Tablet of the Kremlin demon

The topic of radio satellite navigation interference has recently become so hot that the situation resembles a war. And indeed, if you yourself “come under fire” or read about people's problems, a feeling of helplessness arises before the elements of this “First Civil Radio-Electronic War”. She does not regret neither old men, nor women, nor children (a joke, of course). But there was a light of hope - now, somehow, the civilian population can cope with this “radio napalm” with the help of the latest technological advances.

Almost by chance, a useful feature of the u-blox F9P dual-frequency receiver was noticed. It was a field test of a two-frequency antenna. The antenna has separate outputs of different ranges L1 and L2 / L5. By mistake, the output of the L1 range was disabled during operation. And, lo and behold, the synchronization with the satellites and the solution of the navigation problem (3D fix) remained.

There is a short video for two minutes without details.
And a long, uncut, nine minutes.

The nuance of the receiver is as follows: if the L1 band is available when the receiver is turned on, then even if you turn it off, the synchronization with the satellites on L2 / L5 and position acquisition remains. If the shoulder of the L1 antenna is turned off before the receiver is turned on, then there is synchronization with the L2 satellites, but the navigation task is not solved, there is no position. In this case, it should be noted that synchronization with satellites on L5 does not appear.

It is not known whether this is a bug or a feature of the F9P receiver. It is not known whether this feature will work in future versions of the device and / or firmware.

But sin is not to use this feature now. Therefore, combat tests were immediately carried out using the radio napalm of a potential enemy in the form of an L1 navigation suppressor. Fortunately, it was available from the time of my work on direction finding navigation interference .

The experience was as follows. First, the receiver was switched on in pure ether, without suppression. After synchronization and solving by the receiver of the navigation task, our little friend suppressor turned on. Results were recorded. After the receiver was dropped and the results of his work were recorded again. Then the source of interference was turned off and it was checked that the situation returned to the original one - the presence of all satellites and positioning.

Since the tests are very simple, they were simply recorded on video.

Here is a short video for a minute and a half.
And long by three and a half .

As you can see, the receiver is operating under interference!

The long video shows the same mystery with the disappearance of L5 satellites as in the first experiments with the antenna with two outputs. I think this mystery can be solved by experts in satellite navigation who will read the article.

The following positive conclusion is obvious: you can start moving (take off by a drone or plane (!), Start a run or walk, get off the ground by car) in a place where there is no interference, and then even the appearance of interference will not spoil the navigation.

This, of course, with the proviso that the interference will be only on L1. But I think that the two-frequency "ammunition" is still not very popular.

And I hope that you can avoid even the distortion of the navigation field, which, as we know, happens in quite interesting places of our capital . It must be checked.

Work plan:

1. Checking the operation of the receiver under the action of the navigation spool . Kremlin (and he still works?) Or on the SDR.
2. Verification of positioning under interference in motion.
3. Verification of the solution of high-precision navigation problems (RTK) under the influence of interference.

Here, I know for sure, there are people more experienced than me. Please offer more points.

Thanks to u-blox, which gives hope!

Thanks to my friends who helped conduct the experiments.

PS
In motion also works !