Analyzing GSM with Airprobe/GR-GSM and Wireshark

The RTL-SDR software defined radio can be used to analyze cellular phone GSM signals, using Linux based tools GR-GSM (or Airprobe) and Wireshark.

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Cheap AIS Ship Tracking

Large ships and passenger boats are required to broadcast an identification signal containing position, course, speed, destination, and vessel dimension information to help prevent sea collisions. This system is known as the “Automatic Identification System” or AIS for short. AIS can be decoded with an RTL-SDR dongle and right software.

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Decoding DRM Radio

Digital Radio Monodial (DRM) radio is a type of digital shortwave radio signal that is used by international shortwave radio broadcasters. It provides superior audio quality compared to AM signals by using digital audio encoding. With an upconverter, good antenna, and decoding software the RTL-SDR software defined radio can receive and decode DRM signals.

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POCSAG Pager Decoding

Decode POCSAG pager messages with an RTL-SDR. Even in the modern day pagers are still popular with doctors, some fire and ambulance agencies and various service companies, as they tend to be more reliable and have greater coverage.

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Receiving ACARS Airplane Data

ACARS is an acronym for Aircraft Communications Addressing and Reporting System and is a digital communications system that aircraft use to send and receive short messages to and from ground stations. With an RTL-SDR these messages can be decoded.

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List of SDRSharp Plugins

There are a number of SDRSharp plugins that extend its functionality. Here is a collection of all the plugins and download links that we know of.

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Decoding Digital Voice (P25, DMR, NXDN, D-STAR) with DSD+

Learn how to decode digital voice communications like APCO P25, DMR MotoTRBO, NXDN and D-STAR with DSD+ and an RTL-SDR dongle.

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RTL-SDR Direct Sampling Mode

The RTL-SDR software defined radio can be told to run in a mode called “direct sampling mode”, which with a small hardware mod allows the dongle to tune to the HF frequencies where ham radio and many other interesting signals are found. This means that no upconverter circuit is required.

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Receiving NOAA Weather Satellite Images

Everyday multiple NOAA weather satellites pass above you. Each NOAA weather satellite broadcasts an Automatic Picture Transmission (APT) signal, which contains a live weather image of your area. The RTL-SDR dongle combined with a good antenna, SDRSharp and a decoding program can be used to download and display these live images several times a day.

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Following Trunked Radio with Unitrunker

Follow trunked radio conversations with your RTL-SDR and a program called Unitrunker. Also decode digital communications like P25 and DMR using the Digital Speech Decoder (DSD+) software.

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Direct Sampling Front End Board

Over on this Japanese language blog, ttrftech has been experimenting on a type of direct sampling front end board (Use Google Translate) for a direct sampled RTL-SDR dongle. More info about his direct sampling front end can be found on this post. Translated, it appears his board has the following feautres.

  • Filter x2 up to fifth order
  • RF switch
  • Amplifier
  • Power regulator
  • Input transformer (optional)
  • The RJ-45 (optional) or the SMA input connector
  • Power supply to the antenna
  • Output to U-FL or SMA (ipex) connector

The results seem to show his board does improve reception. Note that the RJ-45 appears to be the antenna. There also appears to be review of the board by “pup” here and a video showing the board filtering out a broadcast FM image in the video below. On Pups blog there are also more posts about the board under this tag.

Direct Sampling Front End
Direct Sampling Front End

One comment

  1. TT

    Thank you for introducing my frontend board here and apologize for inconvenience that this blog was written only in Japanese.
    As another solution for receiving HF with RTL dongle, I have developped a budget frequency converter board and have distributed a few hundreds of the parts kit in Japan. Please refer the following link with google translate.
    http://ttrftech.tumblr.com/kit/hfconv
    Thank you.

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