New RTL-SDR Tuner Chip R828D

A new tuner known as the Rafeal R828D has become officially supported by the main software branch of RTL-SDR. Comments on the initial testing from this thread on the Reddit RTL-SDR forum show that there is no real improvement over the cheaper R820T tuner, and that a hardware mod is required to get acceptable results from the tuner.

On the Reddit thread user metropolis_pt2, the developer of the driver for this tuner writes

Internally it seems to be almost identical with the R820T, the only real difference is that it has 3 inputs instead of only one (Air-In, Cable1, Cable2), of which two are connected on the Astrometa DVB-T2 stick. Air-In is connected to an external (probably LC-)highpass which seems to have a cutoff-frequency around 320 MHz, and Cable1 to a low-pass with a similar cutoff-frequency. The driver I’ve added will switch automatically to Air-In if you tune > 345 MHz. The filters are not sharp at all though (not surprising given their low order, I only see a few capacitors and inductors in the input path), and their added benefit is a bit questionable. You might get a bit less WFM interference at, say, 900 MHz, but that’s about it…

In Antti’s LinuxTV blog, Antti talks about the internals of the device and shows many pictures of the insides.

R282D
Dongle containing the new R828D
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Receiving and Decoding Tire Pressure Monitor Systems using an RTL-SDR

Tire Pressure Monitoring Systems (TPMS) are comprised of sensors that are designed to measure the tire pressures on a vehicle and then wirelessly transmit the data to a monitoring computer, which will then alert the driver when the tire pressure is incorrectly set.

At the Toorcon conference, Jared Boon has given a talk showing how he used an RTL-SDR and a GNU Radio program that he developed to reverse engineer the TPMS wireless protocol, and read the data that is sent. Jarod also notes that TPMS is potentially a security risk that could be used to track cars. The talk has been uploaded to YouTube and is shown below.

Reversing Tire Pressure Monitors with a Software-Defined Radio

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HDSDR Updated to Version 2.70. Now with Autocorrelation Feature for Signal Identification

HDSDR, a popular SDR program used with the RTL-SDR dongle has been updated to version 2.70. The new features include

– better CPU utilization
– added Automatic Notch Filter
– added AFC for AM and FM. AFC can be deactivated in ECSS mode
– smoothed S-Meter display
– enhanced parameters for ‘SDR on IF output’
– new keyboard shortcuts for Lo/HiCut and WAV files
– ‘spectrum’ switchable to Autocorrelation/Cepstrum display (Click on ‘Spectrum’ label)
– TX-Button for HRD(DDE) / CAT to HDSDR
– added ‘Double Size’ option in Frequency Input Dialog
– Frequency Manager now provides 5 User Banks

The new autocorrelation feature is particularly useful for signal identification. The authors of HDSDR have created a webpage showing what the autocorrelation feature can be used for, and how to use it.

HDSDR Autocorrelation Feature
HDSDR Autocorrelation Feature
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SDRSharp Frequency Manager Plugin updated to Version 1.4

The commonly used frequency manager and scanner plugin for SDRSharp has been updated to version 1.4. The new features include:

Frequency Manager

  • Frequency Presets – there are now 10 frequency presets you may use to store and recall favorite frequencies.

Scanner

  • A new Signal Strength Indicator displays a real-time measure of a frequency’s signal strength compared to the Minimum Signal Strength that you set. The indicator shows the signal strength as it bounces below and above your minimum, and also shows when the “Seconds wait for transmission” and “Watchdog” timers have been triggered.
  • The Scanner Configuration window now has two tabs which organize scanner behavior into Rules settings and Performance settings.
  • Snap to next Step Size: a new checkbox lets you force the scanner to tune a scanned frequency to the SDR# step size, or instead allow it to tune to the actual detected peak signal strength of a frequency.
  • Update a frequency’s Date when monitored: a new checkbox that causes the scanner to record the current date for a frequency that is already in your database, when the scanner lands on that frequency.
  • Adjacent Frequency Rejection: a new setting that lets you define the width of the area around a tuned frequency that is used to monitor signal strength after tuning to a frequency. This reduces the influence of adjacent strong frequencies that “splatter” into the tuned frequency’s step size or bandwidth size.
  • Faster scanning speed: Scanning speed has been improved yet again, and is now faster than the improvements in version 1.31. On my equipment I now average 1.6 GHz scanning speed as measured with the built-in benchmark tool on a range scan.
  • Improvements to the busy-frequency detection process.

The updated plugin can be downloaded from http://www.sdrsharpplugins.com.

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Tutorial: Creating an FM Receiver in GNURADIO using an RTL-SDR source

Over on instructables.com, user v3l0c1r4pt0r has created an instructable that shows step by step instructions on how to create an FM receiver in GNU Radio using an RTL-SDR and GNU Radio Companion. His instructable explains a bit about the theory of what is required to decode an FM signal, and shows which GNU Radio blocks are required, and how to connect them up.

GNU Radio Tutorial
GNU Radio FM Receiver
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rtl_udp: Fork of rtl_fm with UDP controls

Over on our forums, user sysrun has posted about his fork of the rtl_fm command line tool. His fork allows retuning of the rtl_fm program via UDP without the need to restart the program. In the future he hopes to support UDP PCM streaming. He writes

rtl_udp is a copy of rtl_fm with a special feature: It opens a udp control port (currently fixed to 6020) which takes commands like changing the frequency or mode. No need to restart :)

Credits, Idea & original Code by olgierd (http://qi.reddit.com/user/olgierd)

Usage:
python script udpclient.py for easy operation included.

possible commands:

  • freq (./udpclient.py freq 101900000)
  • mode (./udpclient.py mode 0 (for fm))
    0 = FM
    1 = AM
    2 = USB
    3 = LSB
  • squelch (./udpclient.py squelch 0)
    0 = OFF
    n = Value
  • gain (./udpclient.py agc auto)
    auto = Automatic
    n = Gainvalue; 195 = 19.5db
  • agc (./udpclient.py agc 1)
    0 = OFF
    1 = ON
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SDRTouch Version 1.7 Released

The Android based SDR program SDRTouch has been officially updated to version 1.7. News comes via this forum post. This looks to be a major update which significantly improves audio quality and performance. The new features are listed below.

  • FM is now in STEREO
  • New audio recording feature for PRO users
  • Improved reception and audio quality. All filters were tested for quality and all bugs discovered were removed.
  • The multi-threading logic was completely rewritten. Now it’s faster than ever before.
  • Audio is now using NDK.
  • PPM correction, audio gain setting
  • A lot of bug fixes and UI enhancements
  • Experimental x86 support
sdtouch
SDR Touch Screenshot
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