USB TV tuners on rtl2832 - or how to hear everything on the radio for 600 rubles

For a long time I was going to buy some kind of universal radio receiver / radio scanner to climb on the air, listen to what seasoned and bearded radio amateurs talk at night ...

Until recently, this pleasure cost from $ 300 to infinity. Well, with the transition of government agencies (both in Russia and over the hill) to digital (but not yet encrypted) APCO P25 communication, the cost of satisfying unhealthy curiosity has become even higher.

A year ago, everything changed - the craftsmen found out that many of the Chinese USB TV tuners sold for 600 rubles for us - in fact, are a universal radio receiver, on which you can listen to almost anything in the range of 50-900 MHz without any modifications (if you are lucky - up to 2200 MHz, but they don’t transmit anything much in voice): negotiations between airplanes and dispatchers, builders, taxis, bugs in your apartment and much more.

Under the cut, I’ll tell you what and where to buy, how to connect and configure, and finally, what you can listen to.

Iron

The USB TV tuner consists of two parts - the radio frequency part (determines the possible operating frequencies) and the digital part (digitizes the signal and transfers it to the computer via USB).
The digital part is supported by one - RTL2832.
There are several options for the analog part: Elonics e4000 (a universal favorite, works in the range of 50-1100Mhz and 1250-2200Mhz), FC0013 (~ 45-900Mhz). FC0012 is worse because has problems with signal quality and many frequencies where it does not work.
Thus, it is better to look for receivers with e4000 or FC0013. Unfortunately, Elonics has gone bankrupt at the moment, and recent stocks are running out quickly.

From verified sources, I can mention Dealextreme - on e4000 the receivers have run out of them, and now they are on FC0013. A full list of online stores is collected here, well, in general, at http://www.reddit.com/r/RTLSDR/ there is a lot of information. In the case of a purchase on ebay / aliexpress, it is obligatory for the seller to specify on which chips their tuner is made (since very often they end with them and they send others): “Hi, could you confirm that your tuner have rtl2832 & FC0013 (e4000 ) chips? ”, then if they send you something wrong, it will be easier to return the money.

Inside, the receiver looks like this:

On many models, the protective diode is “forgotten” (it protects the receiver from static electricity) - you can leave it as it is, but try not to touch the antenna with your hands, and disconnect the antenna from the receiver in a thunderstorm. But you can certainly solder yourself: BAV99 or as in my case - 2 separate 1N4148 (one from the ground to the antenna, the other in the opposite direction. What is needed is a “fast” diode with a small capacitance, which doesn’t work anyway).

Antenna

The omnidirectional television antenna MV-DMV (“horns”) is quite suitable. I generally took on a half-meter metal pin. All this needs to be pulled out on a balcony / window. If the computer is far away, it is better to lengthen the USB cable, rather than the antenna. Well, it is better to remove sources of radio-frequency noise away (for example, the same computer with an open case is a big obstacle).

Software

There are a whole bunch of software options, I will consider a popular and quite convenient option - SDR # under Windows (you can also read here in English ):

1) Download the latest version of SDR # Dev and SDR # RTLSDR Plugin here , and the RTLSDR library .
2) Unpack into one directory SDR # Dev and SDR # RTLSDR Plugin. From the RTLSDR library, in the same directory we put the rtlsdr.dll file (it is in the archive in the x32 directory). From the config subdirectory, we remove the SDRSharp.exe.config file one level higher (to the place where the bulk of the files turned out).
3) Download Zadig - a program in order to replace the tuner driver, which can only show the TV - a universal driver. Unpack in the same pile.
4) Run Zadig.exe, click Options-> List all devices, select Builk-in, Interface 0, select the driver to replace - “WinUSB”, click Reinstall Driver, we agree with everything.
5) Run SDRSharp.exe, on the left side there will be an inactive Frontend button, and in front of it there will be a drop-down menu. We select RTL-SDR / USB there, and click Play in the upper left corner. Something should start working already.
6) Now you can either directly drive the desired frequency into the input field from the top left, or drag the frequency scale left-right to tune to the desired frequency.

Want to do something your own? (e.g. GPS)

In the simplest case, you can access the air like this:

rtl_sdr -f 1575520000 -g 34 -s 2048000 out.dat

And in the out.dat file, the contents of the ether are merged at a frequency of 1.575 GHz, with a sampling frequency of 2.048 MHz with a gain of 34 dB. If the resulting file is now for example feeding the Matlab script from here , you can see the gps satellites (unless of course you connected an active GPS antenna to the receiver).

It turned out like this for me (satellites - really correspond to those visible in the window on a regular gps receiver):

What and where you can listen (in Moscow)

88-115Mhz - banal FM radio, WFM mode.
118-135Mhz - communication planes and controllers, AM mode.
433Mhz, 446Mhz - heaps of portable radio stations, builders usually have NFM.
144-145Mhz, 435Mhz - ham radio (almost no one in the afternoon / day), NFM.
864Mhz - a bunch of taxi channels, NFM.
You can also find "baby monitors", old analog cordless telephones, the analog bugs that they listen to you - but here you can’t guess with frequency (all this is usually also in NFM).

But what about the digital communications APCO P25?

Download DSD . The program receives the digital transmission on the default recording device, and plays the decoded result to the default playback device. To “connect” SDR # and DSD you will need Virtual Audio Cable . In the Windows sound properties, we make the VAC “output” - the default recording device, and in SDR # we select the playback device - Line 1 (VAC). AF Gain set about 20-40%. We configure SDR # to the desired frequency (Google knows which one) in NFM mode, the text with the debug information should run in the DSD window, and you should hear decoded conversations in the headphones. I strongly recommend that you do not record or distribute accidentally heard conversations.

Similarly (using VAC), programs for decoding pager messages, photos from weather satellites and other things are connected.

Where to go next?

Ways of improvement are as follows:
1) HF converter to shift frequencies by 100 MHz “up” - then you can listen to 27 MHz radios, a bunch of suspicious spy HF stations and much more.
2) GaAs preamplifier : e4000 is a silicon chip, and it makes a lot of noise. If you put a low-noise amplifier in front of it, you can reduce the noise level by about 3dB (i.e., by half).
3) Discone-antenna - is distinguished by its broadband and horizontal radiation pattern.
4) notch filter of the broadcast range (so that multi-kilowatt FM and television stations less interfere with the receiver)
5) A band antenna for the range that interests you, instead of a disco cone with a wide band but a weak gain (again, already a band - the receiver has to filter out fewer extraneous signals - accordingly, the quality of reception of weak signals is potentially higher). For the last 2 points thanks Moskus

Here's how it all looks to work:

(do not forget the volume quieter)
Negotiations of controllers and pilots, 118-135Mhz:


Builders at 433 / 446Mhz:


Radio amateurs at 144 MHz (an incredible detail - the negotiator was noted in the comments on YouTube):


I just have to wish good luck in your research on radio!

PS. Eh, I see that I'm late for 65 minutes. Fortunately, we talked about RTL2832 from different angles (there is HDSDR, then SDRSharp and cinema).

PPS Unfortunately, the most entertaining dialogue that was heard was not recorded at that time: A
conversation between two builders (apparently a foreman with some other leader)

1: Here the formwork was crookedly made, the concrete turned out thinner than necessary by 5cm
2: Can I fix it somehow?
1: Well ... you need to redo everything ...
1: So what will we do, show the technical supervision?
2: Well, how small are you ...
2: Well, of course not