mirror of
https://github.com/ttrftech/NanoVNA.git
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144 lines
2.9 KiB
C
144 lines
2.9 KiB
C
/*
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* Copyright (c) 2014-2015, TAKAHASHI Tomohiro (TTRFTECH) edy555@gmail.com
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* All rights reserved.
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* The software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Radio; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include <arm_math.h>
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#include "nanovna.h"
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#ifdef ENABLED_DUMP
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int16_t samp_buf[SAMPLE_LEN];
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int16_t ref_buf[SAMPLE_LEN];
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#endif
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float acc_samp_s;
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float acc_samp_c;
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float acc_ref_s;
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float acc_ref_c;
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void
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dsp_process(int16_t *capture, size_t length)
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{
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uint32_t *p = (uint32_t*)capture;
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uint32_t len = length / 2;
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uint32_t i, j;
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int32_t samp_s = 0;
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int32_t samp_c = 0;
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int32_t ref_s = 0;
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int32_t ref_c = 0;
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// quadrature steps for if=12kHz on fs=48kHz
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for (i = 0, j = 0; i < len && j < 12; j++) {
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uint32_t sr;
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int16_t ref, smp;
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sr = *p++;
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ref = sr & 0xffff;
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smp = (sr>>16) & 0xffff;
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#ifdef ENABLED_DUMP
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ref_buf[i] = ref;
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samp_buf[i] = smp;
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#endif
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i++;
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samp_s += smp;
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ref_s += ref;
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sr = *p++;
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ref = sr & 0xffff;
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smp = (sr>>16) & 0xffff;
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#ifdef ENABLED_DUMP
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ref_buf[i] = ref;
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samp_buf[i] = smp;
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#endif
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i++;
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samp_c += smp;
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ref_c += ref;
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sr = *p++;
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ref = sr & 0xffff;
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smp = (sr>>16) & 0xffff;
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#ifdef ENABLED_DUMP
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ref_buf[i] = ref;
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samp_buf[i] = smp;
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#endif
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i++;
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samp_s -= smp;
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ref_s -= ref;
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sr = *p++;
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ref = sr & 0xffff;
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smp = (sr>>16) & 0xffff;
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#ifdef ENABLED_DUMP
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ref_buf[i] = ref;
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samp_buf[i] = smp;
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#endif
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i++;
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samp_c -= smp;
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ref_c -= ref;
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}
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acc_samp_s += samp_s;
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acc_samp_c += samp_c;
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acc_ref_s += ref_s;
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acc_ref_c += ref_c;
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}
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void
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calculate_gamma(float gamma[2])
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{
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#if 1
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// calculate reflection coeff. by samp divide by ref
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float rs = acc_ref_s;
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float rc = acc_ref_c;
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float rr = rs * rs + rc * rc;
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//rr = sqrtf(rr) * 1e8;
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float ss = acc_samp_s;
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float sc = acc_samp_c;
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gamma[0] = (sc * rc + ss * rs) / rr;
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gamma[1] = (ss * rc - sc * rs) / rr;
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#elif 0
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gamma[0] = acc_samp_s;
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gamma[1] = acc_samp_c;
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#else
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gamma[0] = acc_ref_s;
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gamma[1] = acc_ref_c;
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#endif
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}
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void
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fetch_amplitude(float gamma[2])
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{
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gamma[0] = acc_samp_s * 1e-9;
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gamma[1] = acc_samp_c * 1e-9;
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}
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void
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fetch_amplitude_ref(float gamma[2])
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{
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gamma[0] = acc_ref_s * 1e-9;
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gamma[1] = acc_ref_c * 1e-9;
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}
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void
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reset_dsp_accumerator(void)
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{
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acc_ref_s = 0;
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acc_ref_c = 0;
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acc_samp_s = 0;
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acc_samp_c = 0;
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}
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