With the public antenna it is enough, in Spain we have the service for free.
Somos pocos pero vamos creciendo 
Hello.
He tests the F9P set with the ANN-MB antenna in tractors and combines with quite satisfactory results. However, I have a fairly frequent problem in several fields, with the message “Lost RTK” and switching to “Float”, which causes inaccurate guidance. Will replacing the antenna with another help? If so, which one? Beitian BT160 or BT 200 will be good?
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First make sure that the issues are not losing corrections, make sure that the corrections are coming in every second. If the corrections are coming in more than 2s apart something is not optimized in the communication link.
Under open sky any antenna will do. Make sure that the antenna is free of dust periodically.
The antenna is 100% clear. Corrections is this “Age” value? there I always have 1.0 to 1.5, unless I lose my internet connection, but that rarely happens, only then I know when it is happening. On the other hand, the case that I describe happens each time in the same fields, in the same places and in the same direction of movement. For example, in one field it is an area 30m wide and only when I move eastwards, but when I go westwards, the RTK returns.
Where do you get your correction signal from? Do you have all 4 constellations in use? If you have your own base, does the base have good sky view too? How about trees etc. in the field, good sky view in all directions?
I get the correction signal from the base station, 34 km from my field. My problem areas are completely exposed. This station has GPS + GLO + BDS constellations. The next closest is 70km and has GPS + GLO + GAL + BDS.
You can see the power line in your video, so the field is not completely empty. I have met with such a case that the power line that runs somewhere along the field border causes problems. Because if you have these wires over your head, everything is fine, problems are when the wires are on the horizon.
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I have one field on the farm with a low voltage line on one side and a medium voltage line on the other. It is difficult to work with GPS in this field. There is a float. I tried many times to create a border in this field and I always got strange results, the field is 4 ha and the agopene was 20 ha. Only the a-b line can be created and even corn can be sown, but the position drifts quite fast.
Does not lose signal on the field from the film. On those where it loses the signal it is completely clean.
Do mnie można po polsku.
Need a fix from four satellites?
Four is not sufficient for RTK fix, not even theoretically. But why are you referring to this figure? You said the receiver and the base are under open sky, they should see of the order of 40 satellites, not 4.
I was thinking about constellations, not satellites. The station from which I receive the fix signal has the GPS GLO BDS constellations.
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Then you set your rover for same three constellations. A fix can only be calculated from same satellites that both base and rover see at the same time.
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So in the u blox settings I should turn off one constellation? But as I say, such RTK losses are always in the same fields and in the same places. For my mind, the antenna was too weak and it did not receive the signal sufficiently. A bit like white spots of GSM phone signal.
If it is signal interference from some local source (perhaps the offending signal just happens to bounce off terrain to make this particular spot), then using more constellations should help with that, right? Doesn’t sound like that is the case, though. Although all the GNSS constellations uses frequencies in similar bands. Might be helpful if you went to the field where the signal dropouts occur and connect to the receiver with a laptop to see what the signal-to-noise ratios are on the satellites the receiver is seeing.
Will I find these parameters in the u center?
Yes U-Center will give you a real-time bar graph of the SNR for all the satellites it sees.
Which parameter should I check and where to look for it?
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You should select the satellite levels view. But do you have NMEA GSV activated?
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Yes you need NMEA GSV messages turned on for USB. 1 Hz is enough.
Unfortunately I can’t make out what that first picture says for the glare. My u-center display typically looks like this:
The bar graph in the box second from the left on the bottom shows the SNR for various satellites. They should all be at half or greater. If lots are not, then I’d suspect interference of some kind.