RTL-SDR IQ sample reader
rtlsdr: split test.ml into test_rtlsdr.ml + runner (merlint E620)
Also replace Format.fprintf with Fmt.pf.
+422
-418
+1
-418
test/test.ml
+1
-418
test/test.ml
···
1
-
let pi = Float.pi
2
-
3
-
let complex_testable =
4
-
Alcotest.testable
5
-
(fun ppf (c : Dsp.Complex.t) -> Format.fprintf ppf "(%f + %fi)" c.re c.im)
6
-
(fun (a : Dsp.Complex.t) (b : Dsp.Complex.t) ->
7
-
Float.abs (a.re -. b.re) < 1e-6 && Float.abs (a.im -. b.im) < 1e-6)
8
-
9
-
let approx_complex_testable eps =
10
-
Alcotest.testable
11
-
(fun ppf (c : Dsp.Complex.t) -> Format.fprintf ppf "(%f + %fi)" c.re c.im)
12
-
(fun (a : Dsp.Complex.t) (b : Dsp.Complex.t) ->
13
-
Float.abs (a.re -. b.re) < eps && Float.abs (a.im -. b.im) < eps)
14
-
15
-
(* Test 1: of_bytes roundtrip with known values *)
16
-
let test_of_bytes_roundtrip () =
17
-
(* (127, 127) -> approximately (0, 0) -- actually maps to
18
-
(127 - 127.5)/127.5 = -0.003921... for both *)
19
-
(* (0, 0) -> (-1, -1) *)
20
-
(* (255, 255) -> (+1, +1) *)
21
-
let data = Bytes.create 6 in
22
-
Bytes.set data 0 (Char.chr 127);
23
-
Bytes.set data 1 (Char.chr 127);
24
-
Bytes.set data 2 (Char.chr 0);
25
-
Bytes.set data 3 (Char.chr 0);
26
-
Bytes.set data 4 (Char.chr 255);
27
-
Bytes.set data 5 (Char.chr 255);
28
-
let src = Rtlsdr.of_bytes data in
29
-
let samples = Rtlsdr.read_all src in
30
-
Alcotest.(check int) "3 samples" 3 (Array.length samples);
31
-
(* (127,127): (127-127.5)/127.5 = -0.00392156... *)
32
-
let near_zero = -0.5 /. 127.5 in
33
-
let tc = approx_complex_testable 1e-6 in
34
-
Alcotest.check tc "(127,127) -> ~0+0j"
35
-
(Dsp.Complex.make near_zero near_zero)
36
-
samples.(0);
37
-
Alcotest.check tc "(0,0) -> -1-1j"
38
-
(Dsp.Complex.make (-1.0) (-1.0))
39
-
samples.(1);
40
-
Alcotest.check tc "(255,255) -> +1+1j" (Dsp.Complex.make 1.0 1.0) samples.(2)
41
-
42
-
(* Test 2: generate_tone produces correct frequency *)
43
-
let test_generate_tone () =
44
-
let sample_rate = 1000.0 in
45
-
let freq = 100.0 in
46
-
let duration = 0.01 in
47
-
let samples = Rtlsdr.generate_tone ~sample_rate ~freq ~duration in
48
-
(* 10 samples at 1000 Hz sample rate for 0.01s *)
49
-
Alcotest.(check int) "sample count" 10 (Array.length samples);
50
-
(* Check phase rotation: each sample should advance by
51
-
2*pi*freq/sample_rate = 2*pi*100/1000 = 0.2*pi radians *)
52
-
let phase_step = 2.0 *. pi *. freq /. sample_rate in
53
-
let tc = approx_complex_testable 1e-9 in
54
-
Array.iteri
55
-
(fun i s ->
56
-
let expected_angle = phase_step *. Float.of_int i in
57
-
let expected =
58
-
Dsp.Complex.make (Float.cos expected_angle) (Float.sin expected_angle)
59
-
in
60
-
Alcotest.check tc (Fmt.str "sample %d" i) expected s)
61
-
samples
62
-
63
-
(* Test 3: generate_bpsk changes phase on bit transitions *)
64
-
let test_generate_bpsk () =
65
-
let sample_rate = 1000.0 in
66
-
let symbol_rate = 100.0 in
67
-
let carrier_freq = 0.0 in
68
-
(* Use carrier_freq=0 so the signal is just +1 or -1 on I axis *)
69
-
let bits = Bytes.of_string "\x00\x01\x00" in
70
-
let samples =
71
-
Rtlsdr.generate_bpsk ~sample_rate ~symbol_rate ~bits ~carrier_freq
72
-
in
73
-
let sps = 10 in
74
-
(* samples per symbol = 1000/100 *)
75
-
Alcotest.(check int) "total samples" 30 (Array.length samples);
76
-
(* Bit 0 (value 0): no phase offset, so cos(0)=1.0 for all samples *)
77
-
let tc = approx_complex_testable 1e-9 in
78
-
for i = 0 to sps - 1 do
79
-
Alcotest.check tc
80
-
(Fmt.str "bit0 sample %d" i)
81
-
(Dsp.Complex.make 1.0 0.0) samples.(i)
82
-
done;
83
-
(* Bit 1 (value 1): pi phase offset, so cos(pi)=-1.0 *)
84
-
for i = sps to (2 * sps) - 1 do
85
-
Alcotest.check tc
86
-
(Fmt.str "bit1 sample %d" i)
87
-
(Dsp.Complex.make (-1.0) 0.0)
88
-
samples.(i)
89
-
done;
90
-
(* Bit 2 (value 0): back to no offset, cos(0)=1.0 *)
91
-
for i = 2 * sps to (3 * sps) - 1 do
92
-
Alcotest.check tc
93
-
(Fmt.str "bit2 sample %d" i)
94
-
(Dsp.Complex.make 1.0 0.0) samples.(i)
95
-
done
96
-
97
-
(* Test 4: sample_count matches byte length / 2 *)
98
-
let test_sample_count () =
99
-
let data = Bytes.create 100 in
100
-
let src = Rtlsdr.of_bytes data in
101
-
Alcotest.(check int) "50 samples from 100 bytes" 50 (Rtlsdr.sample_count src);
102
-
let data2 = Bytes.create 0 in
103
-
let src2 = Rtlsdr.of_bytes data2 in
104
-
Alcotest.(check int) "0 samples from 0 bytes" 0 (Rtlsdr.sample_count src2);
105
-
(* Odd number of bytes: last byte is ignored *)
106
-
let data3 = Bytes.create 7 in
107
-
let src3 = Rtlsdr.of_bytes data3 in
108
-
Alcotest.(check int) "3 samples from 7 bytes" 3 (Rtlsdr.sample_count src3)
109
-
110
-
(* Test 5: read returns correct number of samples *)
111
-
let test_read_count () =
112
-
let data = Bytes.create 20 in
113
-
let src = Rtlsdr.of_bytes data in
114
-
(* Read 3 samples *)
115
-
let s1 = Rtlsdr.read src 3 in
116
-
Alcotest.(check int) "read 3" 3 (Array.length s1);
117
-
(* Read 5 more *)
118
-
let s2 = Rtlsdr.read src 5 in
119
-
Alcotest.(check int) "read 5" 5 (Array.length s2);
120
-
(* Only 2 remain, ask for 10 *)
121
-
let s3 = Rtlsdr.read src 10 in
122
-
Alcotest.(check int) "read remaining 2" 2 (Array.length s3);
123
-
(* No more samples *)
124
-
let s4 = Rtlsdr.read src 5 in
125
-
Alcotest.(check int) "read at EOF" 0 (Array.length s4)
126
-
127
-
(* Test 6: metadata attach/retrieve roundtrip *)
128
-
let test_metadata () =
129
-
let data = Bytes.create 10 in
130
-
let src = Rtlsdr.of_bytes data in
131
-
Alcotest.(check bool)
132
-
"no metadata initially" true
133
-
(Option.is_none (Rtlsdr.metadata src));
134
-
let meta : Rtlsdr.metadata =
135
-
{ center_freq = 433.92e6; sample_rate = 2.4e6; gain = 40.0 }
136
-
in
137
-
let src2 = Rtlsdr.with_metadata meta src in
138
-
let retrieved = Rtlsdr.metadata src2 in
139
-
Alcotest.(check bool) "has metadata" true (Option.is_some retrieved);
140
-
let m = Option.get retrieved in
141
-
Alcotest.(check (float 0.0)) "center_freq" 433.92e6 m.center_freq;
142
-
Alcotest.(check (float 0.0)) "sample_rate" 2.4e6 m.sample_rate;
143
-
Alcotest.(check (float 0.0)) "gain" 40.0 m.gain
144
-
145
-
(* -- Tone generation: DSP textbook reference vectors -- *)
146
-
147
-
(* fs/4 tone: phase advances pi/2 per sample → (1,0),(0,1),(-1,0),(0,-1),... *)
148
-
let test_tone_fs_over_4 () =
149
-
let samples =
150
-
Rtlsdr.generate_tone ~sample_rate:1.0 ~freq:0.25 ~duration:4.0
151
-
in
152
-
Alcotest.(check int) "4 samples" 4 (Array.length samples);
153
-
let tc = approx_complex_testable 1e-9 in
154
-
Alcotest.check tc "sample[0] = 1+0j" (Dsp.Complex.make 1.0 0.0) samples.(0);
155
-
Alcotest.check tc "sample[1] = 0+1j" (Dsp.Complex.make 0.0 1.0) samples.(1);
156
-
Alcotest.check tc "sample[2] = -1+0j"
157
-
(Dsp.Complex.make (-1.0) 0.0)
158
-
samples.(2);
159
-
Alcotest.check tc "sample[3] = 0-1j" (Dsp.Complex.make 0.0 (-1.0)) samples.(3)
160
-
161
-
(* DC tone: freq=0 → all samples are (1, 0) *)
162
-
let test_tone_dc () =
163
-
let samples =
164
-
Rtlsdr.generate_tone ~sample_rate:1000.0 ~freq:0.0 ~duration:0.01
165
-
in
166
-
Alcotest.(check int) "10 samples" 10 (Array.length samples);
167
-
let tc = approx_complex_testable 1e-9 in
168
-
Array.iteri
169
-
(fun i s ->
170
-
Alcotest.check tc (Fmt.str "DC sample %d" i) (Dsp.Complex.make 1.0 0.0) s)
171
-
samples
172
-
173
-
(* Tone amplitude: |sample| ≈ 1.0 for all samples *)
174
-
let test_tone_unit_magnitude () =
175
-
let samples =
176
-
Rtlsdr.generate_tone ~sample_rate:8000.0 ~freq:1234.5 ~duration:0.01
177
-
in
178
-
Array.iteri
179
-
(fun i (s : Dsp.Complex.t) ->
180
-
let mag = Dsp.Complex.norm s in
181
-
if Float.abs (mag -. 1.0) > 1e-9 then
182
-
Alcotest.failf "sample %d magnitude = %f, expected 1.0" i mag)
183
-
samples
184
-
185
-
(* Nyquist/2 (fs/2): phase advances by pi per sample → alternating ±1 *)
186
-
let test_tone_nyquist_half () =
187
-
let samples = Rtlsdr.generate_tone ~sample_rate:1.0 ~freq:0.5 ~duration:4.0 in
188
-
Alcotest.(check int) "4 samples" 4 (Array.length samples);
189
-
let tc = approx_complex_testable 1e-9 in
190
-
(* freq=0.5*fs: angle = 2*pi*0.5*i = pi*i
191
-
i=0: (1,0), i=1: (-1,~0), i=2: (1,~0), i=3: (-1,~0) *)
192
-
Alcotest.check tc "sample[0]" (Dsp.Complex.make 1.0 0.0) samples.(0);
193
-
Alcotest.check tc "sample[1]" (Dsp.Complex.make (-1.0) 0.0) samples.(1);
194
-
Alcotest.check tc "sample[2]" (Dsp.Complex.make 1.0 0.0) samples.(2);
195
-
Alcotest.check tc "sample[3]" (Dsp.Complex.make (-1.0) 0.0) samples.(3)
196
-
197
-
(* -- BPSK generation: communications reference vectors -- *)
198
-
199
-
(* BPSK bits [1, 0]: first symbol phase π (negative), second phase 0 (positive) *)
200
-
let test_bpsk_bit_polarity () =
201
-
let bits = Bytes.of_string "\x01\x00" in
202
-
let sps = 8 in
203
-
let samples =
204
-
Rtlsdr.generate_bpsk ~sample_rate:8000.0 ~symbol_rate:1000.0 ~bits
205
-
~carrier_freq:0.0
206
-
in
207
-
Alcotest.(check int) "total samples" (2 * sps) (Array.length samples);
208
-
let tc = approx_complex_testable 1e-9 in
209
-
(* bit=1 → phase π → cos(π)=-1 *)
210
-
Alcotest.check tc "bit=1 center sample"
211
-
(Dsp.Complex.make (-1.0) 0.0)
212
-
samples.(sps / 2);
213
-
(* bit=0 → phase 0 → cos(0)=+1 *)
214
-
Alcotest.check tc "bit=0 center sample" (Dsp.Complex.make 1.0 0.0)
215
-
samples.(sps + (sps / 2))
216
-
217
-
(* Verify transitions happen at symbol boundaries *)
218
-
let test_bpsk_transitions () =
219
-
let bits = Bytes.of_string "\x00\x01\x00" in
220
-
let sps = 4 in
221
-
let samples =
222
-
Rtlsdr.generate_bpsk ~sample_rate:4000.0 ~symbol_rate:1000.0 ~bits
223
-
~carrier_freq:0.0
224
-
in
225
-
Alcotest.(check int) "total samples" 12 (Array.length samples);
226
-
let tc = approx_complex_testable 1e-9 in
227
-
(* Last sample of symbol 0 (bit=0): positive *)
228
-
Alcotest.check tc "end of sym0" (Dsp.Complex.make 1.0 0.0) samples.(sps - 1);
229
-
(* First sample of symbol 1 (bit=1): negative *)
230
-
Alcotest.check tc "start of sym1" (Dsp.Complex.make (-1.0) 0.0) samples.(sps);
231
-
(* Last sample of symbol 1 (bit=1): negative *)
232
-
Alcotest.check tc "end of sym1"
233
-
(Dsp.Complex.make (-1.0) 0.0)
234
-
samples.((2 * sps) - 1);
235
-
(* First sample of symbol 2 (bit=0): positive *)
236
-
Alcotest.check tc "start of sym2" (Dsp.Complex.make 1.0 0.0) samples.(2 * sps)
237
-
238
-
(* Verify sps samples per symbol *)
239
-
let test_bpsk_sps () =
240
-
let bits = Bytes.of_string "\x01\x00\x01\x01\x00" in
241
-
let sps = 10 in
242
-
let samples =
243
-
Rtlsdr.generate_bpsk ~sample_rate:10000.0 ~symbol_rate:1000.0 ~bits
244
-
~carrier_freq:0.0
245
-
in
246
-
Alcotest.(check int) "total = nbits * sps" (5 * sps) (Array.length samples)
247
-
248
-
(* -- IQ byte format: RTL-SDR hardware spec -- *)
249
-
250
-
(* RTL-SDR: unsigned 8-bit I,Q interleaved. Center is 127/128. *)
251
-
let test_iq_byte_format () =
252
-
let data = Bytes.create 4 in
253
-
Bytes.set data 0 (Char.chr 127);
254
-
Bytes.set data 1 (Char.chr 128);
255
-
Bytes.set data 2 (Char.chr 0);
256
-
Bytes.set data 3 (Char.chr 255);
257
-
let src = Rtlsdr.of_bytes data in
258
-
let samples = Rtlsdr.read_all src in
259
-
Alcotest.(check int) "2 IQ samples" 2 (Array.length samples);
260
-
let tc = approx_complex_testable 0.01 in
261
-
(* (127,128): I=(127-127.5)/127.5=-0.00392, Q=(128-127.5)/127.5=+0.00392 *)
262
-
Alcotest.check tc "sample 0 near DC"
263
-
(Dsp.Complex.make (-0.5 /. 127.5) (0.5 /. 127.5))
264
-
samples.(0);
265
-
(* (0,255): I=-1.0, Q=+1.0 *)
266
-
Alcotest.check tc "sample 1 = (-1, +1)"
267
-
(Dsp.Complex.make (-1.0) 1.0)
268
-
samples.(1)
269
-
270
-
(* Large buffer: 10000 random bytes → of_bytes → 5000 samples *)
271
-
let test_iq_large_buffer () =
272
-
let n_bytes = 10000 in
273
-
let data = Bytes.init n_bytes (fun _ -> Char.chr (Random.int 256)) in
274
-
let src = Rtlsdr.of_bytes data in
275
-
Alcotest.(check int) "5000 samples" 5000 (Rtlsdr.sample_count src);
276
-
let samples = Rtlsdr.read_all src in
277
-
Alcotest.(check int) "read_all returns 5000" 5000 (Array.length samples);
278
-
(* Verify all values in [-1,+1] range *)
279
-
Array.iteri
280
-
(fun i (s : Dsp.Complex.t) ->
281
-
if s.re < -1.0 || s.re > 1.0 then
282
-
Alcotest.failf "sample %d re=%f out of range" i s.re;
283
-
if s.im < -1.0 || s.im > 1.0 then
284
-
Alcotest.failf "sample %d im=%f out of range" i s.im)
285
-
samples
286
-
287
-
(* -- Source operations -- *)
288
-
289
-
(* of_bytes → read all → verify matches input *)
290
-
let test_source_read_all_matches () =
291
-
let data = Bytes.create 6 in
292
-
Bytes.set data 0 (Char.chr 0);
293
-
Bytes.set data 1 (Char.chr 255);
294
-
Bytes.set data 2 (Char.chr 128);
295
-
Bytes.set data 3 (Char.chr 128);
296
-
Bytes.set data 4 (Char.chr 64);
297
-
Bytes.set data 5 (Char.chr 192);
298
-
let src = Rtlsdr.of_bytes data in
299
-
let samples = Rtlsdr.read_all src in
300
-
Alcotest.(check int) "3 samples" 3 (Array.length samples);
301
-
let tc = approx_complex_testable 1e-6 in
302
-
Alcotest.check tc "sample 0" (Dsp.Complex.make (-1.0) 1.0) samples.(0);
303
-
Alcotest.check tc "sample 1"
304
-
(Dsp.Complex.make (0.5 /. 127.5) (0.5 /. 127.5))
305
-
samples.(1);
306
-
Alcotest.check tc "sample 2"
307
-
(Dsp.Complex.make ((64.0 -. 127.5) /. 127.5) ((192.0 -. 127.5) /. 127.5))
308
-
samples.(2)
309
-
310
-
(* Sequential reads: read(10) + read(10) = read_all for 20-sample source *)
311
-
let test_sequential_reads () =
312
-
let data = Bytes.init 40 (fun i -> Char.chr (i mod 256)) in
313
-
let src1 = Rtlsdr.of_bytes data in
314
-
let all = Rtlsdr.read_all src1 in
315
-
let src2 = Rtlsdr.of_bytes data in
316
-
let first = Rtlsdr.read src2 10 in
317
-
let second = Rtlsdr.read src2 10 in
318
-
Alcotest.(check int) "first batch" 10 (Array.length first);
319
-
Alcotest.(check int) "second batch" 10 (Array.length second);
320
-
let tc = approx_complex_testable 1e-9 in
321
-
for i = 0 to 9 do
322
-
Alcotest.check tc (Fmt.str "first[%d]" i) all.(i) first.(i)
323
-
done;
324
-
for i = 0 to 9 do
325
-
Alcotest.check tc (Fmt.str "second[%d]" i) all.(10 + i) second.(i)
326
-
done
327
-
328
-
(* Read after exhaustion → empty *)
329
-
let test_read_after_exhaustion () =
330
-
let data = Bytes.create 4 in
331
-
let src = Rtlsdr.of_bytes data in
332
-
let _ = Rtlsdr.read_all src in
333
-
let after = Rtlsdr.read src 10 in
334
-
Alcotest.(check int) "empty after exhaustion" 0 (Array.length after);
335
-
let after2 = Rtlsdr.read_all src in
336
-
Alcotest.(check int) "read_all after exhaustion" 0 (Array.length after2)
337
-
338
-
(* sample_count accuracy *)
339
-
let test_sample_count_accuracy () =
340
-
let check n_bytes expected =
341
-
let data = Bytes.create n_bytes in
342
-
let src = Rtlsdr.of_bytes data in
343
-
Alcotest.(check int)
344
-
(Fmt.str "%d bytes -> %d samples" n_bytes expected)
345
-
expected (Rtlsdr.sample_count src)
346
-
in
347
-
check 0 0;
348
-
check 1 0;
349
-
check 2 1;
350
-
check 3 1;
351
-
check 100 50;
352
-
check 255 127;
353
-
check 10000 5000
354
-
355
-
(* -- Metadata -- *)
356
-
357
-
(* Attach metadata → read back → verify all fields match *)
358
-
let test_metadata_roundtrip () =
359
-
let data = Bytes.create 10 in
360
-
let src = Rtlsdr.of_bytes data in
361
-
let meta : Rtlsdr.metadata =
362
-
{ center_freq = 145.8e6; sample_rate = 2.048e6; gain = 49.6 }
363
-
in
364
-
let src2 = Rtlsdr.with_metadata meta src in
365
-
let m = Option.get (Rtlsdr.metadata src2) in
366
-
Alcotest.(check (float 0.0)) "center_freq" 145.8e6 m.center_freq;
367
-
Alcotest.(check (float 0.0)) "sample_rate" 2.048e6 m.sample_rate;
368
-
Alcotest.(check (float 0.0)) "gain" 49.6 m.gain
369
-
370
-
(* Default metadata: None *)
371
-
let test_metadata_default () =
372
-
let data = Bytes.create 10 in
373
-
let src = Rtlsdr.of_bytes data in
374
-
Alcotest.(check bool)
375
-
"no metadata by default" true
376
-
(Option.is_none (Rtlsdr.metadata src))
377
-
378
-
let () =
379
-
Alcotest.run "rtlsdr"
380
-
[
381
-
( "iq",
382
-
[
383
-
Alcotest.test_case "of_bytes roundtrip" `Quick test_of_bytes_roundtrip;
384
-
Alcotest.test_case "sample_count" `Quick test_sample_count;
385
-
Alcotest.test_case "read count" `Quick test_read_count;
386
-
Alcotest.test_case "metadata roundtrip" `Quick test_metadata;
387
-
Alcotest.test_case "IQ byte format" `Quick test_iq_byte_format;
388
-
Alcotest.test_case "IQ large buffer" `Quick test_iq_large_buffer;
389
-
] );
390
-
( "signal",
391
-
[
392
-
Alcotest.test_case "generate_tone" `Quick test_generate_tone;
393
-
Alcotest.test_case "generate_bpsk" `Quick test_generate_bpsk;
394
-
Alcotest.test_case "tone fs/4" `Quick test_tone_fs_over_4;
395
-
Alcotest.test_case "tone DC" `Quick test_tone_dc;
396
-
Alcotest.test_case "tone unit magnitude" `Quick
397
-
test_tone_unit_magnitude;
398
-
Alcotest.test_case "tone Nyquist/2" `Quick test_tone_nyquist_half;
399
-
Alcotest.test_case "BPSK bit polarity" `Quick test_bpsk_bit_polarity;
400
-
Alcotest.test_case "BPSK transitions" `Quick test_bpsk_transitions;
401
-
Alcotest.test_case "BPSK sps" `Quick test_bpsk_sps;
402
-
] );
403
-
( "source",
404
-
[
405
-
Alcotest.test_case "read_all matches" `Quick
406
-
test_source_read_all_matches;
407
-
Alcotest.test_case "sequential reads" `Quick test_sequential_reads;
408
-
Alcotest.test_case "read after exhaustion" `Quick
409
-
test_read_after_exhaustion;
410
-
Alcotest.test_case "sample_count accuracy" `Quick
411
-
test_sample_count_accuracy;
412
-
] );
413
-
( "metadata",
414
-
[
415
-
Alcotest.test_case "metadata roundtrip" `Quick test_metadata_roundtrip;
416
-
Alcotest.test_case "metadata default" `Quick test_metadata_default;
417
-
] );
418
-
]
1
+
let () = Alcotest.run "rtlsdr" Test_rtlsdr.suites
+417
test/test_rtlsdr.ml
+417
test/test_rtlsdr.ml
···
1
+
let pi = Float.pi
2
+
3
+
let complex_testable =
4
+
Alcotest.testable
5
+
(fun ppf (c : Dsp.Complex.t) -> Fmt.pf ppf "(%f + %fi)" c.re c.im)
6
+
(fun (a : Dsp.Complex.t) (b : Dsp.Complex.t) ->
7
+
Float.abs (a.re -. b.re) < 1e-6 && Float.abs (a.im -. b.im) < 1e-6)
8
+
9
+
let approx_complex_testable eps =
10
+
Alcotest.testable
11
+
(fun ppf (c : Dsp.Complex.t) -> Fmt.pf ppf "(%f + %fi)" c.re c.im)
12
+
(fun (a : Dsp.Complex.t) (b : Dsp.Complex.t) ->
13
+
Float.abs (a.re -. b.re) < eps && Float.abs (a.im -. b.im) < eps)
14
+
15
+
(* Test 1: of_bytes roundtrip with known values *)
16
+
let test_of_bytes_roundtrip () =
17
+
(* (127, 127) -> approximately (0, 0) -- actually maps to
18
+
(127 - 127.5)/127.5 = -0.003921... for both *)
19
+
(* (0, 0) -> (-1, -1) *)
20
+
(* (255, 255) -> (+1, +1) *)
21
+
let data = Bytes.create 6 in
22
+
Bytes.set data 0 (Char.chr 127);
23
+
Bytes.set data 1 (Char.chr 127);
24
+
Bytes.set data 2 (Char.chr 0);
25
+
Bytes.set data 3 (Char.chr 0);
26
+
Bytes.set data 4 (Char.chr 255);
27
+
Bytes.set data 5 (Char.chr 255);
28
+
let src = Rtlsdr.of_bytes data in
29
+
let samples = Rtlsdr.read_all src in
30
+
Alcotest.(check int) "3 samples" 3 (Array.length samples);
31
+
(* (127,127): (127-127.5)/127.5 = -0.00392156... *)
32
+
let near_zero = -0.5 /. 127.5 in
33
+
let tc = approx_complex_testable 1e-6 in
34
+
Alcotest.check tc "(127,127) -> ~0+0j"
35
+
(Dsp.Complex.make near_zero near_zero)
36
+
samples.(0);
37
+
Alcotest.check tc "(0,0) -> -1-1j"
38
+
(Dsp.Complex.make (-1.0) (-1.0))
39
+
samples.(1);
40
+
Alcotest.check tc "(255,255) -> +1+1j" (Dsp.Complex.make 1.0 1.0) samples.(2)
41
+
42
+
(* Test 2: generate_tone produces correct frequency *)
43
+
let test_generate_tone () =
44
+
let sample_rate = 1000.0 in
45
+
let freq = 100.0 in
46
+
let duration = 0.01 in
47
+
let samples = Rtlsdr.generate_tone ~sample_rate ~freq ~duration in
48
+
(* 10 samples at 1000 Hz sample rate for 0.01s *)
49
+
Alcotest.(check int) "sample count" 10 (Array.length samples);
50
+
(* Check phase rotation: each sample should advance by
51
+
2*pi*freq/sample_rate = 2*pi*100/1000 = 0.2*pi radians *)
52
+
let phase_step = 2.0 *. pi *. freq /. sample_rate in
53
+
let tc = approx_complex_testable 1e-9 in
54
+
Array.iteri
55
+
(fun i s ->
56
+
let expected_angle = phase_step *. Float.of_int i in
57
+
let expected =
58
+
Dsp.Complex.make (Float.cos expected_angle) (Float.sin expected_angle)
59
+
in
60
+
Alcotest.check tc (Fmt.str "sample %d" i) expected s)
61
+
samples
62
+
63
+
(* Test 3: generate_bpsk changes phase on bit transitions *)
64
+
let test_generate_bpsk () =
65
+
let sample_rate = 1000.0 in
66
+
let symbol_rate = 100.0 in
67
+
let carrier_freq = 0.0 in
68
+
(* Use carrier_freq=0 so the signal is just +1 or -1 on I axis *)
69
+
let bits = Bytes.of_string "\x00\x01\x00" in
70
+
let samples =
71
+
Rtlsdr.generate_bpsk ~sample_rate ~symbol_rate ~bits ~carrier_freq
72
+
in
73
+
let sps = 10 in
74
+
(* samples per symbol = 1000/100 *)
75
+
Alcotest.(check int) "total samples" 30 (Array.length samples);
76
+
(* Bit 0 (value 0): no phase offset, so cos(0)=1.0 for all samples *)
77
+
let tc = approx_complex_testable 1e-9 in
78
+
for i = 0 to sps - 1 do
79
+
Alcotest.check tc
80
+
(Fmt.str "bit0 sample %d" i)
81
+
(Dsp.Complex.make 1.0 0.0) samples.(i)
82
+
done;
83
+
(* Bit 1 (value 1): pi phase offset, so cos(pi)=-1.0 *)
84
+
for i = sps to (2 * sps) - 1 do
85
+
Alcotest.check tc
86
+
(Fmt.str "bit1 sample %d" i)
87
+
(Dsp.Complex.make (-1.0) 0.0)
88
+
samples.(i)
89
+
done;
90
+
(* Bit 2 (value 0): back to no offset, cos(0)=1.0 *)
91
+
for i = 2 * sps to (3 * sps) - 1 do
92
+
Alcotest.check tc
93
+
(Fmt.str "bit2 sample %d" i)
94
+
(Dsp.Complex.make 1.0 0.0) samples.(i)
95
+
done
96
+
97
+
(* Test 4: sample_count matches byte length / 2 *)
98
+
let test_sample_count () =
99
+
let data = Bytes.create 100 in
100
+
let src = Rtlsdr.of_bytes data in
101
+
Alcotest.(check int) "50 samples from 100 bytes" 50 (Rtlsdr.sample_count src);
102
+
let data2 = Bytes.create 0 in
103
+
let src2 = Rtlsdr.of_bytes data2 in
104
+
Alcotest.(check int) "0 samples from 0 bytes" 0 (Rtlsdr.sample_count src2);
105
+
(* Odd number of bytes: last byte is ignored *)
106
+
let data3 = Bytes.create 7 in
107
+
let src3 = Rtlsdr.of_bytes data3 in
108
+
Alcotest.(check int) "3 samples from 7 bytes" 3 (Rtlsdr.sample_count src3)
109
+
110
+
(* Test 5: read returns correct number of samples *)
111
+
let test_read_count () =
112
+
let data = Bytes.create 20 in
113
+
let src = Rtlsdr.of_bytes data in
114
+
(* Read 3 samples *)
115
+
let s1 = Rtlsdr.read src 3 in
116
+
Alcotest.(check int) "read 3" 3 (Array.length s1);
117
+
(* Read 5 more *)
118
+
let s2 = Rtlsdr.read src 5 in
119
+
Alcotest.(check int) "read 5" 5 (Array.length s2);
120
+
(* Only 2 remain, ask for 10 *)
121
+
let s3 = Rtlsdr.read src 10 in
122
+
Alcotest.(check int) "read remaining 2" 2 (Array.length s3);
123
+
(* No more samples *)
124
+
let s4 = Rtlsdr.read src 5 in
125
+
Alcotest.(check int) "read at EOF" 0 (Array.length s4)
126
+
127
+
(* Test 6: metadata attach/retrieve roundtrip *)
128
+
let test_metadata () =
129
+
let data = Bytes.create 10 in
130
+
let src = Rtlsdr.of_bytes data in
131
+
Alcotest.(check bool)
132
+
"no metadata initially" true
133
+
(Option.is_none (Rtlsdr.metadata src));
134
+
let meta : Rtlsdr.metadata =
135
+
{ center_freq = 433.92e6; sample_rate = 2.4e6; gain = 40.0 }
136
+
in
137
+
let src2 = Rtlsdr.with_metadata meta src in
138
+
let retrieved = Rtlsdr.metadata src2 in
139
+
Alcotest.(check bool) "has metadata" true (Option.is_some retrieved);
140
+
let m = Option.get retrieved in
141
+
Alcotest.(check (float 0.0)) "center_freq" 433.92e6 m.center_freq;
142
+
Alcotest.(check (float 0.0)) "sample_rate" 2.4e6 m.sample_rate;
143
+
Alcotest.(check (float 0.0)) "gain" 40.0 m.gain
144
+
145
+
(* -- Tone generation: DSP textbook reference vectors -- *)
146
+
147
+
(* fs/4 tone: phase advances pi/2 per sample → (1,0),(0,1),(-1,0),(0,-1),... *)
148
+
let test_tone_fs_over_4 () =
149
+
let samples =
150
+
Rtlsdr.generate_tone ~sample_rate:1.0 ~freq:0.25 ~duration:4.0
151
+
in
152
+
Alcotest.(check int) "4 samples" 4 (Array.length samples);
153
+
let tc = approx_complex_testable 1e-9 in
154
+
Alcotest.check tc "sample[0] = 1+0j" (Dsp.Complex.make 1.0 0.0) samples.(0);
155
+
Alcotest.check tc "sample[1] = 0+1j" (Dsp.Complex.make 0.0 1.0) samples.(1);
156
+
Alcotest.check tc "sample[2] = -1+0j"
157
+
(Dsp.Complex.make (-1.0) 0.0)
158
+
samples.(2);
159
+
Alcotest.check tc "sample[3] = 0-1j" (Dsp.Complex.make 0.0 (-1.0)) samples.(3)
160
+
161
+
(* DC tone: freq=0 → all samples are (1, 0) *)
162
+
let test_tone_dc () =
163
+
let samples =
164
+
Rtlsdr.generate_tone ~sample_rate:1000.0 ~freq:0.0 ~duration:0.01
165
+
in
166
+
Alcotest.(check int) "10 samples" 10 (Array.length samples);
167
+
let tc = approx_complex_testable 1e-9 in
168
+
Array.iteri
169
+
(fun i s ->
170
+
Alcotest.check tc (Fmt.str "DC sample %d" i) (Dsp.Complex.make 1.0 0.0) s)
171
+
samples
172
+
173
+
(* Tone amplitude: |sample| ≈ 1.0 for all samples *)
174
+
let test_tone_unit_magnitude () =
175
+
let samples =
176
+
Rtlsdr.generate_tone ~sample_rate:8000.0 ~freq:1234.5 ~duration:0.01
177
+
in
178
+
Array.iteri
179
+
(fun i (s : Dsp.Complex.t) ->
180
+
let mag = Dsp.Complex.norm s in
181
+
if Float.abs (mag -. 1.0) > 1e-9 then
182
+
Alcotest.failf "sample %d magnitude = %f, expected 1.0" i mag)
183
+
samples
184
+
185
+
(* Nyquist/2 (fs/2): phase advances by pi per sample → alternating ±1 *)
186
+
let test_tone_nyquist_half () =
187
+
let samples = Rtlsdr.generate_tone ~sample_rate:1.0 ~freq:0.5 ~duration:4.0 in
188
+
Alcotest.(check int) "4 samples" 4 (Array.length samples);
189
+
let tc = approx_complex_testable 1e-9 in
190
+
(* freq=0.5*fs: angle = 2*pi*0.5*i = pi*i
191
+
i=0: (1,0), i=1: (-1,~0), i=2: (1,~0), i=3: (-1,~0) *)
192
+
Alcotest.check tc "sample[0]" (Dsp.Complex.make 1.0 0.0) samples.(0);
193
+
Alcotest.check tc "sample[1]" (Dsp.Complex.make (-1.0) 0.0) samples.(1);
194
+
Alcotest.check tc "sample[2]" (Dsp.Complex.make 1.0 0.0) samples.(2);
195
+
Alcotest.check tc "sample[3]" (Dsp.Complex.make (-1.0) 0.0) samples.(3)
196
+
197
+
(* -- BPSK generation: communications reference vectors -- *)
198
+
199
+
(* BPSK bits [1, 0]: first symbol phase π (negative), second phase 0 (positive) *)
200
+
let test_bpsk_bit_polarity () =
201
+
let bits = Bytes.of_string "\x01\x00" in
202
+
let sps = 8 in
203
+
let samples =
204
+
Rtlsdr.generate_bpsk ~sample_rate:8000.0 ~symbol_rate:1000.0 ~bits
205
+
~carrier_freq:0.0
206
+
in
207
+
Alcotest.(check int) "total samples" (2 * sps) (Array.length samples);
208
+
let tc = approx_complex_testable 1e-9 in
209
+
(* bit=1 → phase π → cos(π)=-1 *)
210
+
Alcotest.check tc "bit=1 center sample"
211
+
(Dsp.Complex.make (-1.0) 0.0)
212
+
samples.(sps / 2);
213
+
(* bit=0 → phase 0 → cos(0)=+1 *)
214
+
Alcotest.check tc "bit=0 center sample" (Dsp.Complex.make 1.0 0.0)
215
+
samples.(sps + (sps / 2))
216
+
217
+
(* Verify transitions happen at symbol boundaries *)
218
+
let test_bpsk_transitions () =
219
+
let bits = Bytes.of_string "\x00\x01\x00" in
220
+
let sps = 4 in
221
+
let samples =
222
+
Rtlsdr.generate_bpsk ~sample_rate:4000.0 ~symbol_rate:1000.0 ~bits
223
+
~carrier_freq:0.0
224
+
in
225
+
Alcotest.(check int) "total samples" 12 (Array.length samples);
226
+
let tc = approx_complex_testable 1e-9 in
227
+
(* Last sample of symbol 0 (bit=0): positive *)
228
+
Alcotest.check tc "end of sym0" (Dsp.Complex.make 1.0 0.0) samples.(sps - 1);
229
+
(* First sample of symbol 1 (bit=1): negative *)
230
+
Alcotest.check tc "start of sym1" (Dsp.Complex.make (-1.0) 0.0) samples.(sps);
231
+
(* Last sample of symbol 1 (bit=1): negative *)
232
+
Alcotest.check tc "end of sym1"
233
+
(Dsp.Complex.make (-1.0) 0.0)
234
+
samples.((2 * sps) - 1);
235
+
(* First sample of symbol 2 (bit=0): positive *)
236
+
Alcotest.check tc "start of sym2" (Dsp.Complex.make 1.0 0.0) samples.(2 * sps)
237
+
238
+
(* Verify sps samples per symbol *)
239
+
let test_bpsk_sps () =
240
+
let bits = Bytes.of_string "\x01\x00\x01\x01\x00" in
241
+
let sps = 10 in
242
+
let samples =
243
+
Rtlsdr.generate_bpsk ~sample_rate:10000.0 ~symbol_rate:1000.0 ~bits
244
+
~carrier_freq:0.0
245
+
in
246
+
Alcotest.(check int) "total = nbits * sps" (5 * sps) (Array.length samples)
247
+
248
+
(* -- IQ byte format: RTL-SDR hardware spec -- *)
249
+
250
+
(* RTL-SDR: unsigned 8-bit I,Q interleaved. Center is 127/128. *)
251
+
let test_iq_byte_format () =
252
+
let data = Bytes.create 4 in
253
+
Bytes.set data 0 (Char.chr 127);
254
+
Bytes.set data 1 (Char.chr 128);
255
+
Bytes.set data 2 (Char.chr 0);
256
+
Bytes.set data 3 (Char.chr 255);
257
+
let src = Rtlsdr.of_bytes data in
258
+
let samples = Rtlsdr.read_all src in
259
+
Alcotest.(check int) "2 IQ samples" 2 (Array.length samples);
260
+
let tc = approx_complex_testable 0.01 in
261
+
(* (127,128): I=(127-127.5)/127.5=-0.00392, Q=(128-127.5)/127.5=+0.00392 *)
262
+
Alcotest.check tc "sample 0 near DC"
263
+
(Dsp.Complex.make (-0.5 /. 127.5) (0.5 /. 127.5))
264
+
samples.(0);
265
+
(* (0,255): I=-1.0, Q=+1.0 *)
266
+
Alcotest.check tc "sample 1 = (-1, +1)"
267
+
(Dsp.Complex.make (-1.0) 1.0)
268
+
samples.(1)
269
+
270
+
(* Large buffer: 10000 random bytes → of_bytes → 5000 samples *)
271
+
let test_iq_large_buffer () =
272
+
let n_bytes = 10000 in
273
+
let data = Bytes.init n_bytes (fun _ -> Char.chr (Random.int 256)) in
274
+
let src = Rtlsdr.of_bytes data in
275
+
Alcotest.(check int) "5000 samples" 5000 (Rtlsdr.sample_count src);
276
+
let samples = Rtlsdr.read_all src in
277
+
Alcotest.(check int) "read_all returns 5000" 5000 (Array.length samples);
278
+
(* Verify all values in [-1,+1] range *)
279
+
Array.iteri
280
+
(fun i (s : Dsp.Complex.t) ->
281
+
if s.re < -1.0 || s.re > 1.0 then
282
+
Alcotest.failf "sample %d re=%f out of range" i s.re;
283
+
if s.im < -1.0 || s.im > 1.0 then
284
+
Alcotest.failf "sample %d im=%f out of range" i s.im)
285
+
samples
286
+
287
+
(* -- Source operations -- *)
288
+
289
+
(* of_bytes → read all → verify matches input *)
290
+
let test_source_read_all_matches () =
291
+
let data = Bytes.create 6 in
292
+
Bytes.set data 0 (Char.chr 0);
293
+
Bytes.set data 1 (Char.chr 255);
294
+
Bytes.set data 2 (Char.chr 128);
295
+
Bytes.set data 3 (Char.chr 128);
296
+
Bytes.set data 4 (Char.chr 64);
297
+
Bytes.set data 5 (Char.chr 192);
298
+
let src = Rtlsdr.of_bytes data in
299
+
let samples = Rtlsdr.read_all src in
300
+
Alcotest.(check int) "3 samples" 3 (Array.length samples);
301
+
let tc = approx_complex_testable 1e-6 in
302
+
Alcotest.check tc "sample 0" (Dsp.Complex.make (-1.0) 1.0) samples.(0);
303
+
Alcotest.check tc "sample 1"
304
+
(Dsp.Complex.make (0.5 /. 127.5) (0.5 /. 127.5))
305
+
samples.(1);
306
+
Alcotest.check tc "sample 2"
307
+
(Dsp.Complex.make ((64.0 -. 127.5) /. 127.5) ((192.0 -. 127.5) /. 127.5))
308
+
samples.(2)
309
+
310
+
(* Sequential reads: read(10) + read(10) = read_all for 20-sample source *)
311
+
let test_sequential_reads () =
312
+
let data = Bytes.init 40 (fun i -> Char.chr (i mod 256)) in
313
+
let src1 = Rtlsdr.of_bytes data in
314
+
let all = Rtlsdr.read_all src1 in
315
+
let src2 = Rtlsdr.of_bytes data in
316
+
let first = Rtlsdr.read src2 10 in
317
+
let second = Rtlsdr.read src2 10 in
318
+
Alcotest.(check int) "first batch" 10 (Array.length first);
319
+
Alcotest.(check int) "second batch" 10 (Array.length second);
320
+
let tc = approx_complex_testable 1e-9 in
321
+
for i = 0 to 9 do
322
+
Alcotest.check tc (Fmt.str "first[%d]" i) all.(i) first.(i)
323
+
done;
324
+
for i = 0 to 9 do
325
+
Alcotest.check tc (Fmt.str "second[%d]" i) all.(10 + i) second.(i)
326
+
done
327
+
328
+
(* Read after exhaustion → empty *)
329
+
let test_read_after_exhaustion () =
330
+
let data = Bytes.create 4 in
331
+
let src = Rtlsdr.of_bytes data in
332
+
let _ = Rtlsdr.read_all src in
333
+
let after = Rtlsdr.read src 10 in
334
+
Alcotest.(check int) "empty after exhaustion" 0 (Array.length after);
335
+
let after2 = Rtlsdr.read_all src in
336
+
Alcotest.(check int) "read_all after exhaustion" 0 (Array.length after2)
337
+
338
+
(* sample_count accuracy *)
339
+
let test_sample_count_accuracy () =
340
+
let check n_bytes expected =
341
+
let data = Bytes.create n_bytes in
342
+
let src = Rtlsdr.of_bytes data in
343
+
Alcotest.(check int)
344
+
(Fmt.str "%d bytes -> %d samples" n_bytes expected)
345
+
expected (Rtlsdr.sample_count src)
346
+
in
347
+
check 0 0;
348
+
check 1 0;
349
+
check 2 1;
350
+
check 3 1;
351
+
check 100 50;
352
+
check 255 127;
353
+
check 10000 5000
354
+
355
+
(* -- Metadata -- *)
356
+
357
+
(* Attach metadata → read back → verify all fields match *)
358
+
let test_metadata_roundtrip () =
359
+
let data = Bytes.create 10 in
360
+
let src = Rtlsdr.of_bytes data in
361
+
let meta : Rtlsdr.metadata =
362
+
{ center_freq = 145.8e6; sample_rate = 2.048e6; gain = 49.6 }
363
+
in
364
+
let src2 = Rtlsdr.with_metadata meta src in
365
+
let m = Option.get (Rtlsdr.metadata src2) in
366
+
Alcotest.(check (float 0.0)) "center_freq" 145.8e6 m.center_freq;
367
+
Alcotest.(check (float 0.0)) "sample_rate" 2.048e6 m.sample_rate;
368
+
Alcotest.(check (float 0.0)) "gain" 49.6 m.gain
369
+
370
+
(* Default metadata: None *)
371
+
let test_metadata_default () =
372
+
let data = Bytes.create 10 in
373
+
let src = Rtlsdr.of_bytes data in
374
+
Alcotest.(check bool)
375
+
"no metadata by default" true
376
+
(Option.is_none (Rtlsdr.metadata src))
377
+
378
+
let suites =
379
+
[
380
+
( "iq",
381
+
[
382
+
Alcotest.test_case "of_bytes roundtrip" `Quick test_of_bytes_roundtrip;
383
+
Alcotest.test_case "sample_count" `Quick test_sample_count;
384
+
Alcotest.test_case "read count" `Quick test_read_count;
385
+
Alcotest.test_case "metadata roundtrip" `Quick test_metadata;
386
+
Alcotest.test_case "IQ byte format" `Quick test_iq_byte_format;
387
+
Alcotest.test_case "IQ large buffer" `Quick test_iq_large_buffer;
388
+
] );
389
+
( "signal",
390
+
[
391
+
Alcotest.test_case "generate_tone" `Quick test_generate_tone;
392
+
Alcotest.test_case "generate_bpsk" `Quick test_generate_bpsk;
393
+
Alcotest.test_case "tone fs/4" `Quick test_tone_fs_over_4;
394
+
Alcotest.test_case "tone DC" `Quick test_tone_dc;
395
+
Alcotest.test_case "tone unit magnitude" `Quick
396
+
test_tone_unit_magnitude;
397
+
Alcotest.test_case "tone Nyquist/2" `Quick test_tone_nyquist_half;
398
+
Alcotest.test_case "BPSK bit polarity" `Quick test_bpsk_bit_polarity;
399
+
Alcotest.test_case "BPSK transitions" `Quick test_bpsk_transitions;
400
+
Alcotest.test_case "BPSK sps" `Quick test_bpsk_sps;
401
+
] );
402
+
( "source",
403
+
[
404
+
Alcotest.test_case "read_all matches" `Quick
405
+
test_source_read_all_matches;
406
+
Alcotest.test_case "sequential reads" `Quick test_sequential_reads;
407
+
Alcotest.test_case "read after exhaustion" `Quick
408
+
test_read_after_exhaustion;
409
+
Alcotest.test_case "sample_count accuracy" `Quick
410
+
test_sample_count_accuracy;
411
+
] );
412
+
( "metadata",
413
+
[
414
+
Alcotest.test_case "metadata roundtrip" `Quick test_metadata_roundtrip;
415
+
Alcotest.test_case "metadata default" `Quick test_metadata_default;
416
+
] );
417
+
]