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Direction finding of FHSS

Hi everyone! I would be thankful for advice how to properly detect FHSS signal via Direction Finding module. When we try to find direction of wide FHSS signal (for ex. 912-926 MHz), signal itself appear on particular frequncy only tiny part time (let say, each 0,2 second). Direction Finding module could not catch signal, and it shows direction on sound noise, but not on signal. So, are there any ideas, how can we avoid this problem? Thank you in advance and Happy New Year!

If you want to track short bursts you would need the chopper mode option which can track signals within the µs range.


Thank you for an answer! In this case, can you tell a bit more on chopper mode? Antenna currently has settings "Chopper mode off", but there is a line below "Chopper time" with 996 µs. Well, what does this time mean if chopper mode is off? In the same time, if we turn on chopper mode, there are different options of chopper mode on (10 µs, 100 µs etc.). So how these options correspond with chopper time below, and what does "generic" option mean? And, does IQ Direction Power Spectrum obligatory for proper use of this function? I attached screens below.

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Actually I just found part of the answer here . However there is still question on IQ Direction Power Spectrum. Also, in aforementioned topic (via link) there are two controversial thesis: DF with chopper mode is more accurate vs is less accurate. So what of them is right?

It is all answered in that post. Btw: Do you have trigger box for the IsoLOG antenna? Otherwise you cant use the choppermode.

I am not sure what is the trigger box: is it some kind of device which should be connected to satelite and antenna via "trigger" output? If yes, we don't have such device. In this case, are there any other options how could we properly find direction at FHSS signals?

The Sector Waterfall block can track "analog" via multiple waterfalls for every sector any modulation but is an optional SW feature:

A very old version is shown at