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Move baseband FIR filter defs to common file.

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They will likely be shared with multiple decimators/demodulators.
Also added normalized filter pass/stop values to each set of taps.
This commit is contained in:
Jared Boone
2015-12-30 12:19:42 -08:00
parent 3db0820b54
commit 7de80edcd3
3 changed files with 132 additions and 230 deletions
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105
firmware/baseband/proc_nfm_audio.cpp
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@@ -24,81 +24,6 @@
#include <cstdint>
#include <cstddef>
// NBFM 16K0F3E emission type /////////////////////////////////////////////
// IFIR image-reject filter: fs=3072000, pass=8000, stop=344000, decim=8, fout=384000
static constexpr std::array<int16_t, 24> taps_16k0_decim_0 { {
1, 67, 165, 340, 599, 944, 1361, 1820,
2278, 2684, 2988, 3152, 3152, 2988, 2684, 2278,
1820, 1361, 944, 599, 340, 165, 67, 1,
} };
// IFIR prototype filter: fs=384000, pass=8000, stop=40000, decim=8, fout=48000
static constexpr std::array<int16_t, 32> taps_16k0_decim_1 { {
-26, -125, -180, -275, -342, -359, -286, -90,
250, 733, 1337, 2011, 2688, 3289, 3740, 3982,
3982, 3740, 3289, 2688, 2011, 1337, 733, 250,
-90, -286, -359, -342, -275, -180, -125, -26,
} };
// Channel filter: fs=48000, pass=8000, stop=12400, decim=1, fout=48000
static constexpr std::array<int16_t, 32> taps_16k0_channel { {
-73, -285, -376, -8, 609, 538, -584, -1387,
-148, 2173, 1959, -2146, -5267, -297, 12915, 24737,
24737, 12915, -297, -5267, -2146, 1959, 2173, -148,
-1387, -584, 538, 609, -8, -376, -285, -73,
} };
// NBFM 11K0F3E emission type /////////////////////////////////////////////
// IFIR image-reject filter: fs=3072000, pass=5500, stop=341500, decim=8, fout=384000
static constexpr std::array<int16_t, 24> taps_11k0_decim_0 { {
38, 102, 220, 406, 668, 1004, 1397, 1822,
2238, 2603, 2875, 3020, 3020, 2875, 2603, 2238,
1822, 1397, 1004, 668, 406, 220, 102, 38,
} };
// IFIR prototype filter: fs=384000, pass=5500, stop=42500, decim=8, fout=48000
static constexpr std::array<int16_t, 32> taps_11k0_decim_1 { {
-42, -87, -157, -234, -298, -318, -255, -75,
246, 713, 1306, 1976, 2656, 3265, 3724, 3971,
3971, 3724, 3265, 2656, 1976, 1306, 713, 246,
-75, -255, -318, -298, -234, -157, -87, -42,
} };
// Channel filter: fs=48000, pass=5500, stop=8900, decim=1, fout=48000
static constexpr std::array<int16_t, 32> taps_11k0_channel { {
-68, -345, -675, -867, -582, 247, 1222, 1562,
634, -1379, -3219, -3068, 310, 6510, 13331, 17795,
17795, 13331, 6510, 310, -3068, -3219, -1379, 634,
1562, 1222, 247, -582, -867, -675, -345, -68,
} };
/// NBFM 8K50F3E emission type ////////////////////////////////////////////
// IFIR image-reject filter: fs=3072000, pass=4250, stop=340250, decim=8, fout=384000
static constexpr std::array<int16_t, 24> taps_4k25_decim_0 { {
38, 103, 222, 409, 671, 1006, 1399, 1821,
2236, 2599, 2868, 3012, 3012, 2868, 2599, 2236,
1821, 1399, 1006, 671, 409, 222, 103, 38,
} };
// IFIR prototype filter: fs=384000, pass=4250, stop=43750, decim=8, fout=48000
static constexpr std::array<int16_t, 32> taps_4k25_decim_1 { {
-33, -74, -139, -214, -280, -306, -254, -87,
222, 682, 1274, 1951, 2644, 3268, 3741, 3996,
3996, 3741, 3268, 2644, 1951, 1274, 682, 222,
-87, -254, -306, -280, -214, -139, -74, -33,
} };
// Channel filter: fs=48000, pass=4250, stop=7900, decim=1, fout=48000
static constexpr std::array<int16_t, 32> taps_4k25_channel { {
-58, -14, 153, 484, 871, 1063, 770, -141,
-1440, -2488, -2435, -614, 3035, 7771, 12226, 14927,
14927, 12226, 7771, 3035, -614, -2435, -2488, -1440,
-141, 770, 1063, 871, 484, 153, -14, -58,
} };
NarrowbandFMAudio::NarrowbandFMAudio() {
set_mode(Mode::Deviation2K5Narrow);
}
@@ -123,30 +48,30 @@ void NarrowbandFMAudio::set_mode(const Mode mode) {
switch(mode) {
default:
case Mode::Deviation5K:
decim_0.configure(taps_16k0_decim_0, 33554432);
decim_1.configure(taps_16k0_decim_1, 131072);
channel_filter.configure(taps_16k0_channel, channel_filter_decimation_factor);
decim_0.configure(taps_16k0_decim_0.taps, 33554432);
decim_1.configure(taps_16k0_decim_1.taps, 131072);
channel_filter.configure(taps_16k0_channel.taps, channel_filter_decimation_factor);
demod.configure(demod_input_fs, 5000);
channel_filter_pass_f = 8000;
channel_filter_stop_f = 12400;
channel_filter_pass_f = taps_16k0_channel.pass_frequency_normalized * channel_filter_input_fs;
channel_filter_stop_f = taps_16k0_channel.stop_frequency_normalized * channel_filter_input_fs;
break;
case Mode::Deviation2K5Wide:
decim_0.configure(taps_11k0_decim_0, 33554432);
decim_1.configure(taps_11k0_decim_1, 131072);
channel_filter.configure(taps_11k0_channel, channel_filter_decimation_factor);
decim_0.configure(taps_11k0_decim_0.taps, 33554432);
decim_1.configure(taps_11k0_decim_1.taps, 131072);
channel_filter.configure(taps_11k0_channel.taps, channel_filter_decimation_factor);
demod.configure(demod_input_fs, 2500);
channel_filter_pass_f = 5500;
channel_filter_stop_f = 8900;
channel_filter_pass_f = taps_11k0_channel.pass_frequency_normalized * channel_filter_input_fs;
channel_filter_stop_f = taps_11k0_channel.stop_frequency_normalized * channel_filter_input_fs;
break;
case Mode::Deviation2K5Narrow:
decim_0.configure(taps_4k25_decim_0, 33554432);
decim_1.configure(taps_4k25_decim_1, 131072);
channel_filter.configure(taps_4k25_channel, channel_filter_decimation_factor);
decim_0.configure(taps_4k25_decim_0.taps, 33554432);
decim_1.configure(taps_4k25_decim_1.taps, 131072);
channel_filter.configure(taps_4k25_channel.taps, channel_filter_decimation_factor);
demod.configure(demod_input_fs, 2500);
channel_filter_pass_f = 4250;
channel_filter_stop_f = 7900;
channel_filter_pass_f = taps_4k25_channel.pass_frequency_normalized * channel_filter_input_fs;
channel_filter_stop_f = taps_4k25_channel.stop_frequency_normalized * channel_filter_input_fs;
break;
}