Category: RTL-SDR

DSD+ Updated to Version 1.101

DSD+ (Digital Speech Decoder+) is a popular decoding tool that can be used to listen to P25, DMR and other unencrypted digital speech signals. Recently DSD+ has been updated from version 1.074 to version 1.101.

The new version brings several changes, including the ability to decode Hytera Extended Pseudo Trunk (XPT) systems, Airspy compatibility, performance improvements and a TCP/IP link from FMP to DSD+ (no longer need to use a virtual audio cable). The full change log is as follows:

DSD+: Fixed AMBE tone frame audio generation.

FMA: Added Airspy-compatible FMP (FMPA.exe)

DSD+: Significant reduction in CPU usage when monitoring busy control channels. Improvement will be most noticeable on low power processors.

DSD+: Detection and decoding of Hytera Extended Pseudo Trunk (XPT) systems.

DSD+: The DSD+ -i command line parameter can contain an IPV4 address; this lets DSD+ connect to a copy of FMP that is running on a different PC in your local network or on the Internet

Example: DSDPlus -i192.168.1.150:20001

DSD+: NEXEDGE radio alias editing

DSD+ now marks auto-generated NEXEDGE radio aliases in the DSDPlus.radios file by prepending an asterisk like so:

NEXEDGE, … yyyy/mm/dd hh:mm, *”aliastext”

If you edit a NEXEDGE alias, you must remove the asterisk; this tells DSD+ that the new alias text is NOT auto-generated and DSD+ will not replace it with OTA alias text

FMP: FMP command line processing

The FMP command line format has been modified and is now similar to the DSD+ command line. A summary is listed here:

FMP rev 1.4t

Usage:
FMP [options] Normal operation
FMP -h Show help

Options:
-i<num> RTL SDR device number (1-255) [-i1]
-o<num> Output audio device (1-255) [-o1]
-o<port> Output audio TCP port (256-65535)
-P<num> PPM value (-999.9-999.9) [-P0.0]
-g<num> RF gain (dB) [max]
-f<MHz> Initial tuned frequency [-f99.9]
-b<kHz> Initial filter bandwidth (4, 7, 9.5, 12.5) [-b7]
-z<num> Show zoomed spectrum (0-1) [-z1]
-e<num> Enable/disable economy mode (0-1) [-e1]
-n<num> Select noise filter (0-2) [-n0]
-v<num> Set volume level (0-500) [-v100]
-s<num> Enable/disable scanner mode (0-1) [-s0]
-wsl<v>.<h> Spectrum window location [-wsl50.50]
-_<num> Minimize windows at startup; bitmapped
-rv Role is trunk voice channel monitor

-rv puts FMP into voice following mode (same as pressing ‘V’ in FMP)

Any shortcuts or batch files that run FMP will have to be modified to match the new command line format.

DSD+: Less processor loading (probably only noticeable on very slow processors)

DSD+: Much faster groups/radios files loading/saving

DSD+: Editing existing radio aliases

In previous versions of DSD+, editing of pre-existing radio aliases can not be done with an external text editor while DSD+ is running; only radio records with no alias text can be edited

With DSD+ 1.092, existing radio alias text can be edited in an
external text editor while DSD+ is running; DSD+ will load and display any updated radio aliases

DSD+: A DSDPlus.radios file corruption bug has been fixed

DSD+: A command line option to add system details to event log entries has been added

-E Add NAC/RAN/DCC/RAS data to event log file entries

DSD+: Decoding of more DMR and TIII messages has been added

DSD+: A symbol recovery bug has been fixed

DSD+: Con+ handling has been modified; previous versions of DSD+ would create “DMR” entries in the DSDPlus.groups and DSDPlus.radios files for traffic on monitored voice channels; DSD+ 1.090 creates “Con+” entries; if you have “DMR” entries with nonzero NID fields, you should either bulk delete them or change their protocol string from “DMR” to “Con+”; Notepad has a simple search/replace function that can be used to do this

DSD+: A command line option to minimize windows at startup has been added

-_<num> Minimize selected windows at startup (bitmapped, 0-15) [-_0]

value window

1 console
2 source audio
4 channel activity
8 event log

sum values to minimize multiple windows

DSD+: Several high contrast display modes have been added

-H<num> High contrast mode (bitmapped, 0-63) [-H0]

two bits are used per graphical window; pressing ‘H’ in a window will cycle it to the next display mode; pressing ‘W’ displays the current -H<num> value in the event log window

DSD+: Control of AMBE and IMBE unvoiced audio levels has been added

-UA<num> AMBE unvoiced speech level (0-100) [-UA50]
-UI<num> IMBE unvoiced speech level (0-100) [-UI50]

pressing ‘A’/’a’/’I’/’i’ will also adjust the levels;
lower levels may reduce the “underwater” sound of some comms

DSD+: DSD+ can get its raw audio source from FMP via a TCP link instead of via Virtual Audio Cable or VB-Cable

-i<TCPport> FMP TCP link port number (256-65535)

linking FMP to DSD+ via VAC or VBC is deprecated; please use the TCP
link feature instead; any port number between 10000 and 65000 should be fine

DSD+: DSD+ can record separate .wav files for each voice call

-P<wav|mp3> Also create per-call wav or mp3 files

the file names encode metadata:

time
duration
protocol
NID
site number
NAC/RAN/DCC/slot
call type (group/private)
target
source

note: per-call mp3 files are not supported at this time

FMP: A command line option to minimize windows at startup has been added

-_<num> Minimize selected windows at startup (bitmapped, 0-3) [-_0]

value window

1 console
2 spectrum display

CANFI: Cheap Automatic Noise Figure Indicator Updated to V2.7

Back in July 2014 we posted about the CANFI (Cheap Automatic Noise Figure Indicator) system. The CANFI system is a set of hardware components that include an RTL-SDR and a corresponding software program for control. Back then the CANFI system only supported E4000 dongles. However, recently CANFI was updated to version 2.7 and now supports the R820T/2 tuners as well. The documentation has also been heavily improved. The authors of CANFI introduce their system as follows:

One of the main tasks for an experimenting microwave amateur is to measure the Gain (G) and Noise Figure (NF) of a particular receiving device. For this one will need a Noise Figure Indicator and a (calibrated) Noise Source.

There are a number of commercial devices available from different vendors at prices which will exceed an amateur’s budget by many times. A lot of them can be found on the surplus market but this doesn’t help very much. A combination of both meter and noise source is barely sold below the 2.000€ margin.

Since a lot of cheap DVB – T sticks became available the idea was born to use it together with a homebrew noise source as a very cheap alternative to commercial devices [1]. It is now possible to build a suitable solution within a budget of 100 – 200€. Using a PC with USB port for communication and power supply such a device is very compact and almost compatible to an industrial solution. Special software gives a convenient user interface. Last not least you can reuse the DVB-T stick (together with the preamplifier) as a sensitive receiver along with SDR software.

To create a CANFI system you will need an RTL-SDR, a MGZ 30889 preamp, a noise source, a 28V boost converter to power the noise source and a serial to USB converter to control the noise source.

The CANFI GUI
The CANFI GUI

RTLSDR-Airband V2 Released

Back in June of 2014 we posted about the released of a new program called RTLSDR-Airband. RTLSDR-Airband is a Windows and Linux compatible command line tool that allows you to simultaneously monitor multiple AM channels per dongle within the same chunk of bandwidth. It is great for monitoring aircraft voice communications and can be used to feed websites like liveatc.net.

Since our post the development of the software has been taken over by a new developer szpajder, who wrote in to us to let us know that he has now updated RTLSDR-Airband to version 2.0.0. The new versions improves performance and support for small embedded platforms such as the Raspberry Pi 2, but the Windows port is now not actively maintained and probably does not work. The full list of changes is shown below:

  •  New libconfig-style config file format
  • util/convert_cfg: can be used to convert old-style config.txt to the new format
  • Syslog logging (enabled by default)
  • Daemon mode
  • Reworked makefiles, added install rule
  • /dev/vcio is now used to access GPU on Raspberry Pi; creating char_dev no longer necessary
  • Startup scripts for Debian and Gentoo
  • Support for auto gain setting
  • Support for multiple outputs per channel
  • Support for recording streams to local MP3 files
  • Support for ARMv7-based platforms other than RPi (eg. Cubieboard)
  • Updated documentation
  • Numerous bugfixes and stability improvements

Compilation and install instructions can be found on the projects main GitHub page.

RTLSDR-Airband
RTLSDR-Airband

Deocoding Orbcomm with MultiPSK 4.31 and an RTL-SDR

MultiPSK is a signals decoding program with many available decoders to choose from. It is also able to directly connect to the RTL-SDR, or be used via a virtual audio cable. The latest beta version (available on the MultiPSK Yahoo mailing list) now allows for decoding of Orbcomm satellites which transmit at around 137 MHz. While it is not possible to decode the encrypted messages, it is still possible to decode pieces of telemetry data from the satellites. MultiPSK writes the following information about Orbcomm:

This system has been developed by the ORBCOMM society which disposes of a constellation of about 28 active LEO (“Low Earth Orbit”) satellites, transmitting between 137.2 and 137.8 MHz (+/- 2.5 KHz maximum of Doppler shift).

This system permits:

  • to handle messages (encrypted) from ground users
    (ships, trucks, oil wells…) until other ground users, through the ORBCOMM satellites, the cover being worldwide. These frames are decoded by Multipsk but not deciphered.
  • to broadcast identification, frequencies, position and orbital elements pieces of information, not encrypted. These frames are decoded and interpreted by Multipsk.

This mode is available for licencied copies, only (otherwise, the decoding is stopped after 5 minutes).

One user of MultiPSK has uploaded a video showing the Orbcomm decoding in action.

Multipsk 4.31 decoding Orbcomm

Signal Direction Finding with an RTL-SDR, Raspberry Pi and REDHAWK

Something we missed posting about from last year was this presentation on “RasHAWK”, a direction finding system (pdf) built out of a Raspberry Pi, an RTL-SDR and four antennas on a 4 way switch running software created with REDHAWK. REDHAWK is a visual DSP development platform that can be considered similar to GNU Radio or some parts of MATLAB. The authors write:

The RasHAWK team has used a Raspberry Pi as the basis for a networked RF sensor capable of supporting spectrum monitoring, signal intercept and direction finding (DF) operations.

Several RasHAWK sensors are deployed in a distributed sensor grid, wirelessly tethered to a command and control (C2) laptop. The system has the following key features and capabilities:

  • A simple operator interface to configure the sensors
  • Falling raster and PSD displays to monitor the spectrum for signal activity
  • Demodulate FM signals from target FRS radios and play audio on selected channels
  • Perform coarse DF on target emitters
  • Display a map of the surrounding terrain that is annotated with the positions of the sensors, the target emitter and calculated lines of bearing (LOB) to the target. The map provides a RF Common Operating Picture (COP) with can be viewed on WiFi enabled tablets or smartphones.

Each RawHAWK sensor can determine the bearing of transmitted signal. By combining several networked RasHAWK sensors at different locations they are able to pinpoint the actual location of the transmitter on a map.

The RasHAWK system.
The RasHAWK system.
Lines of bearings combined from three different RawHAWK sensors.
Lines of bearings combined from three different RawHAWK sensors.

DEFCON 23 – LTE Recon and Tracking with RTLSDR

Back on Dec 5 we posted about some Defcon 23 talks that were released from the Wireless Village set of talks. Recently some more talks from other tracks have been released and one of interest to our blog is the talk by Ian Kline titled “LTE Recon and Tracking with RTLSDR”. The talk’s blurb reads:

Since RTLSDR became a consumer grade RX device, numerous talks and open source tools enabled the community to monitor airplanes, ships, and cars… but come on, what we really want to track are cell phones. If you know how to run cmake and have $50 to pick up an RTLSDR-E4000, I’ll make sure you walk out of here with the power to monitor LTE devices around you on a slick Kibana4 dashboard. You’ll also get a primer on geolocating the devices if you’ve got a second E4000 and some basic soldering skills.

DEF CON 23 - Ian Kline - LTE Recon and Tracking with RTLSDR

Receiving and acquiring GPS positions with an RTL-SDR dongle and GPS antenna

GPS experimenter and blog author e.p. has recently been posting about his experiments in which he uses an RTL-SDR dongle to receive GPS satellite signals and acquire a position lock. 

To receive GPS e.p. uses one of our RTL-SDR blog units (back in stock soon!) with the bias tee enabled which is used to power a cheap 5V active GPS antenna. For software he uses GNSS-SDRLIB and RTKLIB which runs on Windows. Using the RTL-SDR, GPS antenna and the decoding software he was able to get his current position to within about 5 meters of accuracy.

In his blog post e.p. shows a step by step guide on how to install and use the Windows software. In later posts he also shows how to install and use another program called GNSS-SDR which runs in Linux and can also be used to acquire GPS fixes with an RTL-SDR dongle.

The GNSS-SDRLIB GUI setup screen.
The GNSS-SDRLIB GUI setup screen.

To illustrate the software in action e.p. has also uploaded a video to YouTube which is shown below.

SvxLink Now Supports the RTL-SDR

SvxLink is an EchoLink and general purpose voice services system for controlling ham radio repeaters. A repeater is a radio tower that receives a weak transmission from a handheld or remote radio and then repeats the same message with greater power over a wide area. With repeaters radio communications can cover a much further distance.

Ham radio enthusiasts often set up repeaters for their own frequencies, so that they can be heard over a wider range. To control the repeater software like SvxLink is required. In the latest software update of SvxLink they added RTL-SDR support. They write:

The biggest news in this release is the support for RTL2832U based DVB-T USB dongles. This make it possible to use such USB dongles as cheap SDR (Software Defined Radio) receivers. This will open up the world of cheap receiver hardware to all SvxLink users. It will for example be very cheap to set up an extra receiver with local coverage for a SvxLink based repeater, as long as there is a network connection to the repeater. The modulation forms supported are: FM, FM narrow, AM, AM narrow, USB, LSB, CW, CW wide and wideband FM (broadcast). Running multiple receivers on the same dongle is supported as well as using multiple dongles.

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