• Category Archives zendamateur/ham radio
  • MP3 streaming of RTL-SDR receivers

    I have just made some progress with something I had been researching for some time. With the rtl-sdr software and the widely available USB DVB-T sticks it is possible to implement a cheap SDR receiver. I wondered whether it is possible to grab the sound output of the rtl_fm low cpu usage receiving utility and convert it into an MP3 stream.

    I came across this post on the Raspberry Pi forum and tried to make it work. After some messing around with settings I succeeded. The commands I am using are as follows:

    rtl_fm -s 22050 -f 145.575M -l 0  - | lame -b 32 -r -s 22.050 -m m -  | ezstream -c /etc/ezstream.xml

    Basically, it runs rtl_fm, sends the output the lame mp3 encoder which sends its ouput to the ezstream icecast stream generator. /etc/ezstream.xml is as follows:

             For streaming from standard input, the default for continuous streaming
             is bad. Set <stream_once /> to 1 here to prevent ezstream from spinning
             endlessly when the input stream stops:
             The following settings are used to describe your stream to the server.
             It's up to you to make sure that the bitrate/quality/samplerate/channels
             information matches up with your input stream files.
            <svrinfoname>RPi rtl_fm test stream</svrinfoname>
            <svrinfodescription>RPi rtl_fm test stream</svrinfodescription>
            <!-- Turn off YP directory advertising -->

    I run a dedicated icecast server on a separate server but it should be possible to host this on the RPi itself. The stream takes up about half of the RPi’s processor capacity. Currently, squelch does not work because it seems rtl_fm stops sending data when the squelch is on, causing lame and ezstream to stop. A possible workaround is to have rtl_fm output to the RPi line-out and generate the icecast stream from the line-in of another USB sound card plugged into the RPi. To solve this in software looks more elegant to me.

  • Streaming radio receivers with the Raspberry Pi


    The Raspberry Pi is a small computer that has become very popular. Lots of applications and hardware hacks have been made for it. You can run various software like web/file/printservers, read out sensors, the possibilities are endless.

    I own multiple Raspberry Pi’s, one is a test platform for sensors, and a new one pictured above will be dedicated to audio streaming. I use the software packages darkice and icecast2 to capture the audio from an USB audio card and make it available on the internet.

    To stream audio with the RPi you’ll need the following hardware and software: Continue reading  Post ID 1481

  • Some tech frustrations

    Just some venting,

    Why on earth is every interesting technical discussion forum on Yahoo Groups? I absolutely loathe its design. When requesting the main forum it presents you with unthreaded, ungrouped messages by date. To group messages by thread you have to click a link, and even then you have to click each message separately just to view it. It’s 2012 damnit, stupid threaded message boards should be a thing of the past! Continue reading  Post ID 1481

  • Review: Wouxun KG-UV2D handheld VHF/UHF transceiver

    On the radio market DVDRA (day of the radio amateur) I bought this cheap and well-reviewed transceiver because my FT-60R was getting a bit old and battery life was getting limited.

    I’m going to keep this review short because there should be enough other reviews on the internet which are more detailed. I want to offer a quick overview for anyone interested in getting this transceiver. Continue reading  Post ID 1481

  • Repeaterbeleid en het AT

    De laatste tijd ben ik weer wat meer bezig met de zendamateurhobby en er zijn wat dingen die mij minder bevallen in de huidige gang van zaken rond repeaters en de invloed van het Agentschap Telecom op de hobby van zendamateurs.

    Een aantal maanden geleden kwam ik er achter dat de repeater PI2NOS te Hilversum uit de lucht was. Na navraag bleek dat de repeater was uitgezet vanwege problemen met de benodigde vergunning. Repeaters zijn namelijk voor een groot deel onbemande stations en moeten uiteraard aan bepaalde regelgeving voldoen. Dat is begrijpelijk maar in dit geval is dus een repeater uitgezet puur vanwege beleid. Er was geen sprake van piraterij, gerotzooi of storingen op andere gebruikers. Toch werd een prachtrepeater met een flink bereik en vele serieuze gebruikers puur vanwege beleid van het AT uit de lucht gehaald. Continue reading  Post ID 1481