From df7d2d3147671e8d83f2047d72ba05c5ab846a6b Mon Sep 17 00:00:00 2001
From: "Joseph D. Gaeddert" <joseph@liquidsdr.org>
Date: Tue, 21 May 2024 13:18:27 -0400
Subject: [PATCH] nco: adding test for spectral cleanliness

---
 makefile.in                                |  3 +-
 src/nco/tests/nco_crcf_spectrum_autotest.c | 84 ++++++++++++++++++++++
 2 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 src/nco/tests/nco_crcf_spectrum_autotest.c

diff --git a/makefile.in b/makefile.in
index e8b69fa61..a276291a8 100644
--- a/makefile.in
+++ b/makefile.in
@@ -1,4 +1,4 @@
-# Copyright (c) 2007 - 2023 Joseph Gaeddert
+# Copyright (c) 2007 - 2024 Joseph Gaeddert
 # 
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -977,6 +977,7 @@ nco_autotests :=						\
 	src/nco/tests/nco_crcf_mix_autotest.c			\
 	src/nco/tests/nco_crcf_phase_autotest.c			\
 	src/nco/tests/nco_crcf_pll_autotest.c			\
+	src/nco/tests/nco_crcf_spectrum_autotest.c		\
 	src/nco/tests/unwrap_phase_autotest.c			\
 
 # additional autotest objects
diff --git a/src/nco/tests/nco_crcf_spectrum_autotest.c b/src/nco/tests/nco_crcf_spectrum_autotest.c
new file mode 100644
index 000000000..d4ae32cf6
--- /dev/null
+++ b/src/nco/tests/nco_crcf_spectrum_autotest.c
@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2007 - 2024 Joseph Gaeddert
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <complex.h>
+#include "autotest/autotest.h"
+#include "liquid.h"
+
+// autotest helper function
+//  _type   : NCO type (e.g. LIQUID_NCO)
+//  _freq   : normalized frequency (f/Fs), _freq in [-0.5,0.5)
+void nco_crcf_spectrum_test(int _type, float _freq)
+{
+    unsigned long int num_samples = 1UL<<16;
+    unsigned int nfft = 9600;
+
+    // create object and initialize
+    nco_crcf nco = nco_crcf_create(_type);
+    nco_crcf_set_frequency(nco, 2*M_PI*_freq);
+
+    // sample buffer
+    unsigned int  buf_len = 3*nfft;
+    float complex buf_0[buf_len];
+    float complex buf_1[buf_len];
+    unsigned int i;
+    for (i=0; i<buf_len; i++)
+        buf_0[i] = 1.0f / sqrtf((float)nfft);
+
+    // spectrogram for measuring response
+    spgramcf psd = spgramcf_create(nfft, LIQUID_WINDOW_BLACKMANHARRIS, nfft, nfft/2);
+    //spgramcf psd = spgramcf_create_default(nfft);
+
+    // generate signal
+    while (spgramcf_get_num_samples_total(psd) < num_samples) {
+        // mix signal up in block
+        nco_crcf_mix_block_up(nco, buf_0, buf_1, buf_len);
+
+        // apply tapering to beginning to prevent initial transient
+        if (spgramcf_get_num_samples_total(psd) == 0UL) {
+            for (i=0; i<buf_len; i++)
+                buf_1[i] *= liquid_hann(i,2*buf_len);
+        }
+
+        // write samples to spectrogram
+        spgramcf_write(psd, buf_1, buf_len);
+    }
+
+    // verify results: full spectrum
+    autotest_psd_s regions[] = {
+        {.fmin=-0.50f,      .fmax=_freq-0.002,.pmin=  0, .pmax=-60, .test_lo=0, .test_hi=1},
+        {.fmin=_freq-0.002, .fmax=_freq+0.002,.pmin=  0, .pmax=  0, .test_lo=0, .test_hi=1},
+        {.fmin=_freq+0.002, .fmax=0.5,        .pmin=  0, .pmax=-60, .test_lo=0, .test_hi=1},
+    };
+    liquid_autotest_validate_psd_spgramcf(psd, regions, 3,
+        liquid_autotest_verbose ? "autotest/logs/nco_crcf_spectrum.m" : NULL);
+
+    // destroy object
+    nco_crcf_destroy(nco);
+    spgramcf_destroy(psd);
+}
+
+
+// test floating point precision nco phase
+void autotest_nco_crcf_spectrum_f00() { nco_crcf_spectrum_test(LIQUID_NCO, 0.123f); }
+