diff --git a/scan/reset_usb.c b/scan/reset_usb.c
new file mode 100644
index 0000000..48c8aa7
--- /dev/null
+++ b/scan/reset_usb.c
@@ -0,0 +1,25 @@
+
+/*
+http://askubuntu.com/questions/645/how-do-you-reset-a-usb-device-from-the-command-line
+$ lsusb
+Bus 001 Device 006: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T
+$ (sudo) ./reset_usb /dev/bus/usb/001/006
+*/
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/usbdevice_fs.h>
+
+int main(int argc, char **argv) {
+	const char *filename;
+	int fd;
+
+	filename = argv[1];
+	fd = open(filename, O_WRONLY);
+	ioctl(fd, USBDEVFS_RESET, 0);
+	close(fd);
+
+	return 0;
+}
+
diff --git a/scan/rs_detect.c b/scan/rs_detect.c
new file mode 100644
index 0000000..cb6be23
--- /dev/null
+++ b/scan/rs_detect.c
@@ -0,0 +1,345 @@
+
+/*
+ *  detect/identify radiosondes
+ *  DFM, RS92-SGP, RS41, M10, iMet-1-AB
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <time.h>
+
+#ifdef CYGWIN
+  #include <fcntl.h>  // cygwin: _setmode()
+  #include <io.h>
+#endif
+
+
+typedef unsigned char ui8_t;
+typedef unsigned int ui32_t;
+
+time_t rawtime;
+struct tm *gmt;
+
+
+int wavloaded = 0,
+    option_gmt = 0,
+    option_silent = 0;
+
+
+#define  DFM   2
+#define  RS41  3
+#define  RS92  4
+#define  M10   5
+#define  iMet  6
+
+
+#define HEADLEN 32
+#define HEADOFS  0  // HEADLEN+HEADOFS=32
+
+//int  dfm_baudrate = 2500;
+char dfm_header[] = "01100101011001101010010110101010";
+
+//int  vai_baudrate = 4800;
+char rs41_header[] = "00001000011011010101001110001000"
+                     "01000100011010010100100000011111";
+char rs92_header[] = "10100110011001101001"
+                     "10100110011001101001"
+                     "10100110011001101001"
+                     "10100110011001101001"
+                     "1010011001100110100110101010100110101001";
+
+//int  m10_baudrate = 9600;
+char m10_header[] = "00110011001100110101100110110011";
+
+//int  imet_baudrate = 9600;
+char imet_header[] = "11110000111100001111000011110000"
+           "11110000""10101100110010101100101010101100"
+           "11110000""10101100110010101100101010101100";
+
+
+char buf25[HEADLEN+1] = "x";
+int bufpos25 = -1;
+
+char buf48[HEADLEN+1] = "x";
+int bufpos48 = -1;
+
+char buf96[HEADLEN+1] = "x";
+int bufpos96 = -1;
+
+
+/* -------------------------------------------------------------------------- */
+
+int sample_rate = 0, bits_sample = 0, channels = 0;
+
+int findstr(char *buff, char *str, int pos) {
+    int i;
+    for (i = 0; i < 4; i++) {
+        if (buff[(pos+i)%4] != str[i]) break;
+    }
+    return i;
+}
+
+int read_wav_header(FILE *fp) {
+    char txt[4+1] = "\0\0\0\0";
+    unsigned char dat[4];
+    int byte, p=0;
+
+    if (fread(txt, 1, 4, fp) < 4) return -1;
+    if (strncmp(txt, "RIFF", 4)) return -1;
+    if (fread(txt, 1, 4, fp) < 4) return -1;
+    // pos_WAVE = 8L
+    if (fread(txt, 1, 4, fp) < 4) return -1;
+    if (strncmp(txt, "WAVE", 4)) return -1;
+    // pos_fmt = 12L
+    for ( ; ; ) {
+        if ( (byte=fgetc(fp)) == EOF ) return -1;
+        txt[p % 4] = byte;
+        p++; if (p==4) p=0;
+        if (findstr(txt, "fmt ", p) == 4) break;
+    }
+    if (fread(dat, 1, 4, fp) < 4) return -1;
+    if (fread(dat, 1, 2, fp) < 2) return -1;
+
+    if (fread(dat, 1, 2, fp) < 2) return -1;
+    channels = dat[0] + (dat[1] << 8);
+
+    if (fread(dat, 1, 4, fp) < 4) return -1;
+    memcpy(&sample_rate, dat, 4); //sample_rate = dat[0]|(dat[1]<<8)|(dat[2]<<16)|(dat[3]<<24);
+
+    if (fread(dat, 1, 4, fp) < 4) return -1;
+    if (fread(dat, 1, 2, fp) < 2) return -1;
+    //byte = dat[0] + (dat[1] << 8);
+
+    if (fread(dat, 1, 2, fp) < 2) return -1;
+    bits_sample = dat[0] + (dat[1] << 8);
+
+    // pos_dat = 36L + info
+    for ( ; ; ) {
+        if ( (byte=fgetc(fp)) == EOF ) return -1;
+        txt[p % 4] = byte;
+        p++; if (p==4) p=0;
+        if (findstr(txt, "data", p) == 4) break;
+    }
+    if (fread(dat, 1, 4, fp) < 4) return -1;
+
+
+    if (!option_silent) {
+        fprintf(stderr, "sample_rate: %d\n", sample_rate);
+        fprintf(stderr, "bits       : %d\n", bits_sample);
+        fprintf(stderr, "channels   : %d\n", channels);
+    }
+
+    if ((bits_sample != 8) && (bits_sample != 16)) return -1;
+
+    return 0;
+}
+
+
+#define EOF_INT  0x1000000
+
+int read_signed_sample(FILE *fp) {  // int = i32_t
+    int byte, i, ret;         //  EOF -> 0x1000000
+
+    for (i = 0; i < channels; i++) {
+                           // i = 0: links bzw. mono
+        byte = fgetc(fp);
+        if (byte == EOF) return EOF_INT;
+        if (i == 0) ret = byte;
+    
+        if (bits_sample == 16) {
+            byte = fgetc(fp);
+            if (byte == EOF) return EOF_INT;
+            if (i == 0) ret +=  byte << 8;
+        }
+
+    }
+
+    if (bits_sample ==  8) return ret-128;
+    if (bits_sample == 16) return (short)ret;
+
+    return ret;
+}
+
+int par=1, par_alt=1;
+unsigned long sample_count = 0;
+
+int read_bits_fsk(FILE *fp, int *bit, int *len) {
+    int n, sample;
+
+    n = 0;
+    do{
+        sample = read_signed_sample(fp);
+        if (sample == EOF_INT) return EOF;
+        sample_count++;
+        par_alt = par;
+        par =  (sample >= 0) ? 1 : -1;  // 8bit: 0..127,128..255 (-128..-1,0..127)
+        n++;
+    } while (par*par_alt > 0);
+
+    *len = n;
+
+    *bit = (1+par_alt)/2;  // oben 1, unten -1
+    //*bit = (1-par_alt)/2;// sdr#<rev1381?, invers: unten 1, oben -1
+
+    return 0;
+}
+
+/* -------------------------------------------------------------------------- */
+
+char inv(char c) {
+    if (c == '0') return '1';
+    if (c == '1') return '0';
+    return c;
+}
+
+
+void inc_buf(int *bufpos) {
+  *bufpos = (*bufpos+1) % HEADLEN;
+}
+
+int compare(char buf[], char header[], int bufpos) {
+    int i, j;
+    
+    i = 0;
+    j = bufpos;
+    while (i < HEADLEN) {
+        if (j < 0) j = HEADLEN-1;
+        if (buf[j] != header[HEADOFS+HEADLEN-1-i]) break;
+        j--;
+        i++;
+    }
+    if (i == HEADLEN) return 1;
+
+    i = 0;
+    j = bufpos;
+    while (i < HEADLEN) {
+        if (j < 0) j = HEADLEN-1;
+        if (buf[j] != inv(header[HEADOFS+HEADLEN-1-i])) break;
+        j--;
+        i++;
+    }
+    if (i == HEADLEN) return -1;
+
+    return 0;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+
+int main(int argc, char **argv) {
+
+    FILE *fp;
+    char *fpname;
+    int header_found, bit, len, i;
+    int len25, len48, len96;
+    int zeit = 0;
+
+#ifdef CYGWIN
+    _setmode(fileno(stdin), _O_BINARY);  // _setmode(_fileno(stdin), _O_BINARY);
+    setbuf(stdout, NULL);
+#endif
+
+    fpname = argv[0];
+    ++argv;
+    while ((*argv) && (!wavloaded)) {
+        if      ( (strcmp(*argv, "-h") == 0) || (strcmp(*argv, "--help") == 0) ) {
+            fprintf(stderr, "%s [-t nn] audio.wav\n", fpname);
+            return 0;
+        }
+        else if ( (strcmp(*argv, "-s") == 0) || (strcmp(*argv, "--silent") == 0) ) {
+            option_silent = 1;
+        }
+        else if ( (strcmp(*argv, "-z") == 0) || (strcmp(*argv, "--zulu") == 0) ) {
+            option_gmt = 1;
+        }
+        else if ( (strcmp(*argv, "-t") == 0) || (strcmp(*argv, "--time") == 0) ) {
+            ++argv;
+            if (*argv) zeit = atoi(*argv);
+            else return -1;
+        }
+        else {
+            fp = fopen(*argv, "rb");
+            if (fp == NULL) {
+                fprintf(stderr, "%s konnte nicht geoeffnet werden\n", *argv);
+                return -1;
+            }
+            wavloaded = 1;
+        }
+        ++argv;
+    }
+    if (!wavloaded) fp = stdin;
+
+
+    i = read_wav_header(fp);
+    if (i) {
+        fclose(fp);
+        return -1;
+    }
+
+    header_found = 0;
+
+    while (!read_bits_fsk(fp, &bit, &len) && !header_found) {
+
+        len25 = (int) (len * 2500.0 / sample_rate + 0.5);
+        len48 = (int) (len * 4800.0 / sample_rate + 0.5);
+        len96 = (int) (len * 9600.0 / sample_rate + 0.5);
+
+        for (i = 0; i < len25; i++) {
+            inc_buf(&bufpos25);
+            buf25[bufpos25] = 0x30 + bit;  // Ascii
+            header_found = compare(buf25, dfm_header, bufpos25) * DFM;
+            if (header_found) goto ende;
+        }
+
+        for (i = 0; i < len48; i++) {
+            inc_buf(&bufpos48);
+            buf48[bufpos48] = 0x30 + bit;  // Ascii
+            header_found = compare(buf48, rs41_header+16, bufpos48) * RS41;
+            if (header_found) goto ende;
+            header_found = compare(buf48, rs92_header, bufpos48) * RS92;
+            if (header_found) goto ende;
+        }
+
+        for (i = 0; i < len96; i++) {
+            inc_buf(&bufpos96);
+            buf96[bufpos96] = 0x30 + bit;  // Ascii
+            header_found = compare(buf96, m10_header, bufpos96) * M10;
+            if (header_found) goto ende;
+            header_found = compare(buf96, imet_header+32, bufpos96) * iMet;
+            if (header_found) goto ende;
+        }
+
+        if (zeit > 0  &&  sample_count > zeit*sample_rate) goto ende;
+
+    }
+
+ende:
+    fclose(fp);
+
+    if (!option_silent) {
+        printf("sample: %lu\n", sample_count);
+        if (zeit) printf("%ds = %d samples\n", zeit, zeit*sample_rate);
+        printf("found: ");
+        if (!header_found) printf("NO");
+        else {
+            time(&rawtime);
+            gmt = gmtime(&rawtime);
+            if (header_found < 0) printf("-");
+            if (header_found*header_found == DFM*DFM)   printf("DFM");
+            if (header_found*header_found == RS41*RS41) printf("RS41");
+            if (header_found*header_found == RS92*RS92) printf("RS92");
+            if (header_found*header_found == M10*M10)   printf("M10");
+            if (header_found*header_found == iMet*iMet) printf("iMet");
+            if (option_gmt) {
+                printf(" (%4d-%02d-%02d %02d:%02dZ) ", gmt->tm_year+1900, gmt->tm_mon,
+                                                       gmt->tm_mday, gmt->tm_hour, gmt->tm_min);
+            }
+        }
+        printf("\n");
+    }
+
+    return header_found;
+}
+
diff --git a/scan/rtlsdr_scan.pl b/scan/rtlsdr_scan.pl
new file mode 100755
index 0000000..5813de2
--- /dev/null
+++ b/scan/rtlsdr_scan.pl
@@ -0,0 +1,227 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+use POSIX qw(strftime);
+
+
+## rs_detect.c return:
+## #define  DFM   2
+## #define  RS41  3
+## #define  RS92  4
+## #define  M10   5
+## #define  iMet  6
+
+my $log_dir = "log";
+
+my $utc = strftime('%Y%m%d_%H%M%S', gmtime);
+print $utc, "UTC", "\n";
+
+my $powfile = sprintf "log_power\.csv";
+
+
+my $ppm = 54;
+my $fos = 403200000 * ( 1 + $ppm/1000000 );  # 403.2MHz-Linie
+
+my $scan_f1 = "400.6M";
+my $scan_f2 = "405.9M";
+
+my $line;
+my @fields;
+
+my $date;
+my $time;
+my $f1;
+my $f2;
+my $f;
+my $step;
+my @db;
+
+my $i;
+my $j;
+
+my $peak = 0;
+my $peak_start;
+my $peak_end = 0;
+
+my $freq;
+my $ret;
+my $inv;
+my $dec;
+my $wavfile;
+my $filter;
+my $breite = "";
+my $rs;
+my $WFM;
+
+my $squelch;
+my $snr = 6;
+
+my @peakarray;
+my $num_peaks;
+
+print "[rtl_power: scan $scan_f1:$scan_f2]\n";
+system("timeout 30 rtl_power -p $ppm -f $scan_f1:$scan_f2:800 -i20 -1 $powfile 2>/dev/null");
+if ( $? == -1 ) {
+    print "Fehler: $!\n";
+}
+
+
+my $fh;
+open ($fh, '<', "$powfile") or die "Kann '$powfile' nicht oeffnen: $!\n";
+
+
+@peakarray = ();
+my $num_lines = 0;
+
+while ($line = <$fh>) {
+    $num_lines += 1;
+    chomp $line;
+    @db = split(",", $line);
+    $date = $db[0];
+    shift @db;
+    $time = $db[0];
+    shift @db;
+    $f1 = $db[0];
+    shift @db;
+    $f2 = $db[0];
+    shift @db;
+    $step = $db[0];
+    shift @db;
+    shift @db;
+
+    my $sum = eval join '+', @db;
+    my $mean = $sum / scalar(@db);
+    #printf "level: %.1f\n", $mean;
+    $squelch = $mean + $snr;
+
+    $peak = 0;
+    $peak_start = $peak_end = 0;
+
+    for ($j = 0; $j < scalar(@db)-1; $j++) {
+
+        if ($db[$j] > $squelch) {
+            if ($peak == 0) {
+                $peak_start = $f1 + $j*$step;
+            }
+            $peak = 1;
+        }
+        elsif ($peak > 0) {
+            if ($db[$j+1] <= $squelch) {
+                $peak_end = $f1 + ($j-1)*$step;
+                $peak = 0;
+            }
+            if ($peak_start < $peak_end) {
+                $freq = $peak_start + ($peak_end-$peak_start)/2;
+                if  ( !($freq > $fos-1000 && $freq < $fos+1000) ) { ## 403.2MHz-Linie auslassen
+                    push @peakarray, $freq;
+                }
+            }
+        }
+            
+    }
+}
+close $fh;
+
+if ($num_lines == 0) {
+    print "[reset dvb-t ...]\n";
+    reset_dvbt();
+}
+else {
+    $num_peaks = scalar(@peakarray);
+    for ($j = 0; $j < $num_peaks-1; $j++) {    
+        if ($peakarray[$j+1]-$peakarray[$j] < 10e3) {  # DFM peak-to-peak: 6kHz
+            push @peakarray, $peakarray[$j]+($peakarray[$j+1]-$peakarray[$j])/2;
+        }
+        elsif ($peakarray[$j+1]-$peakarray[$j] < 34e3) {  # iMet peak-to-peak: 24kHz
+            push @peakarray, $peakarray[$j]+($peakarray[$j+1]-$peakarray[$j])/2;
+        }
+    }
+
+    print "[rtl_fm: detect/decode]\n";
+
+    for ($j = 0; $j < $num_peaks; $j++) {
+
+        $freq = sprintf "%.0f", $peakarray[$j];
+
+        eval {
+            local $SIG{ALRM} = sub {die "alarm\n"};
+            alarm 30; # beide Bandbreiten
+            print "\n$freq Hz: ";  # detect ohne highpass 20 
+            system("timeout 12s rtl_fm -p $ppm -M fm -s 15k -f $freq 2>/dev/null |\ 
+                    sox -t raw -r 15k -e s -b 16 -c 1 - -r 48000 -t wav - 2>/dev/null |\ 
+                    ./rs_detect -s -z -t 8 2>/dev/null");
+            $ret = $? >> 8;
+            if (!$ret) {  # mehr Bandbreite bei iMet
+                system("timeout 12s rtl_fm -p $ppm -M fm -s 36k -o 4 -f $freq 2>/dev/null |\ 
+                        sox -t raw -r 36k -e s -b 16 -c 1 - -r 48000 -t wav - 2>/dev/null |\ 
+                        ./rs_detect -s -z -t 8 2>/dev/null");
+                $ret = $? >> 8;
+            }
+            alarm 0;
+        };
+        if ($@) {
+            die unless  $@ =~ /alarm/;
+            reset_dvbt();
+            print "[reset dvb-t ...]\n";
+        }
+
+        if ($ret) {
+            if ($ret & 0x80) {
+                $inv = '-i';
+                $ret = - (0x100 - $ret);  # obwohl ($ret & 0x80) = core dump
+            }
+            else { $inv = ''; }
+            $rs = "";
+            $WFM = "";
+            if (abs($ret) == 2) { $rs = "dfm";  $breite = "15k"; $dec = './dfm06 -v'; $filter = "lowpass 2000 highpass 20"; }
+            if (abs($ret) == 3) { $rs = "rs41"; $breite = "12k"; $dec = './rs41stdin -v'; $filter = "lowpass 2600"; }
+            if (abs($ret) == 4) { $rs = "rs92"; $breite = "12k"; $dec = './rs92gps -g -v -a almanac.txt'; $filter = "lowpass 2500 highpass 20"; }
+            if (abs($ret) == 5) { $rs = "m10";  $breite = "24k"; $dec = './m10x -v'; $filter = "highpass 20"; }
+            if (abs($ret) == 6) { $rs = "imet"; $breite = "40k"; $dec = './imet1ab -v'; $filter = "highpass 20";  $WFM = "-o 4"; }
+            if ($inv) { print "-";} print uc($rs)," ($utc)\n";
+            $utc = strftime('%Y%m%d_%H%M%S', gmtime);
+            $wavfile = $rs."-".$utc."Z-".$freq."Hz.wav";
+            if ($rs) {
+                system("timeout 30s rtl_fm -p $ppm -M fm $WFM -s $breite -f $freq 2>/dev/null |\ 
+                        sox -t raw -r $breite -e s -b 16 -c 1 - -r 48000 -b 8 -t wav - $filter 2>/dev/null |\ 
+                        tee $log_dir/$wavfile | $dec $inv 2>/dev/null");
+            }
+        }
+
+    }
+    print "\n";
+}
+
+print "\n=\n";
+
+
+## $snr: peak sensitivity: wenn zu niedrig, viele Kandidaten;
+##       wenn zu hoch, zu wenige (rs41 sendet nur 1/2 sek.
+## andere Methoden:
+## Fenster/Bandbreite aufsummieren/integrieren; Schwerpunkt;
+## rtl-sdr IQ-Band: 1 Minute aufnehmen und dann analysieren/scannen.
+##
+## rs92: aktuellen (SEM) almanac.txt
+##       wenn brdc-emphemerides (-e) benutzt werden, darauf achten, dass diese
+##       aktuell sind, wenn ueber laengeren Zeitraum gescannt wird
+##
+## rs_detect.c und decoder: gleiche Polaritaet in read_bits_fsk(),
+##                          am besten als gemeinsame include-Datei wav_audio.c
+###################################################################################################
+
+
+## http://askubuntu.com/questions/645/how-do-you-reset-a-usb-device-from-the-command-line
+## usbreset.c -> reset_usb
+sub reset_dvbt {
+    my @devices = split("\n",`lsusb`);
+    foreach my $line (@devices) {
+        if ($line =~ /\w+\s(\d+)\s\w+\s(\d+):\sID\s([0-9a-f]+):([0-9a-f]+).+Realtek Semiconductor Corp\./) {
+            if ($4 eq "2832"  ||  $4 eq "2838") {
+                system("./reset_usb /dev/bus/usb/$1/$2");
+            }
+        }
+    }
+}
+