Re: [Discuss-gnuradio] Need help identifying jammer signal
Thanks for the follow-up, this is similar to a 1 second noise burst every 60 seconds or so we had on our ham repeater. The reason could be identified after months of search by coincidence. The repeater sysop visited his fathers office, monitored the input frequency of the repeater like he had done routinely for months to hear exactly nothing - but there it was, some wideband noise pulse! 100 m from this office a paging system for a facility management team was sitting on a tower, not actively used for years, still transmitting its beacon every minute, and with age the TX started emitting noise along with its POCSAG signal. Gnuradio also would have been useful in our case, but it was way before we knew of this exciting stuff :) Ralph. From: discuss-gnuradio-bounces+ralph=schmid@gnu.org [mailto:discuss-gnuradio-bounces+ralph=schmid@gnu.org] On Behalf Of Juha Vierinen Sent: Tuesday, December 17, 2013 11:41 PM Cc: gnuradio mailing list Subject: Re: [Discuss-gnuradio] Need help identifying jammer signal Last Friday we managed to finally track this thing down. It was a broken FSK telemetry system on an FM radio tower. It was about 30 km Southwest of our radar. I did a small write up about this: http://kaira.sgo.fi/2013/12/perfect-incoherent-scatter-radar-jammer.html Thanks for all the help. juha On Wed, Dec 11, 2013 at 4:34 PM, Johnathan Corgan johnat...@corganlabs.com wrote: On 12/10/2013 02:00 PM, Miki Lustig - KK6GEO wrote: These look like 2pi jumps -- which is the an artifact if the unwrapping is not working well. Sure, I see what you mean. Backing up and just plotting the unwrapped phase, you can see in the first image that overall it is increasing at one rate, then shifts to a lower rate about 1.5 seconds into the file. The finer structure is much more interesting. The second image shows the phase making fast jumps every 500 samples (10 ms), with periods of oscillation in between. The detail on this is in image 3. I still have no idea what this is, but it sort of looks like an oscillator that is disciplined at 100 Hz. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
Well done! Patrik On Tue, 2013-12-17 at 17:40 -0500, Juha Vierinen wrote: Last Friday we managed to finally track this thing down. It was a broken FSK telemetry system on an FM radio tower. It was about 30 km Southwest of our radar. I did a small write up about this: http://kaira.sgo.fi/2013/12/perfect-incoherent-scatter-radar-jammer.html Thanks for all the help. juha On Wed, Dec 11, 2013 at 4:34 PM, Johnathan Corgan johnat...@corganlabs.com wrote: On 12/10/2013 02:00 PM, Miki Lustig - KK6GEO wrote: These look like 2pi jumps -- which is the an artifact if the unwrapping is not working well. Sure, I see what you mean. Backing up and just plotting the unwrapped phase, you can see in the first image that overall it is increasing at one rate, then shifts to a lower rate about 1.5 seconds into the file. The finer structure is much more interesting. The second image shows the phase making fast jumps every 500 samples (10 ms), with periods of oscillation in between. The detail on this is in image 3. I still have no idea what this is, but it sort of looks like an oscillator that is disciplined at 100 Hz. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
Last Friday we managed to finally track this thing down. It was a broken FSK telemetry system on an FM radio tower. It was about 30 km Southwest of our radar. I did a small write up about this: http://kaira.sgo.fi/2013/12/perfect-incoherent-scatter-radar-jammer.html Thanks for all the help. juha On Wed, Dec 11, 2013 at 4:34 PM, Johnathan Corgan johnat...@corganlabs.comwrote: On 12/10/2013 02:00 PM, Miki Lustig - KK6GEO wrote: These look like 2pi jumps -- which is the an artifact if the unwrapping is not working well. Sure, I see what you mean. Backing up and just plotting the unwrapped phase, you can see in the first image that overall it is increasing at one rate, then shifts to a lower rate about 1.5 seconds into the file. The finer structure is much more interesting. The second image shows the phase making fast jumps every 500 samples (10 ms), with periods of oscillation in between. The detail on this is in image 3. I still have no idea what this is, but it sort of looks like an oscillator that is disciplined at 100 Hz. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
On 12/10/2013 02:00 PM, Miki Lustig - KK6GEO wrote: These look like 2pi jumps -- which is the an artifact if the unwrapping is not working well. Sure, I see what you mean. Backing up and just plotting the unwrapped phase, you can see in the first image that overall it is increasing at one rate, then shifts to a lower rate about 1.5 seconds into the file. The finer structure is much more interesting. The second image shows the phase making fast jumps every 500 samples (10 ms), with periods of oscillation in between. The detail on this is in image 3. I still have no idea what this is, but it sort of looks like an oscillator that is disciplined at 100 Hz. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com attachment: rfi-unwrapped-phase.pngattachment: rfi-unwrapped-phase2.pngattachment: rfi-unwrapped-phase3.pngattachment: johnathan.vcf signature.asc Description: OpenPGP digital signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
On 12/09/2013 07:26 PM, Juha Vierinen wrote: I recorded a 10 second snippet of 50 kHz baseband signal in interleaved I and Q with 32-bit floating point format. The signal is definitely frequency modulated, but it doesn't appear to be by data. Plotting the unwrap(diff(unwrap(arg(s))) shows a repetitive structure of 10 ms (500 samples) width, as if something is stepping the frequency up or down at 100 Hz in a random walk. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com attachment: rfi-modulation.pngattachment: johnathan.vcf signature.asc Description: OpenPGP digital signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
These look like 2pi jumps -- which is the an artifact if the unwrapping is not working well. On Dec 10, 2013, at 1:55 PM, Johnathan Corgan johnat...@corganlabs.com wrote: On 12/09/2013 07:26 PM, Juha Vierinen wrote: I recorded a 10 second snippet of 50 kHz baseband signal in interleaved I and Q with 32-bit floating point format. The signal is definitely frequency modulated, but it doesn't appear to be by data. Plotting the unwrap(diff(unwrap(arg(s))) shows a repetitive structure of 10 ms (500 samples) width, as if something is stepping the frequency up or down at 100 Hz in a random walk. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com rfi-modulation.pngjohnathan.vcf___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
Hi guys, Thank you for your helpful suggestions. We still haven't managed to pinpoint where the signal is coming from, but we have just dispatched a black SUV with a three letter acronym stencilled on it (our university's initials) to hunt for the signal with a spectrum analyzer and a yagi. Yesterday the interference was a 440.4 MHz and during the night it went down to 440.0 MHz. Today it has drifted up and down between 440.0 and 440.2 MHz. This is very annoying as our frequency is 440.2 MHz. Based in the wild fluctuation in center frequency (including 20 kHz jumps), However, the signal at close inspection kind of looks like FSK, so maybe whatever it is, isn't working properly anymore. I recorded a 10 second snippet of 50 kHz baseband signal in interleaved I and Q with 32-bit floating point format. In python, one would read this with this command: import numpy z = numpy.fromfile(rfi.bin,dtype=numpy.complex64) The file can be downloaded here: http://www.haystack.mit.edu/~j/rfi.bin You can probably feed this into gnuradio with the filesource and complex data type. Patrik, you are doing cool stuff with the POES satellite receiving. I wish I had time to try that at some point. juha On Sun, Dec 8, 2013 at 5:38 AM, Patrik Tast pat...@poes-weather.com wrote: Terve Juha, Some animal neck collar TX:er are very close to that feq (440 MHz). It could be on a wolf, reindeer or a hunter that use a *home brew* (illegal) collar on his dog. Building a *home brew* dog collar is popular today since you can get parts without any questions asked... I would contact the person who count wolfs near you. Eagles here (Vaasa, FI) use ARGOS up-link to POES sats 401.65 and downlink 465.98 MHz (bw 24/80/110 kHz). Patrik On Fri, 2013-12-06 at 13:48 -0500, Juha Vierinen wrote: Hi, In the last few days a signal has entered in the center of our incoherent scatter radar band. It drifts between 440.1 and 440.4 MHz very slowly and has approximately a 10 kHz bandwidth. A scope plot of the signal shows something that looks a little bit like frequency shift keying. While the frequency is stable on short time scales, the signal tends to drift a lot on the scale of days, suggesting that whatever is causing this signal, it is broken. I've attached a GRC plot of the signal. In the plot, the jammer is at a +166 kHz offset. The scope plot is centered at this frequency and has a 40 kHz bandwidth. Does anyone have any idea what this could be? juha ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
In Germany such signals often came from oscillating TV antenna preamps, long forgotten and out of use on top of a roof, but still powered.usually the BNetzA (the regulation authority) was very helpful in finding those. Ralph. From: discuss-gnuradio-bounces+ralph=schmid@gnu.org [mailto:discuss-gnuradio-bounces+ralph=schmid@gnu.org] On Behalf Of Juha Vierinen Sent: Tuesday, 10 December, 2013 04:26 To: Patrik Tast Cc: gnuradio mailing list Subject: Re: [Discuss-gnuradio] Need help identifying jammer signal Hi guys, Thank you for your helpful suggestions. We still haven't managed to pinpoint where the signal is coming from, but we have just dispatched a black SUV with a three letter acronym stencilled on it (our university's initials) to hunt for the signal with a spectrum analyzer and a yagi. Yesterday the interference was a 440.4 MHz and during the night it went down to 440.0 MHz. Today it has drifted up and down between 440.0 and 440.2 MHz. This is very annoying as our frequency is 440.2 MHz. Based in the wild fluctuation in center frequency (including 20 kHz jumps), However, the signal at close inspection kind of looks like FSK, so maybe whatever it is, isn't working properly anymore. I recorded a 10 second snippet of 50 kHz baseband signal in interleaved I and Q with 32-bit floating point format. In python, one would read this with this command: import numpy z = numpy.fromfile(rfi.bin,dtype=numpy.complex64) The file can be downloaded here: http://www.haystack.mit.edu/~j/rfi.bin You can probably feed this into gnuradio with the filesource and complex data type. Patrik, you are doing cool stuff with the POES satellite receiving. I wish I had time to try that at some point. juha On Sun, Dec 8, 2013 at 5:38 AM, Patrik Tast pat...@poes-weather.com wrote: Terve Juha, Some animal neck collar TX:er are very close to that feq (440 MHz). It could be on a wolf, reindeer or a hunter that use a *home brew* (illegal) collar on his dog. Building a *home brew* dog collar is popular today since you can get parts without any questions asked... I would contact the person who count wolfs near you. Eagles here (Vaasa, FI) use ARGOS up-link to POES sats 401.65 and downlink 465.98 MHz (bw 24/80/110 kHz). Patrik On Fri, 2013-12-06 at 13:48 -0500, Juha Vierinen wrote: Hi, In the last few days a signal has entered in the center of our incoherent scatter radar band. It drifts between 440.1 and 440.4 MHz very slowly and has approximately a 10 kHz bandwidth. A scope plot of the signal shows something that looks a little bit like frequency shift keying. While the frequency is stable on short time scales, the signal tends to drift a lot on the scale of days, suggesting that whatever is causing this signal, it is broken. I've attached a GRC plot of the signal. In the plot, the jammer is at a +166 kHz offset. The scope plot is centered at this frequency and has a 40 kHz bandwidth. Does anyone have any idea what this could be? juha ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
Terve Juha, Some animal neck collar TX:er are very close to that feq (440 MHz). It could be on a wolf, reindeer or a hunter that use a *home brew* (illegal) collar on his dog. Building a *home brew* dog collar is popular today since you can get parts without any questions asked... I would contact the person who count wolfs near you. Eagles here (Vaasa, FI) use ARGOS up-link to POES sats 401.65 and downlink 465.98 MHz (bw 24/80/110 kHz). Patrik On Fri, 2013-12-06 at 13:48 -0500, Juha Vierinen wrote: Hi, In the last few days a signal has entered in the center of our incoherent scatter radar band. It drifts between 440.1 and 440.4 MHz very slowly and has approximately a 10 kHz bandwidth. A scope plot of the signal shows something that looks a little bit like frequency shift keying. While the frequency is stable on short time scales, the signal tends to drift a lot on the scale of days, suggesting that whatever is causing this signal, it is broken. I've attached a GRC plot of the signal. In the plot, the jammer is at a +166 kHz offset. The scope plot is centered at this frequency and has a 40 kHz bandwidth. Does anyone have any idea what this could be? juha ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
On 12/06/2013 10:48 AM, Juha Vierinen wrote: A scope plot of the signal shows something that looks a little bit like frequency shift keying. Make sure the signal is filtered to the 10K width and attach an FM demod block to that (just set the sensitivity to 1.0 for now). It definitely looks like 2- or 4-level FSK. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com attachment: johnathan.vcf signature.asc Description: OpenPGP digital signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
On 12/06/2013 11:05 AM, Johnathan Corgan wrote: On 12/06/2013 10:48 AM, Juha Vierinen wrote: A scope plot of the signal shows something that looks a little bit like frequency shift keying. Make sure the signal is filtered to the 10K width and attach an FM demod block to that (just set the sensitivity to 1.0 for now). It definitely looks like 2- or 4-level FSK. Due to the drift apparent on the order of seconds, you may only be able to filter down to 20-30KHz. The 'Frequency Xlating FIR Filter' block would let you downconvert from +166 KHz, filter the signal, and decimate down further from 1 Msps to something that would be suitable for input to the FM demod block. If you want, I could let you upload a capture file to gnuradio.org so everyone could join the hunt. -- Johnathan Corgan, Corgan Labs SDR Training and Development Services http://corganlabs.com attachment: johnathan.vcf signature.asc Description: OpenPGP digital signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Need help identifying jammer signal
On 12/06/2013 02:12 PM, Johnathan Corgan wrote: If you want, I could let you upload a capture file to gnuradio.org so everyone could join the hunt. The hunt for RFI October. This signal will get worse. It'll get worse, and we'll be lucky to live through it. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
