Forums › BB Series Discussions › IQ with external trigger
- This topic has 1 reply, 2 voices, and was last updated 7 years, 1 month ago by Andrew.
I work with BB60 API IQ example with trigger functionality.
My buffer length is 8192 samples (625kHz samplerate with 300kHz bandwidth) but trigger array gives me values like 100000 and bigger.Is it wrong or this values are not indexes in data array.
AndrewModeratorAndrew January 29, 2016 at 9:27 am
The trigger values in the current API provide you with the full resolution pre-decimation. The BB60 has a sample rate of 80MS/s which we convert to a 40MS/s I/Q data stream with decimation 1. The triggers are referenced to the 80MS/s. So at a decimation of 1, you would need to divide a trigger value by 2 to have it reference a sample in a 40MS/s I/Q stream.
If you have a decimation of ‘n’, divide the trigger value by (n*2) to have it reference a sample in your data stream.
Alternatively, the trigger values range between 0 and 2^20 (1048576), so if your getting 8192 samples per acquisition, divide the trigger value by the ration of 2^20 / 8192 = 128.
The reason it is this way, is so that the triggers are still providing 12.5ns resolution for any I/Q data stream.
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