John Galt versus GLONASS: Helping Keep Our RF Environment C - PowerPoint Presentation

Slide1

John Galt versus GLONASS: Helping Keep Our RF Environment Clean

Ken TappingSlide2

Example Problems

1 559-1 610 MHz:

AERONAUTICAL RADIONAVIGATIONRADIONAVIGATION-SATELLITE (space-to-Earth) (space-to-space)

1 610-1

610.6 MHz:

MOBILE-SATELLITE (

Earth-to-space) AERONAUTICAL RADIONAVIGATIONRADIODETERMINATION SATELLITE (Earth-to-space)

1 610.6-1 613.8 MHz:MOBILE-SATELLITE (Earth-to-space) RADIO ASTRONOMYAERONAUTICAL RADIONAVIGATIONRADIODETERMINATION SATELLITE (Earth-to-space)

1 613.8-1 626.5 MHz: MOBILE-SATELLITE (Earth-to-space) AERONAUTICAL RADIONAVIGATIONRADIODETERMINATION SATELLITE (Earth-to-space)Mobile-satellite (space-to-Earth)

Iridium – Another Problem

GLONASS – The Problem

This buffer band is only 0.6 MHz Wide. Not much help.Slide3

Glonass

Comes On-StageSlide4

GLONASS

A Russian satellite navigation system.Uses a spread-spectrum modulation scheme which splatters signal into the 1610.6-1613.8 MHz radio astronomy band.

Serious interference from GLONASS is also experienced as far away as the 1 660‑1 670 MHz radio astronomy band.Satellites already launched could not be modified.At that time the Russians indicated they were not economically in a position to redevelop the non-launched systems or those under construction.In Geneva they said their system related to “safety of life” and is therefore more important than radio astronomy.

Some improvement was achieved by operational changes, but the problem is still there.Slide5

“Post-Mortem” on GLONASS

(Not really a post-mortem because the issue is still alive)This issue combines all the elements of observatory spectrum management – local->international.

Could more vigorous radio astronomer activity at the international level have made a difference? What lessons have we learned?Have we learned enough?Slide6

Example Problems

1 559-1 610 MHz:

AERONAUTICAL RADIONAVIGATIONRADIONAVIGATION-SATELLITE (space-to-Earth) (space-to-space)

1 610-1

610.6 MHz:

MOBILE-SATELLITE (

Earth-to-space) AERONAUTICAL RADIONAVIGATIONRADIODETERMINATION SATELLITE (Earth-to-space)

1 610.6-1 613.8 MHz:MOBILE-SATELLITE (Earth-to-space) RADIO ASTRONOMYAERONAUTICAL RADIONAVIGATIONRADIODETERMINATION SATELLITE (Earth-to-space)

1 613.8-1 626.5 MHz: MOBILE-SATELLITE (Earth-to-space) AERONAUTICAL RADIONAVIGATIONRADIODETERMINATION SATELLITE (Earth-to-space)Mobile-satellite (space-to-Earth)

Iridium – Another Problem

GLONASS – The Problem

This buffer band is only 0.6 MHz Wide. Not much help.Slide7

Then Came Iridium

Iridium – a satellite phone system, using the spectrum just above the 1610-1613 MHz radio astronomy band.Their modulation and channel use system splattered interference into the radio astronomy band.

A filter design for suppressing this ended up overweight and overbudget. So the spacecraft were launched without them.Iridium representatives visited radio observatories getting them into individual agreements and to sign non-disclosure agreements that effectively stopped collaborative opposition.Canada signed no agreements, but the system got licensed here anyway. Iridium was a better lobbyist than we were.Slide8

The Game Had Changed

The diplomacy-driven, collegial system of national and international spectrum management had gone – replaced by a lobbyist and money-driven system. The politics got dirtier. Being able to prove the numbers no longer worked.

Those of the radio astronomy community were outmanoeuvred, outsmarted and humiliated. Attending meetings was a horrible experience.However, in a backhanded way, Iridium did us a favour. The company made a lot of commercial enemies, and also taught radio astronomers still in the spectrum protection arena how things worked now. So we made allies out of Iridium’s enemies (Alcatel for example). We started making progress again.

Some level of lobbying was important to maintain contacts as well as to actually raise issues.Slide9

Canadian Changes

“If radio astronomy is so important to you, why aren’t you in Ottawa telling us?” Vasilius

Mimis (Industry Canada – Ottawa). We had to become lobbyists too.We had to exploit our unique advantages: “we are all civil servants”, and we can tell where our numbers come from. “Radio Astronomy for Spectrum Managers”We needed to get much more involved in spectrum management at all levels, including regular participation as members of the Canadian Delegation to Geneva.

We needed to communicate better within our community.

We needed to be able to see what was coming down the tube before someone deploys it.Slide10

Other Big Changes

Emphasis is shifting to networks of low-power, mobile devices deployed in large numbers (e.g.

Mobile Phones).WiFi everywhere, including in the air.Smart meters and other networked, low-power, fixed devices.Collision avoidance radars and other radio devices on cars.We needed to be able to see what was coming down the tube before someone deploys it.

The

Noise Floor due to large numbers of low-power devices all operating perfectly legally.

In radio astronomy, increased need to observe (as possible) outside frequency bands allocated for radio astronomy (e.g. CHIME).Slide11

What You Can Pick Up at DRAO

(Part of a spectrum monitoring project by John Galt)Slide12

A clean radio spectrum in which to observe is as much a national facility for radio astronomy as is a radio telescope. Unfortunately, that message is not always getting

across, even to radio astronomers.Slide13

The Radio Astronomy Problem

Radio astronomical signals are very weak. A cell phone on the Moon would be the brightest radio source in the sky, and a cell phone on Mars would be detectable using our 26m radio telescope.

Almost all manmade signals are stronger than this.Although frequency bands are specified in the ITU Radio Regulations for radio astronomical use, untended emissions by radio or other electronic devices may be radiated into radio astronomy bands. This problem may be exacerbated by engineering shortcomings, incorrect installation, deployment in the wrong place or damage (e.g.

coffee spilt on it).

Manufacturer testing may be legal but still inadequate.

The total emission from a lot of devices individually too weak to interfere significantly to radio astronomy may collectively add up to a problem that may be hard to deal with.Slide14

Protecting a Radio Observatory

Establish threat criteria: what are we looking for?Establish spectrum monitoring

programmesEstablish a stable and consistent staff supportEstablish protocols for dealing with external interferenceEstablish protocols for dealing with self-inflicted interferenceBe equipped to meaningfully do these thingsEstablish working relationships with spectrum

managers. Educate them.

Get involved in spectrum management, locally, regionally, nationally and internationally

The effort must be consistent and on-going.Slide15

World Radio Conference - GenevaSlide16

The Big Red BookSlide17

Extracts from the Radio RegulationsSlide18

DRAO Radio Protection Zone

a

This zone has been the basis of the spectrum management effort between the Kelowna Office of Industry Canada and the Observatory for more than two decades.Slide19

Transportable and Mobile Station

ICOM F2721D UHF Transceiver

Bird Wattmeter and Return Loss Monitor

Transportable Station transmissions are made using the calibrated dipole antenna. Mobile Station transmissions are made using a whip antenna on the van roof.

Transmission Positions are Determined using a GPS Receiver and in the case of the Mobile Transmissions, Logged Automatically on a Laptop PC

Calibrated Dipole AntennaSlide20

Observatory Equipment Configuration

Amplifier

Splitter

Directional Coupler

Calibration Signal from Precision Signal Generator (

ifr

2023B)

Amplifier

ifr COM-120B Panoramic Receiver/Spectrum Analyzer

Rohde & Schwartz FSP Panoramic Receiver/Spectrum Analyzer

Spectrum Explorer Smart Receiver/Spectrum Monitoring System Slide21

Comparison of Calculated and Measured Path Losses for Fixed Locations

Calculated Path Loss (dB)

Measured Path Loss (dB)

Location

PREDICT

Longley Rice

Median

Std. Dev.

L3

208

187

160

3

L4

215

190

171

2

L5

184

165

154

3

L6

200

165

129

3

L7

208

172

145

3

L8

196

170

149

4

L9

191

175

160

4

L10

191

180

168

3

L11

176

170

153

5Slide22

Revised ZoneSlide23

The Quinn Machine: A Pathfinder Project

A sofware-defined-radio based system that can be tuned over a wide range (70 MHz –

6 GHz).Variable bandwidth (up to only 5 MHz unfortunately).Can record and display power levels and spectra.Can be set up to demodulate most signal types, in order to identify interference sources.Can run automatically for long periods.Slide24

Quinn MachineSlide25

The Aether SnifferSlide26

Who’s Going to Win?

OTHER SPECTRUM USERS

RADIO SPECTRUM MANAGEMENT IS DONE BY EXPERTS WHO MELD YEARS OF EXPERIENCE WITH A CURIOUS BLEND OF REGULATIONS, ELECTRONICS, POLITICS AND NOT A LITTLE BIT OF LARCENY. THEY JUSTIFY REQUIREMENTS, HORSE-TRADE, COERCE, BLUFF AND GAMBLE WITH AN INTUITION THAT CANNOT BE TAUGHT OTHER THAN BY LONG EXPERIENCE.Vice-Admiral Jon L. Boyes, U.S. NAVY

RADIO ASTRONOMERS

I’M GLAD SOMEONE IS DOING IT, BUT I AM TOO BUSY DOING MY SCIENCE.

One of only two identical replies when I sought guidance from the Canadian astronomical community before heading to an international spectrum management meeting. The scientists in question shall remain anonymous.Slide27

Touching the Tar BabySlide28

END SLIDESlide29

The Issues

New radio services are being implemented. They require spectrum space in which to operate, and are likely to produce unwanted radio emissions that may cause problems for radio astronomers, as well as other spectrum users.

The sheer number of radio devices in everyday use is rocketing, meaning that low, legal levels of interference from individual devices may add up to a significant interference problem due to the aggregate emission from many devices.Radio astronomical instrumentation is changing, from (radio-quiet) analogue systems to predominantly digital (radio-noisy) ones.Spectrum politics is becoming much more aggressive, requiring more radio astronomers to participate in this process, taking them away from science and instrumentation development. Many astronomers and observatory managers still don’t appreciate the magnitude of the problem or the need to invest in addressing it. Even here at DRAO protecting the observatory’s function through spectrum monitoring and management has been patchy, mainly based on the action of dedicated individuals, and we’re among the better observatories in this regard.Slide30

Protecting DRAO’s Key Asset

Electromagnetic Hygiene starts at home. How much of our interference is caused by us? What can be done about it?How do we identify sources of interference when they arise.

Working with local, regional and national spectrum managers, and our part in international spectrum management.The DRAO Radio Quiet ZoneSlide31

DRAO Issues

DRAO’s main asset is its low interference site.This quality has to be available over as much as possible of the spectrum of interest to radio astronomers.

We need to identify any issues occurring in bands allocated in the ITU Radio Regulations for radio astronomy .We need to know what other parts of the radio spectrum might be available for opportunistic observing.We need to know what is changing in that environment and to assess the threat potential of any new deployments.Slide32

DRAO Measures

To have on-site spectrum monitoring programmes

covering the full frequency range of astronomical interest.To have the means to demodulate or decode interfering signals to a point where they can be identified.To monitor background noise levels over the spectrum – monitoring possible degradation.To liaise with Industry Canada regarding protection requirements, problem identification and assessment of problem potential for new proposed deployments.To help maintain the DRAO Protection ZoneSlide33

Electromagnetic Hygiene Begins at HomeSlide34

Checking The Zone

The original DRAO Protection Zone had been in place for at least two decades. In that area, spectrum demands have increased.

Are the current restrictions too restrictive, and could be relaxed without impacting us while making room for others? Or not?A recent joint project was conducted in collaboration with Industry Canada to evaluate the zone and to redefine it.The study was done in the 406-410 MHz band, since this one is shared with other services (not purely radio astronomy), so the interference potential is much higher. These other services operate under the restriction that they do not interfere with radio astronomy.Slide35

The Procedure

To make transmissions at 408 MHz at a known power, with an antenna of known properties, from various positions in the Southern Okanagan and elsewhere, and measuring the strength of the received signal at DRAO.

Compare the measured path loss with the loss calculated using terrain data and two propagation models: Predict and Longley-Rice.Use these data to redefine the Protection Zone.Slide36

Basic Measurement Procedures

“This is Industry Canada testing… testing…This is Industry Canada testing… testing… This is …”

Two Modes

Transportable Base Mode

using the mounted folded dipole as shown (more precise but takes longer),

and

Mobile Mode, using the whip antenna on the van roof (less precise but easy to get lots of data)Signals received by both calibrated dipole and log periodic antennas

Folded Dipole

WhipSlide37

Relocatable Station Measurement Procedure

0

1

2

3

4

Tent Peg

Dipole phase centre 3m above ground and vertical (using plumb line – antenna is not vertical in this shot)

Slight null in antenna beam pattern is always pointed south.

0

1

2

3

4

1

m

North

Process repeated for low (4.5 W), medium (24 W) and high (42 W) transmitter power at 406.9875 MHz. Transmission BW = 15 kHz.

This 5-point measuring procedure is recommended by the ITU-R for fixed-point measurements.

GPS Receiver and Thermometer

qSlide38

Comparison of Calculated and Measured Path Losses for Mobile Transmissions

Note that for the terrain local to DRAO, the models dramatically and consistently overestimate the path loss.Slide39

Conclusions

The propagation models always overestimate the path loss, so they cannot be used alone without generous margins (30dB for Predict, 20dB for Longley-Rice).Even so it did look as though there were places were the restrictions could be relaxed a little without affecting DRAO.Slide40

Quinn Machine

Broadband Antenna

Directional Coupler

Noise Source

Broadband Amplifier

Ettus

B200

sdr ModuleUSB/Fibre ConverterUSB/Fibre Converter

Linux PC Running GNU Radio Software plus some additional modules

In Box on RoofSlide41

ITU Involvements

World Radio ConferenceStudy Group 7 (Science Services)Working Party 7C (Space Passive)

Working Party 7D (Radio Astronomy)Task Group 1/5 (Compatibility Studies)Task Group 1/7 (More Compatibility Studies)Task Group 1/8 (Ultra Wideband Technologies)Task Group 1/9 (Yet More Compatibility Studies)

Member of Canadian Delegation to:

Other Committee Involvements:

Inter-Union Committee for the Allocation of Frequencies – IUCAF (International) - a creature of the International Council of Scientific Unions (ICSU)

Committee on Radioastronomy Frequencies – CORF (A US National Committee under the NSF)

CASCA Radio Astronomy CommitteeSlide42

At the ITU In Geneva

The international radio astronomy crew + a RussianSlide43

INTERFERENCE MONITOR

Cosmic radio emissions are far weaker than almost all manmade radio signals. Therefore we need the most sensitive radio technology to observe them, and we need a low-interference environment. Many radio devices in everyday use can severely interfere with our ability to observe the cosmos.

.

Receiver

Antenna

Interference Display Oscilloscope

Roll Up! TRY YOUR LUCK! Are you an interferer?

GIVE IT A TRY!

If the display on the oscilloscope screen changes at all, the device you’re operating will degrade radio observations of cosmic radio waves, because the sensitivity of the radio telescopes to interference is more than a million times greater than the device in this demonstration.

We can’t imagine modern life without these gadgets, and many others that use radio technology. The only solution is to make sure the devices and the radio telescopes are as far apart as feasible.