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Updated Audio Receivers (markdown)

Brumi-2021 2024-03-10 11:28:10 +01:00
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Audio-Receivers.md

@ -57,7 +57,7 @@ The next item is the setting of the bin sizes used for the waterfall (0-63) with
And next right to that field ,while you are still in SPEC mode, you will see Rx_IQ_CAL field.It actually can improve (8 to 10 dB's from worse CAL point to the best one ) the receiver Image Reject Ratio only in the Receiver Applications that are using Zero IF-frequency tuning ,like this SPECTRUM mode. This calibrated value it is stored in the SD card , /settings/rx_audio.ini .
To calibrate it , you will need to try to find some clean isolated continuous carrier , and try to tune it , (example , to the right of the positive frequencies ). Select properly the BW to try to isolate that air carrier signal (in below example , I selected BW = 2 Mhz).
To calibrate it , you will need to try to find some clean air isolated continuous carrier signal (pls make sure that it is a real air signal, not internal harmonic residual interferent clock beats) , and try to tune it , (example , to the right of the positive frequencies ). Select properly the BW to try to isolate that air carrier signal (in below example , I selected BW = 2 Mhz).
Then, to make visible the bare Image mirror frequency -that appears in the other symetric left part screen.-, you will need to start set up CAL to 0 (min). Then , you will need to adjust AMP , LNA and GAIN to receive strong enough signal to the right part (not so strong to not produce intermodulations , otherwise re-adjust again decreasing AMP, LNA, GAIN) , and not so weak , till just getting the carrier +freq. clean (desired carrier signal) , and its bare visible Image mirror Signal (in the other symetrical -xx mirror freq . (unwanted Image signal to be minimized) . Then, when you got similar situation as left below picture, you can start adjusting Rx IQ phase CAL till minimizing the received Image "mirror" signal (as in the middle below picture).
That below example is calibrating H2+ old r6 version (max2837) that has 31 steps ,(Note , using Hackrf r9 (max2839 ,we will have 64 steps)