|
From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] Streaming Funcube Dongle Pro+ over UDP |
Date: | Sat, 10 Aug 2013 12:13:56 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 |
Hi again,
I was a little surprised that your connection couldn't handle the 12.3 Mbit/s for the complex 192ksam/s, so I had a look at the source code of the fcd_source; that basically wraps an audio source. Surprise was mine when I found out that there's no complex 192ksam/s at all... The audio device is set to deliver 96ksam/s of stereo, that gets converted to 96ksam/s of complex samples. Therefore, the data rate is only 6.144Mbit/s for your wifi link... Not very much. Anyway, what (due to that being the default data type in GR), the audio source inside the fcd_source converts the 16bit adc resolution of your dongle to 32bit floats; so, instead of streaming those using GR over your network, you can also just stream raw audio data from your beaglebone to your receiver computer, something like arecord --format={try something like S16_LE, U16_LE, see man arecord} -D beagleboardaudiodev --file-type=raw --channels=2 --disable-resample --disable-channels --disable-format |ncat host port and ncat -l port > rxfifo on the receiver. And then reading that file using a file source, converting the 16bit signed/unsigned ints to floats, packing them into complexes and using that for your receiver; note, however, that a lost packet is not tolerable in this case, you will end up with corrupt samples if lost bytes are not multiples of 4... To the TCP/UDP sources in GR: they do what they were designed for, dropping samples from an outside source makes sense if your flowgraph can't handle the load, since there is no such thing as the infinite buffer or the infinite acceptance of latency; not so much for your fifos. They start blocking when you ram+swap is used up... Greetings Marcus On 08/10/2013 03:15 AM, Vanush Vaswani wrote: Iain, thanks for that. Will be helpful in my gnuradio pursuits. |
[Prev in Thread] | Current Thread | [Next in Thread] |