Go to 300 MHz for FM receiver

grc/PicoSDR-WBFM.grc

@@ -77,7 +77,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [712, 480.0]
+    coordinate: [704, 296.0]
     rotation: 0
     state: true
 - name: analog_wfm_rcv_pll_0
@@ -85,7 +85,7 @@ blocks:
   parameters:
     affinity: ''
     alias: ''
-    audio_decimation: '4'
+    audio_decimation: '1'
     comment: ''
     deemph_tau: 75e-6
     maxoutbuf: '0'
@@ -95,7 +95,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [704, 552.0]
+    coordinate: [456, 408.0]
     rotation: 0
     state: true
 - name: audio_sink_0
@@ -112,7 +112,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1000, 560.0]
+    coordinate: [992, 384.0]
     rotation: 0
     state: true
 - name: blocks_add_xx_0
@@ -130,7 +130,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1000, 632.0]
+    coordinate: [992, 456.0]
     rotation: 0
     state: true
 - name: blocks_interleaved_short_to_complex_0
@@ -184,24 +184,6 @@ blocks:
     coordinate: [704, 16.0]
     rotation: 0
     state: true
-- name: digital_costas_loop_cc_0
-  id: digital_costas_loop_cc
-  parameters:
-    affinity: ''
-    alias: ''
-    comment: ''
-    maxoutbuf: '0'
-    minoutbuf: '0'
-    order: '2'
-    use_snr: 'False'
-    w: 2 * math.pi / 100
-  states:
-    bus_sink: false
-    bus_source: false
-    bus_structure: null
-    coordinate: [704, 296.0]
-    rotation: 0
-    state: true
 - name: import_0
   id: import
   parameters:
@@ -215,6 +197,54 @@ blocks:
     coordinate: [440, 8.0]
     rotation: 0
     state: true
+- name: low_pass_filter_0
+  id: low_pass_filter
+  parameters:
+    affinity: ''
+    alias: ''
+    beta: '6.76'
+    comment: ''
+    cutoff_freq: '22_000'
+    decim: '4'
+    gain: '1'
+    interp: '1'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samp_rate: samp_rate
+    type: fir_filter_fff
+    width: '2_000'
+    win: window.WIN_HAMMING
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [704, 356.0]
+    rotation: 0
+    state: true
+- name: low_pass_filter_0_0
+  id: low_pass_filter
+  parameters:
+    affinity: ''
+    alias: ''
+    beta: '6.76'
+    comment: ''
+    cutoff_freq: '22_000'
+    decim: '4'
+    gain: '1'
+    interp: '1'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samp_rate: samp_rate
+    type: fir_filter_fff
+    width: '2_000'
+    win: window.WIN_HAMMING
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [704, 516.0]
+    rotation: 0
+    state: true
 - name: network_tcp_source_0
   id: network_tcp_source
   parameters:
@@ -235,98 +265,6 @@ blocks:
     coordinate: [48, 200.0]
     rotation: 0
     state: true
-- name: qtgui_const_sink_x_0
-  id: qtgui_const_sink_x
-  parameters:
-    affinity: ''
-    alias: ''
-    alpha1: '1.0'
-    alpha10: '1.0'
-    alpha2: '1.0'
-    alpha3: '1.0'
-    alpha4: '1.0'
-    alpha5: '1.0'
-    alpha6: '1.0'
-    alpha7: '1.0'
-    alpha8: '1.0'
-    alpha9: '1.0'
-    autoscale: 'False'
-    axislabels: 'True'
-    color1: '"blue"'
-    color10: '"red"'
-    color2: '"red"'
-    color3: '"red"'
-    color4: '"red"'
-    color5: '"red"'
-    color6: '"red"'
-    color7: '"red"'
-    color8: '"red"'
-    color9: '"red"'
-    comment: ''
-    grid: 'True'
-    gui_hint: (2, 1, 1, 1)
-    label1: ''
-    label10: ''
-    label2: ''
-    label3: ''
-    label4: ''
-    label5: ''
-    label6: ''
-    label7: ''
-    label8: ''
-    label9: ''
-    legend: 'False'
-    marker1: '0'
-    marker10: '0'
-    marker2: '0'
-    marker3: '0'
-    marker4: '0'
-    marker5: '0'
-    marker6: '0'
-    marker7: '0'
-    marker8: '0'
-    marker9: '0'
-    name: '""'
-    nconnections: '1'
-    size: min(int(samp_rate // 30), 512)
-    style1: '0'
-    style10: '0'
-    style2: '0'
-    style3: '0'
-    style4: '0'
-    style5: '0'
-    style6: '0'
-    style7: '0'
-    style8: '0'
-    style9: '0'
-    tr_chan: '0'
-    tr_level: '0.0'
-    tr_mode: qtgui.TRIG_MODE_FREE
-    tr_slope: qtgui.TRIG_SLOPE_POS
-    tr_tag: '""'
-    type: complex
-    update_time: 1/30
-    width1: '1'
-    width10: '1'
-    width2: '1'
-    width3: '1'
-    width4: '1'
-    width5: '1'
-    width6: '1'
-    width7: '1'
-    width8: '1'
-    width9: '1'
-    xmax: '1'
-    xmin: '-1'
-    ymax: '1'
-    ymin: '-1'
-  states:
-    bus_sink: false
-    bus_source: false
-    bus_structure: null
-    coordinate: [1000, 280.0]
-    rotation: 0
-    state: true
 - name: qtgui_time_sink_x_0
   id: qtgui_time_sink_x
   parameters:
@@ -518,104 +456,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1000, 456.0]
+    coordinate: [992, 272.0]
-    rotation: 0
-    state: true
-- name: qtgui_time_sink_x_0_1
-  id: qtgui_time_sink_x
-  parameters:
-    affinity: ''
-    alias: ''
-    alpha1: '1.0'
-    alpha10: '1.0'
-    alpha2: '1.0'
-    alpha3: '1.0'
-    alpha4: '1.0'
-    alpha5: '1.0'
-    alpha6: '1.0'
-    alpha7: '1.0'
-    alpha8: '1.0'
-    alpha9: '1.0'
-    autoscale: 'False'
-    axislabels: 'True'
-    color1: blue
-    color10: dark blue
-    color2: red
-    color3: green
-    color4: black
-    color5: cyan
-    color6: magenta
-    color7: yellow
-    color8: dark red
-    color9: dark green
-    comment: ''
-    ctrlpanel: 'False'
-    entags: 'False'
-    grid: 'True'
-    gui_hint: (2, 0, 1, 1)
-    label1: I
-    label10: Signal 10
-    label2: Q
-    label3: Signal 3
-    label4: Signal 4
-    label5: Signal 5
-    label6: Signal 6
-    label7: Signal 7
-    label8: Signal 8
-    label9: Signal 9
-    legend: 'False'
-    marker1: '-1'
-    marker10: '-1'
-    marker2: '-1'
-    marker3: '-1'
-    marker4: '-1'
-    marker5: '-1'
-    marker6: '-1'
-    marker7: '-1'
-    marker8: '-1'
-    marker9: '-1'
-    name: '"IQ / Loop"'
-    nconnections: '1'
-    size: min(int(samp_rate // 30), 512)
-    srate: samp_rate
-    stemplot: 'False'
-    style1: '1'
-    style10: '1'
-    style2: '1'
-    style3: '1'
-    style4: '1'
-    style5: '1'
-    style6: '1'
-    style7: '1'
-    style8: '1'
-    style9: '1'
-    tr_chan: '0'
-    tr_delay: '0'
-    tr_level: '0.0'
-    tr_mode: qtgui.TRIG_MODE_FREE
-    tr_slope: qtgui.TRIG_SLOPE_POS
-    tr_tag: '""'
-    type: complex
-    update_time: 1/30
-    width1: '1'
-    width10: '1'
-    width2: '1'
-    width3: '1'
-    width4: '1'
-    width5: '1'
-    width6: '1'
-    width7: '1'
-    width8: '1'
-    width9: '1'
-    ylabel: Amplitude
-    ymax: '1'
-    ymin: '-1'
-    yunit: '""'
-  states:
-    bus_sink: false
-    bus_source: false
-    bus_structure: null
-    coordinate: [1000, 352.0]
     rotation: 0
     state: true
 - name: qtgui_waterfall_sink_x_0_0
@@ -711,9 +552,9 @@ blocks:
     fftsize: '1024'
     freqhalf: 'True'
     grid: 'True'
-    gui_hint: (3, 0, 1, 2)
+    gui_hint: (4, 0, 1, 2)
     int_max: '0'
-    int_min: '-90'
+    int_min: 10 * math.log10(1 / ((2 ** 15 - 1) ** 2))
     label1: ''
     label10: ''
     label2: ''
@@ -737,26 +578,87 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1144, 616.0]
+    coordinate: [1152, 440.0]
+    rotation: 0
+    state: true
+- name: qtgui_waterfall_sink_x_0_0_0_0
+  id: qtgui_waterfall_sink_x
+  parameters:
+    affinity: ''
+    alias: ''
+    alpha1: '1.0'
+    alpha10: '1.0'
+    alpha2: '1.0'
+    alpha3: '1.0'
+    alpha4: '1.0'
+    alpha5: '1.0'
+    alpha6: '1.0'
+    alpha7: '1.0'
+    alpha8: '1.0'
+    alpha9: '1.0'
+    axislabels: 'True'
+    bw: samp_rate
+    color1: '0'
+    color10: '0'
+    color2: '0'
+    color3: '0'
+    color4: '0'
+    color5: '0'
+    color6: '0'
+    color7: '0'
+    color8: '0'
+    color9: '0'
+    comment: ''
+    fc: '0'
+    fftsize: '1024'
+    freqhalf: 'True'
+    grid: 'True'
+    gui_hint: (3, 0, 1, 2)
+    int_max: '0'
+    int_min: 10 * math.log10(1 / ((2 ** 15 - 1) ** 2))
+    label1: ''
+    label10: ''
+    label2: ''
+    label3: ''
+    label4: ''
+    label5: ''
+    label6: ''
+    label7: ''
+    label8: ''
+    label9: ''
+    legend: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    name: '"FM Demodulation"'
+    nconnections: '1'
+    showports: 'False'
+    type: float
+    update_time: 1/30
+    wintype: window.WIN_BLACKMAN_hARRIS
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [992, 168.0]
     rotation: 0
     state: true
 
 connections:
 - [analog_quadrature_demod_cf_0, '0', qtgui_time_sink_x_0_0, '0']
-- [analog_wfm_rcv_pll_0, '0', audio_sink_0, '0']
+- [analog_quadrature_demod_cf_0, '0', qtgui_waterfall_sink_x_0_0_0_0, '0']
-- [analog_wfm_rcv_pll_0, '0', blocks_add_xx_0, '0']
+- [analog_wfm_rcv_pll_0, '0', low_pass_filter_0, '0']
-- [analog_wfm_rcv_pll_0, '1', audio_sink_0, '1']
+- [analog_wfm_rcv_pll_0, '1', low_pass_filter_0_0, '0']
-- [analog_wfm_rcv_pll_0, '1', blocks_add_xx_0, '1']
 - [blocks_add_xx_0, '0', qtgui_waterfall_sink_x_0_0_0, '0']
 - [blocks_interleaved_short_to_complex_0, '0', analog_quadrature_demod_cf_0, '0']
 - [blocks_interleaved_short_to_complex_0, '0', analog_wfm_rcv_pll_0, '0']
 - [blocks_interleaved_short_to_complex_0, '0', blocks_probe_rate_0, '0']
-- [blocks_interleaved_short_to_complex_0, '0', digital_costas_loop_cc_0, '0']
 - [blocks_interleaved_short_to_complex_0, '0', qtgui_time_sink_x_0, '0']
 - [blocks_interleaved_short_to_complex_0, '0', qtgui_waterfall_sink_x_0_0, '0']
 - [blocks_probe_rate_0, rate, blocks_message_debug_0, print]
-- [digital_costas_loop_cc_0, '0', qtgui_const_sink_x_0, '0']
+- [low_pass_filter_0, '0', audio_sink_0, '0']
-- [digital_costas_loop_cc_0, '0', qtgui_time_sink_x_0_1, '0']
+- [low_pass_filter_0, '0', blocks_add_xx_0, '0']
+- [low_pass_filter_0_0, '0', audio_sink_0, '1']
+- [low_pass_filter_0_0, '0', blocks_add_xx_0, '1']
 - [network_tcp_source_0, '0', blocks_interleaved_short_to_complex_0, '0']
 
 metadata:

src/main.c

@@ -40,10 +40,10 @@
 /* FM Radio */
 #if 1
 #define VREG_VOLTAGE VREG_VOLTAGE_1_20
-#define CLK_SYS_HZ (266 * MHZ)
+#define CLK_SYS_HZ (300 * MHZ)
 #define BANDWIDTH 1536000
 #define DECIMATION_BITS 3
-#define LPF_ORDER 3
+#define LPF_ORDER 4
 #define AGC_DECAY_BITS 20
 #define BIAS_STRENGTH 0
 #endif
@@ -64,7 +64,7 @@
 #define DECIMATION (1 << DECIMATION_BITS)
 
 static_assert(RX_SLEEP_US > 0, "RX_SLEEP_US must be positive");
-static_assert(LPF_ORDER <= 3, "LPF_ORDER must be 0-3");
+static_assert(LPF_ORDER <= 4, "LPF_ORDER must be 0-4");
 static_assert(BIAS_STRENGTH >= 0 && BIAS_STRENGTH <= 9, "BIAS_STRENGTH must be 0-9");
 
 #define XOR_ADDR 0x1000
@@ -636,6 +636,13 @@ static void rf_rx(void)
 	int lpQa3 = 0;
 #endif
 
+#if LPF_ORDER >= 4
+	static int lpIh4[DECIMATION];
+	static int lpQh4[DECIMATION];
+	int lpIa4 = 0;
+	int lpQa4 = 0;
+#endif
+
 	int64_t dcI = 0, dcQ = 0;
 
 	while (true) {
@@ -685,6 +692,11 @@ static void rf_rx(void)
 				lpIa3 += I - lpIh3[d];
 				lpIh3[d] = I;
 				I = lpIa3 / DECIMATION;
+#endif
+#if LPF_ORDER >= 4
+				lpIa4 += I - lpIh4[d];
+				lpIh4[d] = I;
+				I = lpIa4 / DECIMATION;
 #endif
 				dI += I;
 			}
@@ -720,6 +732,11 @@ static void rf_rx(void)
 				lpQa3 += Q - lpQh3[d];
 				lpQh3[d] = Q;
 				Q = lpQa3 / DECIMATION;
+#endif
+#if LPF_ORDER >= 4
+				lpQa4 += Q - lpQh4[d];
+				lpQh4[d] = Q;
+				Q = lpQa4 / DECIMATION;
 #endif
 				dQ += Q;
 			}