This only affects scanning, or specifically searching a range of frequencies.  I could hear it in the example from usage -f 118M:137M:25k.  For some reason the step changes as the loop executes so the frequencies look like: 118950000 118975000 119000000  ok to here 119257000 119282000 119307000 119332000 119357000 119382000 119407000 119432000 119457000 119482000 119507000 119532000 119789000 119814000 119839000 119864000 The frequencies should be at 25 KHz intervals. I don't have a diff because I have several other changes in my version, but my frequency_range() now looks like: void frequency_range(struct fm_state *fm, char *arg) {         char *start, *stop, *step;         int i;         int frst, frstp, frdelta;         start = arg;         stop = strchr(start, ':') + 1;         stop[-1] = '\0';         step = strchr(stop, ':') + 1;         step[-1] = '\0';         frst = (int)atofs(start);         frstp = (int)atofs(stop);         frdelta = (int)atofs(step);         fprintf(stderr,"start: %i, stop: %i, step: %i\n",frst,frstp,frdelta); // step was changing here somehow: //      for(i=(int)atofs(start); i<=(int)atofs(stop); i+=(int)atofs(step))         for (i=frst; i<=frstp; i+=frdelta)         {                 fm->freqs[fm->freq_len] = (uint32_t)i;                 fm->freq_len++;         }         stop[-1] = ':';         step[-1] = ':'; } I added the fr* variables and used them in the loop.  It sounds better now that none of the frequencies are off.  I'm also logging and those frequencies look OK.   Alan ----- Radio Astronomy - the ultimate DX