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SDR Trackable?


TechDude
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Hello,

If I use the SDR to listen in on airplane communications, can I be tracked and located? The reason I'm asking is because if I can be located, and it is easy to tell I am listening to such communications, this could be a big safety hazard for me (more than what curiosity is worth) in the part of the world I'm living in.

Should I be worried?

In case it makes a difference, I will interchangeably be using two antennas, the ANT500 Telescopic Antenna and the GSM 900 - 1800 MHz Antenna.

Thanks.

Edited by TechDude
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In the Netherlands for a long time we had these speed traps that worked using radar and for slightly less long a time we had people build radar detectors into their cars to signal the driver when such a speed trap, or more precisely, a radio source at a specific frequency, was nearby. Eventually these devices got so popular and, more importantly, cheap that too many people ended up having one which ended up cutting too much into the country's bottom line (you didn't actually believe this was safety-related, right? That's the small lie used to sell you on the project) so the government did what it does best: they banned the things.

Only problem is, how do you know a car has one? Luckily some science guy made the radar-detector-detector (yes, that's what they actually called the thing). And it worked. It was some nice, small device that was trivially installed in a (patrol) car and somehow (I don't know the physics) did its magic. They'd drive around and every so often the thing would start beeping louder and louder as they approach a car, they pull it over and sure enough, there was one. So it gets removed to the point of nearly ripping it out then and there as you're not allowed to continue driving that car until most parts of it are gone and you get a stiff fine.

Some genius actually made a radar-detector-detector-detector (yes, still not making any of this up) but this was like a 1 meter long directional horn antenna mounted on the hood of a car. It's... rather noticable with the naked eye so that really never took off.

So, yes, if you're listening to a radio signal, you also every so slightly influence that signal and by doing so become detectable.

Oh, and PS: the reason they were allowed to ban these devices but still maintain that all communications over the radio waves are 'public property' as it were is that these devices didn't look for any 'communication' in the signal. There was no actual data you were being prevented from receiving. It worked on detecting any signal on that frequency/waveband/whatever the word is. That's what eventually became the clincher.

We do still have things like radio stations telling you every 30 minutes where other listeners noticed speed traps and there's even a nifty app for it called Flitsmeister (I'm sure there's more, but that's the main one). All perfectly legal. :lol:

Edited by Cooper
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Aircraft transponders squalk at a certain frequency, you can pick up these frequencies right out of the air. I don't think it is possible for the SDR to transmit anything (if it is the cheap one in the hack shop), it is purely a receiver, so there is no way for it to actually participate in any sort of two way protocol. Now one of those hack rf things, those are two way, but I doubt they would be able to transmit far enough for the aircraft to hear you. Unless the company planted some sort of hardware bug you are safe.

Edited by overwraith
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In the Netherlands for a long time we had these speed traps that worked using radar and for slightly less long a time we had people build radar detectors into their cars to signal the driver when such a speed trap, or more precisely, a radio source at a specific frequency, was nearby. Eventually these devices got so popular and, more importantly, cheap that too many people ended up having one which ended up cutting too much into the country's bottom line (you didn't actually believe this was safety-related, right? That's the small lie used to sell you on the project) so the government did what it does best: they banned the things.

Only problem is, how do you know a car has one? Luckily some science guy made the radar-detector-detector (yes, that's what they actually called the thing). And it worked. It was some nice, small device that was trivially installed in a (patrol) car and somehow (I don't know the physics) did its magic. They'd drive around and every so often the thing would start beeping louder and louder as they approach a car, they pull it over and sure enough, there was one. So it gets removed to the point of nearly ripping it out then and there as you're not allowed to continue driving that car until most parts of it are gone and you get a stiff fine.

Some genius actually made a radar-detector-detector-detector (yes, still not making any of this up) but this was like a 1 meter long directional horn antenna mounted on the hood of a car. It's... rather noticable with the naked eye so that really never took off.

So, yes, if you're listening to a radio signal, you also every so slightly influence that signal and by doing so become detectable.

Oh, and PS: the reason they were allowed to ban these devices but still maintain that all communications over the radio waves are 'public property' as it were is that these devices didn't look for any 'communication' in the signal. There was no actual data you were being prevented from receiving. It worked on detecting any signal on that frequency/waveband/whatever the word is. That's what eventually became the clincher.

We do still have things like radio stations telling you every 30 minutes where other listeners noticed speed traps and there's even a nifty app for it called Flitsmeister (I'm sure there's more, but that's the main one). All perfectly legal. :lol:

I think some radar detectors these days now have VG2 (radar detector detector) detection, and when they detect VG2, they shut down. Does the SDR use the same type of frequency as is used in police radar detectors?

Aircraft transponders squalk at a certain frequency, you can pick up these frequencies right out of the air. I don't think it is possible for the SDR to transmit anything (if it is the cheap one in the hack shop), it is purely a receiver, so there is no way for it to actually participate in any sort of two way protocol. Now one of those hack rf things, those are two way, but I doubt they would be able to transmit far enough for the aircraft to hear you. Unless the company planted some sort of hardware bug you are safe.

Yes, it is the cheap SDR from the hak shop.

OK, so this is good news if I cannot be detected. This means I'll be able to give some room to my curiosity, after all.

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I think some radar detectors these days now have VG2 (radar detector detector) detection, and when they detect VG2, they shut down. Does the SDR use the same type of frequency as is used in police radar detectors?

http://en.wikipedia.org/wiki/Radar_detector_detector - To read up on VG2 and the radar detection arms race.

The point I was making is that radar and radio are in essence the same technology, except the transmission, once received, is interpreted differently resulting in a different application. The act of receiving the transmission and the side effects of doing so, I'm arguing, should thus be the same. So if the radar detection scenario also holds true to basically any radio receiver, then yes, you are detectable. I'm fairly sure whomever is trying to detect you must be actively doing so as the detection range is almost certainly short (under 100m I'm guessing).

Edited by Cooper
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http://en.wikipedia.org/wiki/Radar_detector_detector - To read up on VG2 and the radar detection arms race.

The point I was making is that radar and radio are in essence the same technology, except the transmission, once received, is interpreted differently resulting in a different application. The act of receiving the transmission and the side effects of doing so, I'm arguing, should thus be the same. So if the radar detection scenario also holds true to basically any radio receiver, then yes, you are detectable. I'm fairly sure whomever is trying to detect you must be actively doing so as the detection range is almost certainly short (under 100m I'm guessing).

Thanks. This is reassuring. Looks like I'll be able to safely give it a go.

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I think they are detecting the output of the oscillator on the radar detector. I'm not sure if an SDR would put off such a signal; maybe if you had two you could use one as a spectrum analyzer while the other receives the signal in question and look for any data?

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I think they are detecting the output of the oscillator on the radar detector. I'm not sure if an SDR would put off such a signal; maybe if you had two you could use one as a spectrum analyzer while the other receives the signal in question and look for any data?

That is a very good idea. I wish I got two of them. I'm not sure how long it will be before I'll be able to get another one.

Do you think I'd be able to do something similar with my SDR and a cheap radar detector?

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Even if a device can detect a radio reciever, I would think it would be very hard to make out a sdr tuned to 1090 mhz with all the other radio and TV Devices in your home for example television, wireless and cell phones, wifi, bluetooth, wireless keyboards and mice, am and fm radios, that would be amazing technology if it existed to do that, plus not sure what it would accomplish if the could, at least in the US its not illegal

Edited by dougggg
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In the Netherlands for a long time we had these speed traps that worked using radar and for slightly less long a time we had people build radar detectors into their cars to signal the driver when such a speed trap, or more precisely, a radio source at a specific frequency, was nearby. Eventually these devices got so popular and, more importantly, cheap that too many people ended up having one which ended up cutting too much into the country's bottom line (you didn't actually believe this was safety-related, right? That's the small lie used to sell you on the project) so the government did what it does best: they banned the things.

Only problem is, how do you know a car has one? Luckily some science guy made the radar-detector-detector (yes, that's what they actually called the thing). And it worked. It was some nice, small device that was trivially installed in a (patrol) car and somehow (I don't know the physics) did its magic. They'd drive around and every so often the thing would start beeping louder and louder as they approach a car, they pull it over and sure enough, there was one. So it gets removed to the point of nearly ripping it out then and there as you're not allowed to continue driving that car until most parts of it are gone and you get a stiff fine.

Some genius actually made a radar-detector-detector-detector (yes, still not making any of this up) but this was like a 1 meter long directional horn antenna mounted on the hood of a car. It's... rather noticable with the naked eye so that really never took off.

So, yes, if you're listening to a radio signal, you also every so slightly influence that signal and by doing so become detectable.

Oh, and PS: the reason they were allowed to ban these devices but still maintain that all communications over the radio waves are 'public property' as it were is that these devices didn't look for any 'communication' in the signal. There was no actual data you were being prevented from receiving. It worked on detecting any signal on that frequency/waveband/whatever the word is. That's what eventually became the clincher.

We do still have things like radio stations telling you every 30 minutes where other listeners noticed speed traps and there's even a nifty app for it called Flitsmeister (I'm sure there's more, but that's the main one). All perfectly legal. :lol:

I'm going to call BS on this one. As long as you're not transmitting, you're not going to be detectable. These shitty little sdr devices don't have enough antenna to effect the signals enough to do anything. If they did, then everybody would have to transmit at a much higher wattage just to get over all the antennas "absorbing" the signals. There's a shit ton of things that absorb the frequencies even in nature. The reason the radar detector detectors work is because radar detectors aren't passive.

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Well, I'm very much NOT a radio/signals guy at the moment so there was a fair chance I was wrong on this one. I figured both use radio signals, one I know to be detectable without understanding how that is but all things being equal (which they apparently aren't) a radio receiver would then also be detectable. As I stated further down:

So if the radar detection scenario also holds true to basically any radio receiver, then yes, you are detectable.

I honestly didn't know/expect a radar detector to be an active device.

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I'm going to call BS on this one. As long as you're not transmitting, you're not going to be detectable. These shitty little sdr devices don't have enough antenna to effect the signals enough to do anything. If they did, then everybody would have to transmit at a much higher wattage just to get over all the antennas "absorbing" the signals. There's a shit ton of things that absorb the frequencies even in nature. The reason the radar detector detectors work is because radar detectors aren't passive.

Yes mathmatiicaly change things but it would be below a detectable level and every TV Antenna and wires would be about the same level of interference. If you aren't broadcasting you should be fine.

Well if you start mount antennas on your roof they might notice.

Do check the laws in your country. E.g. for my country listening is fine. But you may act on information on radio communications intended for your, store and give to some else or otherwise acknowledge the existence of a communications. My only issue with our current law is that it doesn't allow for responsible disclosure.

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