RTL SDR Anyone?

Peter Shaw

Yep indeed. Iv'e been into RTL SDR for a couple of years now. I actually have one hooked up to my PC< And a proper antenna/Ariel outside on the room of my house with a cable coming in. Apart from making a bloody good Digital TV service (I can watch TV in a window on my desktop while I work) I can grab pager signals, mobile phone paging broadcasts, RDS info (From FM transmissions) to grab things like traffic reports. The device I have works from 200khz right up to 2.5Ghz so I can even grab 802.11b/g/n home wifi transmissions with it (Signal's not too good however) Now that said, I will admit, Iv'e not tried much in the way of programming it directly, however, it's not difficult from what I'm told. The main software folks use is called SDR# and is written in C# There is a library available (the same one SDR# uses) and I believe it's on NuGet. There doesn't seem to be very much documentation about it though. Most folks in the community (Myself included) are happy using the existing tools, and then running recordings through sub modules by routing the sound with windows drivers like VB Audio's virtual audio cable. In the rare few cases where there's not a tool to deal with the data stream, then you have things like "Pothos" ([Pothos SDR](https://github.com/pothosware/PothosSDR/wiki)) which provide you with a sandboxed development environment, where the hard work of aquiring the signal is done for you, and all you need to do is rig up the processing. To be fair, there's actually very little int he way of programming resources for these things ont he windows platform, if you really, really wanna make some good use of it, you need to start looking at Linux based OS's There's software there for example that allows you to take your files and turn them into audio wave files that sound like old 1980's cassette recordings, and then transmit them over the radio waves. In fact there are a bunch of hams around the UK, that have actually set up their own private little internet service, that you can only get at via an SDR radio and a correctly tuned ariel. As for the few folk that are questioning what's still available on SHortwave, Longwave, Medium Wave etc try it and see. There's plenty of online frequency guides, you can find Air Traffic COntrol, Broacasts from weather and scientific sattelites, heck it's even possible to grab the ariel photography transmissions from some of them to get almost realtime images of what the earth looks like from outter space. A great place to start is

Dr Walt Fair PE

Yes, there is plenty of programmingf broadcast on MW, LW and HF There was an international conference on the subject in early March in Philadelphia. I attended as I do each year in March. There were about 300 people from all over the world Of course US and Canadians were the majority, but there were Italians, Germand and Australians as well.

CQ de W5ALT

Walt Fair, Jr., P. E. Comport Computing Specializing in Technical Engineering Software

Dr Walt Fair PE

Thanks for the reply. I've had a Flex radio Flex1000, since the first came out about 15 years ago. It covers 0-50MHz with a direct conversion receiver and 1 watt transmitter. I wrote the software to take the I and Q streams and process for the normal ham modes and take audio from the ccpomputer to transmit in a;ll the normal modes. I used a 2.4kHz IF implemented in the software to provide image rejection and higher order mixing products. It was a fantastic radio! Too bad I can't use it anymore. It requires a bi directionalparallel port for control and I haven't seen one of those for a long time. I also have a Flex1500 which is also pretty nice, but not as sensitive as the 1000. It does all the DSP on an internal chip, so it isn't easy to get t oo the raw IQ signals! I've been in contact with Flexradio. I used to live in Austin, where they are headquartered, but There's no easy wat to get the raw signals like on the 1000. As faras thr RTL-SDRDongles, I have one and it works fine with SDR#, but I want to do my own special processing. I asked about getting the raw I Qignsals on the Forumsand was told to look at the SDR# code, since it's open source, Unfortubatelt the uathor closed the project and withdrew the project from GitHub, so no luck there. I got the product sheets for the chips involved, but no useful info there either.If you have any other ideas, I would really appreciate it! I want to get the dongles in bulk and write software for some specialized purposes. I've already done market analysis, but I need to get the raw I Q datato proceed.

CQ de W5ALT

Walt Fair, Jr., P. E. Comport Computing Specializing in Technical Engineering Software

Peter Shaw

Yes unfortunately it did go closed source, because the original authors did something that seems to be happening with more frequency in OSS these days, they declared they where never ever going to sell, then when the user base got large enough, they backed out of that promise and either went commercial or sold to the highest bidder. In the case of SDR Sharp I believe they went to the highest bidder. :-) and on top of that, the original Developer changed it to some crazy license, then went bat shit crazy and went on a suing spree against every person on the planet that dared to make an SDR capable app using C#, claiming that everyone violated the SDR license (You can look at my code to see how it work,s but your not allowed to use anything that's remotley similar to anything I wrote). Beacuse of his attitude, many in the communty basically gave him a single digit and went and forked the code, then squirreled it away where he couldn't see it, some didn't bother hiding it, and basically waved the single finger in his face. Eventually he just gave up being a jerk, threw his toys out the pram, sold it all and closed down his project. Now the actual SDR# app is commercial, but there are a lot of others still available that use the same (or similar) C# code base which was made public before all of this kicked off. The company that bought it tried to get all the previous copies taken down (I believe the original author stipulated they had to do this in his contract to sell it to them) , but ultimately they where not able too, and soo many derivitives where built. You can find a full list of them [Here](https://www.rtl-sdr.com/big-list-rtl-sdr-supported-software/) Like many, I do know where you can get a copy of the original source code before it was closed down, but for obvious reasons I can't put links info in this post as that might cause problems for CP, so your gonna have to hunt me down privately and ask me about that one :-) You can find me easy enough however, I'm not difficult to find in the .NET community ....

S Douglas

Walt Fair, Jr. wrote:

For abpout $20.00 you can get a dongle that is a real software defined radio.

For this reason alone I've thought about buying one as a cheap device to listen in on HF. Not that I spend much time on VHF/UHF...

Common sense is admitting there is cause and effect and that you can exert some control over what you understand.

Peter Shaw

That's the one I have, an Realtek 2383 or something like that. Cost me about £20 Gbp

S Douglas

Do you use it for listening to the amature radio bands?

Common sense is admitting there is cause and effect and that you can exert some control over what you understand.

Peter Shaw

Occasionally, but I'm not really that type of Radio Ham. The Value I find in it is finding all these data streams floating around, then trying to decode them, see what's in them. For example, on the housing estate I live on, all the Standard Thermostats fitted in my cul-de-sac, are all of exactly the same type, and all have quite strong radios in them, so I can actually sit and watch my neighbors central heating systems talking to the central heating boiler and see what temperatures/times/settings they have things set at. Iv'e also on occasion, used the UK pager network to find out about railway delays, prior to going on a journey, allowing me to better plan things, and usually before the notifications are posted on the train operators web sites :-)

S Douglas

Peter Shaw wrote:

The Value I find in it is finding all these data streams floating around, then trying to decode them, see what's in them.

Ah snooping, never really thought about that. That would be interesting to see what's floating around (my neighbors are far enough away from me that any low powered RF would not likely be fully receivable). I do listen into the State Patrol radio to see how many accidents there are out in the Morning on snow days. Its always a better indication of traffic flow than the DOT websites. :)

Common sense is admitting there is cause and effect and that you can exert some control over what you understand.

Peter Shaw

There's tons of stuff to find. Here in the UK, we don't have towns and houses where everyone on the street has a 10 Acre garden :-) As a result, it's usually quite a PIA to get your WiFi onto an unused channel, or at least one that has a minimal amount of overlap. However, here in the UK we also have a staggering amount of stuff that's WiFi enabled, from computer mice and keyboards right through to Baby Monitors. One of my neighbor's appears to have a microwave oven that's WiFi enabled (Don't ask....) Iv'e even successfully managed to pick up the occasional bit of Bluetooth traffic, mostly from the cars parked in driveways and on the street. We used to be able to listen to the Police/Fire emergency services too in the UK, but not for a very long time now, not since they all moved to using the TETRA system, which is based on the same principles as GSM Mobile and is encrypted, I do however often see pager messages being sent to ambulance staff via POCSAG on the unencrypted UK pager network.

S Douglas

Peter Shaw wrote:

Here in the UK, we don't have towns and houses where everyone on the street has a 10 Acre garden

Well, I live in the city so we don't have 10 acre spreads. Most of the city lots in my area are .5 acre. Which ends up being about 100yrds between neighbors (give or take). Just enough that that WIFI doesn't interfere. Might be interesting to snoop though now that you have me wondering about it. Just to see what all even in my house is broadcasting. I know the Insteon (lighting control) system all operate on 70cm. hmmm...

Peter Shaw wrote:

One of my neighbor's appears to have a microwave oven that's WiFi enabled (Don't ask....)

You know that a microwave works off RF right? Is it really WIFI, or just bleeding over? [https://io9.gizmodo.com/why-does-your-microwave-oven-mess-with-the-wi-fi-connec-1666117933\](https://io9.gizmodo.com/why-does-your-microwave-oven-mess-with-the-wi-fi-connec-1666117933)

Peter Shaw wrote:

We used to be able to listen to the Police/Fire emergency services too in the UK, but not for a very long time now, not since they all moved to using the TETRA system, which is based on the same principles as GSM Mobile and is encrypted

Thankfully, Emergency Services in the US still believe in being open. While on a digital trunked network, its still relatively easy to listen in. So far, most agencies have resisted the calls to encrypt their radio traffic (what the hell are they trying to hide anyways? Where accidents are)

Common sense is admitting there is cause and effect and that you can exert some control over what you understand.

Peter Shaw

Yup to the Microwave Oven and RF Q :-) (Iv'e previously worked as a Radio Access Networks Engineer), the reason for the "Don't Ask" was to be fair in reference to that as in (Don't ask me, I have no Idea how this would actually work). It may not be a Microwave, it may just be a regular oven, I dunno, but some of the ASCII data Iv'e pulled out of what Iv'e sniffed seems to suggest that there is some kind of Microwave cooking ability. :-) As for our emergency services, I seem to remember a long time back now, that the reasons sighted for moving to a secured channel for broadcasts, was because they got sick of people turning up at incidents to "spectate", and getting in the way of the services trying to do their job. I know certainly, when I was growing up, if we heard sirens outside, we grab our bikes and try to follow them to see what was going on.

S Douglas

Peter Shaw wrote:

It may not be a Microwave, it may just be a regular oven, I dunno, but some of the ASCII data Iv'e pulled out of what Iv'e sniffed seems to suggest that there is some kind of Microwave cooking ability.

Hmmm, so have you tried to send it data? Or just reply a capture? :)

Peter Shaw wrote:

because they got sick of people turning up at incidents to "spectate",

That many people listening in? I would suspect that in the scanner boards there would be a lot more questions from people in the UK then. More likely paranoia over the subject. More likely people just followed the flashing lights...Maybe they should encrypt those :) really be safe then.

Peter Shaw wrote:

heard sirens outside, we grab our bikes and try to follow them to see what was going on.

I bet a lot of kids did that! Half the fun was seeing how fast you can get the bike going!

Common sense is admitting there is cause and effect and that you can exert some control over what you understand.

Peter Shaw

Nah, not tried to send it anything.... there is still time though, I get the impression it's not going anywhere :-) When I get time I would actually like to try cracking the proto on my Thermostat too. Like all the houses on the estate, it's around the 400Mhz area +- 20 or so to prevent too much over lap, mine I think is at about 405. Apparently it's a 2 way protocol from the very limited info Iv'e been able to find online about Honeywell thermo control units, if it is, then it actually means I could probably control my central heating from my computer network, and thus from my phone :-) Again though, it's a matter of time, I just don't get much of it to do the things I want to these days, and end up spending time doing the things I have to do...

S Douglas

Peter Shaw wrote:

Apparently it's a 2 way protocol from the very limited info Iv'e been able to find online about Honeywell thermo control units, if it is, then it actually means I could probably control my central heating from my computer network, and thus from my phone

Depending on the thermostat you have, some have defined interfaces. I used to have a honeywell thermostat, and controlling it was pretty easy.

Peter Shaw wrote:

Again though, it's a matter of time,

I know that feeling all to well...

Common sense is admitting there is cause and effect and that you can exert some control over what you understand.