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Increase more BW Options to Capture App

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PR to increase the BW Options in the Capture App , beyond the current max, 500khz.  (from 600Khz till 2,75Mhz)  all of them work well into  the screen, but only <=  600Khz BW are correctly saved  into SD Card with full captured data. (Onwards, >600Khz optiions, at the moment ,  the created SD card  file has  decimated data, due - to SD Card writting speed limitations),-  but I feel still quite interesting feature to keep them.
This commit is contained in:
Brumi-2021 2021-11-21 19:35:31 +01:00
parent 848dba44d8
commit 14484b550a
2 changed files with 53 additions and 5 deletions
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47
firmware/application/apps/capture_app.cpp
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@ -74,17 +74,58 @@ CaptureAppView::CaptureAppView(NavigationView& nav) {
option_bandwidth.on_change = [this](size_t, uint32_t base_rate) {
sampling_rate = 8 * base_rate; // Decimation by 8 done on baseband side
/* base_rate is used for FFT calculation and display LCD, and also in recording writing SD Card rate. */
/* ex. sampling_rate values, 4Mhz, when recording 500 khz (BW) and fs 8 Mhz , when selected 1 Mhz BW ...*/
/* ex. recording 500khz BW to .C16 file, base_rate clock 500khz x2(I,Q) x 2 bytes (int signed) =2MB/sec rate SD Card */
waterfall.on_hide();
record_view.set_sampling_rate(sampling_rate);
receiver_model.set_sampling_rate(sampling_rate);
/* Set up proper anti aliasing BPF bandwith in MAX2837 before ADC sampling according to the new added BW Options . */
switch(sampling_rate) { // we use the var fs (sampling_rate) , to set up BPF aprox < fs_max/2 by Nyquist theorem.
case 0 ... 2000000: // BW Captured range (0 <= 250Khz max ) fs = 8 x 250 Khz
anti_alias_baseband_bandwidth_filter = 1750000; // Minimum BPF MAX2837 for all those lower BW options.
break;
case 4000000 ... 6000000: // BW capture range (500k ... 750Khz max ) fs_max = 8 x 750Khz = 6Mhz
// BW 500k ... 750khz , ex. 500khz (fs = 8*BW = 4Mhz) , BW 600Khz (fs = 4,8Mhz) , BW 750 Khz (fs = 6Mhz)
anti_alias_baseband_bandwidth_filter = 2500000; // in some IC MAX2837 appear 2250000 , but both works similar.
break;
case 8800000: // BW capture 1,1Mhz fs = 8 x 1,1Mhz = 8,8Mhz . (1Mhz showed slightly higher noise background).
anti_alias_baseband_bandwidth_filter = 3500000;
break;
case 14000000: // BW capture 1,75Mhz , fs = 8 x 1,75Mhz = 14Mhz
// good BPF ,good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
anti_alias_baseband_bandwidth_filter = 5000000;
break;
case 16000000: // BW capture 2Mhz , fs = 8 x 2Mhz = 16Mhz
// good BPF ,good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
anti_alias_baseband_bandwidth_filter = 6000000;
break;
case 20000000: // BW capture 2,5Mhz , fs= 8 x 2,5 Mhz = 20Mhz
// good BPF ,good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
anti_alias_baseband_bandwidth_filter = 7000000;
break;
default: // BW capture 2,75Mhz, fs = 8 x 2,75Mhz= 22Mhz max ADC sampling) and others.
// We tested also 9Mhz FPB stightly too much noise floor , better 8Mhz
anti_alias_baseband_bandwidth_filter = 8000000;
}
receiver_model.set_baseband_bandwidth(anti_alias_baseband_bandwidth_filter);
waterfall.on_show();
};
option_bandwidth.set_selected_index(7); // 500k
option_bandwidth.set_selected_index(7); // 500k, Preselected starting default option 500khz
receiver_model.set_modulation(ReceiverModel::Mode::Capture);
receiver_model.set_baseband_bandwidth(baseband_bandwidth);
receiver_model.enable();
record_view.on_error = [&nav](std::string message) {