From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Sun, 31 Aug 2014 05:08:35 +0000 (+0000)
Subject: UT to measure rms noise on ADC ports
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=bb74a4fdb9437abe7ed88e6d1b9ac94e96d0c40a;p=freetel-svn-tracking.git

UT to measure rms noise on ADC ports

git-svn-id: https://svn.code.sf.net/p/freetel/code@1823 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/stm32/src/adc_sd.c b/codec2-dev/stm32/src/adc_sd.c
new file mode 100644
index 00000000..91414d2c
--- /dev/null
+++ b/codec2-dev/stm32/src/adc_sd.c
@@ -0,0 +1,75 @@
+/*---------------------------------------------------------------------------*\
+
+  FILE........: adc_sd.c
+  AUTHOR......: David Rowe
+  DATE CREATED: 30 May 2014
+
+  Measures the std deviation of the ADC signals.  Used to check noise
+  levels on each ADC.
+
+\*---------------------------------------------------------------------------*/
+
+/*
+  Copyright (C) 2014 David Rowe
+
+  All rights reserved.
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License version 2.1, as
+  published by the Free Software Foundation.  This program is
+  distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+  License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdlib.h>
+#include <math.h>
+#include "stm32f4_adc.h"
+#include "stm32f4_dac.h"
+#include "gdb_stdio.h"
+
+#define REC_TIME_SECS 10
+#define  N  (ADC_BUF_SZ*4)
+#define FS  16000
+
+static float calc_sd(short x[], int n) {
+    float sum, mean, sum_diff, sd;
+    int   i;
+
+    sum = 0.0;
+    for(i=0; i<n;i++) {
+        sum += (float)x[i];
+    }
+    mean = sum/n;
+
+    sum_diff = 0.0;
+    for(i=0; i<n;i++) {
+        sum_diff += ((float)x[i] - mean)*((float)x[i] - mean);
+    }
+    
+    sd = sqrtf(sum_diff/n);
+
+    return sd;
+}
+
+int main(void){
+    short  buf[N];
+    float  sd1, sd2;
+
+    adc_open(2*N);
+
+    printf("Starting!\n");
+    while(1) {
+        while(adc1_read(buf, N) == -1);
+        sd1 = calc_sd(buf, N);
+        while(adc2_read(buf, N) == -1);
+        sd2 = calc_sd(buf, N);
+
+        printf("adc1: %5.1f adc2: %5.1f\n", (double)sd1, (double)sd2);
+    }
+
+}