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VDL Mode 2 message decoder and protocol analyzer
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README.md

dumpvdl2

dumpvdl2 is a VDL Mode 2 message decoder and protocol analyzer.

Current stable version: 1.6.0 (released Jan 19, 2019)

Features

  • Runs under Linux (tested on: x86, x86-64, ARM) and MacOS (not tested very well, feedback welcome)
  • Supports following SDR hardware:
  • Decodes up to 8 VDL2 channels simultaneously
  • Outputs messages to standard output or to a file (with optional daily or hourly file rotation)
  • Outputs ACARS messages to PlanePlotter over UDP/IP socket
  • Supports message filtering by type or direction (uplink, downlink)
  • Outputs decoding statistics using Etsy StatsD protocol

Example

dumpvdl2 screenshot

Protocol support status

  • AVLC - supported
  • ACARS over AVLC - supported
  • ISO 8208 (X.25) control packets - supported
  • ISO 8473 (CLNP) - partially supported (CLNP header is skipped over without decoding)
  • ISO 9542 (ES-IS) - supported
  • ISO 10747 (IDRP) - partially supported (decoding of a few unimportant attributes is TODO)
  • ISO 8073 (COTP) - supported
  • ICAO ATN-B1 CM (Context Management) - supported
  • ICAO ATN-B1 CPDLC (Controller-Pilot Data Link Communications) - supported
  • ICAO ATN-B1 ADS-C (Automatic Dependent Surveillance - Contract) - not supported
  • All applications and protocols handled by libacars library (full list here)

Installation

Dependencies

Mandatory dependencies:

  • gcc
  • make
  • cmake
  • pkg-config
  • git (unless you intend to use only packaged releases of dumpvdl2 and all dependencies)
  • glib2
  • libacars

Optional dependencies:

  • librtlsdr
  • libmirisdr-4
  • SDRPlay binary driver
  • SoapySDR
  • statsd-c-client

Install necessary dependencies (unless you have them already). Example for Debian / Raspbian:

sudo apt-get install build-essential cmake git libglib2.0-dev pkg-config

Install libacars library - either:

  • download a stable release package from here
  • or clone the source repository with:
cd
git clone https://github.com/szpajder/libacars
cd libacars

Compile and install the library:

mkdir build
cd build
cmake ../
make
sudo make install
sudo ldconfig

RTLSDR support (optional)

Install librtlsdr library (unless you have it already). Raspbian has a packaged version:

apt-get install librtlsdr-dev

If your distribution does not provide a package, then clone the source repository and compile manually:

apt-get install libtool autoconf libusb-1.0-0-dev
cd
git clone git://git.osmocom.org/rtl-sdr.git
cd rtl-sdr/
autoreconf -i
./configure
make
sudo make install
sudo ldconfig
sudo cp $HOME/rtl-sdr/rtl-sdr.rules /etc/udev/rules.d/rtl-sdr.rules

Mirics support (optional)

libmirisdr-4 is an open-source alternative to SDRPlay binary driver (Mirics is the chipset brand which SDRPlay RSPs are based on). However, as of December 2017, it works properly with RSP1 only. For other RSP types (RSP2, RSP/1A) gain control does not work too well, so the native closed source driver is a better option (see next section). libmirisdr-4 is a good choice for RSP1 and various Mirics-based DVB-T dongles which are detected as RSP1 device. An advantage over RSP binary API is lower CPU utilization in dumpvdl2 thanks to a lower sampling rate.

Install libmirisdr-4 library:

apt-get install libusb-1.0-0-dev
cd
git clone https://github.com/f4exb/libmirisdr-4.git
cd libmirisdr-4
./build.sh
cd build
sudo make install
sudo ldconfig
sudo cp $HOME/libmirisdr-4/mirisdr.rules /etc/udev/rules.d/mirisdr.rules

SDRPLAY RSP support (optional)

Download and install API/hardware driver package from http://www.sdrplay.com/downloads/. Make sure you have selected the right hardware platform before downloading, otherwise the installer will fail.

SoapySDR support (optional)

Download and install the SoapySDR library from https://github.com/pothosware/SoapySDR. Then install the driver module for your device. Refer to SoapySDR wiki for a list of all supported modules.

Note: The device must support a sampling rate of 2100000 samples per second to work correctly with dumpvdl2. It is therefore not possible to use devices which only support predefined, fixed sampling rates (notably Airspies). This limitation will be removed in a future release of dumpvdl2.

Etsy StatsD statistics (optional)

Install statsd-c-client library from https://github.com/romanbsd/statsd-c-client:

cd
git clone https://github.com/romanbsd/statsd-c-client.git
cd statsd-c-client
make
sudo make install
sudo ldconfig

Compiling dumpvdl2

  • Download a stable release package from here
  • or clone the repository:
cd
git clone https://github.com/szpajder/dumpvdl2.git
cd dumpvdl2

Configure the build:

mkdir build
cd build
cmake ../

cmake attempts to find all required libraries and SDR drivers. If a mandatory dependency is not installed, it will throw out an error. Missing optional dependencies will cause the relevant feature to be disabled. At the end of the process cmake displays a short configuration summary, like this:

-- dumpvdl2 configuration summary:
-- - SDR drivers:
--   - librtsdr:        requested: ON   enabled: TRUE
--   - mirisdr:         requested: ON   enabled: TRUE
--   - sdrplay:         requested: ON   enabled: FALSE
--   - soapysdr:        requested: ON   enabled: TRUE
-- - Other options:
--   - Etsy StatsD:     requested: ON   enabled: FALSE
-- Configuring done

Here you can verify whether all the SDR drivers which you need were properly detected and enabled. Then compile and install the program:

make
sudo make install

The last command installs the binary named dumpvdl2 to the default bin directory (on Linux it's /usr/local/bin). To display a list of available command line options, run:

/usr/local/bin/dumpvdl2 --help

or just dumpvdl2 --help if /usr/local/bin is in your PATH.

Build options

Build options can be configured with -D option to cmake, for example:

cmake -DRTLSDR=FALSE ../

causes RTLSDR support in dumpvdl2 to be disabled. It will not be compiled in, even if librtlsdr library is installed.

Disabling optional features:

  • -DRTLSDR=FALSE
  • -DMIRISDR=FALSE
  • -DSDRPLAY=FALSE
  • -DSOAPYSDR=FALSE
  • -DETSY_STATSD=FALSE

Setting build type:

  • -DCMAKE_BUILD_TYPE=Debug - enables a lot of debugging output (useful for troubleshooting, not recommended for general use)
  • -DCMAKE_BUILD_TYPE=Release - debugging output disabled (the default)

Note: Always recompile the program with make command after changing build options.

Note: cmake stores build option values in its cache. Subsequent runs of cmake will cause values set during previous runs to be preserved, unless they are explicitly overriden with -D option. So if you disable a feature with, eg. -DRTLSDR=FALSE and you want to re-enable it later, you have to explicitly use -DRTLSDR=TRUE option. Just omitting -DRTLSDR=FALSE will not revert the option value to the default.

Basic usage

RTL-SDR

Simplest case on RTLSDR dongle - uses RTL device with index 0, sets the tuner gain to 40 dB and tuning correction to 42 ppm, listens to the default VDL2 frequency of 136.975 MHz, outputs to standard output:

./dumpvdl2 --rtlsdr 0 --gain 40 --correction 42

Device ID numbers are not persistent - they depend on the USB device order and the sequence which they were plugged in. You may specify the device by its serial number to get deterministic behavior:

./dumpvdl2 --rtlsdr 771111153 --gain 40 --correction 42

Use rtl_test utility to get serial numbers of your devices. dumpvdl2 will print them to the screen on startup as well.

If you want to decode a different VDL2 channel than the default, just add its frequency as a last parameter:

./dumpvdl2 --rtlsdr 0 --gain 40 --correction 42 136725000

dumpvdl2 can decode up to 8 VDL2 channels simultaneously. Just list their frequencies at the end of the command line:

./dumpvdl2 --rtlsdr 0 --gain 40 --correction 42 136725000 136975000 136875000

If your receiver has a large center spike, you can set the center frequency a bit to the side of the desired channel frequency, like this:

./dumpvdl2 --rtlsdr 0 --gain 40 --correction 42 --centerfreq 137100000 <channel freqs here...>

Mirics

Mirics is similar, however libmirisdr-4 library currently lacks support for configuring correction in ppm. If your receiver needs a non-zero correction, you can pass the appropriate value in Hertz, instead of ppm. Note: this value will be subtracted from the center frequency, so if your receiver tunes a bit too low, the parameter value shall be negative:

./dumpvdl2 --mirisdr 0 --gain 100 --correction -2500

Device serial number can be given instead of ID, the same way, as for RTLSDR receivers.

libmirisdr-4 supports two types of hardware: generic Mirics (0 - the default) and SDRPlay (1). SDRPlay users should add --hw-type 1 option. It uses frequency plans optimized for SDRPlay and reportedly gives better results than the default mode.

If you get error messages about lost samples on Raspberry Pi, try adding --usb-mode 1. This switches USB transfer mode from isochronous to bulk, which is usually enough to rectify this problem. If it does not help, it might be that your Pi is overloaded or not powerful enough for the task. Try reducing the number of decoded VDL2 channels as a workaround.

SDRPLAY RSP native driver

SDRPlay RSP native driver supports several advanced configuration options:

  • switching antenna ports (RSP2)
  • bias-T (RSP2, RSP1A)
  • notch filter for AM/FM broadcast bands (RSP2, RSP1A, RSPduo)
  • tuner selection (RSPduo)
  • Automatic Gain Control

Type ./dumpvdl2 --help to find out all the options and their default values.

SDRPlay driver has a concept of "gain reduction", which is an amount of gain (in decibels) which shall be deducted from the maximum gain. As a result, --gain option is not available with this driver - use --gr option to specify requested end-to-end gain reduction instead. The smallest possible value is 20. The highest value depends on receiver type, but it's not that important, because in dumpvdl2 you will hardly be using a GR larger than 59 dB.

Another way to go is to skip the --gr option altogether. This will enable Automatic Gain Control with a default set point of -35 dBFS, which shall converge to a reasonable gain reduction value in a couple of seconds after the program starts. AGC set point can be changed with --agc option, but treat this as an "expert mode" knob, which is hardly ever needed.

Example 1: use SDRplay device ID=0, with auto gain and three VDL2 channels:

./dumpvdl2 --sdrplay 0 136975000 136875000 136775000

Example 2: use SDRplay device with serial number 35830222, set gain reduction to 40 dB, use antenna A port, disable Bias-T, enable AM/FM notch filter, set frequency correction to -1ppm:

./dumpvdl2 --sdrplay 35830222 --gr 40 --correction -1 --antenna A --biast 0 --notch-filter 1 136975000

SoapySDR library

Note: The device must support a sampling rate of 2100000 samples per second.

Tested with the following devices:

  • SDRPLAY RSP2
  • RTLSDR

Using SoapySDRServer it is possible to access a SDR device connected to another machine.

Features supported by dumpvdl2:

  • switching antenna ports
  • setting device-specific configuration parameters
  • setting the gain globally or using individual gain components
  • automatic gain control

Type ./dumpvdl2 --help to find out all the options and their default values.

Type SoapySDRUtil --find to find available devices.

Example 1: use SDRPLAY device with Antenna B, AGC and biasT activated:

./dumpvdl2 --soapysdr soapy=0,driver=sdrplay --soapy-antenna "Antenna B" --device-settings biasT_ctrl=true 136975000 136875000 136775000

Example 2: use RTLSDR device with AGC

./dumpvdl2 --soapysdr soapy=0,driver=rtlsdr 136975000 136875000 136775000

Example 3: use SDRPLAY device with separate gain reduction for RFGR for LNA and normal gain reduction IFGR

./dumpvdl2 --soapysdr soapy=0,driver=sdrplay --gain -1 --soapy-gain RFGR=0,IFGR=56 136975000 136875000 136775000

Example 4: Use a remote SDRPLAY with antenna B, Soapy server started with command line

SoapySDRServer --bind

Then you may run dumpvdl2 on any remote machine with :

./dumpvdl2 --soapysdr driver=remote,remote=tcp://<ip address>:55132,remote:driver=sdrplay,remote:format=CS16 \
--gain -100 --soapy-antenna "Antenna B" 136975000 136875000 136775000

Output options

  • Decoded messages are printed to standard output by default. You can direct them to a disk file instead:
./dumpvdl2 --output-file vdl2.log [other_options]
  • If you want the file to be automatically rotated on top of every hour, add --hourly option. The file name will be appended with _YYYYMMDDHH suffix. If file extension is present, it will be placed after the suffix.

  • If you prefer daily rotation, --daily option does just that. The file name suffix will be _YYYYMMDD in this case. If file extension is present, it will be placed after the suffix.

  • Add --utc option if you prefer UTC timestamps rather than local timezone in output and filenames.

  • Add --raw-frames option to display payload of AVLC frames in raw hex for debugging purposes.

  • Add --dump-asn1 option to display full ASN.1 structure dumps of CPDLC and CM messages.

Integration with Planeplotter

dumpvdl2 can send ACARS messages to Planeplotter, which in turn can extract aircraft position information from them and display blips on the map. First, configure your Planeplotter as follows:

  • Stop data processing (press 'Stop' button on the toolbar)

  • Go to Options / I/O Settings...

  • Tick 'UDP/IP Data from net'

  • Set 'UDP/IP local port' to some value (default is 9742)

  • Close the settings window by clicking OK and restart data processing

Supply dumpvdl2 with the address (or host name) and port where the Planeplotter is listening:

./dumpvdl2 --output-acars-pp 10.10.10.12:9742 [other_options]

That's all. Switch to 'Message view' in Planeplotter and look for incoming messages.

Message filtering

By default dumpvdl2 logs all decoded messages. You can use --msg-filter option to ignore things you don't want to see. If you do not want messages sent by ground stations, run the program like this:

./dumpvdl2 --msg-filter all,-uplink [other_options]

Or if you want to filter out empty ACARS messages, because they are boring, use this:

./dumpvdl2 --msg-filter all,-acars_nodata [other_options]

For full list of supported filtering options, run:

./dumpvdl2 --msg-filter help

Refer to doc/FILTERING_EXAMPLES.md file for more examples and details.

Statistics

The program does not calculate statistics by itself. Instead, it sends metric values (mostly counters) to the external collector using Etsy StatsD protocol. It's the collector's job to receive, aggregate, store and graph them. Some examples of software which can be used for this purpose:

  • Collectd is a statistics collection daemon which supports a lot of metric sources by using various plugins. It has a StatsD plugin which can receive statistics emitted by dumpvdl2, aggregate them and write to various time-series databases like RRD, Graphite, MongoDB or TSDB.

  • Graphite is a time-series database with powerful analytics and aggregation functions. Its graphing engine is quite basic, though.

  • Grafana is a sophisticated and elegant graphing solution supporting a variety of data sources.

Here is an example of some dumpvdl2 metrics being graphed by Grafana:

Statistics

Metrics are quite handy when tuning the antenna installation or receiver parameters (like gain or correction). Full list of currently supported counters can be found in statsd.c source file. dumpvdl2 produces a separate set of counters for each configured VDL2 channel.

To enable statistics just give dumpvdl2 your StatsD collector's hostname (or IP address) and UDP port number, for example:

./dumpvdl2 --statsd 10.10.10.15:1234 [other_options]

Processing recorded IQ data from file

The syntax is:

dumpvdl2 --iq-file <file_name> [--sample-format <sample_format>] [--oversample <oversample_rate>]
  [--centerfreq <center_frequency>] [vdl_freq_1] [vdl_freq_2] [...]

The symbol rate for VDL2 is 10500 symbols/sec. dumpvdl2 internal processing rate is 10 samples per symbol. Therefore the file must be recorded with sampling rate set to an integer multiple of 105000. Specify the multiplier value with --oversample option. The default value is 10, which is valid for files sampled as 1050000 samples/sec. For example, if you have recorded your file at 2100000 samples/sec, then use --oversample 20 (because 105000 * 20 = 2100000).

The program accepts raw data files without any header. Files produced by rtl_sdr and miri_sdr programs are perfectly valid input files. Different radios produce samples in different formats, though. dumpvdl2 currently supports following sample formats:

  • U8 - unsigned 8-bit samples. This is the format produced by rtl_sdr utility.
  • S16_LE - 16-bit signed, little endian. Produced by miri_sdr utility (by default).

Use --sample-format option to set the format. The default format is U8.

The program assumes that the VDL2 channel is located at baseband (0 Hz), ie. the center frequency of your radio was set to the VDL2 channel frequency during recording. If this is not the case, you have to provide correct center frequency and channel frequency. For example, if your receiver was tuned to 136.955 MHz during recording and you want to decode the VDL2 channel located at 136.975 MHz, then use this:

dumpvdl2 --iq-file <file_name> --centerfreq 136955000 136975000

Putting it all together:

dumpvdl2 --iq-file iq.dat --sample-format S16_LE --oversample 13 --centerfreq 136955000 136975000 136725000

processes iq.dat file recorded at 1365000 samples/sec using 16-bit signed samples, with receiver center frequency set to 136.955 MHz. VDL2 channels located at 136.975 and 136.725 MHz will be decoded.

Launching dumpvdl2 in background on system boot

There is an example systemd unit file in etc subdirectory (which means you need a systemd-based distribution, like Debian/Raspbian Jessie or newer).

First, go to dumpvdl2 source directory and install the binary to /usr/local/bin:

sudo make install

Copy the unit file to the systemd unit directory:

sudo cp etc/dumpvdl2.service /etc/systemd/system/

Copy the example environment file to /etc/default directory:

sudo cp etc/dumpvdl2 /etc/default/

Edit /etc/default/dumpvdl2 with a text editor (eg. nano). Uncomment the DUMPVDL2_OPTIONS= line and put your preferred dumpvdl2 option set there. Example:

DUMPVDL2_OPTIONS="--rtlsdr 0 --gain 39 --correction 0 --output-file /home/pi/vdl2.log --daily 136975000 136875000 136775000"

Reload systemd configuration:

sudo systemctl daemon-reload

Start the service:

sudo systemctl start dumpvdl2

Verify if it's running:

systemctl status dumpvdl2

It should show: Active: active (running) since <date>. If it failed, it might be due to an error in the DUMPVDL2_OPTIONS value. Read the log messages in the status output and fix the problem.

If everything works fine, enable the service, so that systemd starts it automatically at boot:

systemctl enable dumpvdl2

Frequently Asked Questions

What is VDL Mode 2?

VDL (VHF Data Link) Mode 2 is a communication protocol between aircraft and a network of ground stations. It has a higher capacity than ACARS and a lot more applications. More information can be found on Wikipedia or SigIdWiki.

Who uses it?

Civil airlines - not all, but many. Military? Umm, no.

What frequencies it runs on?

The most ubiquitous is 136.975 MHz (so called Common Signalling Channel). In some areas where the capacity of a single channel is not enough, 136.725, 136.775 or 136.875 is used as well. Because they are closely spaced, dumpvdl2 can receive all of them simultaneously with a single receiver.

Is it used in my area?

It's quite probable. Launch your favorite SDR Console (like SDRSharp or GQRX), tune 136.975 MHz and place your antenna outside (or near the window, at least). If you see short bursts every now and then, it's there.

What antenna shall I use?

VDL2 runs on VHF airband, so if you already have a dedicated antenna for ACARS or airband voice, it will be perfect for VDL2. However VDL2 transmissions are not very powerful, so do not expect thousands of messages per hour, if your antenna is located indoors. If you have already played with ADS-B, you know, what to do - put the antenna outside and high with unobstructed sky view, use short and good quality feeder cable, shield your radio from external RF interference.

Two hours straight and zero messages received. What's wrong?

It basically comes down to three things:

The signal has to be strong enough (preferably 15 dB over noise floor, or better)

  • set your tuner gain quite high. I get good results with 40 dB for RTLSDR and 75 dB for Mirics dongles. Do not be tempted to crank the gain up to the max. Keep your noise floor low because higher noise yields higher bit error rate and may cause signal clipping when the transmission is strong (eg. the transmitting aircraft is just overflying your antenna). On SDRPlay it should be good enough to use auto gain control.

  • check SDR Console with the same gain setting - do you see data bursts clearly? (they are very short, like pops).

  • if your DC spike is very high, set the center frequency manually to dodge it (use --centerfreq option).

  • RTL dongles are cheap - some of them have higher noise figure than others. If you have several dongles at hand, just try another one.

Channel frequency must be correct

  • initially, just don't set it manually, use the default of 136.975 MHz. It is used everywhere where VDL2 is available.

PPM correction setting must be (more or less) accurate

  • oscillators in cheap receivers are not 100% accurate. It is usually necessary to introduce manual correction to get precise tuning. There is no one-size-fits-all correction value - it is receiver-specific. See next question.

How do I estimate PPM correction value for my dongle?

Method 1: use rtl_test utility which comes with librtlsdr library. Run it with -p option and observe the output:

root@linux:~ # rtl_test -p
Found 1 device(s):
  0:  Realtek, RTL2838UHIDIR, SN: 00000002

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
[R82XX] PLL not locked!
Sampling at 2048000 S/s.
Reporting PPM error measurement every 10 seconds...
Press ^C after a few minutes.
Reading samples in async mode...
real sample rate: 2048207 current PPM: 101 cumulative PPM: 101
real sample rate: 2048159 current PPM: 78 cumulative PPM: 89
real sample rate: 2048137 current PPM: 67 cumulative PPM: 81
real sample rate: 2048184 current PPM: 90 cumulative PPM: 84
real sample rate: 2048163 current PPM: 80 cumulative PPM: 83
real sample rate: 2048165 current PPM: 81 cumulative PPM: 82
real sample rate: 2048140 current PPM: 69 cumulative PPM: 81
real sample rate: 2048178 current PPM: 87 cumulative PPM: 81
real sample rate: 2048168 current PPM: 82 cumulative PPM: 81
real sample rate: 2048117 current PPM: 57 cumulative PPM: 79
real sample rate: 2048202 current PPM: 99 cumulative PPM: 81
real sample rate: 2048173 current PPM: 85 cumulative PPM: 81
real sample rate: 2048164 current PPM: 80 cumulative PPM: 81
real sample rate: 2048135 current PPM: 66 cumulative PPM: 80
real sample rate: 2048179 current PPM: 88 cumulative PPM: 80
real sample rate: 2048170 current PPM: 83 cumulative PPM: 81
real sample rate: 2048167 current PPM: 82 cumulative PPM: 81
real sample rate: 2048155 current PPM: 76 cumulative PPM: 80
real sample rate: 2048160 current PPM: 78 cumulative PPM: 80
real sample rate: 2048159 current PPM: 78 cumulative PPM: 80
real sample rate: 2048154 current PPM: 75 cumulative PPM: 80
real sample rate: 2048155 current PPM: 76 cumulative PPM: 80
real sample rate: 2048181 current PPM: 89 cumulative PPM: 80

After a couple of minutes the cumulative PPM value converges to a stable reading. This is an approximate correction value for your dongle. Run dumpvdl2 with --correction <value> option. dumpvdl2 can compensate correction errors up to a certain amount. Once you have received some messages, look for the frequency offset field which is printed in the header of each message (it's the value expressed in ppm). Your tuning is good, when this value is close to 0. If you see a systematic offset from 0, tweak your correction value to compensate it.

What do these numbers in the message header mean?

[2017-02-26 19:18:00 GMT] [136.975] [-18.9/-43.9 dBFS] [25.0 dB] [0.4 ppm]

From left to right:

  • date and time with timezone.

  • channel frequency on which the message has been received.

  • signal power level (averaged over all symbol sampling points in the burst). Full scale is 0 dB.

  • noise floor power level. Full scale is 0 dB.

  • signal to noise ratio (ie. signal power level minus noise floor power level).

  • frequency offset of the received burst from the channel center frequency, in parts per million.

There is an --extended-header command line option which enables additional fields:

[2017-02-26 19:18:00 GMT] [136.975] [-18.9/-43.9 dBFS] [25.0 dB] [0.4 ppm] [S:0] [L:34] [F:0] [#0]
  • number of bit errors corrected in the VDL2 burst header (up to 2).

  • burst length in octets.

  • number of octets corrected by Reed-Solomon FEC.

  • number of frame in this particular transmission. Multiple AVLC frames (messages) may be concatenated and sent as a single transmission burst. When a multiframe burst is received, frames will be numbered incrementally.

Can you add support for [my favourite SDR receiver type]?

Maybe. However do not expect me to purchase all SDRs available on the market just to make dumpvdl2 work with them. If your life absolutely depends on it, consider donating, or at least lending me the hardware for some time for development and testing.

Alternatively, if you can write code, you may do the work by yourself and submit it as a pull request. Most of the program code is hardware-agnostic anyway. Adding new device type basically comes down to the following:

  • dumpvdl2.c, dumpvdl2.h - add new input type and necessary command line options.

  • rtl.c, rtl.h - this is the code specific to the RTLSDR hardware. Make a copy and modify it to use the API of your SDR device. Or you can start off from mirics.c and mirics.h, if you prefer.

  • demod.c - if your SDR device uses a sample format other than 8-bit unsigned and 16-bit signed, it is necessary to write a routine which handles this format and converts the samples to signed float in the <-1;1> range. Refer to process_buf_uchar() and process_buf_short() routines for details.

  • Makefile - add new WITH_DEVICE compile time option and your new source files, add necessary LDLIBS, etc.

Can you add support for Windows?

To be honest, I don't use Windows very often and I don't know the programming intricacies of this OS. However, if you feel like you could port the code and maintain the port later on, please do so. Pull requests welcome.

Credits and thanks

I hereby express my gratitude to everybody who helped with the development and testing of dumpvdl2. Special thanks go to:

  • Fabrice Crohas
  • Dick van Noort
  • acarslogger
  • Piotr Herko, SP5XSB
  • LamaBleu

License

Copyright (c) 2017-2019 Tomasz Lemiech szpajder@gmail.com

Contains code from the following software projects:

  • libfec, (c) 2006 by Phil Karn, KA9Q

  • Rocksoft^tm Model CRC Algorithm Table Generation Program V1.0 by Ross Williams

  • DarwinPthreadBarrier, (c) 2015, Aleksey Demakov

  • librtlsdr-keenerd, (c) 2013-2014 by Kyle Keen

  • asn1c, (c) 2003-2017 by Lev Walkin and contributors

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

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