Digital dB meter ut Clil!!pion

s:: ..... aS

j ., rl

~ E-o

.. 0 ~

s:: 0 ..... ~ 0

t 8 ~

-1.

-.9

-.8

-.7

-.6

-.5

I -.4

-.3 I

-.2

-.1

0 15

Correction to Table Mountain 20

25 5dB S:lpal atrength

,.

each 5-degree aegaent of aziauth as obaerv'ed at Table Mountain. In coaputing these averages, any individual pair having a difference in excess of 45 degrees was disregarded. 4,998 such instances occurred. The data were then repro­ceased in a similar manner except excl~ding any individual pair having a difference of aore than -15 degrees from the average difference as previously calculated for that 5-degree sector. 10,727 pairs of signals were excluded on this basis. The remaining 63 1 234 pairs did not, of course, have unifora diatribution as a function of azimuth. The average population is 878 pairs per 5-decree cell, the mean population is 421 pairs and the minimum is 14 pairs.

The average difference in azimuth as computed above repreaenta the aagnitude of the combined effects of siting errors at both stations for infinitely distant signal sources. Since the actual signals employed have an estimated average range of approximately 900 ka, a convergence of approximately 1.7 degrees is indicated at an aziauth of 90 degrees. The convergence would decrease sinusoidally to zero at zero degree azimuth. The correction for convercence baa been applied to the average difference in azimuth and the results are shown in Figure IV-5.

In order to evaluate the relative contribution of each station to the total siting errors shown in Figure IV-5, it is necessary to compare observed azimuth data with centers of ~tmoapherica activity in known locations. The u.s. Weather Bureau disseminates radar aumaariea of cloud eover over the aajor portion of the continental United State~ at two hour nominal intervals. These charta were reviewed for the months of September and October 1967 to determine time intervals when suitably isolated areas of activity were reported. Three such instances were noted and eaaples of the Campion and Table Mountain data collected during these tiaee waa printed out and analyzed. In the one case in which siting errors were large, it waa found that the Caapion contribution waa at least twice the Table Mountain contribution to the total siting error. The inatancea where weather activity could be correlated with azimuth data aa deacri~ed above occurred within relatively restricted regions of azimuth 123• - 121•, 212• - 228• and 40• - 42•. Of theae, only the firet is in a region where total aziauthal eitiag errore were large.

21

ll

-lS

-20

0

a a;c; &at nt&UJ s aza:a c;a £1%41

20 40 60 80 fig-.lre numbe !" Tv- 5

Amount ot correction to be applied to the Campion Azimuth

In!ormation is derived from signals having amplitudes not greater than 10 dB.

Includes geographical corrections. Derived tram tapes /12, 113 and up to day

271 o1' /14.

100 :!.20 140 160 180 200 220 240 260 2BC 300 320 340 360 Degrees Azimuth Correctio~ t~ Campi~n

I

As an aid in evaluating the effect of applying the total a1iauth correction to either station, Figure IV-6 was constructed. This figure shows the apparent d!etance as a function of Table Mountain a1iauth to fix positions resulting fro• a 12-degree convergence in aziauth. One set of curves shove the total correction applied to the Table Mountain indicated azimuth. A second set of cu~ves represents application of the total correction to the Campion indicated aziauth. The difference in distance is indicated by a third set of curves.

The greatest percentage error occurs in directions where aaplitude differences would be expected to be useful in establishing range. An arbitrary decision was therefore made to apply the total correction to the Campion azimuth data.

V. EXPERIMENTAL RESULTS

The installation of the equipment described in Section Ill vas aade by a team of engineers and technicians from NBS, Washington, D.C. in June and July 1967, acting in collabora­tion vitb the regular BANDS staff.

During this period, it vas ascertained that the original plan involving real-tiae proceseing of the two-station aaiaath and aaplitude data on the SDS 930 computer at Table Mountain could not be iaplaaanted due to unavailability of the necessary coaputer prograas and the unavailability of personnel to generate thea and integrate thea in the existlug 930 operating systea within the tiae constraints established by the saaaer thunderstora season.

There was no reasonable alternative but to aodify the ezperiaental plan to provide for digital acquisition only of the two-station data vith the 930 computer and to process these data at N!S, Washington, where they would be correlated vith independently recorded data obtained from the sferic receiver and vavefora analy1er.

Under this ar~anceaent, the two-station data could be recorded along vith data fro• the other BANDS sensors with an acceptable aaoant of procraaaina effort and ainiaua aodifica­tion to the 930 operatinc systea.

The. output or •t• tapes froa th .. 930 each contain aevaral days of aaltisaasor data. They ara processed using the central coaputar facilitiaa at Boulder Laboratories. As one of the procassinc staps, arranaeaents vera aade to stcip

23 l i

\

130

IZO

110

100

10

.. lt

~ l<lft Distance from Tobit Mt bostd on 12• conver91nce

e Oist with Com Con

0 Oist wilt! TM Con

..

0

FIGURE IV-6 TABLE Mt. AZIMUTH

off the two-station data and rerecord this on separate digital magnetic tapes which were then shipped to Washington.

Dat~ fro& the sferic receiver and waveform analyzer was recorded on the high-speed digital transient recorder and these tapes were then shipped directly to Washington without prior processing at Boulder.

The first two-station data tape was received in Washing­too late in July and preliminary examination of printouts of the raw data indicated the probability that equipment mal­function had occurred. This probability was confirmed and several equipaent failures were located and corrected by August 19, 1967. Data collection was again initiated but almost immediately interrupted by a aeries of computer outages and another failure of the AWRE azimuth digitizer at Table Mountain. Following the correction of these f~ults, two-station data collection was again resumed on September 6 1

1967 (day 249) and maintained for continuous periods ranging froa a few hours to a few days duration until Novembet 3 (day 307). The tiaes at which data was collected which was presuaed (at the time) to be valid are shown in bar graph fora in Figure V-1 for the period from dey 249 to day 268. The operation from day 2o9 to day 307 was more nearly continuous but little or no local thunderstorm activity occurred during this time.

The second and third tapes of two-station data were received in late September and early October. They were accompanied by sample print-outs of the raw data as shown in Figure V-2. The format is deRcribed as follows:

HEADING Record No., Day of Year, nour of Day, etc.

~ CAMPION AMP TABLE MT AMP THIE

CAt-!PJON AZ!!!!!!!! TABLE MT .AZHIUTH, etc.

TIME: The time word consists of 6 digits: minutes, seco~and centiseconds.

AMPLITUDE: The amplitude word consists of 24 hits (8 octal digits) encoded as follows:

2S

HOUR UT DAY 0 2 4 6 8 10 12 14 1b l.b 20 22 211

249

250

2~1

2)2

?5) -254 -255 -256

257

258 !

259

26o -261

?62

21l)

264

265

266

26'{

?68

I Figu.J;e V-1

26

ollC 21

~I

21

21

21

21

21

21

21

21

Zl

21

21

21

21

932, lJAT ~f>\)

327 ... ~

20?4.1•

nllll•l ?1 11'1('611 1C.,,.. ~9 CS ?34~:!.86 _HS f,t19?L63~- _______ _ 3Z7.-Z 1 JO 1~24 327.92 60~0 ~JilO 3~7.~~ 6000 ~000 3?7.94 1000 3026 ~~7.•b 1."0 lno• 3?7.~6 e.ouo 6~uo J~H.~~ 1000 Jooo 328.~2 6000 6000 lc~o>4 A QO ~~P~ 3~~.6\J 10~0 3U~5 ~~ri.t>U 6000 6000 329.('6 1065 3130 3~9.~~ I t1 l1~b 3?~.JO ou~o 4JJO J~Y.JJ 1053 JOt>6 329.J3 5Q67 4462 J .. <~. ,., ::>1•·7 "4td 3('9 ... 2 t>O'''' f:>II"'O JC'<,~.it'> 11lSo .J065 329.46 5106 4445 3'-"•"'2 ., liO .. "'?4 3ZY 0 ~Y 1031 _lllc!.4 3~Y.~-4 __ (1110.!)_t>O!!.!I. lZ~.!!q 1l7I.. 3ZJ2. 1~39.~4 4l~L ::>6~(' 1~3Y.S8 11~4 3c!15 1~39.~8 4147 0000 123Y.~A 4147 6000 1~~9.•\J ~~7~ .,zo1 1239.bl ,.z~ .. t>~wu tc!3Y.71 600U t>OOO 1239.~2 1000 31!7 1?39.~4 1·oo J~oo 1c39.ao e.cuo 6~uo 1239.~7 1131 J165 1Z39.A7 S14o 4441 12" .14 ltiJ JI•J lc4o.14 ~Zu7 •2JO 12 .. ~.11 1021 3130 1Z4o.17 6ouo e.ooo 1c!• .~~ 111" ~?OJ 124J.c~ 512S 4 .. ,.1 1Z40.2ri 10?1 30S4 1740.2~ 6000 6000 1?•~.~5 St•r .. 44? 1241.a~ ~tAl:. 4::>*0 12 .. l.d4 1ooo 3ooo 12to1.u4 t.ooo 4000 2ldJ.~1 I r4 ~"~~ 2vZ3.•L! t>llUC """0 z;,;iJ.H3 6000 <>~ilO C'023.t<~ iooo 3000 ZJ23.~7 1 11 tnoo 2)2J.d7 60~0 6JJO Z1c3.~~ 1001 J041 znz3.90 6000 6000 2u~". •4 to oo '-.JuC 2'1<.-·11 ,,q '161 2Cl•.~S I ~0 ~1~1 ?CC:• .t"> b ••u "G;H 2t>'"~• ? 1 J~ Jo31 2t>4..;.J.? I H JlC'o 2b~~.·~ ~ ~0 ~~0~

z~c,- .• ~., "'21 .. 4f.1 ('6-:> '• ~-r. ~' •ioJ "0C~ 2b~uob~ 117(' 12('7 32~~.•Y ~ 00 6~00 32~A.~3 I .?7 31~~

.l~">"• •9 I CO 3'31 3<'~ .... ~ .. 11<-:; 1231 3C:'>r. •:1 "l'ov7 ••·J2" 3.?-:i<,.l'> I 44 j~t>~ l~I1.~G h 0n ,•tG~

39L<o •7 " CO ~(100 3~13 •• ~ " rJ ~uo~ )914. ~ I o7 J11-391~· 1 h_~n ~.o~~

~q14.l(' ~ 00 ~0~0 4~~~.r2 ~-b~ '>Oil~

-s~;,.~7 ~- "" '>OOO .. s .. ~.~~ ~ o? .,~oo -~4~. ~ s~ .. o •o~v 454b. ~ ~-.oJO t>~OO 45•'>·13 ~ ~0 600U 525'"·'? .. ~r3 60il0 52~4.~4 6.~0 ?OOU 5c!~~.-6 6.~7 "DOG sz~•-~2 ~.10 t>oo~

52~•·"~ ~.oo •so~ 52'>~. 5 ~-0~ ?J~~

?~?4.09 1?1~ 3c!~7 ~tc! ... 1'> 4S6~ 4566 2024.10 1000 3123 2lZ4.13 ~025 4~•2 ?~24.14 1000 ~020 20?4.14 6COO 4206 z~z4.J~ 4St>J 4t>~1 2~c4.4~ 1043 J132 2oz ..... o S657 4565 Z;z ... td 10u0 3JUO 2~c!4.7~ 600U 6~00 20?4.93 1111 3157 2bot<~.~Z 6Cu0 ., .. .,7 ?6.,9.;;4 1cJ32 3165 C'64't~c .. t>OOO 6000 264'1 0 13 t>Qu(. b.I.IO 26 .. 9.17 1001 J203 2f.49.17 5062 4462 2o4~.21 t>C~O ~~"0 264~.~3 1~71 3104 2649.54 SJ .. O 4544 2o~o.~~ 1vOil 31~~ z~~o.s" 6oou t>OOO 265o.o~ 1000 3044 2n~u.o1 oovo n~uo 2n~o.n1 600~ bOUO 2650.6~ 1000 3032 26Su,66 51'>1 4'!_'tj 26~0.6'! 1000 30o0 ?65C.b'll 6000 6000 3ls~:~.•~ .,ooo 6o.~o 32~R~so Tf26-"J2•3 32!i.e:~o5Tof-4t.z5-3zs~.~3 t>O~O buvO 3Z5~.S4 600U bOOO 3('5R.S~ 1076 3150 325~.~~ 60uU ~UJO 32,~.~9 6000 6000 325H.b3 6000 6000 J~5H.o9 4U~7 ~::>~(' 3l5k.iO 1274 3350 3('5A.91 5504 4021 lc!5ri.'ll4 1u2~ 311/ 32~M.Q4 6QOu 40l5 325~.?7 1067 3156 J~59.7t> s21~ 41b6 3J~o.~~ 122b J3oi 33oo.•6 5o4o 4527 JY}.;.<!O 10c!f. 2JJO 3'ol1:,.'1,. 10.00 30l.l-O 3~1J:>< .. 6coo 60-00 3Y1J.o7 60UO 6UJ0 3Q13.97 1103 3111 3~11.91 5020 4546 3913 ... ~ 60Ju 6vvo 3~11.99 1103 ~140 3913.9~ 6ooo 6000 l~l·.~3 4hl1 4~·· 3914.q3 4631 .. 544 3914.~7 ~000 3000 3Y14.J~ 1C2J Jv71 3'114.J~ 6COU ~~00 3914.~" t>OOIJ 6000 JY14.12 bO~O 6vU0 3~14 ... 6 1064 J075 3914 ... ~ 51?0 4450 ~~·s.~ .. tooo 3uvo 4~•s • ., .. t>oou bOOG 454s.e .. t>ooo 6ooo .. ~45.d7 60llO 60vo 4S-5.ri~ 1153 3250 4545.88 1000 2000 4s .. s.9s fo~o &~~o 4546.o4 1042 3o72 4546.o4 5420 4066 4~4f..06 JOUS 3~o5 4S .. 6.07 6000 t>OUO 4546.uR 1000 ~u)J 4~46.10 11~3 3~~0 4~46.10 S451 4o41 4546.12 1000 2000 4::>4t>.13 t>OCO 6000 454t>.1 .. 1000 JOOO 4546.14 6QOO 6000 ~zs ... ~:~o 3001 3J::>6 5c!5 ... ~1 5041 bQOO 5254.H4 1000 3023 5C'54.tl5 10JO 30~2 S254.85 6000 t>OOO 5254.b5 6000 6000 Sl54.d6 60~7 6Jv0 Sc!§ ... dH 1001 3030 5254.88 4445 6000 52~4.Y2 447C 60~0 5254.9 .. 1000 J26t> 5254.94 4510 4402 5255.03 5231 44~0 S25S.o• 6104 0000 5?55.04 6104 6000 ~~S~a.l)5_ !>.JLU.Q 6.\UHL __ ~ . ...z.L ~!!:!!.. fW.ft.IL_ _ _5Z55_.•;3 I ooo 3000

FIGURE V-2. SA.f.IPLE PRINT-OUT OF RAW DATA

327.q5 600o 6ooo J26.53 1000 3000 ~2'!1.26 5122 4472 32'!1.36 1004 3011 J2<,1.52 1044 3071 l~_'t..i'! 4_12_~ 5165

li::3CJ.60 3127 J127- ----1239.83 6000 6000 1239.92 6000 6000 1c4U.22 5211 ~201 1240.65 1115 3161 1c4l.o5 1021 3124 2uz3.s6-6ooo b"ouo 2U24.08 1000 3Q15 2.~2•.10 6ooo booo 2J24o14 6000 4206 2~24,74 1000 3QQ4 2u24o94 bOOO 6000 2b4q::12-600o e.o-oo ------2t>49.19 6000 6000 2b5Q.58 1174 3255 2t>5U,60 6000 6000 2o5o.65 6401 6000

--~z~~. 72_ s! 3! __!_444 __ _ , .51 6000 6000 l256.56 5066 442J 3258.64 6000 6000 325Ho92 1136 3140 3~59.('7 5347 ~405 3300.64 1146 3242 3~n.ei.-100o 3000 3~13o9H 1040 3QOb 3914.QO 5103 44b4 3~14o07 6000 bOOO 3914.12 1074 3C42 3~14.58 1104 3115 4!>45~'1Yiooo 3ooo-4~45.97 1064 3065 4~46.o5 1013 3142 4~4b.o8 6ooo "009 4S4b.13 1000 3000 4~46.14 6000 6000 ~c54.84 6000 6000 5254.86 1000 3000 5254.88 4445 bOOO 5c54.96 6oro 4502 5255.o5 3033 30b6 ~j!_55.S3 60oo 600IL--.----

-- ~lag - must be zero to indicate amplitude word

-- V/m~s bit- used Jnly in summary statistics

-- Overload bit - must be a 1 for ~alid data

I -- 9-bit binary amplitude data - LSB I equal to 0.1 dB, ~SB • 25.6 dR

0 X 1 X X X X X X X X X 0 X 1 X X X X X X X X X .. ----------------------~ Same meanings

as first half of word

CAMPION AMPLITUDE --- -TABLE KT A~PLITUDE

AZIMUTHz The azimuth word consists of 24 bits {8 octal digits) encoded as follows:

-- Flag - must be 1 to indicate azimuth ~ord -- Validity - aust be 0 to indicate valid data

-- Binary hundreds of degrees

l -- nr.D tens degrees

"'~its degrees

1 0 X X X X X X X X X X 1 0 X X X X X X X X X X

Same meanings

a9 first half of word

CAMPION AZIMUTH --- -TABLE MT AZIMUTH

The first step in processing was the preparation of a "Valid Data" tape by screening the raw two-station data against the following aeries of teats:

A valid amplitude word must:

1) be associated with a valid azimuth word having the same ti~e to ±.01 second, and,

2) the octal repreaent~tion of each half word •ust begin with 1 or l, i.e., both flag bits ~ust be 0 and both overload bits •ust be 1, and,

l) have a non-zero value for the binary representation of amplitude.

2R

t

Any word not meeting these three criteria should be rejected. A valid azimuth word must:

1) have 4 or 5 as the octal representation of the start of each half word, i.e., the flag bit must be 1 and the validity bit must be 0, and,

2) contain no illegal BCD characters in the tens or units positions.

Any invalid azimuth word should be rejected from further processing.

This screening was intended to eliminate signals which had been observed only at Table Mountain or only at Campion rather than at both sites, and to further eliminate time correlated pairs of signals when the validitv of the data was questionable because of overload, zero amplitude indication, etc.

A program was then prepared to convert the information to engineering units, coMpute the difference in observed amplitude and aziMuth for each signal pair and print out the first twenty records after the start of each hour for manual inspection. A sample of this output is shown in Figure V-3. The time span covered by the first twenty records of each hour is a useful indicator of the relative level of sferic activity. It ranges from a few seconds during active periods to a few hnndred seconds during tlmes of low activity.

The "Valid Data" tapes were then processed to develop the average difference in amplitude and average difference in azimuth curves plotted as a function of aziMuth for calibra­tion purposes as described in Section IV of thio report. The 3 dB offset in difference in amplitiJde was observed at this time and identification of its cause a few days later raised grave douhts •s to whether or not any valid conclu­sions could be drawn from these data.

As a test, however, two sample time intervals were selected when there was moderate activity as indicated by the data recordin~ rates. These were periods of a few hours duration ~eginning on days 258 and 259. They are desi~nated by wide bars in Figure V-1. An "Edited Valid Data" tape vas prepared which encompassed these time periods and in which 3.0 dB was added to each Campion amplitude measurement. This tape was processed with the R-45 tape from the Rferic receiver and waveform analyzer to extract information to

29

~><·-----~~-----~------------------------...,...-------------

~.,.., ... lt;WAUJt~limli -------!ll!ll!!'!l!ll!l!lllll!t'!l!lllll!lllll!t'!"""_,IIINMII!!IIIliii!-.I!IIIIJI----------------------·------·

PAuE.: 111U

,-STATIUt.,. UAIA

O"Y Nu. 2oU HUU~ 2 AMpL I JUu£ (Uu) AZ lt•llJT H CUE.ti~~E--.)

T.a...,E(~I:..C) "'"..,p· Tl¥1 tJ.lFf. '-A~"lP. IM l),lt-t- •

-~~ ~.IJ ~-b -·h 14h lt>l -]") 1.H3 .7 .... ., -n·2 1411 lY.j -:-. .; 1+.11 7.H He\.) --~ 156 173 -17 ... f>b ~ ... q.l -.,. 7 132 U£ IJ 1+.7.5 .5.1 u. u -1·':1 .)~A 347 11 o.HY bob 11·9 -~-1 11M 1~4 - ..... h 1U.53 d.2 1.?.1 -:'\.':J 9U 1u3 -J3

1~.50 10.1 111.7 -·h 1611 lo'l _, lY.3l 9.7 12.1 -2·4 l5A 173 -l~ c-o 1'.i.Y9 l2•H 17. 7 -4.9 97 1£~ -£'A c:> 2ts.7ll 5.0 13·4 -A·4 12~ 145 -20 3U.87 9.1 111.3 -1·2 16H lMo -JH 3)!.Hn 9.1 4.d -·1 14K 173 -<:>~ .54. 16 .7 111·2 -11.!) 911 lu4 -1<+ 34.2U 9.1 4.3 -.2 b7 1tJ~ -:-1 3o.o~ 10.2 l4ob -4·4 14~ 111 -...-n 4j.f>IJ 4.6 Ho7 -4·1 101 uu -;-y 4::,.55 l3ob 17.1+ -3•H 103 1.!2 -lY .. ~.57 3.5 111.2 -n·7 101 11~ -14 4~.57 3.1 ..,.9 -2·11 94 115 - .. b

FIGURE V-3. SAMPLE OUTPlfl' OF FIRST 20 RECORDS OF AN HOUR

I

t

I I I ..___

prepare a "coincidel'\ce" tape. The "Coincidence" tape contained measurement data made from signals which were positively correlated. Both time and Tahle Hountain Azimuth were required to he in agreement from both source tapes for the Aignal to be accepted for entry on the "Coincidence" tape. A flow diagram of the selection process is shown in Figure V-4.

The "Coincidence" tape was then processed to extract only those signals which were indicated as being within the potential ranging distance of the system. That is, signals which showed > 12• convergence in corrected azimuth or > 2 dB difference in amplitude. Signals which did not meet these criteria were considered unresolved as their normalized source function amplitude could not be determined with "acceptable" accuracy from the available data. The flow diagram for this selection prucesA is shown in Figure v-s.

The sferic receiver and waveform analyzer equipment was arranged to initiate a record on the high-speed transient recorder (~-45 tape) under any of several conditions which might occur individually or collectively. The circumstances contributing to record initiation are indicated by the contents of two six-bit "Identity" characters contained in each record.

Recording was initiated under any of the following circumatances:

a. Receipt of a signal having waveform features as described in Table V-1 but provided also that the peak amplitude of the first half-cycle was > 0.5 V/m and ita duration (or the duration of the immediately following half­cycle was > lOua.

b. Receipt of any signal having a peak a•plitude > 10 V/m.

c. Simultaneous (within propagation delay time) triggers fro• the AWRE transient detectors at Campion and Table Hountain.

d. The overflow of a 9-hit counter that is advanced by one count for each signal accep~ed for processing by the wavefor• analyzer, i.e., a•p > 0.5 V/•, duration > 10 us. Each overflow indicates that 512 signals have been accepted for processing.

31

R-45 Tape

Talley E No. of Waveform ~ser Entries

Bo

Tally D No. Good Entries

Write 011

Co1Dc1dence Tape

Yes

Ta.lly C No. UDequal

Table Mt. AdliiUth

Discard Entry

DAY

From 258 To ~

From 259 To 26o

Edited Valid Data Tape for

Times Shown

Talley A No. of Two-station

Entries

No

Times

HOUR

2' 6

20 02

Tally B No. Non­

Coincident in Time

Discard Entry

SECOND

2925.42 ~.

5. }2 }18o.

nGURE V-4 - Flov diagram for the prep8l'ation of "COINCIDENCE" t.a~ t'rca two-station data aDd sferic receiver IUld vn~fc>rm aaalyuer data.

32

,•

Yea

·.

Yea

lo

Read BDtry f:r.clll

Co1Dc1dence Tape

Correct Cam Az. tor S1t1ng

Brror per Table

lea

8

Cam. Azimuth Minua

T.M. AziJauth

Tal..ly F No. UDreaobed

IDtriea

ft&ure v-' -Fl.ov ~ tar pre:s-rat10D or uaef\&1 eut.r1e8 •

33

e. The overflow of a 7-bit counter that is advanced by one count each time the quantization of the 1aveform features of an accepted low level signal (O.J V/a < amplitude < 10 V/m) matches the features of the immediately preceding signal and provided less than 200 ms has elapsed since the receipt of that signal.

Table V-1

First half-cicle features

.£!.!.!.!. Rate of Rise Duration Peak Ame. Polariti

A 5 1.0 V/m/)JS ; 30 IJS > 1.0 V/m Neg.

11 >20.0 V/m/ps < 20 us > 1.0 V/m

c >10.0 V/m/o~s < 30 :Js > 1.0 V/m

The settings shown in Table V-1 above may be associated with the classes of interesting events described in Volume I of this report.

During the time interval from day 258, hour 23, second 2925.42 until day 259, hour 6, second JOOO.OO, there were 18,43~ sets of two-station amplitude and azimuth entries on the "Edited Valid Data Tape". During the same time lnterva~ there were 4,567 entries on the waveform analyzer (R-45) tape. Of these. 444 were coincident in b~~h time and Ta~le ~ountain azimuth on both records and these Jere transferred to the "Coincidence Tape".

Analysis of the "Identity" characters associated with the 4,567 waveform analyzer records reveals the followin~:

+ a. 15,360 -511 signals were accepted for processing by the waveform analyzer.

b. 3,371 signals had peak amplitude ~ 10 V/m and the remainder, 11 1 989 ±s11 had peak amplitude 5 0.5 V/m.

c. 768 t127 signals had waveform features matchin~ those of a signal processed 200 ms or less earlier and were discarded as multiple stroke sferics.

d. 1162 signals fell in one or more of the classifica­tion levels shown in Table V-1.

e. 849 signals fell in Class A.

34

•

f. 3 signals fell in Class B.

g. 266 signals fell in Class C.

h. 4 signals fell in Classes A and B.

i. 40 signals fell in Classes A and c.

j. No entries resulted from coincident triggers from the AWRE transient detectors at Campion and Table Mountain •

The 444 entries which were coincident with the two­station data were reduced to 290 "useful data" entries by the procensing shown in Figure V-5. These 290 entries had the following classifications:

a. 39 signals had peak amplitude ~ 10 V/m.

h. 159 ~ignals fell in Class A.

c. 78 signals fell in Class c.

d. 10 signals fell in Classes A and c.

e. 4 entries resulted from overflow of the signal accept counter.

These 290 entries were printed out and are reproduced in Appendix I.

The second time period, beginning on day 259, hour 20, second 5.32 and extending to day 260, hour 1, second 41.00 contained 15,580 sets of two-station data and 3318 entries of waveform analyzer data. Of these, only one was coincident in time and in Table Mountain azimuth and was transferred to the "Coincidence Tape".

Analysis of the "Identity" characters associated with the 3,318 waveform analysis entries resulted in the following summaries:

a. 15,360 ±511 signals were accepted for processing by the waveform analyzer.

b. 422 signals had peak a•plitudes 5 10 V/m.

c. 1024 ±121 signals ~ad wavefora features matching those of a signal processed 200 as or less earlier and were discarded as aultiple stroke sferics.

35

I

d. 2,868 si~nals fell in one or more of the ~lassification levels shown in Table V-1.

e. 2,213 signals fell in Class h.

f. 4R signals fell in Class R.

g. 503 signals fell in Class c.

h. 7 signals fell in Classes A and B.

i. 97 signals fell in Classes A and c.

j. One entry resulted from coincident triggers from the AWRE transient detectors at Campion and Table Mountain. This was also coincident with one of the 7 signals falling in Classes A and c.

The 290 "useful data" records from time period one were transcribed from computer tapes to a printed output for manual examination and evaluation. This was accomplished using a plotting table at a scale of 5 km • 1 inch. Fixed azimuth circles with pull strings were centered over the scaled positions of Table Mountain and Campion and curves representing selected equal differences in amplitude were laid out around each station. The distance from Table Mountain to a sferic source was determined by measurinR from the intersection of the azimuths and by measuring from the intersection of the Table Mountain azimuth with the curves of equal difference in aMplitude.

The radar summary report for day No. 258 hour 23:45 shows only one area of cloud cover within 900 km of Tahle ~ountain. This is a small, well defined region of thund~r­storm and light shower activity extending from about 50 k~

north of Pueblo, Colorado to about 150 km nortla northeast of Pueblo as reported by the Pueblo weather radar. There i~ no complete assurance that there were not other regions of activity outside of coverage of the weather radar network; however, the records at Stapleton Fleld, Denver, Colorado report light thunderstorm activity to the ~outh~est to southeast at that time.

The radar summAry report two hour& later shows the area of activity to have spread considerably to tlae south and east. Stapleton Field records do not indicate thunderstor~ activity for this later time.

36

The 23:45 position of the active area as reported by radar vas centered at the approximate position represented by an azimuth of 130• and range of 155 km to Table Mountain as shown by the hatched outline in Figures V-6 through v-11. These figures also show the plotted position of the "useful data" fixes for six successive 10-mioute Intervals beginning at about 23:50.

The plotted fixes show an average range from Table ftountain that is considerably less than the range to the active area. In fact, •any of the fixes are at a range that is less than the 50 km distance fr~m Table Mountain to Stapleton Field. Sin~e Stapleton reported no thunderstorm activity to the north, it seems unlikely that these fixes could be valid.

In Figure V-6 the average range of the ftxes shown is about 60 km. The average amplitude is approximately 1.2 V/m indicating an average normalized source function amplitude on the order of 72 V/m at 1.0 km. Such a low value further supports the conviction th4t the fixes are invalid and that the sferic activity took place in the region reported by the radar summary.

The results from plotting these data from the selected time periods are interpreted as confirming the invalidity of the Campion amplitude data. In addition, they show evidence of considerably ~reater ''ariations in azimuth data than had been anticipated. Because of t~ese gross incon­sistencies, no attempt was made to plot the remaining data from time period one, and further processing of two-station data from other time period~ was terminated.

lata from two of the tapes from the high-speed transient recorder were processed independently to deternine the number of entries which were initiated as a result of tiMe coincidental (within equipment and propagation delay 11mlts) trigger~ from the AWRE Transient ~etectors at Campion and Table Mountain. These triggers were generated hy signals exceeding 10 V/n in amplitude and having a rate of rise of at leas: 10 V/•/~s which did not persist for more than one •icrosecond. One tape covered the period fro~ day 2J5 through day 238 and contained three entries; one each on day 235, 237 and 238. The second tape covered the period fro• day 255 through day 269. Sixteen entries occurred on day 255 and one each on days 259, 260, 261 and 269. The 16 entries on day 255 were not considered valid as they were n~t supported by dally counts accu•ulated on electromeci•an­ical counters activated by the Table Mountain Transient Detector. They are believed to have been caused by system testa.

37

0 40 120 16o

. A. FIX DASID <II D'i'1UCSBt.-fiQI f:. 'lW ~.

• nx BABID CJt al'IRda1fiOI o; ,. .a&lJQft V1'1'H ~ ~ DDI&IDICS CQift.

Figure v-6 58

200

0

•

0 40

•

------

60 120

/

/ /// ..... . . .

16o

' / v' / ""o /

• 1"'X BASED ~ lH'1 PAiL-ri~ \JF 'D4 AZ.D41.11'H VITB ~UAL AMPJ..I'1U)K DI~ CURVE.

Figure V-7

59

200

0

l !

\ I

0 40 60 l20

/ /

/'

/ "--b

...

l6o

A PIX BASID CB It'.t'tiC811l."'ff<II f:. ftO AZDitlfiE.

• PIX MS!D Cit UliiM&'I'I<II :JI !II AtDIU!'I VlTil !~QUAL AMPLI'l'\IJI Dll'riltBI'C& CUJn.

0

0

----- --- -- -

40 8o 120 16o

A FIX BA8ID Cit IftER64"l''CII or 'l'WO AZDIU!IB.

• m BABID "' DtliiiOhiiWl'ICJI crr 'DC AZDM'B VITH EQUAL AMPI.I'l'lm DlfiEREii\,'1 CUR'fl.

Figure V-9 41

200

0

l ~ 1 I

I i

0 40

----------------....

'8

f)O 120

/

,.,.- .. '

/ I

/ I.J

I ~

~ l"'X BASED "" IJn'ERSECTIOI\ OF ":' tiO AZ DIU'I'HS •

II me BASED c.i ~Ofi Of 'l't', 1\2.~\Jl'H Vl'l'H ~UAI. WU'LITUDE oiml'.F.NC! CURVE·

Figure V-10 42

200

0

•

·'

0 40 8o 120 16o

I I

/

/\,;,/ //.t--o

__ .,., • 4 '

A FIX BASID Cll li'J.'E:RSJ'.l:ION OF 'l'WO AZIMIJ'l'BS.

• l"'X BASID Cll IJfli!RSiil.""l'lCif OF 'l)t AZIMtn'H Wl'1'R EQUAL .AMJII.I'lU)I DiwrnENC! CURVE.

Fi ~;Urc V -ll

4;.

200

0

Discussion of Results

The fixes of sferic activity shown in Figures V-6 through V-11 result from what is believed to be a single area of thunderstorm activity located in the approximate position of the hatch-bounded rectangle. The storm is centered at an azimuth nearly midway between that at which bearing.information only could be used for establishing fixes and one on which only azimuth-amplitude difference fixing could be employed. In fact, its azimuth would have been almost ideal for a comparative evaluation of these two methods of obtaining range if the Campion amplitude data had been reliable. It is, however, slightly beyond the nominal ransing capability of the system based on the design assumptions of ±1.0 dB amplitude measurement capability and ±2• azimuth measuring capability and the ''useful signal" processing shown in Figure V-5. Had these original measure­ment accuracy assumptions been realized, most of the "coincident'' records from the time period should not have appeared in the "useful data'' output but rather have been reported as unresolved. Only 154 nf the 444 coincident data points were so classified. 290 records, nearly two-thirds of the total, showed azimuth convergence > 12• or amplitude difference > 12• dB. Of the 104 records ~lotted in Figures V-6 through V-11, 80 were baaed on an azimuth difference > 12•, 68 were represented by an amplitude difference > 2 dB and 44 met both criteria.

Because of the malfunction in the Campion equipment for measuring amplitude, no conclusions can be drawn from the fixes which are based on difference in amplitude inter­~ections with a single azimuth.

The fixes based on the intersection of two azimuths, however, were obtained from equipment which was believed to be functioning normally. These show a considerable variation in range for events occurring on the same azimuth as obeerved at Table Mountain. If the thunderstorm activity is accepted as being in the area shown by the radar summary, the dispersion in fix positions strongly suggests that the uncertainty in azimuth determination is somewhat greater than was anticipated. For example, the azimuth fixes in Figures V-6 through V-11 on an azimuth of from 130• to 140• at Table Mountain were plotted from azimuths having an averase convergence of 15• but the range· of convergence was from 4• to 32•. Of the 42 sets of data in this group, 22 seta show azimuth convergence that is more than %2• different froM the average converg~nce, 15 sets show ~zimuth convergence more than t4• different from the average

44

convergence, and 10 sets of data are more than ±6• from the average value of convergence. The rather broad skirts of this distribution curve may have additional significance in that these data were centered in a narrow 9egment of azimuth and since the presumed region of origin was moderately distant compared to the inter-station separation, large differences in the effects of polarization induced errors would hardly be expected.

The data shown in Appendiz I lists signal amplitude as obseived by the AWRE signal normalizer at Table Mountain. These values correlate very poorly with the values obtained from the Digital dB Meter at Table Mountain. Some differences would be expected as a result of the differences in bandwidth and sample time aperture in the two equipments, but the variations appear to be greater than anticipated from those factors.

Another anomaly in the data results from the low number of data entrieR which were coincidental in both time and azimuth. During the first time period there were approxi­m&tely 18 thousand two-station data entries and about 15 thous3nd signals were processed by the ~~aveform analyzer, yet only 444 of these were coincident in bot.h time and Table Mountain azimuth. Considerable difficulty was experienced in reading the magnetic tape from the waveform analyzer and it was necessary to ignore the parity check in the tape reading process. The reading problems ma) accourt for the small number of coincident records and probably are the reason for the occasional instance where the Table Mountain azimuth as derived from two record sources operating from the same instrument differs by one degree.

VI. CONCLUSIONS AND RECOMMENDATIONS

The results of processing the data b~se sample as described in Section V lead to only a few conclusions which may be approached with confidence.

There appears tQ be no doubt that the malfuncticn of the ~mplitude measuring equipment at Campion has result~d in apparent differences in amplitude which m3y be as much a function of ~feric waveform as they are of sferic location. Thus, it is not possihle to evaluate the effectiveness of obtaining fixes from the amplitude difference technique using the available data base.

45

l l I l l

There is clear ~vidence from the data that variations in the amplitude of signals received over propagation paths a few hundred kilometers long were dependent on the direction of arrival. The average combined magnitude of these variations was on the order of one dB for the two sites employed in the experiment. These variations appear to be reasonably consistent and reproducible nnd could presumably be at least partly corrected by a suitable fixed compensa­tion curve,

The observed dispersion in indicated azimuth does not permit establishing range from the intersection of two azimuths to the desired accuracy in even the most favorable quadrants. Thus. even if the experimental design objectives ragarding amplitude measurements had been obtained. the results might have been satisfactory in quadrants centered along the baseline direction but would hav~ still been in­adequate in the quadrants centered on 90° and 210•. From examination of the data observed durine tiMe period one. it appears that the waveform characteristics shown in Table V-1 may be useful as discriminants against more than 90 percent of sferics which have propagated over distances of about 150 km, It is significant that this discrimination ratio could not have been materially improved by the two-st~t1on system under any circumstances as the activity occurred at a distance beyond the design ranging limits of the system, froM this• it may be concluded that if all sferics within a 100 km radius were correctly ranged and identified. there would still be a false alarm rate of about 10 percent due to signals which met the wav~form acceptance criteria employed but were outside the ranging distance of this type of two­station system,

rt is interesting to note the ratios of signals which were observed tn each of the three classes shown in Table V-1. A hieh rate of rise appears to be a very powerful discriminant even at amplitude thresholds as low as 1.0 V/m. At 20 V/m/~s rate cf rise. a rejection ratio of over 2000:1 occurred. This i11 over 40 times greater than th•! rejection ratio observed at 10 V/m/~s rate of rise,

The use of the spaced pair of AW~E Transient netcctor f.ystens is reported by r.rubb* to provide a discri~ination

* Grubb• R.~ •• Lightning Background Discrimination Experi­ment3 Using a Spaced Pair of AWRE Transient Detector Systems. ijands Grou~ Note. 26 October 1967.

46

•

ratio of about 100:1 against lightning signals exceeding 10 V/m. During the two periods selected for data reduction, only a single coincident trigger was recorded from these transient detectors. Based on the somewhat limited experimental evidence, they appear to offer considerable promise as a discriminator against high amplitude atmospherics. Vsed in conjunction with other sensors responsive to a high altitude nuclear burst within the field of view, they should contribute to a significant reduction in false alarm rates and to enhanced detection capability for this class of event.

If the rate-of-rise criteria of the spaced transient detectors were increased from 10 ~V/m/~s to 20 ~V/m/~s. it is believed that the false alarm rate should be reduced to a value very close to zero. An experiment to verify this conviction has been proposed to the HANDS group with the recommendation that it be conducted during the summer of 1968.

It is also recommended that additional experiments be conducted using the waveform analyzer equipment. This equipment includes several parameter quantizers in addition to those listed in Table V-1, and their potential as discriminants has not been fully investigated.

47

USCOMM-DC-NBS

' ' • \

I

I

APPENDIX I

Single and 2-station Coincident Data Points

The listing of single and 2-station data points from time period one follows the format described below:

Each page of the listing is headed with the day of the year (1967) and hour of the dey and the remaining data is listed in 1~ columns.

Column 1 lists the time in seconds and centiseconds past the hour shown in the heading.

Columns 2, ~ and 4 show the indicated amplitude in dB (1.0 V/m .. 15.9 dB) at Campion and Table Mountain and their difference, respectively. The Campion values have been adjusted by +~.0 dB based on the calibration procedures described in the report.

Col'LlJIIDS 5, 6 and 7 show the azimuth observed at Campion and Table Mountain and their difference ,respectively. Azimuth data are referenced to the baseline between the two sites and Campion values have been adjusted in accordance with the correction curve shown in Figure IV-5.

Coli.IIIIDB 8 and 9 show the amplitude and azimuth data recorded tram the AWRE Sigaal Normalizer and Azimuth Digitizer at Table Mountain. Amplitude is indicated in dB but is inverted in sense tram data shown in col\DIIDS 2 and 3, i.e., decreuing values indicate increasing sigaal amplitude and a value of zero indicates overload.

ColUIIID.s 10 and 11 are flag characters • Flag 1 (column 10) was not used. nag 2 shows a value of 15 during periods of normal data record­ing.

I-1

•.

Column l2 shows a coarsely quantized value of peak amplitude as ob­tained trom the Steric Receiver and Waveform Analyser. A value ot 32 reprePents a peak amplitude ot approximately 0. 5 V /m. Decreasing values indicate increasing signal strength in steps of approximately 3 dB, e.g., 30 indicates approximately 1.0 V /m peak amplitude,

Column 13 shows a tour digit value used to:r identification ot signal classification:

It digit one ~ 4 It digit one = 2 It digit one = l If digit two • 4 If digit two • 2 If digit two = 1

Signal is Class A* Signal is Class B* Signal is Class C*

Signal amplitude > 10 V /m Transient detector-coincidence occurred Not used

If digit three = 4 512 events have been accepted for processing

It digit three .. 2 128 signals have bad matching wave­forms

If digit three • l Not used

Digit four Not used

SUIIIIII&tion is allowed, i.e., a value of 5 in digit one indicates a signal meeting both Class A and Class C criteria,

* See Table V-1.

I-2

I 1 ! \ ~ t

I l

j I

} •

I • ~

J • J

------------------------------ - ---•..t.: :, "'1..6Li .. ~ .... --2-!>I~HuN t-uttoeiliC:IiiiJillA POINT~----- -- ----------------------------

SINGLE STATION DATA AZ• Fl -F'2-- IDtNt

-------------- ------------

-----------------------------------------------------------------

---------- -- ------------

"""" u ~Lll~IOdJ

'"""'· T"' ulff. _ _ ______ AllMUIHlDE~&IIJRI!It.E=S~I~,----- ----:- ~A,_T,_,A,____--==co----=

CAMP. TM Olff, AMPLo Al· Fl F2 PEAX IOENT

--• .,:-.¥ bool! 1.)~9- ---::.7;7 ------156 136 20 0 135 0 15 30 4000 _ _I .a_."-. J.'l·'t-~ -1.1 &iii: &:a~ ;)Z 211 &:ifl Sl Ali a 3.11!11

7~.<!7 ,4).!) l'ilo3 10·2 169 160 9 39 160 0 15 30 1000 --l.ii.Jl.. 211 .. "b·~-- ___ a..,d 12.-l_ 64_ Ul2 2(11 II l'Jl II l:i ;MI !!Ill

ll<&:.IS'il ..... :0•1 o'il 150 us 15 18 136 0 15 22 0480 __ l2l..JI7 "'·"' ftt,) ___ ~·'l. - -~»-- ll~ __ u _____ .L___1J3 !I __J!L _ ___u_ __ o~••

lol!oo% 47•b .:., . ., -5·8 1b!i 137 28 0 137 0 15 28 4000 , .. ~.~ __ .-JJI•!' il.IIZ -.2·2 &:i" &J:i II ii ~~~ s 15 H 1000 184:oftft .... ~ 1!>oll -b•ft 15.5 136 :7 0 13 0 4000

_ljl.7._o-, -'~·~- .!1_oL_ ----=•·•-- 15.1__ l.H __ H. \9 l38 0 15 u o•oo 221.71 ,~.c. ~··tit -2·2 1ft7 128 1-, 0 128 0 15 It> 10A

~~~-·~!1 H•i! .loel -5·1 ft!> u~ 9 28 1.55 0 15 ~ 5000 .5II:Oo2:0 .a. ... u -----i~-:s-· -2·.5 1611 1D7 1 0 1(>7 0 15 30 I oil

~~~--- .J. 7_•9 U•U _,., U1Z ,c:~ &!! ill ~~ 0 15 ~ .... .. 6f4.~tl •1.·1 a g ... ·" 18.5 111 12 u 72 0 15 so 4611

~4!,.. .. ,_~~-- 48•-'-.-Ji•O __ -=:i..•.A.. l:i& u~ &11 Q__ q3 0 15 28 ...,. ftii:0.7,5 ....... llool! 1·7 1S.S Uft 19 u .,.. 0 15 so ""' ft81.97 - boD .).7 -'•1 us 1.54 ft 26 1,.. 0 15 28 , ... ft9.)~311 lllo1 ---- il; .. - --:,_~-- 17ll 157 13 ~ 157 0 15 so , ... ~~·"9 ~J·b il!•-' bo.5 182 1~ 0 27 181 0 15 26

~-· '·51 "'' .. .!~·9 -1.s 1t.s 153 12 :!6 15j 0 15 II •••• 63.So8<L -- ~,!_ ... __ -~'?..!.L...- ~.!.1.__ 1ft7 1~ 9 19 1.58 0 15 a 10 .. Wt:0.:02 boo 11•-' -·7 13U 1u8 22 19 108 0 1!1 22 OiiM

_ID_.o1!2__ ~II·.S !!!•.!.--~~- 1"-' 1.51 12 0 132 0 15 30 , ... 7ft1o7U Soo 1.9 -2·1 137 122 15 33 121 0 15 26 4101 7S.:s-'l! "'U•7 ~.5·1 -2·" 1ftb uu lb 0 130 0 15 ~ .... l6oo6.! ll.•ol 1.S•:O -l·l lftS uS 12 36 U!!l 0 15 30 46A 79b.YII ~b·J! ___ t_7,:. ---·· -1·0 1115 123 72 0 123 0 - 15 30 .... CJ1loftU 1 ..... lft•S -·1 1 .... 13i 12 19 131 0 IS IZ Afi \llloftO 1·::0 .!1·1 -1-'•b 1ftS 1.52 13 9 J.-:'>1 0 0 22 MOO

~J.o;u!, lb; .. - ---11·U-------;10 1"1 12ft 17 28 ~24 15 Sl , ... 9l!!·"l ---~,·ft &1!•9 -·~ lft2 1~5 17 0 126 0 15 31 , ... 91bo2(> oft ll•' -... , &Si> u7 19 117 0 15 Zf ....

_.'lfb~-- -~"·(- ----~-~b.!__ &5ft 1~1 23 0 132 0 15 26 .... 99~ ..... ~ ... 7 27·8 -.5·1 U7 12" 13 ----0 124 0 15 21 AA

~.~~.~- - 19•:>_- _...21•:0 - _-2_,_0_ ----~7 ____ 1_25 12 0 126 0 15 0 , ... 100J.32 fto1 rio9 - ... a 162 1S't 8 26 -1511 0 15 ~~ .... l!!lil!o7l ..... -'li·~ -!l!!·~

,,.. l"~ u 2ft 1 .. 3 0 15 27 , ...

1011Y•68 15•11 lltoi! -2·ft 127 123 .. 0 125 0 1! R COR .... .U!!~dY------~.!.11. __ l~,ft-~1_ __ 1 .. 2 __ _!ll_ __ -

l~ 19 123 0 15 22 ..... 11211.71 11·9 11•7 •2 17U 1ftS 29 lft6 0 15 H !JIIH US...9!._ l_b_;_} __ I !Sob -2·3 169 1S.. 1!> 29 1511 0 15 27 , ... 129boftb ... , -'b·~--- -"2-.t.------1..-7-- 121 2b 19 122 0 15 D 14ft ~ft!!Oo71t

·~·~ l'"8 -3.5 lft2 1,57 5 0 137 0 15 30 1 ... .. u7.16

l "' 111.7 -2.::. 1!!17 1S3 ft 0 133 0 15 so IUW

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