Empathy List Archives

JL

Joe Leikhim

Thu, Jan 9, 2014 6:20 AM

Brian;

Regarding mobile jammers..

Many years ago I was faced with finding the cause of sporadic
interference to a new 800 MHz trunked LMR system in Miami. This problem
dogged several engineers and myself for months as the customer was
reluctant to make final payment on the $8million system. The
interference was received nicely by the many remote receivers throughout
the city and disturbed the system audio and caused alarms to be
reported. At street level, little was heard and when heard, it
disappeared quickly. We could get weak intermittent signals from various
rooftops and after a while it became obvious than many emitters were
responsible. Finally I had permission to bring a spectrum analyzer and
antenna aboard a Miami PD helicopter while a co-worker with a spectrum
analyzer took to the streets. About 10 minutes after taking off, I got
a strong hit near a downtown parking lot. My coworker arrived and
confirmed same hit. To make a long story short, it was the local
oscillator of a Motorola MOSTAR radio. The problem was both a design
problem of the mobile radio and more importantly a network design
problem of the trunked system to be unable to deal with the momentary
illegal carriers. (A point I argued with the product manager from the
start).

Once we had the first interfering radio captured, we determined that
they belonged to a radio system two counties away, and whenever they
arrived in Miami, they would scan for a missing control channel and
create havoc. To confirm this, I drove to the other county, and parked
at a major intersection and took note of the commercial vehicles that
drove by with their LO's leaking. This confirmed the model radio
involved was limited to the one initially found.

This is documented in Chapter 2.7 of Gary C. Hess' book titled "Land
Mobile Radio System Engineering. "

GPS jamming, intentional or not is pretty serious, and the FCC takes this seriously, but unless you have some pretty hard evidence they may not find it.

If you have the time and equipment, you should monitor the L1 frequency from a high vantage point with a spectrum analyser to see if either it is a fixed emitter or mobile. If the latter, I would suggest doing as I did, set up a monitoring point at a traffic choke point to see if mobiles drive by that are emitting energy.

A possible source is harmonic energy from mobile radio transmitters in the VHF, UHF, 700 and 800 MHz bands, or strong fundamental energy overloading the amplifed antenna to the point harmonics occur, or the MMIC amplifer is saturated.

Someone on timenuts mentioned a GPS vendor who made a metal shield can to put over the GPS antenna that was essentially a waveguide slot/ bandpass filter. It was to test for out of band interference. This you might try at one or two sites.

--
Joe Leikhim

Leikhim and Associates

Communications Consultants

Oviedo, Florida

JLeikhim@Leikhim.com

407-982-0446

WWW.LEIKHIM.COM

Brian; Regarding mobile jammers.. Many years ago I was faced with finding the cause of sporadic interference to a new 800 MHz trunked LMR system in Miami. This problem dogged several engineers and myself for months as the customer was reluctant to make final payment on the $8million system. The interference was received nicely by the many remote receivers throughout the city and disturbed the system audio and caused alarms to be reported. At street level, little was heard and when heard, it disappeared quickly. We could get weak intermittent signals from various rooftops and after a while it became obvious than _many_ emitters were responsible. Finally I had permission to bring a spectrum analyzer and antenna aboard a Miami PD helicopter while a co-worker with a spectrum analyzer took to the streets. About 10 minutes after taking off, I got a strong hit near a downtown parking lot. My coworker arrived and confirmed same hit. To make a long story short, it was the local oscillator of a Motorola MOSTAR radio. The problem was both a design problem of the mobile radio and more importantly a network design problem of the trunked system to be unable to deal with the momentary illegal carriers. (A point I argued with the product manager from the start). Once we had the first interfering radio captured, we determined that they belonged to a radio system two counties away, and whenever they arrived in Miami, they would scan for a missing control channel and create havoc. To confirm this, I drove to the other county, and parked at a major intersection and took note of the commercial vehicles that drove by with their LO's leaking. This confirmed the model radio involved was limited to the one initially found. This is documented in Chapter 2.7 of Gary C. Hess' book titled "Land Mobile Radio System Engineering. " GPS jamming, intentional or not is pretty serious, and the FCC takes this seriously, but unless you have some pretty hard evidence they may not find it. If you have the time and equipment, you should monitor the L1 frequency from a high vantage point with a spectrum analyser to see if either it is a fixed emitter or mobile. If the latter, I would suggest doing as I did, set up a monitoring point at a traffic choke point to see if mobiles drive by that are emitting energy. A possible source is harmonic energy from mobile radio transmitters in the VHF, UHF, 700 and 800 MHz bands, or strong fundamental energy overloading the amplifed antenna to the point harmonics occur, or the MMIC amplifer is saturated. Someone on timenuts mentioned a GPS vendor who made a metal shield can to put over the GPS antenna that was essentially a waveguide slot/ bandpass filter. It was to test for out of band interference. This you might try at one or two sites. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM

BL

Brian Lloyd

Thu, Jan 9, 2014 2:46 PM

On 1/9/14 12:20 AM, Joe Leikhim wrote:

GPS jamming, intentional or not is pretty serious, and the FCC takes
this seriously, but unless you have some pretty hard evidence they may
not find it.

In my case my most interesting outage was when I lost all GPS while over
the Atlantic ocean between Haiti and the island of Great Inagua in the
Bahamas. It is a bit difficult to stop and look around while flying at
8,500'. I took it for a general GPS outage but now I suspect jamming.

When I was living on my boat in the Virgin Islands (I built a WiFi-based
WISP for marinas and anchorages in the USVI) the US Customs interdiction
boat was only about 4 slips away from me. I often talked with the agents
either going out or coming back from "a run". (You do NOT want to screw
with these guys! They are armed to the teeth!) I now realize that they
would jam GPS so that the druggies couldn't get their drops right. (They
also admitted that, most of the time, they couldn't find the drug
runners' boats anyway and figured they got less than 5% of what they
were after. So much for the "War on Drugs.")

The US Coast Guard had (has?) a base on Great Inagua. They run a fleet
of helicopters out of there for ______________ (redacted - read between
the lines). I got a kick how, when they were coming and going, they
would announce their movements to other aircraft using a civil ID rather
than their military flight ID. At this point I suspect I may have been
shadowed and my GPS jammed. Thank god my airplane still had an LF/MF
automatic direction finder (ADF) aboard. I was able to fall back to
navigating using the non-directional LF beacon on Great Inagua. After
refueling at Great Inagua I continued on sans GPS for nearly 100mi when

POOF< GPS suddenly came back on.

I wonder what the FCC does if it discovers it is another governmental
agency that is doing the jamming? ;-)

I must admit, I like the idea of multi-system sensors that will track
GPS, GLONASS, and (hopefully) Galileo and the Chinese satellite-based
navigation system that is going up. For that matter, is anyone running
one of the new multi-system receivers? I notice that Garmin is selling
them as a matter of course now. The prevalence of jamming might be the
reason why.

--

Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070 USA
brian@lloyd.com
+1.916.877.5067

On 1/9/14 12:20 AM, Joe Leikhim wrote: > > GPS jamming, intentional or not is pretty serious, and the FCC takes > this seriously, but unless you have some pretty hard evidence they may > not find it. In my case my most interesting outage was when I lost all GPS while over the Atlantic ocean between Haiti and the island of Great Inagua in the Bahamas. It is a bit difficult to stop and look around while flying at 8,500'. I took it for a general GPS outage but now I suspect jamming. When I was living on my boat in the Virgin Islands (I built a WiFi-based WISP for marinas and anchorages in the USVI) the US Customs interdiction boat was only about 4 slips away from me. I often talked with the agents either going out or coming back from "a run". (You do NOT want to screw with these guys! They are armed to the teeth!) I now realize that they would jam GPS so that the druggies couldn't get their drops right. (They also admitted that, most of the time, they couldn't find the drug runners' boats anyway and figured they got less than 5% of what they were after. So much for the "War on Drugs.") The US Coast Guard had (has?) a base on Great Inagua. They run a fleet of helicopters out of there for ______________ (redacted - read between the lines). I got a kick how, when they were coming and going, they would announce their movements to other aircraft using a civil ID rather than their military flight ID. At this point I suspect I may have been shadowed and my GPS jammed. Thank god my airplane still had an LF/MF automatic direction finder (ADF) aboard. I was able to fall back to navigating using the non-directional LF beacon on Great Inagua. After refueling at Great Inagua I continued on sans GPS for nearly 100mi when >POOF< GPS suddenly came back on. I wonder what the FCC does if it discovers it is another governmental agency that is doing the jamming? ;-) I must admit, I like the idea of multi-system sensors that will track GPS, GLONASS, and (hopefully) Galileo and the Chinese satellite-based navigation system that is going up. For that matter, is anyone running one of the new multi-system receivers? I notice that Garmin is selling them as a matter of course now. The prevalence of jamming might be the reason why. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 USA brian@lloyd.com +1.916.877.5067

GZ

Graeme Zimmer

Thu, Jan 9, 2014 11:35 PM

Hi Brian,

Thanks for the fascinating story!

For that matter, is anyone running one of the new multi-system receivers?

I hope to play with Resolution SMT GG which is the Multi-GNSS version of
the Desolution SMT.

What I'm keen to find out is which of the standard GPS diagnostic
software also handles the newer satelites (GLONASS, QZSS, SBAS, etc) or
whether specialist software is needed.

Anybody know?

Thanks ........... Zim

Hi Brian, Thanks for the fascinating story! > For that matter, is anyone running one of the new multi-system receivers? I hope to play with Resolution SMT GG which is the Multi-GNSS version of the Desolution SMT. What I'm keen to find out is which of the standard GPS diagnostic software also handles the newer satelites (GLONASS, QZSS, SBAS, etc) or whether specialist software is needed. Anybody know? Thanks ........... Zim

JL

J. L. Trantham

Fri, Jan 10, 2014 1:53 AM

I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396)
when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit
loses its position. I think it is related to some 'spur' related to the #1
Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's
GPS antenna with the 'remote' antenna, secured to the windshield, all the
problems go away.

I think it is a 'spur' of the appropriate magnitude when the 'portable'
antenna is still installed.

Joe

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Brian Lloyd
Sent: Thursday, January 09, 2014 8:47 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WAAS.....

On 1/9/14 12:20 AM, Joe Leikhim wrote:

GPS jamming, intentional or not is pretty serious, and the FCC takes
this seriously, but unless you have some pretty hard evidence they may
not find it.

In my case my most interesting outage was when I lost all GPS while over the
Atlantic ocean between Haiti and the island of Great Inagua in the Bahamas.
It is a bit difficult to stop and look around while flying at 8,500'. I took
it for a general GPS outage but now I suspect jamming.

When I was living on my boat in the Virgin Islands (I built a WiFi-based
WISP for marinas and anchorages in the USVI) the US Customs interdiction
boat was only about 4 slips away from me. I often talked with the agents
either going out or coming back from "a run". (You do NOT want to screw with
these guys! They are armed to the teeth!) I now realize that they would jam
GPS so that the druggies couldn't get their drops right. (They also admitted
that, most of the time, they couldn't find the drug runners' boats anyway
and figured they got less than 5% of what they were after. So much for the
"War on Drugs.")

The US Coast Guard had (has?) a base on Great Inagua. They run a fleet of
helicopters out of there for ______________ (redacted - read between the
lines). I got a kick how, when they were coming and going, they would
announce their movements to other aircraft using a civil ID rather than
their military flight ID. At this point I suspect I may have been shadowed
and my GPS jammed. Thank god my airplane still had an LF/MF automatic
direction finder (ADF) aboard. I was able to fall back to navigating using
the non-directional LF beacon on Great Inagua. After refueling at Great
Inagua I continued on sans GPS for nearly 100mi when

POOF< GPS suddenly came back on.

I wonder what the FCC does if it discovers it is another governmental agency
that is doing the jamming? ;-)

I must admit, I like the idea of multi-system sensors that will track GPS,
GLONASS, and (hopefully) Galileo and the Chinese satellite-based navigation
system that is going up. For that matter, is anyone running one of the new
multi-system receivers? I notice that Garmin is selling them as a matter of
course now. The prevalence of jamming might be the reason why.

--

Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070 USA
brian@lloyd.com
+1.916.877.5067

time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396) when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit loses its position. I think it is related to some 'spur' related to the #1 Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's GPS antenna with the 'remote' antenna, secured to the windshield, all the problems go away. I think it is a 'spur' of the appropriate magnitude when the 'portable' antenna is still installed. Joe -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Brian Lloyd Sent: Thursday, January 09, 2014 8:47 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WAAS..... On 1/9/14 12:20 AM, Joe Leikhim wrote: > > GPS jamming, intentional or not is pretty serious, and the FCC takes > this seriously, but unless you have some pretty hard evidence they may > not find it. In my case my most interesting outage was when I lost all GPS while over the Atlantic ocean between Haiti and the island of Great Inagua in the Bahamas. It is a bit difficult to stop and look around while flying at 8,500'. I took it for a general GPS outage but now I suspect jamming. When I was living on my boat in the Virgin Islands (I built a WiFi-based WISP for marinas and anchorages in the USVI) the US Customs interdiction boat was only about 4 slips away from me. I often talked with the agents either going out or coming back from "a run". (You do NOT want to screw with these guys! They are armed to the teeth!) I now realize that they would jam GPS so that the druggies couldn't get their drops right. (They also admitted that, most of the time, they couldn't find the drug runners' boats anyway and figured they got less than 5% of what they were after. So much for the "War on Drugs.") The US Coast Guard had (has?) a base on Great Inagua. They run a fleet of helicopters out of there for ______________ (redacted - read between the lines). I got a kick how, when they were coming and going, they would announce their movements to other aircraft using a civil ID rather than their military flight ID. At this point I suspect I may have been shadowed and my GPS jammed. Thank god my airplane still had an LF/MF automatic direction finder (ADF) aboard. I was able to fall back to navigating using the non-directional LF beacon on Great Inagua. After refueling at Great Inagua I continued on sans GPS for nearly 100mi when >POOF< GPS suddenly came back on. I wonder what the FCC does if it discovers it is another governmental agency that is doing the jamming? ;-) I must admit, I like the idea of multi-system sensors that will track GPS, GLONASS, and (hopefully) Galileo and the Chinese satellite-based navigation system that is going up. For that matter, is anyone running one of the new multi-system receivers? I notice that Garmin is selling them as a matter of course now. The prevalence of jamming might be the reason why. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 USA brian@lloyd.com +1.916.877.5067 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

BL

Brian Lloyd

Fri, Jan 10, 2014 4:14 AM

On 1/9/14 7:53 PM, J. L. Trantham wrote:

I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396)
when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit
loses its position. I think it is related to some 'spur' related to the #1
Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's
GPS antenna with the 'remote' antenna, secured to the windshield, all the
problems go away.

I think it is a 'spur' of the appropriate magnitude when the 'portable'
antenna is still installed.

Before a panel-mount GPS in an airplane may be used for IFR (instrument) flight
it must be tested with the comm radios set to a number of harmonically-related
frequencies to ensure there is no interference with the GPS signal and then
signed off.

So, yes, it is very likely a harmonic of one of your comm radios was jamming the
GPS.

--
Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067

On 1/9/14 7:53 PM, J. L. Trantham wrote: > I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396) > when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit > loses its position. I think it is related to some 'spur' related to the #1 > Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's > GPS antenna with the 'remote' antenna, secured to the windshield, all the > problems go away. > > I think it is a 'spur' of the appropriate magnitude when the 'portable' > antenna is still installed. Before a panel-mount GPS in an airplane may be used for IFR (instrument) flight it must be tested with the comm radios set to a number of harmonically-related frequencies to ensure there is no interference with the GPS signal and then signed off. So, yes, it is very likely a harmonic of one of your comm radios was jamming the GPS. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 brian@lloyd.com +1.916.877.5067

RA

Robert Atkinson

Fri, Jan 10, 2014 7:48 AM

Hi,
This is a known problem. It's leakage form the local oscillator (LO) of the Ky197. The KYa97 has a 10.7 MHz IF and high side local oscillator. So the LO is 119.9 + 10.7 = 130.6MHz. 12th harmonic is in the GPS bandwith.
Cure is a notch filer on the KY197 antenna connector. examples are a TED 4-70-54 http://www.edmo.com/index.php?module=products&func=display&prod_id=18006 or Telegartner J01006A0017 or make your own with a BNC "T" and a bit of rigid coax (Experimental or permit Acft only :-).

Other radios including VHF Nav have similar issues.

Robert G8RPI
(CEng MRAeS)

From: J. L. Trantham jltran@att.net
To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com
Sent: Friday, 10 January 2014, 1:53
Subject: Re: [time-nuts] WAAS.....

I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396)
when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit
loses its position. I think it is related to some 'spur' related to the #1
Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's
GPS antenna with the 'remote' antenna, secured to the windshield, all the
problems go away.

I think it is a 'spur' of the appropriate magnitude when the 'portable'
antenna is still installed.

Joe

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Brian Lloyd
Sent: Thursday, January 09, 2014 8:47 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WAAS.....

On 1/9/14 12:20 AM, Joe Leikhim wrote:

GPS jamming, intentional or not is pretty serious, and the FCC takes
this seriously, but unless you have some pretty hard evidence they may
not find it.

In my case my most interesting outage was when I lost all GPS while over the
Atlantic ocean between Haiti and the island of Great Inagua in the Bahamas.
It is a bit difficult to stop and look around while flying at 8,500'. I took
it for a general GPS outage but now I suspect jamming.

When I was living on my boat in the Virgin Islands (I built a WiFi-based
WISP for marinas and anchorages in the USVI) the US Customs interdiction
boat was only about 4 slips away from me. I often talked with the agents
either going out or coming back from "a run". (You do NOT want to screw with
these guys! They are armed to the teeth!) I now realize that they would jam
GPS so that the druggies couldn't get their drops right. (They also admitted
that, most of the time, they couldn't find the drug runners' boats anyway
and figured they got less than 5% of what they were after. So much for the
"War on Drugs.")

The US Coast Guard had (has?) a base on Great Inagua. They run a fleet of
helicopters out of there for ______________ (redacted - read between the
lines). I got a kick how, when they were coming and going, they would
announce their movements to other aircraft using a civil ID rather than
their military flight ID. At this point I suspect I may have been shadowed
and my GPS jammed. Thank god my airplane still had an LF/MF automatic
direction finder (ADF) aboard. I was able to fall back to navigating using
the non-directional LF beacon on Great Inagua. After refueling at Great
Inagua I continued on sans GPS for nearly 100mi when

POOF< GPS suddenly came back on.

I wonder what the FCC does if it discovers it is another governmental agency
that is doing the jamming? ;-)

I must admit, I like the idea of multi-system sensors that will track GPS,
GLONASS, and (hopefully) Galileo and the Chinese satellite-based navigation
system that is going up. For that matter, is anyone running one of the new
multi-system receivers? I notice that Garmin is selling them as a matter of
course now. The prevalence of jamming might be the reason why.

--

Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070 USA
brian@lloyd.com
+1.916.877.5067

time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi, This is a known problem. It's leakage form the local oscillator (LO) of the Ky197. The KYa97 has a 10.7 MHz IF and high side local oscillator. So the LO is 119.9 + 10.7 = 130.6MHz. 12th harmonic is in the GPS bandwith. Cure is a notch filer on the KY197 antenna connector. examples are a TED 4-70-54 http://www.edmo.com/index.php?module=products&func=display&prod_id=18006 or Telegartner J01006A0017 or make your own with a BNC "T" and a bit of rigid coax (Experimental or permit Acft only :-). Other radios including VHF Nav have similar issues. Robert G8RPI (CEng MRAeS) ________________________________ From: J. L. Trantham <jltran@att.net> To: 'Discussion of precise time and frequency measurement' <time-nuts@febo.com> Sent: Friday, 10 January 2014, 1:53 Subject: Re: [time-nuts] WAAS..... I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396) when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit loses its position. I think it is related to some 'spur' related to the #1 Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's GPS antenna with the 'remote' antenna, secured to the windshield, all the problems go away. I think it is a 'spur' of the appropriate magnitude when the 'portable' antenna is still installed. Joe -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Brian Lloyd Sent: Thursday, January 09, 2014 8:47 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WAAS..... On 1/9/14 12:20 AM, Joe Leikhim wrote: > > GPS jamming, intentional or not is pretty serious, and the FCC takes > this seriously, but unless you have some pretty hard evidence they may > not find it. In my case my most interesting outage was when I lost all GPS while over the Atlantic ocean between Haiti and the island of Great Inagua in the Bahamas. It is a bit difficult to stop and look around while flying at 8,500'. I took it for a general GPS outage but now I suspect jamming. When I was living on my boat in the Virgin Islands (I built a WiFi-based WISP for marinas and anchorages in the USVI) the US Customs interdiction boat was only about 4 slips away from me. I often talked with the agents either going out or coming back from "a run". (You do NOT want to screw with these guys! They are armed to the teeth!) I now realize that they would jam GPS so that the druggies couldn't get their drops right. (They also admitted that, most of the time, they couldn't find the drug runners' boats anyway and figured they got less than 5% of what they were after. So much for the "War on Drugs.") The US Coast Guard had (has?) a base on Great Inagua. They run a fleet of helicopters out of there for ______________ (redacted - read between the lines). I got a kick how, when they were coming and going, they would announce their movements to other aircraft using a civil ID rather than their military flight ID. At this point I suspect I may have been shadowed and my GPS jammed. Thank god my airplane still had an LF/MF automatic direction finder (ADF) aboard. I was able to fall back to navigating using the non-directional LF beacon on Great Inagua. After refueling at Great Inagua I continued on sans GPS for nearly 100mi when >POOF< GPS suddenly came back on. I wonder what the FCC does if it discovers it is another governmental agency that is doing the jamming? ;-) I must admit, I like the idea of multi-system sensors that will track GPS, GLONASS, and (hopefully) Galileo and the Chinese satellite-based navigation system that is going up. For that matter, is anyone running one of the new multi-system receivers? I notice that Garmin is selling them as a matter of course now. The prevalence of jamming might be the reason why. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 USA brian@lloyd.com +1.916.877.5067 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

JL

J. L. Trantham

Fri, Jan 10, 2014 12:52 PM

Robert,

Thought as much but hadn't researched it. The next time it goes into
annual, I'll see if I can get them to install the filter on the KY197. I
haven't tried tuning the #2 Nav/Com, a KX165, to see if the same problem
arises there as well. Perhaps the KX165 has a better behaved LO.

As I said, just installing the 'remote' antenna on the GPSMAP 396, which
brings a much stronger GPS signal, solves the problem as well.

Thanks again.

Joe

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Robert Atkinson
Sent: Friday, January 10, 2014 1:49 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WAAS.....

Hi,
This is a known problem. It's leakage form the local oscillator (LO) of the
Ky197. The KYa97 has a 10.7 MHz IF and high side local oscillator. So the LO
is 119.9 + 10.7 = 130.6MHz. 12th harmonic is in the GPS bandwith.
Cure is a notch filer on the KY197 antenna connector. examples are a TED
4-70-54
http://www.edmo.com/index.php?module=products&func=display&prod_id=18006 or
Telegartner J01006A0017 or make your own with a BNC "T" and a bit of rigid
coax (Experimental or permit Acft only :-).

Other radios including VHF Nav have similar issues.

Robert G8RPI
(CEng MRAeS)

From: J. L. Trantham jltran@att.net
To: 'Discussion of precise time and frequency measurement'
time-nuts@febo.com
Sent: Friday, 10 January 2014, 1:53
Subject: Re: [time-nuts] WAAS.....

I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396)
when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit
loses its position. I think it is related to some 'spur' related to the #1
Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's
GPS antenna with the 'remote' antenna, secured to the windshield, all the
problems go away.

I think it is a 'spur' of the appropriate magnitude when the 'portable'
antenna is still installed.

Joe

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Brian Lloyd
Sent: Thursday, January 09, 2014 8:47 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WAAS.....

On 1/9/14 12:20 AM, Joe Leikhim wrote:

GPS jamming, intentional or not is pretty serious, and the FCC takes
this seriously, but unless you have some pretty hard evidence they may
not find it.

In my case my most interesting outage was when I lost all GPS while over the
Atlantic ocean between Haiti and the island of Great Inagua in the Bahamas.
It is a bit difficult to stop and look around while flying at 8,500'. I took
it for a general GPS outage but now I suspect jamming.

When I was living on my boat in the Virgin Islands (I built a WiFi-based
WISP for marinas and anchorages in the USVI) the US Customs interdiction
boat was only about 4 slips away from me. I often talked with the agents
either going out or coming back from "a run". (You do NOT want to screw with
these guys! They are armed to the teeth!) I now realize that they would jam
GPS so that the druggies couldn't get their drops right. (They also admitted
that, most of the time, they couldn't find the drug runners' boats anyway
and figured they got less than 5% of what they were after. So much for the
"War on Drugs.")

The US Coast Guard had (has?) a base on Great Inagua. They run a fleet of
helicopters out of there for ______________ (redacted - read between the
lines). I got a kick how, when they were coming and going, they would
announce their movements to other aircraft using a civil ID rather than
their military flight ID. At this point I suspect I may have been shadowed
and my GPS jammed. Thank god my airplane still had an LF/MF automatic
direction finder (ADF) aboard. I was able to fall back to navigating using
the non-directional LF beacon on Great Inagua. After refueling at Great
Inagua I continued on sans GPS for nearly 100mi when

POOF< GPS suddenly came back on.

I wonder what the FCC does if it discovers it is another governmental agency
that is doing the jamming? ;-)

I must admit, I like the idea of multi-system sensors that will track GPS,
GLONASS, and (hopefully) Galileo and the Chinese satellite-based navigation
system that is going up. For that matter, is anyone running one of the new
multi-system receivers? I notice that Garmin is selling them as a matter of
course now. The prevalence of jamming might be the reason why.

--

Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070 USA
brian@lloyd.com
+1.916.877.5067

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Robert, Thought as much but hadn't researched it. The next time it goes into annual, I'll see if I can get them to install the filter on the KY197. I haven't tried tuning the #2 Nav/Com, a KX165, to see if the same problem arises there as well. Perhaps the KX165 has a better behaved LO. As I said, just installing the 'remote' antenna on the GPSMAP 396, which brings a much stronger GPS signal, solves the problem as well. Thanks again. Joe -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Robert Atkinson Sent: Friday, January 10, 2014 1:49 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WAAS..... Hi, This is a known problem. It's leakage form the local oscillator (LO) of the Ky197. The KYa97 has a 10.7 MHz IF and high side local oscillator. So the LO is 119.9 + 10.7 = 130.6MHz. 12th harmonic is in the GPS bandwith. Cure is a notch filer on the KY197 antenna connector. examples are a TED 4-70-54 http://www.edmo.com/index.php?module=products&func=display&prod_id=18006 or Telegartner J01006A0017 or make your own with a BNC "T" and a bit of rigid coax (Experimental or permit Acft only :-). Other radios including VHF Nav have similar issues. Robert G8RPI (CEng MRAeS) ________________________________ From: J. L. Trantham <jltran@att.net> To: 'Discussion of precise time and frequency measurement' <time-nuts@febo.com> Sent: Friday, 10 January 2014, 1:53 Subject: Re: [time-nuts] WAAS..... I have had loss of GPS position on a 'hand-held' unit (Garmin GPSMAP 396) when flying into PNS. When I switch to tower frequency (119.9 MHz) the unit loses its position. I think it is related to some 'spur' related to the #1 Nav/Com (King KY197) being tuned to that frequency. If I replace the unit's GPS antenna with the 'remote' antenna, secured to the windshield, all the problems go away. I think it is a 'spur' of the appropriate magnitude when the 'portable' antenna is still installed. Joe -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Brian Lloyd Sent: Thursday, January 09, 2014 8:47 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WAAS..... On 1/9/14 12:20 AM, Joe Leikhim wrote: > > GPS jamming, intentional or not is pretty serious, and the FCC takes > this seriously, but unless you have some pretty hard evidence they may > not find it. In my case my most interesting outage was when I lost all GPS while over the Atlantic ocean between Haiti and the island of Great Inagua in the Bahamas. It is a bit difficult to stop and look around while flying at 8,500'. I took it for a general GPS outage but now I suspect jamming. When I was living on my boat in the Virgin Islands (I built a WiFi-based WISP for marinas and anchorages in the USVI) the US Customs interdiction boat was only about 4 slips away from me. I often talked with the agents either going out or coming back from "a run". (You do NOT want to screw with these guys! They are armed to the teeth!) I now realize that they would jam GPS so that the druggies couldn't get their drops right. (They also admitted that, most of the time, they couldn't find the drug runners' boats anyway and figured they got less than 5% of what they were after. So much for the "War on Drugs.") The US Coast Guard had (has?) a base on Great Inagua. They run a fleet of helicopters out of there for ______________ (redacted - read between the lines). I got a kick how, when they were coming and going, they would announce their movements to other aircraft using a civil ID rather than their military flight ID. At this point I suspect I may have been shadowed and my GPS jammed. Thank god my airplane still had an LF/MF automatic direction finder (ADF) aboard. I was able to fall back to navigating using the non-directional LF beacon on Great Inagua. After refueling at Great Inagua I continued on sans GPS for nearly 100mi when >POOF< GPS suddenly came back on. I wonder what the FCC does if it discovers it is another governmental agency that is doing the jamming? ;-) I must admit, I like the idea of multi-system sensors that will track GPS, GLONASS, and (hopefully) Galileo and the Chinese satellite-based navigation system that is going up. For that matter, is anyone running one of the new multi-system receivers? I notice that Garmin is selling them as a matter of course now. The prevalence of jamming might be the reason why. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 USA brian@lloyd.com +1.916.877.5067 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

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Re: [time-nuts] WAAS.....