Radios

Articles and blogs about radio receivers and transmitters. Both commercial off the shelf radios and home made DIY experiments by Alexandru Csete OZ9AEC.

GNU Radio 3.3.0 on Mac OS X

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Few days ago Michael Dickens announced that the GNU Radio packages on MacPorts have now been updated to 3.3.0 and so I took this opportunity to try it. I didn’t have MacPorts installed so I had to start from scratch; however, installation was quite straightforward because the dependencies are resolved automatically. All I had to do was to download the latest MacPorts dmg and then execute the command

  sudo port install gnuradio

then let it run overnight. It takes a long time since MacPorts builds everything from source. On my iMac it took more than 6 hours. Note that gnuradio is a meta packages that depends on all GNU Radio components.

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Broken RFX1200 and more sensitivity measurements

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I went to OZ7SAT today to do some measurements on the receiver boards. I wanted to see how the sensitivities compare to that of the WBX receiver that I have measured earlier using a CW signal and SSB receiver. The criteria was again to find the weakest signal that I could both hear and see on the spectrum scope and that I would be able to decode if it was a Morse code transmission. The limiting parameter is actually the spectrum scope, because I can hear tones much weaker than what is visible on the 512 channel FFT scope.

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Simple SSB transmitter using complex bandpass filter

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There are several ways to generate a single side band signal in a software radio and I am slowly exploring each and every one of them. For this first attempt I have decided to try using a basic amplitude modulation followed by a bandpass filter with complex taps that can select either the upper or the lower side bands.

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Full duplex transceiver version of the DVB setup

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One MacBook Pro (2.4 GHz) and one USRP running the full duplex video transceiverThis weekend I have been playing with a full duplex transceiver version of the simple DVB setup that allows to use only one computer and one USRP as a transmitter and receiver. By using separate daughterboards I can use one side to transmit and the other side to receive. Using two sets and two frequencies the transceiver can be used for two-way video conferencing over the air 🙂

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Simple DVB with Gstreamer and GNU Radio

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I have had this idea of using my webcam for digital video transmission for quite some time now. Capturing and processing video from UVC webcams has been a routine for a long time and I have had great success with Logitech webcams (the 9000 series) that have great UVC support. I still had a problem though with finding a good way to interface the GNU Radio transmitter and receiver to the video processing pipeline implemented in Gstreamer.

An idea for a DVB setup using a webcam, a laptop with Gstreamer and GNU Radio and the USRP

In my experiment with receiving packet radio from the ISS I used a named pipe to create a real time interface between the GNU Radio receiver and the packet decoder multimon. I decided to try this trick for sending video in to and out of GNU Radio and it works! The following experiments were implemented and executed on the 27th and 28th of July with some minimal preparation on the 26th.

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