The Spectrum Monitoring

8/22/2019 The Spectrum Monitoring

1/134

1

The spectrum monitoring

Mr.Zhao ZhengEngineer of Beijing Monitoring Station

State Radio Monitoring Center

[email protected]

+8610-60271116

Radio Monitoring and Spectrum Management Training

(China,23-31,May,2005)


2/134

2

General introduction

DF method and location

Siting of monitoring stations

Typical Procedure for Dealing withInterference Complaints

Contents


3/134

3

General Introduction

Brief introduction

Types of monitoring stations


4/134

4

Spectrum management

Spectrum monitoring

Eyeandear

Spectrum monitoring function

Efficiency ofusing spectrum


5/134

5

The goals of monitoring

General

support the management

Specially

resolution of EMC problemensuring an acceptable quality of radio and TV

providing valuable monitoring data

providing valuable monitoring information


6/134

6

Tasks of the monitoring service

From radio regulation (RR)

On national basis

Assigned to the radio inspectionCooperation with other bodies


7/134

7

Tasks from RR

Monitoring emissions for compliance with frequencyassignment

Frequency band observations and frequency channel

occupancy measurementsInvestigating cases of interference

Identifying and stopping unauthorized emissions


8/134

8

Tasks on national basis

Assistance on special occasions

Radio coverage measurements

Radio compatibility and EMC studies

Technical and scientific studies


9/134

9

Tasks assigned to the radio inspection

Inspecting radio equipment on site

Measuring radio equipment

Processing cases EMC

Market surveillance activities


10/134

10

Cooperation with other bodies

Police and court


11/134

11

Measurement tasks

Frequency Frequency counter

Field strength spectrum analyzer

Bandwidth spectrum analyzer

Modulation vector analyzer

Spectrum occupancy automatic receiver

Direction finding DFer


12/134

12

Type of monitoring station

Frequency band

HF, V/UHF station

Different application

fixed, mobile, portable


13/134

13

Fixed monitoring station

Central element of the monitoring system

Advantages:

without limitation of workspace

setup of antenna

power supply

Disadvantage:

limited by environment

coverage

C Fi d i i i


14/134

14

Common Fixed monitoring station

block diagram

Spec-022

GPSreceiver

Video recordersand other

peripheralequipment

Frequencystandard to

equipment VLF/HF - VHF/UHFDF and measuring

receivers

L

A

N

RFdistribution

and

antennaswitching

DFantenna

switching

DatarecordersConsole

Console

Console

Printers

Database

Uninterruptablepower supply

Enginegenerator

110/220 V50/60 HzRouter

Wide area network

DF: direction finding

GPS: global positioning system


15/134

15

ExampleDF system

Antenna array

triangle array (cross-loop element))


16/134

16

Picture of antenna array


17/134

17

ExampleDF system interface

DF techniquecorrelative interferometer


18/134

18

Examplelistening system

Log antenna


19/134

19

Pictures of listening site


20/134

20

Listening interface


21/134

21

Mobile monitoring station

Advantagesflexibility

expanded coverage

Disadvantageslimited by workspace

setup antennapower supply

living condition


22/134

22

What is the first important thing for mobile

monitoring station?

GPS system

ensure the location

know the bearing


23/134

23

Division by differenttransportation

Vehicle station

Airborne stationMarinetime station


24/134

24

Vehicles

General consideration

Antennas for vehicle monitoring station

Requirements to be fulfilled by thevehicle

Power supply

Examples of a vehicle concept


25/134

25


what functions the vehicle is to be used for

general-purpose or specialized

What manner it is to be used in

(where and how long)


26/134

26

Antennas for vehicle monitoring station

The size and the number

Distorting effectcalibration

Directional antenna


27/134

27

Requirements to be fulfilled by the vehicle

Communication system

Sufficient leg room

Windows

SafetyConvenient seat location

Interior light

Thermal insulation

WeightPowerful built-in generating set

Speed


28/134

28

Spec-023

Telescopic mast

Air conditioning

system

Onboard Diesel

generator

19" cabinet

equipment

Operat

or

table

Interior of a mobile monitoring station


29/134

29

Power supply

Equipment type Power consumption(W)

Spectrum analyser (26GHz, portable) 210

Oscilloscope (400MHz, portable) 120Signal generator (100kHz-2GHz) 200

DF (20MHz-3GHz) 140

HF receiver 150Industrial personal computer (PC) with colour display monitor 200


30/134

30

Power supply

Batteries and secondary cells

Alternators coupled to the engine-InvertersGenerating sets

Mains supply

Diesel engine preferred

E amples of a ehicle concept


31/134

31

Examples of a vehicle concept


32/134

32


33/134

33


34/134

34

The vehicle example


35/134

35

Rear view


36/134

36

Interior View 1


37/134

37

Interior View 2


38/134

38

Brief introduction of this example

Frequency band :HF and V/UHF bands.DF method:

Watson-Watt method on HFcorrelative interferometer on V/UHF

ITU measurement


39/134

39

Airborne monitoring stations

advantage1. Quick exploration of broad geographical areas

2. obtaining several lines of bearing from different locations

3. Better opportunity to perform measurements due to line of sight4. Rapid location of emergency beacons, interferers and Earth stations

which sometimes cannot be detected from ground

5. All means of measurement of aeronautical flight aid transmissions


40/134

40

Airborne monitoring stations

Disadvantage1.Cost of flight

2.Limitations in weight, power, size, cooling

3.Limited by weather, winds4.Limited flight time due to fuel limitations

5.Requires accurate azimuth and depression angle, fast DF capability andantenna tracking

6. Frequency compensation for relative velocity may be needed


41/134

41

Maritime monitoring stations

Advantagethe area surrounding the marine vessel is generally very quiet

from a radio frequency point of view

Disadvantage Corrosive atmosphere

Multipath due to sea state reflection

Antenna mounting

Radio frequency ducting over warm bodies ofwater


42/134

42

Portable monitoring station

advantage

more flexibility than mobiles

one person can carry

Disadvantage

less functions

less accuracy


43/134

43

DF and Location


44/134

44

Contents

DFGeneral principle of DF

Main DFers features

DF methods

Bearing related topicsDF features due to frequency difference

DF antenna

Location

Location overview

Cross-bearing location

Single station location


45/134

45

General Principle of DF

Concept of radio DF

Concept of azimuth

The basic architecture of DF system


46/134

46

The process to determine the line of bearing(LOB) of any source of electromagnetic radiationby means of the propagation properties of radiowaves.

Normally, direction is expressed by azimuth.

Concept of Radio DF


47/134

47

Direction Finder

Reference direction radiation source

Concept of Azimuth

Azimuth: the clockwiseangle from the line

( the radiation source tothe direction finder) toa reference direction.

Geographicalnorth ;geomagnetic north;or the heading ofvehicle in mobile DF.


48/134

48

The Basic Architecture of DF System

Antenna

system

Inputswitching

networkReceiver Terminal

devices

receive the signalfrom the radiationsource.

transmit the signal withoutdistortion. includeimpedance convertor,distribution, etc.

signal processing.Such as amplify,demodulate, etc.

get and display theazimuth.


49/134

49

Main DF Engineering Features


50/134

50

Accuracy

Concept:

DF error=Vm-Vreal

within 1to 3.


51/134

51

Sensitivity

Concept:Emin ensure the accuracy within certain range

Importance:extending the coverage of DFer

under good receiving conditions

sufficiently reliable DF

under less favourable receiving conditions.


52/134

52

Response time

Concept:Tmin to finish one DF task

Duration of signal > response time


53/134

53

Immunity to distorted wavefronts

(coherent interference)

obstacle

transmitterwhat produce distortedwavefronts?

reflection by obstacles and

diffraction by edges.

multi-path reception.

Result:There are interferences andthe original plane wavefrontis distorted.


54/134

54

Depending on its diameter D, a DF antenna detects only a smallpart of the wavefront.

D/

narrow-apertureDF antennas

medium aperture

DF antennas

Wide-apertureDF antennas

D/


55/134

55

Narrow/wide aperture DF antenna

bearing with wide-aperture DF antenna

bearing with narrow-aperture DF antenna

nominal bearing

Narrow- /w ide-aper ture

DF ant enna s

undistortedwave front

distorted

wave front


56/134

56

Immunity to co-channel interference

Concept:

non-coherent ,co-channel interference.

Erroneous bearings

should be recognized and identified.

Individual bearings

should be taken of all the signals.


57/134

57

DF methods

Rotating DF method

Non-rotating DF method Amplitude-comparison DF method

Phase-comparison DF method

Combination of amplitude and phase DF method


58/134

58

Rotating antenna DF method

receiver

90

0

270

Bearing indicator


59/134

59

Advantages

High sensitivity due to the directivity ofthe antenna

Simple and inexpensive realizationResolution of multi-wavefronts

Same antenna can be used for direction

finding and monitoring


60/134

60

Disadvantages

Probability of intercept is reciprocal ofthe directivity

in case of short-duration signals


61/134

61

Non-rotatingDF methods

Phase-comparisonDF methods

Amplitude-comparisonDF methods

Dopplers

interferometers

Wullenwebers

Watson-Watts

Combination of amplitudeand phase DF methods

Correlation


62/134

62

Amplitude-comparison DF methods

Watson-Watt DF method

Wullenweber DF method


63/134

63

Watson-Watt DF method

CosKUmSin

N-S

E-W

NSU = CosKUmCos

EWU

CosKUmSin=

Cos

Sinarctg

U

Uarctg

NS

EW=

: Azimuth

: Elevation

Can not get the Elevation

A 1 2


64/134

64

Accuracy

(without site influence)

1 to 2

Sensitivity Med-High

NOTEPerformance based on antenna selection

Response time < 1 ms

Immunity against

distorted wavefronts


Limited, as no wide aperture antenna arrays possible

Immunity against co-channel interference

(non-coherent

interference)

Separation possible using analogues CRT displaytechniques. Operator interpretation of CRT used in

resolving interference pattern.

Digital signal processing cannot algorithmically

separate time coincident co-channel signals. Histogram

techniques may be employed for non-time coincident

signals

Adcock/Watson-Watt DF systems


65/134

65

A B

O

120

C

D

Antennas:ACB (arc) Time delay network

Antennas:ADB (line)

AD BD

-+

Incomingwave

+ radiation

pattern

- radiation

pattern



66/134

66

Wullenweber direction finder


67/134

67

Advantages: High accuracy High sensitivity

Strong immunity to co-channel interference

Disadvantages: Long response time

Complicated structure



68/134

68

Phase-comparison DF methods

Doppler/pseudo-Doppler

Phase interferometer

D l / d D l


69/134

69

Doppler/pseudo-Doppler

f

f

1

12

2

3

34

4 1

Incoming

wave


70/134

70

Accuracy HF/VHF/UHF: 1,VHF: 0.1(D/>4)

Sensitivity High

Response time HF: approx 100ms; VHF/UHF: approx 10ms

Immunity against distorted

wavefronts


D/>1, wide-aperture DF antennas

Immunity against co-channelinterference

(non-coherent interference)

Limited, only measure the strongest signal

HF skywave capability With across circle antennas, the signal with

elevation up to 90 can be measured (sensitivity

reduce), SSL function

Doppler/pseudo-Doppler DF system


71/134

71

L = d sin t = Lc

t = L = 2f d sin c c

f = c , = 2 c d sin c

2 d sin d

N

Phase interferometer


72/134

72

a = d sin cos t = a/c (distance/speed) = (d sin cos )/c = * t = (2 d / ) sin cos 2d sin cos

1 2d

a

P1

P2

P3

Considering elevation angle


73/134

73

Accuracy (without siteinfluence)

1

Sensitivity High

Response time 10 ms 1 ms*

*NOTE

Successful systems, which use antenna switchingto a pair of coherent measurement channels, are common.

Response time is most rapid when one receiver is used for

each antenna, and all measurements are made in parallel.

Immunity against distorted

wavefronts


High when using wide aperture antenna arrays

Immunity against co-channel

interference (non-coherent

interference)

Separation possible using histogram techniques for non-time

coincident signals; for time coincident signals only the

signal that is stronger by 3 to 5 dB can be evaluated

Phase interferometer system

Combination of amplitude and


74/134

74

Combination of amplitude and

phase DF methods

Correlation/Super-resolution

C l ti / l ti


75/134

75

Correlation/super-resolution

Antenna array 1

2

3

A,

Referencechannel

1

2

9

3

8

4

7

5

6

MemoryA ref,ref

Incoming wave (azimuth:,elevation:)

,

DF converter


76/134

76

Sensitivity High

Accuracy (without siteinfluence)

1

Response time for HF 100 msfor VHF/UHF 10 ms

NOTESystem processing times will be lengthened if only one or

two parallel receiver channels are used

Immunity against

distorted wavefronts


High when using wide aperture antenna arrays

Immunity against co-

channel interference(non-coherent

interference)

Separation possible using histogram techniques for non-time

coincident signals; for time coincident signals in the vectorcorrelation system, only the signal that is stronger by 3 to 5 dB can

be evaluated; the SR-DF system separates multiple signals

Correlative interferometer/Super-resolution-DF (SR-DF)


77/134

77

Bearing related topics

Display of bearings

Sources and expression of bearing errors

Classification of bearingsCalibration and correction


78/134

78

Display of Bearings

Display of results of a single channel DFer:Parameters indicated: numeric DF value

azimuth in polar coordinates elevation as bar graph (combined with

azimuth display)

DF quality

level Histogram of DF values

Waterfall (DF values versus time)


79/134

79

Sources and expression


80/134

80

bearing errors

instrumenterror

Environmenterror

Propagationerror

Operationerror

Maximumerror

Averagingerror

Statisticprobability error

Averaging squareroot error

error sources

error expression

Sources and expressionof bearing error:


81/134

81

Classification of bearings

Class Bearing

error

(degrees)

Observational characteristics

Signal

strength

Bearing

indication

Fading Interference Bearing

swing

(degrees)

Duration of

observation

A 2 Verygood

or good

definite negligible negligible


82/134

82

Classification of bearings

Class Bearing

error

(degrees)

Observational characteristics

Signal

strength

Bearing

indication

Fading Interference Bearing

swing

(degrees)

Duration of

observation

A 1 Verygood

or good

definite negligible negligible


83/134

83

Calibration and Correction

Because oferrors due

to thedirectionfinder site

andequipment

To check the impact of thesite and re-radiation fromnearby structures, forest etc

on direction findersperformance

To check ifthe DFer

works well andis in goodconditionsafter being

installed at thesite

Calibration of mobile

Direction finders

Calibration of fixed

Direction finders

Instrument Calibration

Site Calibration

To eliminate the influenceof the vehicle on the DFer

DF features due to


84/134

84

DF features due tofrequency difference

DF below 30MHz

DF above 30MHz


85/134

85

DF Below 30MHz

Different propagation modes

DFers are remote from the area of interest

Measurements are relatively unstable

Susceptible to errors induced by reflectionsfrom the ionosphere


86/134

86

DF above 30MHz

DFers are in the vicinity of the area ofinterest

Measurements are reliable DF measurements can be made difficult

due to the presence of interference and

the reflections suffered by waves.


87/134

87

DF antenna

Antenna parameters

DF antennas in common use

A t t


88/134

88

Mainly includes:

Radiation Pattern

Directivity

Efficiency and Gain

Impedance characteristic

Antenna PolarizationBandwidth

Antenna parameters

DF t i


89/134

89

HF rangefixedarrays of monopoles or crossed-loop elementsmobileeither loops or ferrite elements

VHF/UHF rangemostly arrays of dipoles or fans

DF antennas in common use

E l 1 HF l t


90/134

90

Example 1: HF cross loop antenna

Array of 7 or more crossloop antennas installedalong an 81 mequilateral triangle.


91/134

91

Example 2: V/UHF dipole antenna


92/134

92

UHF1 sub band antenna (160 - 500MHz)

h = 55 cm

O = 100.8 cm

VHF sub band antenna (20 - 160

MHz)h = 180 cm

O = 295.6 cm

UHF2 Sub band antenna (500 MHz

- 1350 MHz)

h =22 cm

O = 36 cm

Example 2: V/UHF dipole antenna


93/134

93


94/134

94


95/134

95

Location

Location overview

Cross-bearing locationSingle station location


96/134

96

Location Overview

Location method

Cross-bearing Location(In V/UHF or HF band)

Single Station Location(Only in HF band)

More accurate butneeds at least twodirection finders

Only need onedirectionfinder

C b i l ti th d


97/134

97

Cross-bearing location method

Using two or more direction finders indifferent geo-positions;

test and get two or more azimuths ofthe interference at the same time;

According to the azimuths, along thearc of the great circleconnect interference with the

receiving point on an electronic map.

the point of intersection is thelocation of the radiation source .

Station B

Station C

Station A

Locationarea


98/134

98

Cross-bearing Location Principle

Basic principle of triangulationusing two direction finders

DFer1: A

DFer2: B

Emitter: E

The reference direction: X axis

Azimuth from DFer1: 1

Azimuth from DFer2: 2

Ye-Y1=(Xe-X1) tg1

Ye-Y2=(Xe-X1) tg(180-2)X

Y

A(X1,Y1) B(X2,Y2)

E(Xe,Ye)

1 2

0

Bearingerrors arenot taken

into account.

C b i L i P i i l


99/134

99


DFer

Bearing

Uncertainty onbearing due to

errors


100/134

100


DFer1 DFer2

Bearing


101/134

101

Location calculation


Triangulation method

Large circles,spherical triangles method

LongdistancesWhen a direction finder is very far from atransmitter, the bearing line cannot beconsidered as a straight line but an arc.


102/134

102

Cross-bearing Location Systems

Most common and economical way ofcross-bearing location is a remote-controlled

direction finding system.

ll d


103/134

103

Remote-controlled DF Systems

Monitoring center

Remote

DF station

Remote

DF station

Remote

DF station

l l


104/134

104


dependent on the quality of bearings

Bearings should be analyzed at both DF stationsand monitoring station.

L i l l i


105/134

105


DF stations analysis what mainly consist in?

Classifying the bearings

Eliminating aberrant shootingsCalculating the mean value and the

variance of shootings

L ti l l ti


106/134

106


What mainly consist in mobile station?

Determining the bearings to be used for

the location calculationCalculating the position

Calculating the uncertainty ellipse

L ti l l ti t


107/134

107

Location calculation steps

Determining bearing

made reliable for each

DFer

Eliminat ing off-center

shootings

Location

calculation

Uncertanty ellipse

calculation

Elementary bearings

Azimuth, elevation, typi cal deviation

Technical measurements

Frequency, modulation, bandwidth

Ellipce

charactristics

Qualitynotation

Bearing processing by

the monitoring center

Bearing by

the direction-finder

Bearing made

reliable by DFer

Bearing geograophically

consistent

Lattitude,

longitude

The computer program TRIANGULATION, that generally

follows these steps, is available in the ITU.

Eliminating non convergent bearings


108/134

108

Eliminating non-convergent bearings

DFer 1

DFer 2

DFer 3DFer 4

Areas of uncertainty on each

intersection on bearing from

DFer 1

Uncertainty on

bearing

Bearing

E l ti th l ti i t


109/134

109

Evaluating the location point

The optimum point is searched applying the leastsquares method.

...)/()/()/( 3232

221

21 vdvdvdSp

Pis any one point

d1, d2, d3,... the angular variations to be applied toeach bearing to intersect P

v1, v2, v3,... the variances of the various bearings.

The optimum point is the point minimizing Sp,

SSL Principle


110/134

110

SSL Principle

DF.

= Geographical Azimuth = Elevation AngleD = Distance

h = Virtual Reflection Height

DF.

h

DNorth

Li i i f SSL h i


111/134

111

Limitation of SSL technique

Multi-hops propagation

The reflection may take place from

layers of different heights.


112/134

112

Siting of MonitoringStations

G l id ti


113/134

113

General considerations

Frequency ranges and geographicalareas;

International or domestic ;Whether special installations required;

On-site field strengths;

Administrative considerations;Land costs;

Desirable minimum site


114/134

114

Desirable minimum site

criteria for a stationLocation;Protected from obstacles;

Electromagnetically protected.

Additi l d i bl it


115/134

115

Additional desirable site

criteria with DFerGeneral considerations:Obstacles

Terrain deviationSoil requirement

Underground pipes etc.


116/134

116

Additional desirable site criteria with

DFers (below 30MHz)

Obstacles: see table 1Terrain: flat ground with watertable near the surface



117/134

117

DFers (below 30MHz)

Guiding rules:

Terrain:

no more than 1% within 100m area (HF)

slopes can be steeper within larger areaObstacles: 2-3 degrees

Ground: clear within 200m area

Cables: 1-2m deep (30m range),0.5m deep(30-250m)



118/134

118

DFers (above 30MHz)

For VHF/UHF DFers requirements in Table1

may be reduced

In smaller zones: fixed and mobile radios

should be restricted

In larger zones:high power ISM equipmentand major obstacles should be restricted

Protection from strong

t ansmitte fields


119/134

119

transmitter fields


To protect monitoring capability

Protection from strongt ansmitte fields(2)


120/134

120

transmitter fields(2)

How to evaluate?

Harmonics as well as fundamental

Two or more transmitters(other range)Experiential way of evaluating

Protection from strongtransmitter fields(3)


121/134

121

transmitter fields(3)

License applications

Strong signal area:

avoid active antennas

Protection from local computer

systems


122/134

122

systems

Computer systems may causeinterference

Computer emissions may be hard toidentify


123/134

123

Recommendations:

Shielded cables

computer system installed apartmonitoring offices close to the antennas

avoid or minimize interference in the planningstage

Land requirements


124/134

124

Land requirements

Largely mission dependent

The use of adjacent property

legal aspects related to operationalsafety and public safety

Other considerations


125/134

125

Other considerations

Road access

Fencing


126/134

126

Typical Procedure for Dealing

with Interference Complaints

St


127/134

127

Steps

Complaint report received

Preliminary diagnosis

Localization by mobile means

Measurement of emissions

Measurement evaluation and actions

Final check-up

Interference Report


128/134

128

Interference Report

Details of the following are required:

Information of party experiencing the interference;

Data about the interfered-with device;

Data about the following of the interference

1.occurrence

2.description

3.suspected source



129/134

129


Preliminary diagnosis are performed withthe help of the following:

Fixed and remotely controlled measurement

equipmentDirection-finding

Frequency assignment databases

Switching off the transmitter of the suspectedoperator (if possible)

l b b l


130/134

130

Localization by Mobile Means

A complementary means

Could be very time-consuming

M f i i


131/134

131

Measurements of emissions

Once the source has been localized and identified,

Measure the technical characteristics todetermine the nature of the interference;

equipments and their settings should berecorded for use in the next step.

Measurement Evaluation and


132/134

132

Necessary Action

Measurement results compared withassignment and standards

Actions:1.Taken out of operation

2.Modification or system rectification

3.AcceptedFine or other penalty may take place

Measurement Evaluation and


133/134

133

Necessary Action

Actions should

Conform to the law;Be reasonable;

Final check-up


134/134

Final check up

Check if remedial actions has been taken

Using fixed or remotely controlled equipment

On-site inspection

Asking the interfered party

The Spectrum Monitoring

Documents

Transcript of The Spectrum Monitoring