From 9f4c79a2f6316266a93e4f73d97118c73653de6a Mon Sep 17 00:00:00 2001 From: FreeArtMan Date: Thu, 17 Sep 2015 18:33:22 +0100 Subject: Moved all files to md dir --- writeup/article.md | 183 ---------------- writeup/article1.md | 462 ---------------------------------------- writeup/gdb_helper_functions.md | 0 writeup/rtlsdr_usage.md | 183 ---------------- 4 files changed, 828 deletions(-) delete mode 100644 writeup/article.md delete mode 100644 writeup/article1.md delete mode 100644 writeup/gdb_helper_functions.md delete mode 100644 writeup/rtlsdr_usage.md (limited to 'writeup') diff --git a/writeup/article.md b/writeup/article.md deleted file mode 100644 index c198ecf..0000000 --- a/writeup/article.md +++ /dev/null @@ -1,183 +0,0 @@ -# RTLSDR usage - -# Index - - -1. Setup rtlsdr - 1.1. Get sources - 1.2. Drivers - 1.3. Check if works -2. Collection of tools - 2.1. FM - 2.2. Spectrum diagram - 2.3. ADSB - 2.4. AFSK1200 -3. Projects where rtlsdr used - 3.1. WebSDR -4. Problems - 4.1. Sync errors -5. Links -6. Changelog - - -## 1.Setup rtlsdr - - -By rtlsdr usually call RTL2832U chip based tv-tunners which -can be used for not just recievin DVB-T frequencies but much more -and yes price is ~$10 it mean that anyone can just buy and try -without "loosing" money. - - -### 1.1.Get sources - - -Main development repository is on http://sdr.osmocom.org/trac/wiki/rtl-sdr -on github you can find more repos with experminental -features (https://github.com/keenerd/rtl-sdr). - -Getting sources from git: -``` - git clone git://git.osmocom.org/rtl-sdr.git -``` -I prefer using plain binaries without any kind of installation. Just -compile and use binary without any troubles. -Build: -```bash - cmake . - make -``` -All binaries is in src dir - - -### 1.2.Drivers - - -Linux kernel have some drivers for rtlsdr stick and DVB-T. When you will plug -rtlsdr then kernel probably will load DVB-T drivers and you will not able -to use you rtlsdr for sdr. Way yo fix is it add some drivers to black list and -next time when you will plug rtlsdr this drivers will not be loaded. - -Check if rtlsdr related drivers is loaded: -```bash - lsmod | grep rtl28 -``` -If there is some drivers then balcklist driver by creating file -in */etc/modprobe.d/* with content: -``` - blacklist dvb_usb_rtl28xxu -``` -Next thing that could appear is permissions on rtlsdr usage when its pluged in. -To allow everyone to use create file in */etc/udev/rules.d/* with content: -``` - SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", \ - GROUP="adm", MODE="0666", SYMLINK+="rtl_sdr" -``` - -### 1.3.Check if works - -How to test if rtlsdr works? Run one of commands: - rtl_test - -I like to run rtl_adsb as you can see there that something is recieved and -you see that everything "works": - rtl_adsb - -There should be line by line showing up some "hex" lines. If some data is showen -then adsb data from plains is recieved. - -## 2.Collection of tools - - -### 2.1.FM - -Get some sound trancmited from FM radio stations. - -```bash - rtl_fm -f 96.3e6 -M wbfm -s 200000 -r 48000 - | aplay -r 48k -f S16_LE -``` - - -### 2.2.Spectrum diagram - -Scan spectrum to find some activities on different frequencies. -Good link with all description is http://kmkeen.com/rtl-power/ . -Main usage of rtl_power is : -```bash - rtl_power -f 76M:108M:125k -i 1 fm_stations.csv -``` -and then draw image : -```bash - heatmap.py fm_stations.csv fm_stations.png -``` - -### 2.3.ADSB - -ADS-B ( Automatic dependent surveillance broadcast ) in simple words airplain -geoposition, speed, height and flight number broadcasting. You can recieve -this data and see how many plains is around and sometimes flight number. - -rtlsdr have default one rtl_adsb programm but it shows only recieved data, -without any decoding. Here is dump1090 specifically for rtlsdr and nothing -more: - - https://github.com/antirez/dump1090 - -description howto install could be found also here - - http://www.satsignal.eu/raspberry-pi/dump1090.html - -Using in interactive mode with height in metrs: -```bash - dump1090 --interactive --metric -``` -Output: - -``` - Hex Flight Altitude Speed Lat Lon Track Messages Seen . - ------------------------------------------------------------------------------ - 71be01 10052 1009 36.434 33.544 45 9 1 sec - 424913 SDM6329 10966 711 36.440 33.405 221 65 0 sec -``` - - -### 2.4.AFSK1200 - -Gqrx is graphical SDR software where you can travel across frequencies -and in real time search for some transmission. - - http://gqrx.dk/ - -It have builtin AFSK1200 demodulator or in simple words ham radio packets. -And you could try to see what people sending in tex around the world. - -## 3.Projects where rtlsdr used - -### 3.1.WebSDR - -WebSDR probably best site where you can go and click on some radio reciever -and liste what happends in some particular country. WebSDR site contains -about 80 radio recievers around the world that can be accessed trought web -interface. - http://websdr.org/ - -If you whant setup your own radio reciever read FAQ, prepare mail and send mail -after that you could recieve precompiled websdr software with is easy -to setup with rtlsdr stick. - -## 4.Problems - -### 4.1.Sync errors - -Once there was sync error when was trying to use rtl_test or rtl_adsb. -To fix that changes for better quality usb cable. - -# 5.Links - -1. [http://kmkeen.com/rtl-demod-guide/](http://kmkeen.com/rtl-demod-guide/) -2. http://kmkeen.com/rtl-power/ -3. http://sdr.osmocom.org/trac/wiki/rtl-sdr -4. http://www.rtl-sdr.com/ -5. https://github.com/antirez/dump1090 -6. http://gqrx.dk - diff --git a/writeup/article1.md b/writeup/article1.md deleted file mode 100644 index 4995b15..0000000 --- a/writeup/article1.md +++ /dev/null @@ -1,462 +0,0 @@ -
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-+                                RTLSDR usage                                  +
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-+                                    INDEX                                     +
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
- 1. Setup rtlsdr
-   1.1. Get sources
-   1.2. Drivers
-   1.3. Check if works
- 2. Collection of tools
-   2.1. FM
-   2.2. Spectrum diagram
-   2.3. ADSB
-   2.4. AFSK1200
- 3. Projects where rtlsdr used
-   3.1. WebSDR
- 4. Problems
-   4.1. Sync errors
- 5. Links
- 6. Changelog
-
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-+                               1.Setup rtlsdr                                 +
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
-By rtlsdr usually call RTL2832U chip based tv-tunners which
-can be used for not just recievin DVB-T frequencies but much more
-and yes price is ~$10 it mean that anyone can just buy and try
-without "loosing" money.
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-1.1.Get sources
-
-
-Main development repository is on http://sdr.osmocom.org/trac/wiki/rtl-sdr
-on github you can find more repos with experminental 
-features (https://github.com/keenerd/rtl-sdr).
-
-Getting sources from git:
-  git clone git://git.osmocom.org/rtl-sdr.git
-
-I prefer using plain binaries without any kind of installation. Just
-compile and use binary without any troubles.
-Build:
-  cmake .
-  make
-
-All binaries is in src dir
-
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-1.2.Drivers
-
-
-Linux kernel have some drivers for rtlsdr stick and DVB-T. When you will plug
-rtlsdr then kernel probably will load DVB-T drivers and you will not able
-to use you rtlsdr for sdr. Way yo fix is it add some drivers to black list and
-next time when you will plug rtlsdr this drivers will not be loaded.
-
-Check if rtlsdr related drivers is loaded:
-  lsmod | grep rtl28
-
-If there is some drivers then balcklist driver by creating file
-in /etc/modprobe.d/ with content:
-  blacklist dvb_usb_rtl28xxu
-
-Next thing that could appear is permissions on rtlsdr usage when its pluged in.
-To allow everyone to use create file in /etc/udev/rules.d/ with content:
-  SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", \
-  GROUP="adm", MODE="0666", SYMLINK+="rtl_sdr"
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-1.3.Check if works
-
-How to test if rtlsdr works? Run one of commands:
-  rtl_test
-
-I like to run rtl_adsb as you can see there that something is recieved and
-you see that everything "works":
-  rtl_adsb
-
-There should be line by line showing up some "hex" lines. If some data is showen
-then adsb data from plains is recieved.
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-+                            2.Collection of tools                             +
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-2.1.FM
-
-Get some sound trancmited from FM radio stations.
-
-  rtl_fm -f 96.3e6 -M wbfm -s 200000 -r 48000 - | aplay -r 48k -f S16_LE
-
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-2.2.Spectrum diagram
-
-Scan spectrum to find some activities on different frequencies.
-Good link with all description is http://kmkeen.com/rtl-power/ . 
-Main usage of rtl_power is :
-
-  rtl_power -f 76M:108M:125k -i 1 fm_stations.csv
-
-and then draw image :
-
-  heatmap.py fm_stations.csv fm_stations.png
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-2.3.ADSB
-
-ADS-B ( Automatic dependent surveillance broadcast ) in simple words airplain
-geoposition, speed, height and flight number broadcasting. You can recieve
-this data and see how many plains is around and sometimes flight number.
-
-rtlsdr have default one rtl_adsb programm but it shows only recieved data,
-without any decoding. Here is dump1090 specifically for rtlsdr and nothing
-more:
-
-  https://github.com/antirez/dump1090
-
-description howto install could be found also here
-
-  http://www.satsignal.eu/raspberry-pi/dump1090.html
-
-Using in interactive mode with height in metrs:
-  
-  dump1090 --interactive --metric
-
-Output:
-
-  Hex    Flight   Altitude  Speed   Lat       Lon       Track  Messages Seen .  
-  ------------------------------------------------------------------------------
-  71be01          10052     1009    36.434    33.544    45    9         1 sec
-  424913 SDM6329  10966     711     36.440    33.405    221   65        0 sec
-
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-2.4.AFSK1200
-
-Gqrx is graphical SDR software where you can travel across frequencies
-and in real time search for some transmission.
-
-  http://gqrx.dk/
-
-It have builtin AFSK1200 demodulator or in simple words ham radio packets.
-And you could try to see what people sending in tex around the world.
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-+                        3.Projects where rtlsdr used                          +
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-3.1.WebSDR
-
-WebSDR probably best site where you can go and click on some radio reciever 
-and liste what happends in some particular country. WebSDR site contains
-about 80 radio recievers around the world that can be accessed trought web
-interface. 
-  http://websdr.org/
-
-If you whant setup your own radio reciever read FAQ, prepare mail and send mail
-after that you could recieve precompiled websdr software with is easy
-to setup with rtlsdr stick.
-
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-+                                 4.Problems                                   +
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-4.1.Sync errors
-
-Once there was sync error when was trying to use rtl_test or rtl_adsb.
-To fix that changes for better quality usb cable.
-
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-+                                   5.Links                                    +
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-[1] http://kmkeen.com/rtl-demod-guide/
-[2] http://kmkeen.com/rtl-power/
-[3] http://sdr.osmocom.org/trac/wiki/rtl-sdr
-[4] http://www.rtl-sdr.com/
-[5] https://github.com/antirez/dump1090
-[6] http://gqrx.dk
-
- -```c - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#define _GNU_SOURCE -#include - - -struct ihex_binrec { - struct ihex_binrec *next; /* not part of the real data structure */ - uint32_t addr; - uint16_t len; - uint8_t data[]; -}; - -/** - * nybble/hex are little helpers to parse hexadecimal numbers to a byte value - **/ -static uint8_t nybble(const uint8_t n) -{ - if (n >= '0' && n <= '9') return n - '0'; - else if (n >= 'A' && n <= 'F') return n - ('A' - 10); - else if (n >= 'a' && n <= 'f') return n - ('a' - 10); - return 0; -} - -static uint8_t hex(const uint8_t *data, uint8_t *crc) -{ - uint8_t val = (nybble(data[0]) << 4) | nybble(data[1]); - *crc += val; - return val; -} - -static int process_ihex(uint8_t *data, ssize_t size); -static void file_record(struct ihex_binrec *record); -static int output_records(int outfd); - -static int sort_records = 0; -static int wide_records = 0; -static int include_jump = 0; - -static int usage(void) -{ - fprintf(stderr, "ihex2fw: Convert ihex files into binary " - "representation for use by Linux kernel\n"); - fprintf(stderr, "usage: ihex2fw [] \n"); - fprintf(stderr, " -w: wide records (16-bit length)\n"); - fprintf(stderr, " -s: sort records by address\n"); - fprintf(stderr, " -j: include records for CS:IP/EIP address\n"); - return 1; -} - -int main(int argc, char **argv) -{ - int infd, outfd; - struct stat st; - uint8_t *data; - int opt; - - while ((opt = getopt(argc, argv, "wsj")) != -1) { - switch (opt) { - case 'w': - wide_records = 1; - break; - case 's': - sort_records = 1; - break; - case 'j': - include_jump = 1; - break; - default: - return usage(); - } - } - - if (optind + 2 != argc) - return usage(); - - if (!strcmp(argv[optind], "-")) - infd = 0; - else - infd = open(argv[optind], O_RDONLY); - if (infd == -1) { - fprintf(stderr, "Failed to open source file: %s", - strerror(errno)); - return usage(); - } - if (fstat(infd, &st)) { - perror("stat"); - return 1; - } - data = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED, infd, 0); - if (data == MAP_FAILED) { - perror("mmap"); - return 1; - } - - if (!strcmp(argv[optind+1], "-")) - outfd = 1; - else - outfd = open(argv[optind+1], O_TRUNC|O_CREAT|O_WRONLY, 0644); - if (outfd == -1) { - fprintf(stderr, "Failed to open destination file: %s", - strerror(errno)); - return usage(); - } - if (process_ihex(data, st.st_size)) - return 1; - - return output_records(outfd); -} - -static int process_ihex(uint8_t *data, ssize_t size) -{ - struct ihex_binrec *record; - uint32_t offset = 0; - uint32_t data32; - uint8_t type, crc = 0, crcbyte = 0; - int i, j; - int line = 1; - int len; - - i = 0; -next_record: - /* search for the start of record character */ - while (i < size) { - if (data[i] == '\n') line++; - if (data[i++] == ':') break; - } - - /* Minimum record length would be about 10 characters */ - if (i + 10 > size) { - fprintf(stderr, "Can't find valid record at line %d\n", line); - return -EINVAL; - } - - len = hex(data + i, &crc); i += 2; - if (wide_records) { - len <<= 8; - len += hex(data + i, &crc); i += 2; - } - record = malloc((sizeof (*record) + len + 3) & ~3); - if (!record) { - fprintf(stderr, "out of memory for records\n"); - return -ENOMEM; - } - memset(record, 0, (sizeof(*record) + len + 3) & ~3); - record->len = len; - - /* now check if we have enough data to read everything */ - if (i + 8 + (record->len * 2) > size) { - fprintf(stderr, "Not enough data to read complete record at line %d\n", - line); - return -EINVAL; - } - - record->addr = hex(data + i, &crc) << 8; i += 2; - record->addr |= hex(data + i, &crc); i += 2; - type = hex(data + i, &crc); i += 2; - - for (j = 0; j < record->len; j++, i += 2) - record->data[j] = hex(data + i, &crc); - - /* check CRC */ - crcbyte = hex(data + i, &crc); i += 2; - if (crc != 0) { - fprintf(stderr, "CRC failure at line %d: got 0x%X, expected 0x%X\n", - line, crcbyte, (unsigned char)(crcbyte-crc)); - return -EINVAL; - } - - /* Done reading the record */ - switch (type) { - case 0: - /* old style EOF record? */ - if (!record->len) - break; - - record->addr += offset; - file_record(record); - goto next_record; - - case 1: /* End-Of-File Record */ - if (record->addr || record->len) { - fprintf(stderr, "Bad EOF record (type 01) format at line %d", - line); - return -EINVAL; - } - break; - - case 2: /* Extended Segment Address Record (HEX86) */ - case 4: /* Extended Linear Address Record (HEX386) */ - if (record->addr || record->len != 2) { - fprintf(stderr, "Bad HEX86/HEX386 record (type %02X) at line %d\n", - type, line); - return -EINVAL; - } - - /* We shouldn't really be using the offset for HEX86 because - * the wraparound case is specified quite differently. */ - offset = record->data[0] << 8 | record->data[1]; - offset <<= (type == 2 ? 4 : 16); - goto next_record; - - case 3: /* Start Segment Address Record */ - case 5: /* Start Linear Address Record */ - if (record->addr || record->len != 4) { - fprintf(stderr, "Bad Start Address record (type %02X) at line %d\n", - type, line); - return -EINVAL; - } - - memcpy(&data32, &record->data[0], sizeof(data32)); - data32 = htonl(data32); - memcpy(&record->data[0], &data32, sizeof(data32)); - - /* These records contain the CS/IP or EIP where execution - * starts. If requested output this as a record. */ - if (include_jump) - file_record(record); - goto next_record; - - default: - fprintf(stderr, "Unknown record (type %02X)\n", type); - return -EINVAL; - } - - return 0; -} - -static struct ihex_binrec *records; - -static void file_record(struct ihex_binrec *record) -{ - struct ihex_binrec **p = &records; - - while ((*p) && (!sort_records || (*p)->addr < record->addr)) - p = &((*p)->next); - - record->next = *p; - *p = record; -} - -static int output_records(int outfd) -{ - unsigned char zeroes[6] = {0, 0, 0, 0, 0, 0}; - struct ihex_binrec *p = records; - - while (p) { - uint16_t writelen = (p->len + 9) & ~3; - - p->addr = htonl(p->addr); - p->len = htons(p->len); - if (write(outfd, &p->addr, writelen) != writelen) - return 1; - p = p->next; - } - /* EOF record is zero length, since we don't bother to represent - the type field in the binary version */ - if (write(outfd, zeroes, 6) != 6) - return 1; - return 0; -} -``` \ No newline at end of file diff --git a/writeup/gdb_helper_functions.md b/writeup/gdb_helper_functions.md deleted file mode 100644 index e69de29..0000000 diff --git a/writeup/rtlsdr_usage.md b/writeup/rtlsdr_usage.md deleted file mode 100644 index c198ecf..0000000 --- a/writeup/rtlsdr_usage.md +++ /dev/null @@ -1,183 +0,0 @@ -# RTLSDR usage - -# Index - - -1. Setup rtlsdr - 1.1. Get sources - 1.2. Drivers - 1.3. Check if works -2. Collection of tools - 2.1. FM - 2.2. Spectrum diagram - 2.3. ADSB - 2.4. AFSK1200 -3. Projects where rtlsdr used - 3.1. WebSDR -4. Problems - 4.1. Sync errors -5. Links -6. Changelog - - -## 1.Setup rtlsdr - - -By rtlsdr usually call RTL2832U chip based tv-tunners which -can be used for not just recievin DVB-T frequencies but much more -and yes price is ~$10 it mean that anyone can just buy and try -without "loosing" money. - - -### 1.1.Get sources - - -Main development repository is on http://sdr.osmocom.org/trac/wiki/rtl-sdr -on github you can find more repos with experminental -features (https://github.com/keenerd/rtl-sdr). - -Getting sources from git: -``` - git clone git://git.osmocom.org/rtl-sdr.git -``` -I prefer using plain binaries without any kind of installation. Just -compile and use binary without any troubles. -Build: -```bash - cmake . - make -``` -All binaries is in src dir - - -### 1.2.Drivers - - -Linux kernel have some drivers for rtlsdr stick and DVB-T. When you will plug -rtlsdr then kernel probably will load DVB-T drivers and you will not able -to use you rtlsdr for sdr. Way yo fix is it add some drivers to black list and -next time when you will plug rtlsdr this drivers will not be loaded. - -Check if rtlsdr related drivers is loaded: -```bash - lsmod | grep rtl28 -``` -If there is some drivers then balcklist driver by creating file -in */etc/modprobe.d/* with content: -``` - blacklist dvb_usb_rtl28xxu -``` -Next thing that could appear is permissions on rtlsdr usage when its pluged in. -To allow everyone to use create file in */etc/udev/rules.d/* with content: -``` - SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", \ - GROUP="adm", MODE="0666", SYMLINK+="rtl_sdr" -``` - -### 1.3.Check if works - -How to test if rtlsdr works? Run one of commands: - rtl_test - -I like to run rtl_adsb as you can see there that something is recieved and -you see that everything "works": - rtl_adsb - -There should be line by line showing up some "hex" lines. If some data is showen -then adsb data from plains is recieved. - -## 2.Collection of tools - - -### 2.1.FM - -Get some sound trancmited from FM radio stations. - -```bash - rtl_fm -f 96.3e6 -M wbfm -s 200000 -r 48000 - | aplay -r 48k -f S16_LE -``` - - -### 2.2.Spectrum diagram - -Scan spectrum to find some activities on different frequencies. -Good link with all description is http://kmkeen.com/rtl-power/ . -Main usage of rtl_power is : -```bash - rtl_power -f 76M:108M:125k -i 1 fm_stations.csv -``` -and then draw image : -```bash - heatmap.py fm_stations.csv fm_stations.png -``` - -### 2.3.ADSB - -ADS-B ( Automatic dependent surveillance broadcast ) in simple words airplain -geoposition, speed, height and flight number broadcasting. You can recieve -this data and see how many plains is around and sometimes flight number. - -rtlsdr have default one rtl_adsb programm but it shows only recieved data, -without any decoding. Here is dump1090 specifically for rtlsdr and nothing -more: - - https://github.com/antirez/dump1090 - -description howto install could be found also here - - http://www.satsignal.eu/raspberry-pi/dump1090.html - -Using in interactive mode with height in metrs: -```bash - dump1090 --interactive --metric -``` -Output: - -``` - Hex Flight Altitude Speed Lat Lon Track Messages Seen . - ------------------------------------------------------------------------------ - 71be01 10052 1009 36.434 33.544 45 9 1 sec - 424913 SDM6329 10966 711 36.440 33.405 221 65 0 sec -``` - - -### 2.4.AFSK1200 - -Gqrx is graphical SDR software where you can travel across frequencies -and in real time search for some transmission. - - http://gqrx.dk/ - -It have builtin AFSK1200 demodulator or in simple words ham radio packets. -And you could try to see what people sending in tex around the world. - -## 3.Projects where rtlsdr used - -### 3.1.WebSDR - -WebSDR probably best site where you can go and click on some radio reciever -and liste what happends in some particular country. WebSDR site contains -about 80 radio recievers around the world that can be accessed trought web -interface. - http://websdr.org/ - -If you whant setup your own radio reciever read FAQ, prepare mail and send mail -after that you could recieve precompiled websdr software with is easy -to setup with rtlsdr stick. - -## 4.Problems - -### 4.1.Sync errors - -Once there was sync error when was trying to use rtl_test or rtl_adsb. -To fix that changes for better quality usb cable. - -# 5.Links - -1. [http://kmkeen.com/rtl-demod-guide/](http://kmkeen.com/rtl-demod-guide/) -2. http://kmkeen.com/rtl-power/ -3. http://sdr.osmocom.org/trac/wiki/rtl-sdr -4. http://www.rtl-sdr.com/ -5. https://github.com/antirez/dump1090 -6. http://gqrx.dk - -- cgit v1.2.3