Freqwatch – RTL-SDR Frequency Scanner and Recorder

Freqwatch is a new Linux based software program that has recently been released by programmer Joshua Davis. Freqwatch makes use of rtl_power to scan a wide swath of RF spectrum and then automatically records and stores in a database sound files of active signals by using rtl_fm.

The software is capable of making use of multiple RTL-SDR dongles in order to efficiently monitor larger bandwidths. After running the software for a while and generating a large database, you can then use a database analyzer like Splunk to find trends in the data or find out when something changes.

The software can be downloaded from its GitHub at https://github.com/covertcodes/freqwatch. Previously we featured some other software called ScanEyes which has a similar logging feature but focused on trunking radio channels and we also featured RTL Airband which monitors multiple airband frequencies simultaneously for logging and streaming.

Freqwatch Database Logs
Freqwatch Database Logs
Tweet18
Share
Reddit
Vote
Email
18 Shares

Chrome RTL-SDR Radio Receiver Updated

Chrome Radio Receiver has been updated and now supports NFM, AM, LSB and USB reception modes. The software can be downloaded for free from the Chrome store. Chrome Radio Receiver is a simple Javascript based RTL-SDR radio receiver without any spectrum or waterfall graphs. It is perfect for quickly listening to saved stations. The software also has the ability to record audio, save stations and automatically scan looking for active frequencies.

In order to receive AM/LSB/USB radio on HF frequencies you will need to use an upconverter and input the frequency offset in the settings menu.

[First seen at http://blog.livedoor.jp/bh5ea20tb/archives/4893438.html]

Chrome Radio Receiver
Chrome Radio Receiver
Tweet15
Share
Reddit
Vote
Email
15 Shares

Listening to SSTV from the ISS with an RTL-SDR

On December 18 and 20 the International Space Station transmitted several SSTV images to celebrate what would have been the 80th birthday of Yuri Gagarin who was the first human to orbit the Earth. SSTV stands for Slow Scan Television and is a method for sending small low resolution images over radio.

Over on YouTube several RTL-SDR users captured these images. UltraTechie shows a video where he captures the SSTV image using a portable set up consisting of a Windows 8 tablet running SDR#. He used a handheld 3 element 2m Yagi antenna to tune into the 145.8 MHz signal. UltraTechie writes that he also used an LNA, but that it was probably not required as the signal was quite strong.

ISS SSTV reception on a portable setup using RTL-SDR

Another YouTube user Tom Mladenov shows another video where the SSTV image is received. Tom used a QFH antenna.

Tweet
Share
Reddit
Vote
Email

SDR Comparison: Airspy vs Funcube vs E4000 RTL-SDR vs BladeRF

Over on YouTube user sm5bsz (aka Leif, programmer of Linrad) has uploaded a video showing an in depth technical comparison between the Airspy, Funecube, E4000 RTL-SDR and BladeRF software defined radios. His test focuses on the dynamic range when each SDR is used as a narrowband receiver at 144 MHz with appropriate filtering applied. The video is quite long and technical, but most of the results are summarized at 4:41.

SDRcompareTunersNarrow

Tweet13
Share
Reddit
Vote
Email
13 Shares

Testing Keenerds RTL-SDR Drivers

Keenerd (aka Kyle Keen) recently ran a fundraiser to support him to work on improving the RTL-SDR driver and related software. A few months ago he released an update to the driver which made some improvements including some tweaks by another programmer teejeez that optimized the R820T’s filters which may help with out of band aliasing. The list of issues he is working on and has completed can be found at http://igg.kmkeen.com/.

To use keenerds drivers on Windows with SDR# you can go to http://igg.kmkeen.com/builds/, and download the latest build zip file. Then simply copy all the non .exe files into the SDR# folder and rename librtlsdr.dll to rtlsdr.dll. We recently tested the new drivers and show screenshots of the difference below. Nearby to the marine weather report frequency used in the screenshots is a very strong pager signal which causes significant interference. With the gain turned up on the original drivers the entire band is wiped out when the pager signal is transmitting. With keenerds drivers most of the band is usable and the weather signals can be heard. There do seem to be some issue with what looks like WFM interference appearing now however. Testing at other frequencies with nearby strong signals also seem to show that aliasing is significantly reduced. We also noticed a lower noise floor at some frequencies resulting in about a 2-3 dB better signal. However, we also noticed that the noise floor was raised slightly at some other frequencies. We suggest you give keenerds drivers a try and comment with any improvements or issues you see.

Keenerds Driver
Keenerds Driver
Original Driver
Original Driver

Tweet
Share
Reddit
Vote
Email

Airspy Vs RTL-SDR on VLF and Broadcast FM

Over on YouTube user Mile Kokotov has uploaded two videos showing a comparison between the Airspy and RTL-SDR software defined radios. The Airspy is a high performance SDR that costs $199 USD.

The first video shows a comparison between the two SDR’s and two hardware radios on receiving a very weak broadcast FM station amongst several very strong ones. Mile first tested his hardware radios and found that his Onkyo radio was able to clearly receive the weak station, whilst his Pioneer radio could not at all. Then he tested his SDR’s and found that his Airspy was able to receive the station, but the RTL-SDR could not and suffered from intermodulation when the gain was turned up because of the nearby strong stations. This shows how the 12-bit Airspy ADC vs the 8-bit ADC on the RTL-SDR can make a difference.

The second video shows a comparison between the RTL-SDR and Airspy on a VLF time signal at 60 kHz using a ham-it-up upconverter. His video shows that the Airspy signal is about 8dB stronger the the RTL-SDR.

http://www.youtube.com/watch?v=OgU7Gv3lca8#t=118

Airspy vs RTL SDR receiving VLF

Tweet
Share
Reddit
Vote
Email

New SDR# Plugin: Multiple VFO’s

Over on the rtl-sdr.ru blog the programmer of many well used SDR# plugins has released a new one which allows you to have up to two extra VFO’s in SDR# (note in Russian, use Google Translate). In order words this means that you can now listen to up to three signals simultaneously if they are in the same swath of live bandwidth. Previously on Windows only the SDR-Radio V2 software was capable of doing multiple VFO’s.

Listening to multiple frequencies simultaneously has many uses including the ability to now monitor multiple ACARS, AIS, pager and other data frequencies at the same time. However, as of yet it seems that the ability to output to other audio devices such as a virtual audio cable is not yet implemented.

Extra VFO's Plugin
Extra VFO’s Plugin
Tweet
Share
Reddit
Vote
Email

Digital Ding Dong Ditch – Hacking wireless doorbells with Arduino and RTL-SDR

Over on YouTube user Samy Kamkar has uploaded a video showing how he was able to use an RTL-SDR to copy his friends wireless doorbell signal and prank him by replaying it using an Arduino and 433 MHz transmitter. His video goes through the entire reverse engineering process he used from recording the wireless doorbell signal with the RTL-SDR, to analyzing and understanding the signal and finally to programming the Arduino with the code to replicate the doorbell signal. If you don’t like video explanations, Samy has also done a write up of the same material on his website. 

Digital Ding Dong Ditch Prank - hacking wireless doorbells w/Arduino and RTL-SDR

Tweet
Share
Reddit
Vote
Email