Measurements of E4000 Filter Responses

I wrote a octave wrapper around the rtl-sdr library of osmocon. With a little change, to also export the rtlsdr_i2c_read/write_reg function as well as the rtlsdr_set_i2c_repeater function. I then let the standard library do its normal work and just before measuring, I overwrite the E4K_REG_BIAS, E4K_REG_SYNTH1 and E4K_REG_FILT1 registers to their appropriate settings.

Raw data is available. The image itself is pretty raw. The only modifications are a shift of 3 dB below 350 MHz, to compensate the loss due to for 3-phase mixing. and a moving average of 10 samples, to smoothen the curve a little.” — kirepudsje

Source: Reddit Post

Alternative ExtIO for Compatible SDR Software

The folks over at SDR# have uploaded an updated plugin for ExtIO compatible software.

You can download your copy from [LINK REMOVED – it appears SDR# has removed the file]

To use it, extract to the same folder as SDR#/HDSDR/WRPlus/etc and select the ExtIO_RTLSDR.dll depending on your software instructions. (HDSDR will prompt you which ExtIO plugin you want to use if you already have another ExtIO DLL installed.)

Pager Traffic with RTL SDR, PDW and HDSDR

In this video Superphish shows a RTL2832 based dongle being used to receive and decode POCSAG/FLEX pager data. Make sure you view the video in 720P to see the text clearly.

Note: This is likely illegal in most parts of the world, especially sharing what was received.

GQRX Using an RTLSDR to Receive Temperature Sensor Data

“Monitoring 433.9 MHz – picking up plenty of local weather temperature sensors and the likes. Using a newsky dvb-t tuner and a modified version of gqrx that supports rtl sdr. Antenne is a 2m/70cm in my attic.” — trylleklovn

SATCOM pirates received via RTLSDR

“Using gqrx with my newsky dvb-t dongle (rtlsdr) to listen to the geostationary SATCOM which is frequently utilized by brazil radio pirates.” – trylleklovn

SDR# With RTL-SDR Support

“SDR# (read SDR Sharp) is a simple, intuitive, small and fast PC-based DSP application for Software Defined Radio. It’s written in C# with both object design correctness and performance in mind. The main purpose is to offer a simple proof of concept application to get hands into DSP techniques. It supports SoftRock, FiFiSDR, FUNcube Dongle, SDR-4 [,rtl-sdr] and any sound card based SDR front end.” —


SDR# (SDR-Sharp) versions 244+ (dev) have added support for RTL based SDRs supported by ExtIO. Extract the download link to the same folder you installed ExtIO to. If you haven’t done that yet, try this guide.

Download Link

To use the software with an RTLSDR dongle, Select USRP under the ‘Front End’ drop down box beside the Front End button. Then use the now active ‘Front End’ button to show the ExtIO GUI. Don’t forget to add your device hint!


“Receiving COSPAS-SARSAT transponder on board of a low earth orbiting satellite on 1544.5 MHz (frequency on the SDR display was not calibrated, please ignore).

Using the famous RTL SDR…”the cheapest SDR in town”” for VHF/UHF/SHF covering 64-1700 (up to 2.1 GHz “out of spec” )….this particular one was a Hama Nano.” — MegaOscarVideos


[Wikipedia: COSPAS-SARSAT]


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