Morning Watch, or join Radio Robinhood

I always considered myself lucky. So rarely was in Moscow, I still caught the signal that carries everyone to Vnukovo. But not all the carnival. The last two times I did not get on this holiday EW and RR (radio-electronic warfare and radio intelligence), I had to go to St. Petersburg with nothing. It is clear that after the white band always comes black, but I want to take control of the situation with your help.

Moscow and even Peter are already full of rumors. It is by rumors, not clear information, I want to note. Here is a note , under which in the comments everything, anything, but not a confirmation. Someone writes what was, someone that was not. Here is a message about teleporting to Pulkovo residents of St. Petersburg at the end of October. And again, no confirmation from readers. When it was? Was it here before? Where did the radiation come from?

Here you can understand the people, the safety of the first persons and all that, but the headlines about taxi drivers using interference and spoofing - one , two and three - already something out of the ordinary! Who will catch them, if you can not even say it is true or not? You can always say that the user of a taxi service thought something.

But abroad, they are already working on creating monitoring systems for jamming in the navigation range, and even receive prizes at competitions. They are going to monitor GPS interference using users' smartphones.

We will go the other way!
I suggest another way, more accurate and professional.

Now the population of Russia has accumulated a huge amount of radio weapons - inexpensive SDR cards. And the authorities are not going to withdraw these weapons, and they cannot, of course. I propose to use their small part to monitor the radio situation.

It would be ideal to make the positioning of interference sources and a subtle analysis of their signals by recording. True, this will require the creation of a single time system for gauges and direction finders, which, under the conditions of suppressing the main time source, GPS or GLONASS satellites, is not a trivial task.

Therefore, at first, I propose to simplify the task as much as possible. Let several people, let's call them radio partisans, stand on the windowsill flower kit, as in the picture below.

It may consist of a LimeSDR card or another similar, inexpensive single-board computer ROCK64 or any other with USB3 that is on hand, and an antenna that receives at 1.6 GHz. On this hardware, let the software work, which, for example, once a minute, sends to the central server information about the signal level on the GPS and GLONASS L1 frequencies. Let this information be stored on the server and displayed on request via the Internet in open access to anyone who is interested.

Then, if you have doubts about the correct operation of your navigation, you can simply go to the site and see if the navigation is now suppressed. You can also see statistics on the presence of interference with navigation in this area, at this time of the day, on this day of the week, etc.

Any sort of radio intelligence hooligans like me will be able to predict the appearance of interference and not make idle trips to analyze them. If the system is developed to the positioning and analysis of signals, then I will not be able to go to Moscow at all.

I encourage everyone who can help with the software to join. You need to do a simple part on the side of the SDR software, you need to make a server, you need to make a display of information on the web. All, of course, open source. I have even made an empty repository on Github for sources. I will put the server myself in my apartment so far. I will also put an SDR card with a small computer in a place where I can turn on the generator for a short time so that the person who will be doing the SDR software can remotely debug the system.

We also need your ideas on how to improve everything and change where to develop.

Are needed heroes good people who install at home or at work devices and connect them to the web. They can assemble these devices themselves, from their own funds, or ask friends. First of all, such radio monitors are needed in places where interference has already been detected earlier. This is the center of Moscow and St. Petersburg and airports.

Now I will describe my idea for digital signal processing at this stage. Once a minute, you need to tune in to the GPS frequency L1, 1575.42 MHz and remove the sample with a duration of, say, 10 milliseconds with a 2 MHz band, then average the sampling power (find the average sum of squares of the in-phase and quadrature components) and send this number to the server with a time stamp . Then do the same thing with the center frequency of GLONASS - 1605, but the band needs to be increased to 10 MHz.

This method does not allow to distinguish the spoofer from a simple interference transmitter, but it is simple to implement. From this option, you can start a discussion, it is best to give a specific scheme of DSP at the mercy of the one who undertakes to implement it. This software can be done on the basis of GNURadio.

Samples of average power should be recorded in a database on the server, so that it would be convenient then to select data for displaying desktop and mobile versions in the browser. Here my fantasy is limited, since I am not an expert on these issues. I fully rely on you.

The antenna for this range can simply be a wire 1/4 wave length, 4.5 cm, soldered to the antenna connector of the SDR card.

As you can see, everything is quite simple. You just need to take and do.

I await the reaction of the community and help in the implementation of software. Hopefully, we will accumulate a database of radio interference together and ultimately make our radio broadcast cleaner!

PS The morning watch, as the GPS-spoofer in Moscow usually turns on in the morning.