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Consolidate anti_alias BW selection into function (#1217)
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@ -60,41 +60,8 @@ CaptureAppView::CaptureAppView(NavigationView& nav)
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/* ex. recording 500kHz BW to .C16 file, base_rate clock 500kHz x2(I,Q) x 2 bytes (int signed) =2MB/sec rate SD Card */
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waterfall.on_hide();
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/* Set up proper anti aliasing BPF bandwith in MAX2837 before ADC sampling according to the new added BW Options . */
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switch (sampling_rate) { // we use the var fs (sampling_rate) , to set up BPF aprox < fs_max/2 by Nyquist theorem.
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case 0 ... 2000000: // BW Captured range (0 <= 250kHz max ) fs = 8 x 250 kHz
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anti_alias_baseband_bandwidth_filter = 1750000; // Minimum BPF MAX2837 for all those lower BW options.
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break;
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case 4000000 ... 6000000: // BW capture range (500k ... 750kHz max ) fs_max = 8 x 750kHz = 6Mhz
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// BW 500k ... 750kHz , ex. 500kHz (fs = 8*BW = 4Mhz) , BW 600kHz (fs = 4,8Mhz) , BW 750 kHz (fs = 6Mhz)
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anti_alias_baseband_bandwidth_filter = 2500000; // in some IC MAX2837 appear 2250000 , but both works similar.
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break;
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case 8800000: // BW capture 1,1Mhz fs = 8 x 1,1Mhz = 8,8Mhz . (1Mhz showed slightly higher noise background).
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anti_alias_baseband_bandwidth_filter = 3500000;
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break;
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case 14000000: // BW capture 1,75Mhz , fs = 8 x 1,75Mhz = 14Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 5000000;
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break;
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case 16000000: // BW capture 2Mhz , fs = 8 x 2Mhz = 16Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 6000000;
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break;
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case 20000000: // BW capture 2,5Mhz , fs= 8 x 2,5 Mhz = 20Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 7000000;
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break;
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default: // BW capture 2,75Mhz, fs = 8 x 2,75Mhz= 22Mhz max ADC sampling) and others.
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// We tested also 9Mhz FPB stightly too much noise floor, better 8Mhz
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anti_alias_baseband_bandwidth_filter = 8000000;
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}
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/* Set up proper anti aliasing BPF bandwith in MAX2837 before ADC sampling according to the new added BW Options. */
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auto anti_alias_baseband_bandwidth_filter = filter_bandwidth_for_sampling_rate(sampling_rate);
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record_view.set_sampling_rate(sampling_rate);
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receiver_model.set_sampling_rate(sampling_rate);
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@ -56,7 +56,6 @@ class CaptureAppView : public View {
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app_settings::Options::UseGlobalTargetFrequency};
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uint32_t sampling_rate = 0;
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uint32_t anti_alias_baseband_bandwidth_filter = 2500000;
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Labels labels{
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{{0 * 8, 1 * 16}, "Rate:", Color::light_grey()},
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@ -205,34 +205,7 @@ size_t LevelView::change_mode(freqman_index_t new_mod) {
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receiver_model.set_modulation(ReceiverModel::Mode::Capture);
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field_bw.set_by_value(0);
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field_bw.on_change = [this](size_t, OptionsField::value_t sampling_rate) {
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uint32_t anti_alias_baseband_bandwidth_filter = 2500000;
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switch (sampling_rate) { // we use the var fs (sampling_rate) , to set up BPF aprox < fs_max/2 by Nyquist theorem.
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case 0 ... 2000000: // BW Captured range (0 <= 250kHz max ) fs = 8 x 250 kHz
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anti_alias_baseband_bandwidth_filter = 1750000; // Minimum BPF MAX2837 for all those lower BW options.
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break;
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case 4000000 ... 6000000: // BW capture range (500k ... 750kHz max ) fs_max = 8 x 750kHz = 6Mhz
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// BW 500k ... 750kHz , ex. 500kHz (fs = 8*BW = 4Mhz) , BW 600kHz (fs = 4,8Mhz) , BW 750 kHz (fs = 6Mhz)
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anti_alias_baseband_bandwidth_filter = 2500000; // in some IC MAX2837 appear 2250000 , but both works similar.
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break;
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case 8800000: // BW capture 1,1Mhz fs = 8 x 1,1Mhz = 8,8Mhz . (1Mhz showed slightly higher noise background).
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anti_alias_baseband_bandwidth_filter = 3500000;
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break;
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case 14000000: // BW capture 1,75Mhz , fs = 8 x 1,75Mhz = 14Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 5000000;
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break;
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case 16000000: // BW capture 2Mhz , fs = 8 x 2Mhz = 16Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 6000000;
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break;
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case 20000000: // BW capture 2,5Mhz , fs= 8 x 2,5 Mhz = 20Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 7000000;
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break;
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default: // BW capture 2,75Mhz, fs = 8 x 2,75Mhz= 22Mhz max ADC sampling) and others.
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// We tested also 9Mhz FPB stightly too much noise floor, better 8Mhz
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anti_alias_baseband_bandwidth_filter = 8000000;
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}
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auto anti_alias_baseband_bandwidth_filter = filter_bandwidth_for_sampling_rate(sampling_rate);
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receiver_model.set_sampling_rate(sampling_rate);
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receiver_model.set_baseband_bandwidth(anti_alias_baseband_bandwidth_filter);
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};
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@ -1399,34 +1399,7 @@ size_t ReconView::change_mode(freqman_index_t new_mod) {
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receiver_model.set_modulation(ReceiverModel::Mode::Capture);
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field_bw.set_by_value(0);
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field_bw.on_change = [this](size_t, OptionsField::value_t sampling_rate) {
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uint32_t anti_alias_baseband_bandwidth_filter = 2500000;
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switch (sampling_rate) { // we use the var fs (sampling_rate) , to set up BPF aprox < fs_max/2 by Nyquist theorem.
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case 0 ... 2000000: // BW Captured range (0 <= 250kHz max ) fs = 8 x 250 kHz
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anti_alias_baseband_bandwidth_filter = 1750000; // Minimum BPF MAX2837 for all those lower BW options.
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break;
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case 4000000 ... 6000000: // BW capture range (500k ... 750kHz max ) fs_max = 8 x 750kHz = 6Mhz
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// BW 500k ... 750kHz , ex. 500kHz (fs = 8*BW = 4Mhz) , BW 600kHz (fs = 4,8Mhz) , BW 750 kHz (fs = 6Mhz)
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anti_alias_baseband_bandwidth_filter = 2500000; // in some IC MAX2837 appear 2250000 , but both works similar.
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break;
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case 8800000: // BW capture 1,1Mhz fs = 8 x 1,1Mhz = 8,8Mhz . (1Mhz showed slightly higher noise background).
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anti_alias_baseband_bandwidth_filter = 3500000;
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break;
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case 14000000: // BW capture 1,75Mhz , fs = 8 x 1,75Mhz = 14Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 5000000;
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break;
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case 16000000: // BW capture 2Mhz , fs = 8 x 2Mhz = 16Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 6000000;
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break;
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case 20000000: // BW capture 2,5Mhz , fs= 8 x 2,5 Mhz = 20Mhz
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// good BPF, good matching, but LCD making flicker , refresh rate should be < 20 Hz , but reasonable picture
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anti_alias_baseband_bandwidth_filter = 7000000;
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break;
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default: // BW capture 2,75Mhz, fs = 8 x 2,75Mhz= 22Mhz max ADC sampling) and others.
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// We tested also 9Mhz FPB stightly too much noise floor, better 8Mhz
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anti_alias_baseband_bandwidth_filter = 8000000;
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}
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auto anti_alias_baseband_bandwidth_filter = filter_bandwidth_for_sampling_rate(sampling_rate);
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record_view->set_sampling_rate(sampling_rate);
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receiver_model.set_sampling_rate(sampling_rate);
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receiver_model.set_baseband_bandwidth(anti_alias_baseband_bandwidth_filter);
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@ -367,4 +367,35 @@ void WaterfallView::on_audio_spectrum() {
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}
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} /* namespace spectrum */
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uint32_t filter_bandwidth_for_sampling_rate(int32_t sampling_rate) {
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switch (sampling_rate) { // Use the var fs (sampling_rate) to set up BPF aprox < fs_max / 2 by Nyquist theorem.
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case 0 ... 2000000: // BW Captured range (0 <= 250kHz max) fs = 8 x 250 kHz.
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return 1750000; // Minimum BPF MAX2837 for all those lower BW options.
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case 4000000 ... 6000000: // BW capture range (500k...750kHz max) fs_max = 8 x 750kHz = 6Mhz
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// BW 500k...750kHz, ex. 500kHz (fs = 8 x BW = 4Mhz), BW 600kHz (fs = 4,8Mhz), BW 750 kHz (fs = 6Mhz).
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return 2500000; // In some IC, MAX2837 appears as 2250000, but both work similarly.
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case 8800000: // BW capture 1,1Mhz fs = 8 x 1,1Mhz = 8,8Mhz. (1Mhz showed slightly higher noise background).
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return 3500000;
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case 14000000: // BW capture 1,75Mhz, fs = 8 x 1,75Mhz = 14Mhz
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// Good BPF, good matching, but LCD flickers, refresh rate should be < 20 Hz, reasonable picture.
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return 5000000;
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case 16000000: // BW capture 2Mhz, fs = 8 x 2Mhz = 16Mhz
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// Good BPF, good matching, but LCD flickers, refresh rate should be < 20 Hz, reasonable picture.
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return 6000000;
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case 20000000: // BW capture 2,5Mhz, fs = 8 x 2,5 Mhz = 20Mhz
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// Good BPF, good matching, but LCD flickers, refresh rate should be < 20 Hz, reasonable picture.
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return 7000000;
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default: // BW capture 2,75Mhz, fs = 8 x 2,75Mhz = 22Mhz max ADC sampling and others.
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// We tested also 9Mhz FPB slightly too much noise floor, better at 8Mhz.
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return 8000000;
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}
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}
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} /* namespace ui */
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@ -192,6 +192,10 @@ class WaterfallView : public View {
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};
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} /* namespace spectrum */
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/* Calculates the best anti_alias_baseband_bandwidth_filter for the given sampling rate. */
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uint32_t filter_bandwidth_for_sampling_rate(int32_t sampling_rate);
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} /* namespace ui */
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#endif /*__UI_SPECTRUM_H__*/
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