fmscan.c

   1 /* scan.c - v4l radio band scanner using signal strength
   2
   3    Copyright (C) 1999  Russell Kroll <rkroll@exploits.org>
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18  */
  19
  20 #include <math.h>
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <fcntl.h>
  24 #include <stdlib.h>
  25 #include <unistd.h>
  26 #include <string.h>
  27 #include <sys/ioctl.h>
  28 #include "videodev.h"
  29
  30 #include "version.h"
  31
  32 #define TRIES           25              /* get 25 samples                 */
  33 #define LOCKTIME        400000          /* wait 400ms for card to lock on */
  34 #define SAMPLEDELAY     15000           /* wait 15ms between samples      */
  35 #define THRESHOLD       .5              /* minimum acceptable signal %    */
  36
  37 void help(char *prog)
  38 {
  39         printf("fmtools fmscan version %s\n\n", FMT_VERSION);
  40         printf("usage: %s [-h] [-d <dev>] [-s <freq>] [-e <freq>] [-i <freq>] [-t <%%>]\n\n", prog);
  41
  42         printf("Auxiliary program to scan a frequency band for radio stations.\n\n");
  43
  44         printf("  -h        - display this help\n");
  45         printf("  -d <dev>  - select device (default: /dev/radio0)\n");
  46         printf("  -s <freq> - set start of scanning range to <freq>\n");
  47         printf("  -e <freq> - set end of scanning range to <freq>\n");
  48         printf("  -i <freq> - set increment value between channels to <freq>\n");
  49         printf("  -t <%%>    - set signal strength percentage to lock onto <%%>\n");
  50         printf("  <freq>    - a value in the format nnn.nn (MHz)\n");
  51
  52         exit(0);
  53 }
  54
  55 int main(int argc, char **argv)
  56 {
  57         int     fd, ret, i, tries = TRIES;
  58         struct  video_tuner vt;
  59         float   perc, begval, incval, endval, threshold;
  60         long    lowf, highf, freq, totsig, incr, fact;
  61         char    *progname, *dev = NULL;
  62
  63         progname = argv[0];     /* getopt munges argv[] later */
  64
  65         /* USA defaults */
  66         begval = 87.9;          /* start at 87.9 MHz */
  67         incval = 0.20;          /* increment 0.2 MHz */
  68         endval = 107.9;         /* stop at 107.9 MHz */
  69
  70         threshold = THRESHOLD;
  71
  72         while ((i = getopt(argc, argv, "+e:hi:s:d:t:")) != EOF) {
  73                 switch (i) {
  74                         case 'd':
  75                                 dev = strdup(optarg);
  76                                 break;
  77                         case 'e':
  78                                 endval = atof(optarg);
  79                                 break;
  80                         case 'i':
  81                                 incval = atof(optarg);
  82                                 break;
  83                         case 's':
  84                                 begval = atof(optarg);
  85                                 break;
  86                         case 't':
  87                                 threshold = atof(optarg)/100.;
  88                                 break;
  89                         case 'h':
  90                         default:
  91                                 help(progname);
  92                                 break;
  93                 }
  94         }
  95
  96         if (!dev)
  97                 dev = strdup("/dev/radio0");    /* default */
  98
  99         fd = open(dev, O_RDONLY);
 100         if (fd < 0) {
 101                 fprintf(stderr, "Unable to open %s: %s\n", dev, strerror(errno));
 102                 exit(1);
 103         }
 104
 105         vt.tuner = 0;
 106         ret = ioctl(fd, VIDIOCGTUNER, &vt);     /* get initial info */
 107         if (ret < 0) {
 108                 perror("ioctl VIDIOCGTUNER");
 109                 exit(1);
 110         }
 111
 112         if ((vt.flags & VIDEO_TUNER_LOW) == 0)
 113                 fact = 16;
 114         else
 115                 fact = 16000;
 116
 117         /* cope with bizarre things from atof() like 95.099998 */
 118         lowf = fact * (ceil(rint(begval * 10)) / 10);
 119         highf = fact * (ceil(rint(endval * 10)) / 10);
 120
 121         incr = fact * incval;
 122
 123         printf("Scanning range: %2.1f - %2.1f MHz (%2.1f MHz increments)...\n",
 124                 begval, endval, incval);
 125
 126         for (freq = lowf; freq <= highf; freq += incr) {
 127                 ret = ioctl(fd, VIDIOCSFREQ, &freq);            /* tune */
 128
 129                 if (ret < 0) {
 130                         perror("ioctl VIDIOCSFREQ");
 131                         exit(1);
 132                 }
 133
 134                 printf("%2.1f:\r", (freq / (double) fact));
 135                 fflush(stdout);
 136                 usleep(LOCKTIME);               /* let it lock on */
 137
 138                 totsig = 0;
 139                 for (i = 1; i < tries+1; i++) {
 140                         vt.tuner = 0;
 141                         ret = ioctl(fd, VIDIOCGTUNER, &vt);     /* get info */
 142                         if (ret < 0) {
 143                                 perror("ioctl VIDIOCGTUNER");
 144                                 exit(1);
 145                         }
 146
 147                         totsig += vt.signal;
 148                         perc = (totsig / (65535.0 * i));
 149
 150                         printf("%2.1f: checking: %3.1f%% (%d/%d)    \r",
 151                               (freq / (double) fact), perc * 100.0, i, tries);
 152                         fflush(stdout);
 153                         usleep(SAMPLEDELAY);
 154                 }
 155
 156                 /* clean up the display */
 157                 printf("                                              \r");
 158
 159                 perc = (totsig / (65535.0 * tries));
 160
 161                 if (perc > threshold)
 162                         printf("%2.1f: %3.1f%%          \n",
 163                               (freq / (double) fact), perc * 100.0);
 164         }
 165
 166         close(fd);
 167         return 0;
 168 }