The console based FM decoder for the RTL-SDR, rtl_fm has had a code overhaul which contains improvements and bugfixes. The updated code has been merged into the official rtl-sdr release.
The rtl_fm guide has also been updated to include information on the new options.
The rtl_acars console based ACARS decoder which is based on rtl_fm has been updated by a new author, gat3way on Reddit. The new updates include decoder sensitivity improvements and the following:
- Multiple frequencies scanning is now supported (by providing multiple -f arguments at command line and -l
). Since there is no audio output and it’s hard to determine right squelch level, a squelch debug option (-r) is implemented. Use it to experiment with squelch value, it’s simple: good squelch values flood stdout with “hopping freq!” messages yet avoid too high squelch levels. In general, values between 20-30 work good with my setup (big city, lots of radio interference, NOAA turnstile which gives -3db due to rhcp polarization).
- Aircraft and airline databases now supported (using the acarsdec builtin ones). DBs are text files using simple format, so you may easily update them. I would very much appreciate your help to keep that up-to-date.
- Certain improvements in frequency hopping code as compared to rtl_fm, but don’t expect wonders, it takes time to retune so data loss is not avoidable especially if you provide lots of frequencies to scan or huge ranges.
- A simple Makefile to make it simpler š
In the future gat3way hopes to support the decoding of multiple ACARS channels as well. The updated rtl_acars software can be downloaded from github here.
Linrad is an advanced SDR software program which supports the RTL-SDR. It is not as easy to use as the more popular SDR#, but some people prefer to use it as it has a very high information density GUI. The author of Linrad has uploaded two videos to YouTube that show how to install Linrad on Windows XP and Linux, which may be useful to those wishing to try Linrad out.
Omri Iluz wrote in to us to let us know about his recent project which involves sniffing and decoding wireless packets at 2.4 GHz from NRF24L01+ and Bluetooth Low Energy (BTLE) transceivers. The NRF24L01+ is a popular wireless transceiver which is used in many common devices such as keyboards, mice, remote controls, toys and appliances.
Since 2.4 GHz is out of any of the RTL-SDR’s receivable range, Omri used a cheap downconverter which he was able to buy from China using Aliexpress. The downconverter converts the 2.4 GHz signal into a lower frequency at around 400 MHz which is in the receivable range of the RTL-SDR.
He was then able to use hisĀ NRF24-BTLE-Decoder software that he developed to convert the received data from the NRF24L01+ transceiver into a decoded packet by simply piping the output of RTL_FM into his program.
Since the NRF24L01+ uses hardware similar to the Bluetooth Low Energy (BTLE) protocol, Omri was able to modify his code to be able to also decode BTLE packets.
Over on our Facebook pageĀ memberĀ ŠŠ»ŠµŠŗŃŠ°Š½Š“Ń has let us know about a Russian amateur astronomer, Alex who has been using the RTL-SDRĀ for radio astronomy. Alex uses an Elonics E4000 RTL-SDR combined with a 3.7m mesh parabola dish with 1420 MHz waveguide.
At the center of his system is an LNA with 40dB gain and a very low noise figure of 0.2dB. This LNA appears to be based on G4DDK’s VLNA, but modified to work with the 1420 MHz frequency used for radio astronomy. It seems the LNA can be ordered for 140 USD from the above link.
Note: The above Russian links are machine translated with Google to English.
Over on our Facebook page, memberĀ ŠŠ»ŠµŠŗŃŠ°Š½Š“Ń has posted about a project he found by Georg CampanaĀ which involves using an RTL-SDR to capture signals from his TI Chronos watch which has a programmable 433 MHz RF transmitter built into it.
GeorgĀ used his TI Chronos watch to transmit a signal copied from remote controls which are used to open his house gate, garage door, light switches and set his house alarm.Ā When he discovered that the watch signal was not transmitting properly, he used his RTL-SDR to compare the signal coming from the watch to the original signals from the remote controls to help him with debugging. In order to detect the bit stream from the RF signal, he used a GNURadio program for decoding wireless temperature sensors, which he modified slightly to work with his watch.
The beta version of the popular ADS-B decoding software RTL1090 has been updated to version 3. Version 3 comes with a simple radar visualization scope built into the software, which allows you to see aircraft directly in the RTL1090 software.
News via this Radarspotting forumĀ post
On YouTubeĀ Eric WilliamĀ has posted a video showing him unboxing two new antennas that he intends to use with his RTL-SDR. He unboxes a new QFH antenna for use with receiving NOAA weather satellite images, and a new Discone antenna for general wideband receiving. If you are interested in buying commercial antennas for use with your RTL-SDR, this video may be useful at giving you some idea of what’s available.
Eric also recently posted a video showing an overview of his RTL-SDR setup which is also an interesting watch.
