Artifacts on DRS25A-NXT Display

[Quitsa]

Sometimes I get very big radial artifacts on the screen of my DRS25A-NXT radar. It seems independent of range or gain or sea state. It doesn't happen all the time and they areen't stable, getting painted in different places and in differing numbers. Cycling through transmit and standby a couple of times or worst case turning off the whole system and restarting makes it stop. I have two TZT 3 16 displays and it is identical on both.

Any thoughts?

The screen shots below illustrate what is happening.

 

[Johnny Electron]

That is what you see when one nearby radar transmits directly into the receive of your radar. This can be resolved by using your interference rejection filter.

 

[Quitsa]

Thanks. I thought I had tried the filter but maybe not since I know you probably have seen this issue many times and recognize it. I will try that solution.

How close would the other vessel need to be for this to happen and does it matter if they have S band or X band radars? There were two very large survey ships several miles away mapping the sea bottom for the huge offshore windfarm that is going to destroy our pristine area next year when its final permits are granted. I am sure they would have been operating at least one and probably two radars.

 

[Johnny Electron]

Both type can cause interference but x-band will be worse. The more power the other radar is the more the expected interference.

 

[Quitsa]

I wouldn't be surprised if those big survey ships had 50kW X band radars and a high power S band too. When I have passed close by, they have a veritable forest of electronics on the masts. That might explain why I haven't really noticed it very much closer to home where the traffic would have lower power recreational radars, mostly small domes. Thanks.

 

[Quitsa]

I saw the pie wedge interference again yesterday similar to what was in the screen shots I had posted above. The interference rejection was definitely on at the time (I checked). There were several commercial fishing boats and a large yacht within 3-4 miles so I assume it was the radar on one of those vessels. It was very sporadic but I saw it a number of times.

Is there anything else that will mitigate these false returns? I would have thought the solid state DRS25A-NXT would operate on different frequencies.

 

[Johnny Electron]

The pulse is different (like CHIRP) called pulse compression but the freq is about the same and subject to physics and interference just like a Magnetron radar. Interference rejection normally takes care of any other area radars when applied.