dear list readers,

I would like to briefly report on the operation RaspberryPi.

Basically, the system with 460 BogoMIPS is just barely suitable in
normal operation, to operate the Codec2 and FDMDV. Without the graphics,
RaspberryPi can provide sufficient power for that.

We need hardware:
USB Hub - $ 5
2 USB sound cards (for example CM108 for about $ 4)
RaspberryPi (RAM 500 MB)

circuit:TX / RX - Sound Card hw: 1 - Raspi - Sound Card hw: 2 - micro /
speaker

The RaspberryPI is configured
1.  with
sudo raspi-config
allow an overclock to 900 MHz and reboot. The computer then adjusts
dynamically the clock frequency during runtime when heavy loaded up to
900 MHz .
2. Install all needed software with apt-get install
3. Freedv with graphics can be compiled and can be executed. (Do not
hesitate to ask for my binary package)Unfortunately, the performance of
the CPU is not sufficient to allow for graphics and signal processing.

But:

RaspberryPI as a modem / Demodem and codec
We use the files in the compiled directory codec2-dev
with two scripts for send and receive (see below)
We can call the scripts or cancel when switching a bit on the GPIO port.

The RaspberryPI has a 90 - 95% CPU load and is able to work as expected.

The GPIO switching could be done with a Python script (eg with
raspberry-gpio-python - http://code.google.com/p/raspberry-gpio-python)
calling an killing the both scripts.

It was done on this Rasbian-OS:
Linux raspberrypi 3.6.11+ #371 PREEMPT Thu Feb 7 16:31:35 GMT 2013 armv6l

receive-1600.sh
-----8<------------
#!/bin/bash
# by Michael, dk5hh at darc.de
#audio-input
AI="hw:1"
AO="hw:2"
#
echo Audio von $AI demod - fec1300+300 c2-1300 play auf $AO
D=/home/pi/Scratch/fdmdv2/src/codec2-dev/src
arecord -Dplug$AI -r 48000  -t raw -f S16_LE -c 1  - \
| sox -t raw -r 48000 -e signed-integer -c1 -b 16 - \
-t raw -r 8000 -e signed-integer -c1 -b 16 - | \
$D/fdmdv_demod - - 16 \
$D/fec_dec - - 1600 | \
$D/c2dec 1300 - - | \
aplay -Dplug$AO  --rate 48k -t raw -r 8000 -f S16_LE -c 1 -
-----8<------------

transmit-1600.sh
-----8<------------
#!/bin/bash
# by Michael, dk5hh at darc.de
#audio-input
AI="hw:2"
AO="hw:1"
#
echo Micro von $AI C2enc-1300 FEC-1300+300 mod_1600 play auf $AO
D=/home/pi/Scratch/fdmdv2/src/codec2-dev/src
arecord -Dplug$AI -r 48000  -t raw -f S16_LE -c 1  - \
| sox -t raw -r 48000 -e signed-integer -c1 -b 16 - \
-t raw -r 8000 -e signed-integer -c1 -b 16 - | \
$D/c2enc 1300 - - | \
$D/fec_enc - - 1600 | \
$D/fdmdv_mod - - 16 \
aplay -Dplug$AO  --rate 48k -t raw -r 8000 -f S16_LE -c 1 -
-----8<------------

scripts for 1400 Bit (freedv mode 0.91) can be easily obtained.

Michael, DK5HH

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