Bicentennial GOES satellite clock
In message 96e995c4-5ca2-af02-9738-0a6d87a9f813@pacific.net, Brooke Clarke writes:
But it's extremely hard to make a jammer for WWVB (60 kHz) [...]
You can do it city-scale with a 18-wheeler sized loop-antenna
and a good size diesel-generator.
However pedestrians will very likely note metalic items vibrating
as they pass the "mystery white truck".
Sweden were much more serious about it:
http://www.antus.org/RT02.html
Tl;drs:
They erected 9 200m tall Loran-C class antennas each driven by
a Loran-C transmitter with an advanced degree which could jam
Loran-C or Chayka.
They even mounted decoy parabolas on the towers them to hide their
true purpose.
The fact that all the transmitters were on the east coast does drop
a hint that swedens much touted neutrality had a bit of a slant.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
As Brooke notes while low frequency jammers are possible, practicality is another matter, All it takes to jam a city scale area is a box the size of a pack of cigarettes. Because the GPS signal is very, very weak.
As an intentional denial put a couple hundred on stray animals. Now track those jammers down.
I doubt if any agency owns enough DF equipment to find them all in a reasonable amount of time.
Thats why we need backup systems and each backup system will have less and less accuracy as it increases in robustness. The HF systems could provide adequate syncing for the Market example.
On Aug 30, 2018, at 6:18 PM, Poul-Henning Kamp phk@phk.freebsd.dk wrote:
In message 96e995c4-5ca2-af02-9738-0a6d87a9f813@pacific.net, Brooke Clarke writes:
But it's extremely hard to make a jammer for WWVB (60 kHz) [...]
You can do it city-scale with a 18-wheeler sized loop-antenna
and a good size diesel-generator.
However pedestrians will very likely note metalic items vibrating
as they pass the "mystery white truck".
Sweden were much more serious about it:
http://www.antus.org/RT02.html
Tl;drs:
They erected 9 200m tall Loran-C class antennas each driven by
a Loran-C transmitter with an advanced degree which could jam
Loran-C or Chayka.
They even mounted decoy parabolas on the towers them to hide their
true purpose.
The fact that all the transmitters were on the east coast does drop
a hint that swedens much touted neutrality had a bit of a slant.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke brooke@pacific.net wrote:
I would disagree in that ease of jamming/spoofing is strongly related to wavelength. That's because antenna efficiency
goes down as the size of the antenna gets smaller than 1/4 wave.
So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength is a few inches, something that you can
hold in your hand.
However, the short wavelengths of GPS make beam forming a reasonable
countermeasure against jamming.
By having a small array of GPS antennas a receiver can digitally form
beams that both aim directly at the relevant satellites (so even
reducing intersatellite interference) while also steering a deep null
in the direction of the jammer. If the jammer is powerful enough to
overload the front-end then this won't help, but against a
non-targeted area denying jammer it should be fairly effective.
There are many papers on GNSS beamforming. ( e.g.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ )
This kind of anti-jamming solution should even be pretty inexpensive
-- really no more than the cost of N receivers. Except that it is
specialized technology and thus very expensive. :)
Seeing some open source software implementing beam-forming was one of
the things I hoped to see result from the open hardware multi-band
GNSS receivers like the GNSS firehose project (
http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once
you're going through the trouble of running three coherent receivers
for three bands, stacking three more of them and locking them to the
same clock doesn't seem like a big engineering challenge... and the
rest is just DSP work.
Even absent fancy beam forming, for GNSS timing with a surveyed
position except at high latitudes it should be possible to use a
relatively high gain antenna pointed straight up and by doing so blind
yourself to terrestrial jammers at a cost of fewer SVs being
available. But I've never tried it.
In an urban area I noticed my own GPSDOs losing signal multiple times
per week. Monitoring with an SDR showed what appeared to be jammers.
As others have noted intermittent jamming is pretty benign to a GPSDO.
Spoofing, OTOH, can trivially mess up the timing. It's my view that
if you need timing for a security critical purpose there isn't really
any GNSS based solution commercially available to the general public
right now, the best bet is a local atomic reference with a GPSDO used
to monitor and initially set it.
Is there a translation of this anywhere?
Don
Sweden were much more serious about it:
http://www.antus.org/RT02.html
Tl;drs:
They erected 9 200m tall Loran-C class antennas each driven by
a Loran-C transmitter with an advanced degree which could jam
Loran-C or Chayka.
They even mounted decoy parabolas on the towers them to hide their
true purpose.
The fact that all the transmitters were on the east coast does drop
a hint that swedens much touted neutrality had a bit of a slant.
--
Dr. Don Latham
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
Before retiring I did some field work on the Tomahawk AGR
(https://www.raytheon.com/capabilities/products/gps_anti-jam)
Wes N7WS
On 8/30/2018 4:05 PM, Gregory Maxwell wrote:
However, the short wavelengths of GPS make beam forming a reasonable
countermeasure against jamming.
Hi
Actually it’s pretty simple to track down that sort of jammer ….. and yes, the gear to do it
is out there in quantity.
Bob
On Aug 30, 2018, at 6:51 PM, Scott McGrath scmcgrath@gmail.com wrote:
As Brooke notes while low frequency jammers are possible, practicality is another matter, All it takes to jam a city scale area is a box the size of a pack of cigarettes. Because the GPS signal is very, very weak.
As an intentional denial put a couple hundred on stray animals. Now track those jammers down.
I doubt if any agency owns enough DF equipment to find them all in a reasonable amount of time.
Thats why we need backup systems and each backup system will have less and less accuracy as it increases in robustness. The HF systems could provide adequate syncing for the Market example.
On Aug 30, 2018, at 6:18 PM, Poul-Henning Kamp phk@phk.freebsd.dk wrote:
In message 96e995c4-5ca2-af02-9738-0a6d87a9f813@pacific.net, Brooke Clarke writes:
But it's extremely hard to make a jammer for WWVB (60 kHz) [...]
You can do it city-scale with a 18-wheeler sized loop-antenna
and a good size diesel-generator.
However pedestrians will very likely note metalic items vibrating
as they pass the "mystery white truck".
Sweden were much more serious about it:
http://www.antus.org/RT02.html
Tl;drs:
They erected 9 200m tall Loran-C class antennas each driven by
a Loran-C transmitter with an advanced degree which could jam
Loran-C or Chayka.
They even mounted decoy parabolas on the towers them to hide their
true purpose.
The fact that all the transmitters were on the east coast does drop
a hint that swedens much touted neutrality had a bit of a slant.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Hi
Since timing receivers are actually going to prefer high angle sats, an antenna that rejects
close to the horizon is a pretty common thing. Enhancing that sort of rejection doesn’t take
a lot of effort.
Bob
On Aug 30, 2018, at 7:05 PM, Gregory Maxwell gmaxwell@gmail.com wrote:
On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke brooke@pacific.net wrote:
I would disagree in that ease of jamming/spoofing is strongly related to wavelength. That's because antenna efficiency
goes down as the size of the antenna gets smaller than 1/4 wave.
So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength is a few inches, something that you can
hold in your hand.
However, the short wavelengths of GPS make beam forming a reasonable
countermeasure against jamming.
By having a small array of GPS antennas a receiver can digitally form
beams that both aim directly at the relevant satellites (so even
reducing intersatellite interference) while also steering a deep null
in the direction of the jammer. If the jammer is powerful enough to
overload the front-end then this won't help, but against a
non-targeted area denying jammer it should be fairly effective.
There are many papers on GNSS beamforming. ( e.g.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ )
This kind of anti-jamming solution should even be pretty inexpensive
-- really no more than the cost of N receivers. Except that it is
specialized technology and thus very expensive. :)
Seeing some open source software implementing beam-forming was one of
the things I hoped to see result from the open hardware multi-band
GNSS receivers like the GNSS firehose project (
http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once
you're going through the trouble of running three coherent receivers
for three bands, stacking three more of them and locking them to the
same clock doesn't seem like a big engineering challenge... and the
rest is just DSP work.
Even absent fancy beam forming, for GNSS timing with a surveyed
position except at high latitudes it should be possible to use a
relatively high gain antenna pointed straight up and by doing so blind
yourself to terrestrial jammers at a cost of fewer SVs being
available. But I've never tried it.
In an urban area I noticed my own GPSDOs losing signal multiple times
per week. Monitoring with an SDR showed what appeared to be jammers.
As others have noted intermittent jamming is pretty benign to a GPSDO.
Spoofing, OTOH, can trivially mess up the timing. It's my view that
if you need timing for a security critical purpose there isn't really
any GNSS based solution commercially available to the general public
right now, the best bet is a local atomic reference with a GPSDO used
to monitor and initially set it.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Just ask the NY Port authority how ‘easy’ knocking these jammers offline is. Usually done by vehicle to vehicle inspection with a SA.
And yes the day job all too frequently searching for and identifying interference sources.
One of the more interesting ones was a halogen leak detector wiping out WiFi at a manufacturing plant. So my opinions on interference location are informed by leading teams of people doing just that.
Content by Scott
Typos by Siri
On Aug 30, 2018, at 8:24 PM, Bob kb8tq kb8tq@n1k.org wrote:
Hi
Since timing receivers are actually going to prefer high angle sats, an antenna that rejects
close to the horizon is a pretty common thing. Enhancing that sort of rejection doesn’t take
a lot of effort.
Bob
On Aug 30, 2018, at 7:05 PM, Gregory Maxwell gmaxwell@gmail.com wrote:
On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke brooke@pacific.net wrote:
I would disagree in that ease of jamming/spoofing is strongly related to wavelength. That's because antenna efficiency
goes down as the size of the antenna gets smaller than 1/4 wave.
So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength is a few inches, something that you can
hold in your hand.
However, the short wavelengths of GPS make beam forming a reasonable
countermeasure against jamming.
By having a small array of GPS antennas a receiver can digitally form
beams that both aim directly at the relevant satellites (so even
reducing intersatellite interference) while also steering a deep null
in the direction of the jammer. If the jammer is powerful enough to
overload the front-end then this won't help, but against a
non-targeted area denying jammer it should be fairly effective.
There are many papers on GNSS beamforming. ( e.g.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ )
This kind of anti-jamming solution should even be pretty inexpensive
-- really no more than the cost of N receivers. Except that it is
specialized technology and thus very expensive. :)
Seeing some open source software implementing beam-forming was one of
the things I hoped to see result from the open hardware multi-band
GNSS receivers like the GNSS firehose project (
http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once
you're going through the trouble of running three coherent receivers
for three bands, stacking three more of them and locking them to the
same clock doesn't seem like a big engineering challenge... and the
rest is just DSP work.
Even absent fancy beam forming, for GNSS timing with a surveyed
position except at high latitudes it should be possible to use a
relatively high gain antenna pointed straight up and by doing so blind
yourself to terrestrial jammers at a cost of fewer SVs being
available. But I've never tried it.
In an urban area I noticed my own GPSDOs losing signal multiple times
per week. Monitoring with an SDR showed what appeared to be jammers.
As others have noted intermittent jamming is pretty benign to a GPSDO.
Spoofing, OTOH, can trivially mess up the timing. It's my view that
if you need timing for a security critical purpose there isn't really
any GNSS based solution commercially available to the general public
right now, the best bet is a local atomic reference with a GPSDO used
to monitor and initially set it.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
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To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.antus.org%2FRT02.html&edit-text=
On Thu, Aug 30, 2018 at 7:14 PM djl djl@montana.com wrote:
Is there a translation of this anywhere?
Don
Sweden were much more serious about it:
http://www.antus.org/RT02.html
Tl;drs:
They erected 9 200m tall Loran-C class antennas each driven by
a Loran-C transmitter with an advanced degree which could jam
Loran-C or Chayka.
They even mounted decoy parabolas on the towers them to hide their
true purpose.
The fact that all the transmitters were on the east coast does drop
a hint that swedens much touted neutrality had a bit of a slant.
--
Dr. Don Latham
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Hi
….. ok, so you are dealing with city wide jammers that take out all of New York City on a daily basis?
Again, that was the original example tossed out. “A cigarette pack sized jammer that takes out an entire
city”. A jammer with that sort of range is an easy jammer to spot.
Somehow I find that a bit difficult to believe. What I’ve seen and gone after are far shorter range than
that magic device. A short rang mobile jammer aimed at an ankle bracelet takes out an infrastructure device
for minutes. That’s why those devices have holdover capabilities.
Indeed at the point they do start interfering with major systems over a wide range…. bigger gear gets brought in.
Jamming that actually takes utility systems down is very rare. No cell phone service anywhere in New York is
something that gets noticed pretty fast. It also fires up meetings that last quite literally for years …..
Bob
On Aug 30, 2018, at 8:43 PM, Scott McGrath scmcgrath@gmail.com wrote:
Just ask the NY Port authority how ‘easy’ knocking these jammers offline is. Usually done by vehicle to vehicle inspection with a SA.
And yes the day job all too frequently searching for and identifying interference sources.
One of the more interesting ones was a halogen leak detector wiping out WiFi at a manufacturing plant. So my opinions on interference location are informed by leading teams of people doing just that.
Content by Scott
Typos by Siri
On Aug 30, 2018, at 8:24 PM, Bob kb8tq kb8tq@n1k.org wrote:
Hi
Since timing receivers are actually going to prefer high angle sats, an antenna that rejects
close to the horizon is a pretty common thing. Enhancing that sort of rejection doesn’t take
a lot of effort.
Bob
On Aug 30, 2018, at 7:05 PM, Gregory Maxwell gmaxwell@gmail.com wrote:
On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke brooke@pacific.net wrote:
I would disagree in that ease of jamming/spoofing is strongly related to wavelength. That's because antenna efficiency
goes down as the size of the antenna gets smaller than 1/4 wave.
So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength is a few inches, something that you can
hold in your hand.
However, the short wavelengths of GPS make beam forming a reasonable
countermeasure against jamming.
By having a small array of GPS antennas a receiver can digitally form
beams that both aim directly at the relevant satellites (so even
reducing intersatellite interference) while also steering a deep null
in the direction of the jammer. If the jammer is powerful enough to
overload the front-end then this won't help, but against a
non-targeted area denying jammer it should be fairly effective.
There are many papers on GNSS beamforming. ( e.g.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ )
This kind of anti-jamming solution should even be pretty inexpensive
-- really no more than the cost of N receivers. Except that it is
specialized technology and thus very expensive. :)
Seeing some open source software implementing beam-forming was one of
the things I hoped to see result from the open hardware multi-band
GNSS receivers like the GNSS firehose project (
http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once
you're going through the trouble of running three coherent receivers
for three bands, stacking three more of them and locking them to the
same clock doesn't seem like a big engineering challenge... and the
rest is just DSP work.
Even absent fancy beam forming, for GNSS timing with a surveyed
position except at high latitudes it should be possible to use a
relatively high gain antenna pointed straight up and by doing so blind
yourself to terrestrial jammers at a cost of fewer SVs being
available. But I've never tried it.
In an urban area I noticed my own GPSDOs losing signal multiple times
per week. Monitoring with an SDR showed what appeared to be jammers.
As others have noted intermittent jamming is pretty benign to a GPSDO.
Spoofing, OTOH, can trivially mess up the timing. It's my view that
if you need timing for a security critical purpose there isn't really
any GNSS based solution commercially available to the general public
right now, the best bet is a local atomic reference with a GPSDO used
to monitor and initially set it.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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