Fix DC offset, lower noise floor even more

grc/.gitignore

@@ -0,0 +1 @@
+/*.py

grc/base.grc

@@ -11,7 +11,7 @@ options:
     gen_linking: dynamic
     generate_options: qt_gui
     hier_block_src_path: '.:'
-    id: file
+    id: base
     max_nouts: '0'
     output_language: python
     placement: (0,0)
@@ -53,7 +53,7 @@ blocks:
     comment: ''
     maxoutbuf: '0'
     minoutbuf: '0'
-    scale: '128'
+    scale: '127'
     vlen: '1'
   states:
     bus_sink: false
@@ -119,24 +119,6 @@ blocks:
     coordinate: [592, 72.0]
     rotation: 0
     state: enabled
-- name: dc_blocker_xx_0
-  id: dc_blocker_xx
-  parameters:
-    affinity: ''
-    alias: ''
-    comment: ''
-    length: '256'
-    long_form: 'True'
-    maxoutbuf: '0'
-    minoutbuf: '0'
-    type: ff
-  states:
-    bus_sink: false
-    bus_source: false
-    bus_structure: null
-    coordinate: [592, 272.0]
-    rotation: 0
-    state: enabled
 - name: qtgui_freq_sink_x_0
   id: qtgui_freq_sink_x
   parameters:
@@ -153,7 +135,7 @@ blocks:
     alpha8: '1.0'
     alpha9: '1.0'
     autoscale: 'False'
-    average: '0.2'
+    average: '1.0'
     axislabels: 'True'
     bw: samp_rate
     color1: '"blue"'
@@ -210,7 +192,7 @@ blocks:
     width9: '1'
     wintype: window.WIN_BLACKMAN_hARRIS
     ymax: '0'
-    ymin: '-120'
+    ymin: '-140'
   states:
     bus_sink: false
     bus_source: false
@@ -349,7 +331,7 @@ blocks:
     grid: 'False'
     gui_hint: ''
     int_max: '0'
-    int_min: '-120'
+    int_min: '-140'
     label1: ''
     label10: ''
     label2: ''
@@ -379,12 +361,11 @@ blocks:
 
 connections:
 - [blocks_char_to_float_0, '0', blocks_probe_rate_0, '0']
-- [blocks_char_to_float_0, '0', dc_blocker_xx_0, '0']
+- [blocks_char_to_float_0, '0', qtgui_freq_sink_x_0, '0']
+- [blocks_char_to_float_0, '0', qtgui_time_sink_x_0, '0']
+- [blocks_char_to_float_0, '0', qtgui_waterfall_sink_x_0, '0']
 - [blocks_file_source_0, '0', blocks_char_to_float_0, '0']
 - [blocks_probe_rate_0, rate, blocks_message_debug_0, print]
-- [dc_blocker_xx_0, '0', qtgui_freq_sink_x_0, '0']
-- [dc_blocker_xx_0, '0', qtgui_time_sink_x_0, '0']
-- [dc_blocker_xx_0, '0', qtgui_waterfall_sink_x_0, '0']
 
 metadata:
   file_format: 1

grc/ir38.grc

@@ -11,7 +11,7 @@ options:
     gen_linking: dynamic
     generate_options: qt_gui
     hier_block_src_path: '.:'
-    id: file
+    id: ir38
     max_nouts: '0'
     output_language: python
     placement: (0,0)
@@ -49,7 +49,7 @@ blocks:
   id: variable
   parameters:
     comment: ''
-    value: '64'
+    value: '32'
   states:
     bus_sink: false
     bus_source: false
@@ -77,7 +77,7 @@ blocks:
     comment: ''
     maxoutbuf: '0'
     minoutbuf: '0'
-    scale: '128'
+    scale: '127'
     vlen: '1'
   states:
     bus_sink: false
@@ -86,8 +86,8 @@ blocks:
     coordinate: [224, 280.0]
     rotation: 0
     state: enabled
-- name: blocks_complex_to_mag_0
+- name: blocks_complex_to_mag_squared_0
-  id: blocks_complex_to_mag
+  id: blocks_complex_to_mag_squared
   parameters:
     affinity: ''
     alias: ''
@@ -99,7 +99,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [960, 448.0]
+    coordinate: [928, 448.0]
     rotation: 180
     state: enabled
 - name: blocks_file_source_0
@@ -154,7 +154,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [744, 288.0]
+    coordinate: [680, 288.0]
     rotation: 0
     state: enabled
 - name: blocks_message_debug_0
@@ -181,7 +181,7 @@ blocks:
     comment: ''
     maxoutbuf: '0'
     minoutbuf: '0'
-    mintime: 1e3
+    mintime: 10e3
     name: ''
     type: complex
     vlen: '1'
@@ -192,24 +192,6 @@ blocks:
     coordinate: [592, 72.0]
     rotation: 0
     state: enabled
-- name: dc_blocker_xx_0
-  id: dc_blocker_xx
-  parameters:
-    affinity: ''
-    alias: ''
-    comment: ''
-    length: '32'
-    long_form: 'True'
-    maxoutbuf: '0'
-    minoutbuf: '0'
-    type: cc
-  states:
-    bus_sink: false
-    bus_source: false
-    bus_structure: null
-    coordinate: [592, 288.0]
-    rotation: 0
-    state: enabled
 - name: fir_filter_xxx_0
   id: fir_filter_xxx
   parameters:
@@ -220,14 +202,22 @@ blocks:
     maxoutbuf: '0'
     minoutbuf: '0'
     samp_delay: '0'
-    taps: '[0.002855073321371961, 0.004217810045954073, 0.006070979752995526, 0.008513978883235714,
+    taps: '[0.001406713158940830, 0.001710044136011884, 0.002065729959831640, 0.002479729084898883,
-      0.011633445764465426, 0.015487673582478250, 0.020089356277603183, 0.025389133050128021,
+      0.002958008261689403, 0.003506380063969166, 0.004130313846119902, 0.004834722781341408,
-      0.031263078326193357, 0.037507457211444148, 0.043843530949484712, 0.049933894562348549,
+      0.005623731273043186, 0.006500428742502637, 0.007466617484016239, 0.008522563837635781,
-      0.055409900908815000, 0.059907517556544401, 0.063106964465950877, 0.064770205340986750,
+      0.009666763243126521, 0.010895730688633577, 0.012203828541343623, 0.013583143648022388,
-      0.064770205340986750, 0.063106964465950877, 0.059907517556544401, 0.055409900908815000,
+      0.015023424848037427, 0.016512090610851241, 0.018034314394853066, 0.019573192570893717,
-      0.049933894562348549, 0.043843530949484712, 0.037507457211444148, 0.031263078326193357,
+      0.021109996455252005, 0.022624506291803306, 0.024095421090913748, 0.025500834283291689,
-      0.025389133050128021, 0.020089356277603183, 0.015487673582478250, 0.011633445764465426,
+      0.026818761409887478, 0.028027702777307838, 0.029107221383386426, 0.030038514652248167,
-      0.008513978883235714, 0.006070979752995526, 0.004217810045954073, 0.002855073321371961]
+      0.030804957761237182, 0.031392596685491395, 0.031790570555833404, 0.031991445477584902,
+      0.031991445477584902, 0.031790570555833404, 0.031392596685491395, 0.030804957761237182,
+      0.030038514652248167, 0.029107221383386426, 0.028027702777307838, 0.026818761409887478,
+      0.025500834283291689, 0.024095421090913748, 0.022624506291803306, 0.021109996455252005,
+      0.019573192570893717, 0.018034314394853066, 0.016512090610851241, 0.015023424848037427,
+      0.013583143648022388, 0.012203828541343623, 0.010895730688633577, 0.009666763243126521,
+      0.008522563837635781, 0.007466617484016239, 0.006500428742502637, 0.005623731273043186,
+      0.004834722781341408, 0.004130313846119902, 0.003506380063969166, 0.002958008261689403,
+      0.002479729084898883, 0.002065729959831640, 0.001710044136011884, 0.001406713158940830]
 
       '
     type: ccf
@@ -235,7 +225,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [936, 288.0]
+    coordinate: [872, 288.0]
     rotation: 0
     state: enabled
 - name: qtgui_freq_sink_x_0
@@ -285,7 +275,7 @@ blocks:
     label7: ''''''
     label8: ''''''
     label9: ''''''
-    legend: 'True'
+    legend: 'False'
     maxoutbuf: '0'
     minoutbuf: '0'
     name: '""'
@@ -293,7 +283,7 @@ blocks:
     norm_window: 'True'
     showports: 'False'
     tr_chan: '0'
-    tr_level: '0.0'
+    tr_level: '0'
     tr_mode: qtgui.TRIG_MODE_FREE
     tr_tag: '""'
     type: complex
@@ -311,12 +301,12 @@ blocks:
     width9: '1'
     wintype: window.WIN_BLACKMAN_hARRIS
     ymax: '0'
-    ymin: '-100'
+    ymin: '-140'
   states:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1176, 376.0]
+    coordinate: [1168, 376.0]
     rotation: 0
     state: enabled
 - name: qtgui_time_sink_x_0
@@ -374,7 +364,7 @@ blocks:
     marker9: '-1'
     name: '""'
     nconnections: '1'
-    size: '512'
+    size: '1024'
     srate: data_rate
     stemplot: 'True'
     style1: '1'
@@ -389,7 +379,7 @@ blocks:
     style9: '1'
     tr_chan: '0'
     tr_delay: '0'
-    tr_level: '0.0'
+    tr_level: '0'
     tr_mode: qtgui.TRIG_MODE_FREE
     tr_slope: qtgui.TRIG_SLOPE_POS
     tr_tag: '""'
@@ -413,7 +403,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1176, 280.0]
+    coordinate: [1168, 280.0]
     rotation: 0
     state: enabled
 - name: qtgui_time_sink_x_0_0
@@ -471,7 +461,7 @@ blocks:
     marker9: '-1'
     name: '""'
     nconnections: '1'
-    size: '512'
+    size: '1024'
     srate: data_rate
     stemplot: 'False'
     style1: '1'
@@ -485,9 +475,9 @@ blocks:
     style8: '1'
     style9: '1'
     tr_chan: '0'
-    tr_delay: '0'
+    tr_delay: 10e-3
-    tr_level: '0.0'
+    tr_level: 1e-6
-    tr_mode: qtgui.TRIG_MODE_FREE
+    tr_mode: qtgui.TRIG_MODE_AUTO
     tr_slope: qtgui.TRIG_SLOPE_POS
     tr_tag: '""'
     type: float
@@ -503,14 +493,14 @@ blocks:
     width8: '1'
     width9: '1'
     ylabel: Magnitude
-    ymax: '1'
+    ymax: 10e-6
-    ymin: '-1'
+    ymin: '0'
     yunit: '""'
   states:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [744, 424.0]
+    coordinate: [672, 424.0]
     rotation: 180
     state: enabled
 - name: qtgui_waterfall_sink_x_0
@@ -547,7 +537,7 @@ blocks:
     grid: 'False'
     gui_hint: ''
     int_max: '0'
-    int_min: '-120'
+    int_min: '-140'
     label1: ''
     label10: ''
     label2: ''
@@ -571,20 +561,19 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1176, 184.0]
+    coordinate: [1168, 184.0]
     rotation: 0
     state: enabled
 
 connections:
 - [blocks_char_to_float_0, '0', blocks_float_to_complex_0, '0']
-- [blocks_complex_to_mag_0, '0', qtgui_time_sink_x_0_0, '0']
+- [blocks_complex_to_mag_squared_0, '0', qtgui_time_sink_x_0_0, '0']
 - [blocks_file_source_0, '0', blocks_char_to_float_0, '0']
+- [blocks_float_to_complex_0, '0', blocks_freqshift_cc_0, '0']
 - [blocks_float_to_complex_0, '0', blocks_probe_rate_0, '0']
-- [blocks_float_to_complex_0, '0', dc_blocker_xx_0, '0']
 - [blocks_freqshift_cc_0, '0', fir_filter_xxx_0, '0']
 - [blocks_probe_rate_0, rate, blocks_message_debug_0, print]
-- [dc_blocker_xx_0, '0', blocks_freqshift_cc_0, '0']
+- [fir_filter_xxx_0, '0', blocks_complex_to_mag_squared_0, '0']
-- [fir_filter_xxx_0, '0', blocks_complex_to_mag_0, '0']
 - [fir_filter_xxx_0, '0', qtgui_freq_sink_x_0, '0']
 - [fir_filter_xxx_0, '0', qtgui_time_sink_x_0, '0']
 - [fir_filter_xxx_0, '0', qtgui_waterfall_sink_x_0, '0']

src/main.c

@@ -21,7 +21,7 @@
 #define IRN_SM 1
 
 #define NUM_SAMPLES_BITS 10
-#define NUM_SAMPLES (1 << NUM_SAMPLES_BITS)
+#define NUM_SAMPLES      (1 << NUM_SAMPLES_BITS)
 static uint16_t irp_buffer[NUM_SAMPLES] __aligned(2 * NUM_SAMPLES);
 static int dma_ch_irp_rx;
 
@@ -36,7 +36,7 @@ static void init_pio_sm(pio_hw_t *pio, int sm, int rx_pin, int fb_pin)
 		pio_encode_jmp_x_dec(4),
 		pio_encode_in(pio_y, 16) | pio_encode_sideset_opt(1, 1),
 		pio_encode_mov(pio_x, pio_osr),
-		pio_encode_nop() | pio_encode_sideset_opt(1, 0),
+		pio_encode_set(pio_y, 0) | pio_encode_sideset_opt(1, 0),
 		pio_encode_jmp_pin(6),
 		pio_encode_jmp(0) | pio_encode_sideset_opt(1, 1),
 		pio_encode_jmp_y_dec(0) | pio_encode_sideset_opt(1, 0),
@@ -94,27 +94,17 @@ static bool read_sample(int *sample)
 	if (tail == head)
 		return false;
 
-	uint16_t next_pos = irp_buffer[tail];
+	int pos = irp_buffer[tail] << 16;
-	uint16_t next_neg = irn_buffer[tail];
+	int neg = irn_buffer[tail] << 16;
 	tail = (tail + 1) % NUM_SAMPLES;
 
-	static uint16_t prev_pos;
+	int s = pos - neg;
-	int pos = prev_pos - next_pos;
-	prev_pos = next_pos;
 
-	static uint16_t prev_neg;
+	static int dc;
-	int neg = prev_neg - next_neg;
+	dc += (s - dc) >> 16;
-	prev_neg = next_neg;
+	s -= dc;
 
-	static int dc_pos;
+	*sample = s >> 16;
-	dc_pos += ((pos << 16) - dc_pos) >> 12;
-	pos -= (dc_pos >> 16);
-
-	static int dc_neg;
-	dc_neg += ((neg << 16) - dc_neg) >> 12;
-	neg -= (dc_neg >> 16);
-
-	*sample = pos - neg;
 	return true;
 }