DF using the Chopper Mode | Best settings

#1 · 17/07/2023, 09:36

Dear Team,

We have measured the signal hopping of a radio control for direction finding processing. These signals are activated on one of the frequencies at any given moment. Therefore, we believe that with the chopper mode capability, we can determine its entry angle. We used a chopper time of 8 microseconds and approximately accumulation of 10000 and accumulation type of "Power". anyway the measured angle was unstable and even the absolute angle was not true. could you please help us to DF these signals?

and our "IQ directional power spectrum" block configuration is as the screenshot

attached screenshot2 shows our signal and the measured angle (note that in the Histogram we sat the persistence too much so you can see the signals well)

Uploaded files:

#2 · 26/07/2023, 08:09

This is the setup you should use for the chopper mode. Make sure to set the right number of segments (24 for a 8 sector and 48 for a 16 sector antenna):

Chopper Mode Default Settings

Are you sure you have a HARDWARE module attached to the IsoLOG 3D DF antenna generating the chopper signal?

#3 · 26/07/2023, 08:32

P.S. for a perfect tracking of very short signals you should use our new patent pending DF blocks as seen attached. Please contact our sales for price information.

Patent Pending DF from Aaronia

#4 · 26/07/2023, 15:02

Quote from AdminTC on 26/07/2023, 08:09

This is the setup you should use for the chopper mode. Make sure to set the right number of segments (24 for a 8 sector and 48 for a 16 sector antenna):

Are you sure you have a HARDWARE module attached to the IsoLOG 3D DF antenna generating the chopper signal?

Actually my IsoLOG has 16 segments on 8 sector.

And do you mean "Trigger Box" by the "HARDWARE module attached to the IsoLOG 3D DF antenna"?

#5 · 26/07/2023, 15:28

Yes, otherwise the chopper mode will not work.

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#6 · 15/08/2023, 14:30

Quote from AdminTC on 26/07/2023, 08:09

This is the setup you should use for the chopper mode. Make sure to set the right number of segments (24 for a 8 sector and 48 for a 16 sector antenna):

Are you sure you have a HARDWARE module attached to the IsoLOG 3D DF antenna generating the chopper signal?

Dear AdminTC,

Could you explain what "FFT Detect" and "FFT Conv" are?

I have never been able to get output from block "IQ Direction Power Spectrum" with 1024 or higher "FFT Conv size"! What could be the problem ?

#7 · 15/08/2023, 17:16

Use those settings with default only. Internal use.

The maximum FFT Conv -> FFT Size depends on your IQ bandwidth. The higher the IQ bandwidth the higher the FFT size can be set.

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