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Security Idea/test: firewall rule...

Robert Simmons

22 Jan 2022 22 Jan '22

4:10 a.m.

All... I am new to this forum... this topic might not be relevant, but here goes... Does anyone here have any interest in remote reporting radio direction finders ? ( RDFs ) I have developed technology for that, using Doppler direction finders.. suitable mostly for VHF and above. ============== Explaining it takes some time, but I have posted a YouTube video of a single DF station, running in TEST mode, located at my residence in California. ( video is about 1 minute long ) https://www.youtube.com/watch?v=GdJqKNpWG5c The DF displays on any PC's GoogleEarth screen, if a suitable PLACEMARK is installed for it. ( not sure about smart phone versions... ) It "refreshes" once every 3 seconds, and ( in TEST mode ) the DF bearing line ( 25 miles long ) rotates clockwise at 1 RPM. ============== This is a YouTube recording, but the real DF station ( still running in TEST mode ) can be viewed "in realtime" if I provide a KML link for it. Contact me if you want to see that... I will provide more info "off forum" about how to install and use the link in GoogleEarth. Bob Simmons / WB6EYV / pelican2(a)silcom.com ============= Multiple DF stations can be plotted simultaneously, on multiple displays... yielding a plot showing the approximate location of the "hunted" station... literally, "in seconds". If multiple hunters ( at many different locations ) are watching the same plot, those "far away" can ignore it... but those "nearby" can jump on it and maybe find the hunted station. That's the general idea... a jammer can't even "cough" without revealing their ( general ) location. ============= I'll provide more details for those who enquire, I prefer a phone call, ( include your number, if you please ) because e-mails are slow to compose. This is still in an "experimental" phase, but the basic technology is all mature and solid... All the pieces have been individually tested, time for a complete network to be built.... and I can't do that alone. More about me here : www.picodopp.com TNX DE WB6EYV

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Tony Langdon

23 Jan 23 Jan

3:26 a.m.

Interesting, though I'm guessing not directly on topic here. I'd be interested to know more. Might be better to take it off list though. On 22/1/22 8:10 am, Robert Simmons via 44Net wrote:

...

-- 73 de Tony VK3JED/VK3IRL http://vkradio.com

Ruben ON3RVH

4:08 a.m.

Isn’t this incorporated in kiwisdr? I know kiwisdr has the ability to do direction finding and triangulating position of a signal Ruben - ON3RVH

...

On 22 Jan 2022, at 21:27, Tony Langdon via 44Net <44net(a)mailman.ampr.org> wrote: Interesting, though I'm guessing not directly on topic here. I'd be interested to know more. Might be better to take it off list though.

On 22/1/22 8:10 am, Robert Simmons via 44Net wrote: All... I am new to this forum... this topic might not be relevant, but here goes... Does anyone here have any interest in remote reporting radio direction finders ? ( RDFs ) I have developed technology for that, using Doppler direction finders.. suitable mostly for VHF and above. ============== Explaining it takes some time, but I have posted a YouTube video of a single DF station, running in TEST mode, located at my residence in California. ( video is about 1 minute long ) https://www.youtube.com/watch?v=GdJqKNpWG5c The DF displays on any PC's GoogleEarth screen, if a suitable PLACEMARK is installed for it. ( not sure about smart phone versions... ) It "refreshes" once every 3 seconds, and ( in TEST mode ) the DF bearing line ( 25 miles long ) rotates clockwise at 1 RPM. ============== This is a YouTube recording, but the real DF station ( still running in TEST mode ) can be viewed "in realtime" if I provide a KML link for it. Contact me if you want to see that... I will provide more info "off forum" about how to install and use the link in GoogleEarth. Bob Simmons / WB6EYV / pelican2(a)silcom.com ============= Multiple DF stations can be plotted simultaneously, on multiple displays... yielding a plot showing the approximate location of the "hunted" station... literally, "in seconds". If multiple hunters ( at many different locations ) are watching the same plot, those "far away" can ignore it... but those "nearby" can jump on it and maybe find the hunted station. That's the general idea... a jammer can't even "cough" without revealing their ( general ) location. ============= I'll provide more details for those who enquire, I prefer a phone call, ( include your number, if you please ) because e-mails are slow to compose. This is still in an "experimental" phase, but the basic technology is all mature and solid... All the pieces have been individually tested, time for a complete network to be built.... and I can't do that alone. More about me here : www.picodopp.com TNX DE WB6EYV _________________________________________ 44Net mailing list 44Net(a)mailman.ampr.org https://mailman.ampr.org/mailman/listinfo/44net

-- 73 de Tony VK3JED/VK3IRL http://vkradio.com _________________________________________ 44Net mailing list 44Net(a)mailman.ampr.org https://mailman.ampr.org/mailman/listinfo/44net

Steve L

24 Jan 24 Jan

1:48 p.m.

On Sat, Jan 22, 2022 at 11:14 AM Robert Simmons via 44Net <44net(a)mailman.ampr.org> wrote:

...

Does anyone here have any interest in remote reporting radio direction finders ? ( RDFs )

I think if it can be developed as open source software using cheap hardware like the RTL-SDR (the kiwisdr is expensive), that would be a very good project worthy of an ARDC grant.

Tony Langdon

2:11 p.m.

On 24/1/22 5:48 pm, Steve L via 44Net wrote:

...

On Sat, Jan 22, 2022 at 11:14 AM Robert Simmons via 44Net <44net(a)mailman.ampr.org> wrote:

Does anyone here have any interest in remote reporting radio direction finders ? ( RDFs )

I think if it can be developed as open source software using cheap hardware like the RTL-SDR (the kiwisdr is expensive), that would be a very good project worthy of an ARDC grant.

I agree. An RTL-SDR may or may not cut it (one way to find out ;) ), but open source software, and open and inexpensive hardware would be interesting to pursue. -- 73 de Tony VK3JED/VK3IRL http://vkradio.com

Matt - VK2FLY

3:13 p.m.

...

On 24/1/22 5:48 pm, Steve L via 44Net wrote:

On Sat, Jan 22, 2022 at 11:14 AM Robert Simmons via 44Net <44net(a)mailman.ampr.org> wrote:

Does anyone here have any interest in remote reporting radio direction finders ? ( RDFs )

I think if it can be developed as open source software using cheap hardware like the RTL-SDR (the kiwisdr is expensive), that would be a very good project worthy of an ARDC grant.

I agree. An RTL-SDR may or may not cut it (one way to find out ;) ), but open source software, and open and inexpensive hardware would be interesting to pursue.

Rob PE1CHL

4:05 p.m.

We have been considering doing that kind of thing to triangulate abusers on our multi-site repeater PI2NOS. At some point in time it had 25 receivers and 5 co-channel transmitters covering the entire country, so there were always miscreants active. Some work has been done, e.g. the general location was determined by comparing the relative receive signal strength on the 25 receiver sites, but that only worked for strong signals that hit multiple receivers, and were themselves transmitting omnidirectionally. The typical mobile or portable user could not really be located. With TDOA the problem is that you cannot really timestamp a signal with such a small bandwidth accurately enough. It requires correlation of the signal and that does not work too well on a barely modulated NBFM carrier. A German amateur demonstrated use with DMR and there it is much easier because there is a nicely structured and clocked signal even when the user does not talk. But to really get it to work you need wideband signals. There is a reason why GPS systems use spread spectrum! Of course with doppler direction finding it is possible to locate all signals, also NBFM or unmodulated carriers, but it requires a dedicated antenna which would make it more difficult to deploy. I recently saw an announcement for a board with I think 5 circuits similar to the RTL-SDR clocked from a common clock source, and it should be possible to do direction finding with that. (the classical solution uses a single receiver and a pin diode switch to connect the antennas alternately. the receiver ideally should have both FM and AM detection) With this solution you do not need accurate time. Rob On 1/24/22 09:13, Matt - VK2FLY via 44Net wrote:

...

I did the math on RDF using 2 and 70 using difference time of arrival. The math worked out that I needed gps clocks to get accuracy down to a 50m with 4 receiving stations. However the gps clocks increased the price somewhat. I did not investigate the latency involved with RTL dongles or even if that latency could be fixed/measured which would be a key component. A dedicated radio may also need to be built to get RX carrier detection latency predictable. But in theory it would be possible to build a network with unlimited cheap RX stations reporting locations on a map APRS style from every received signal. Matt On 24/1/2022 5:11 pm, Tony Langdon via 44Net wrote: > On 24/1/22 5:48 pm, Steve L via 44Net wrote: >> On Sat, Jan 22, 2022 at 11:14 AM Robert Simmons via 44Net >> <44net(a)mailman.ampr.org> wrote: >> >>> Does anyone here have any interest in remote reporting radio direction >>> finders ? ( RDFs ) >>> >> I think if it can be developed as open source software using cheap >> hardware like the RTL-SDR (the kiwisdr is expensive), that would be a >> very good project worthy of an ARDC grant. > I agree. An RTL-SDR may or may not cut it (one way to find out ;) ), > but open source software, and open and inexpensive hardware would be > interesting to pursue. >

Steve L

25 Jan 25 Jan

2:14 a.m.

...

Does anyone here have any interest in remote reporting radio direction finders ? ( RDFs )

I think if it can be developed as open source software using cheap hardware like the RTL-SDR (the kiwisdr is expensive), that would be a very good project worthy of an ARDC grant.

I agree. An RTL-SDR may or may not cut it (one way to find out ;) ), but open source software, and open and inexpensive hardware would be interesting to pursue.

True, but as you put it, one never knows till it's tried. Ever since all my friends have been hosting the flightaware receivers, the idea of a few internet connected frequency agile receivers able to compare signals with a map overlay has been in the back of my mind.

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Matt - VK2FLY
Rob PE1CHL
Robert Simmons
Ruben ON3RVH
Steve L
Tony Langdon