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., 675 Mass Ave, Cambridge, MA 02139, 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 <asm/types.h>
  28 #include <sys/ioctl.h>
  29 #include <linux/videodev.h>
  30
  31 #define TRIES           25              /* get 25 samples                 */
  32 #define LOCKTIME        400000          /* wait 400ms for card to lock on */
  33 #define SAMPLEDELAY     15000           /* wait 15ms between samples      */
  34 #define THRESHOLD       .5              /* minimum acceptable signal %    */
  35
  36 void help(char *prog)
  37 {
  38         printf("usage: %s [-h] [-d <dev>] [-s <freq>] [-e <freq>] [-i <freq>]\n\n", prog);
  39
  40         printf("  -h        - display this help\n");
  41         printf("  -d <dev>  - select device (default: /dev/radio0)\n");
  42         printf("  -s <freq> - set start of scanning range to <freq>\n");
  43         printf("  -e <freq> - set end of scanning range to <freq>\n");
  44         printf("  -i <freq> - set increment value between channels to <freq>\n");
  45         printf("  <freq>    - a value in the format nnn.nn (MHz)\n");
  46
  47         exit (0);
  48 }
  49
  50 int main(int argc, char **argv)
  51 {
  52         int     fd, ret, i, tries = TRIES;
  53         struct  video_tuner vt;
  54         float   perc, begval, incval, endval;
  55         long    lowf, highf, freq, totsig, incr, fact;
  56         char    *progname, *dev = NULL;
  57
  58         progname = argv[0];     /* getopt munges argv[] later */
  59
  60         /* USA defaults */
  61         begval = 87.9;          /* start at 87.9 MHz */
  62         incval = 0.20;          /* increment 0.2 MHz */
  63         endval = 107.9;         /* stop at 107.9 MHz */
  64
  65         while ((i = getopt(argc, argv, "+e:hi:s:d:")) != EOF) {
  66                 switch (i) {
  67                         case 'd':
  68                                 dev = strdup(optarg);
  69                                 break;
  70                         case 'e':
  71                                 endval = atof(optarg);
  72                                 break;
  73                         case 'i':
  74                                 incval = atof(optarg);
  75                                 break;
  76                         case 's':
  77                                 begval = atof(optarg);
  78                                 break;
  79                         case 'h':
  80                         default:
  81                                 help(progname);
  82                                 break;
  83                 }
  84         }
  85
  86         if (!dev)
  87                 dev = strdup("/dev/radio0");    /* default */
  88
  89         fd = open(dev, O_RDONLY);
  90         if (fd < 0) {
  91                 fprintf(stderr, "Unable to open %s: %s\n", dev, strerror(errno));
  92                 exit(1);
  93         }
  94
  95         vt.tuner = 0;
  96         ret = ioctl(fd, VIDIOCGTUNER, &vt);     /* get initial info */
  97         if (ret < 0) {
  98                 perror("ioctl VIDIOCGTUNER");
  99                 exit(1);
 100         }
 101
 102         if ((vt.flags & VIDEO_TUNER_LOW) == 0)
 103                 fact = 16;
 104         else
 105                 fact = 16000;
 106
 107         /* cope with bizarre things from atof() like 95.099998 */
 108         lowf = fact * (ceil(rint(begval * 10)) / 10);
 109         highf = fact * (ceil(rint(endval * 10)) / 10);
 110
 111         incr = fact * incval;
 112
 113         printf("Scanning range: %2.1f - %2.1f MHz (%2.1f MHz increments)...\n",
 114                 begval, endval, incval);
 115
 116         for (freq = lowf; freq <= highf; freq += incr) {
 117                 ret = ioctl(fd, VIDIOCSFREQ, &freq);            /* tune */
 118
 119                 if (ret < 0) {
 120                         perror("ioctl VIDIOCSFREQ");
 121                         exit(1);
 122                 }
 123
 124                 printf("%2.1f:\r", (freq / (double) fact));
 125                 fflush(stdout);
 126                 usleep(LOCKTIME);               /* let it lock on */
 127
 128                 totsig = 0;
 129                 for (i = 1; i < tries+1; i++) {
 130                         vt.tuner = 0;
 131                         ret = ioctl(fd, VIDIOCGTUNER, &vt);     /* get info */
 132                         if (ret < 0) {
 133                                 perror("ioctl VIDIOCGTUNER");
 134                                 exit(1);
 135                         }
 136
 137                         totsig += vt.signal;
 138                         perc = (totsig / (65535.0 * i));
 139
 140                         printf("%2.1f: checking: %3.1f%% (%d/%d)    \r",
 141                               (freq / (double) fact), perc * 100.0, i, tries);
 142                         fflush(stdout);
 143                         usleep(SAMPLEDELAY);
 144                 }
 145
 146                 /* clean up the display */
 147                 printf("                                              \r");
 148
 149                 perc = (totsig / (65535.0 * tries));
 150
 151                 if (perc > THRESHOLD)
 152                         printf("%2.1f: %3.1f%%          \n",
 153                               (freq / (double) fact), perc * 100.0);
 154         }
 155
 156         close (fd);
 157         return 0;
 158 }