Capture spectra with STRF and an RLT SDR

rtl_capture.sh

#!/bin/bash

# Settings
SKY_FREQ=2242.5e6
LO_FREQ=1833e6
RATE=1e6
OUTPUT=${HOME}/satobs
FIFO=${HOME}/satobs/fifo
GAIN=30

# Remove fifo if it exists
if [ -p ${FIFO} ]; then
    rm ${FIFO}
fi

# Create fifo
mkfifo ${FIFO}

# Compute IF
INTER_FREQ=`echo ${SKY_FREQ} ${LO_FREQ} | awk '{printf("%e",$1-$2)}'`
echo ${INTER_FREQ}

# Kill previous rffft instance
ps aux | grep -e "rffft" | grep -v -e "grep" | awk '{printf("kill -9 %s\n",$2)}' | sh

# Start rffft
rffft -i ${FIFO} -p ${OUTPUT} -f ${SKY_FREQ} -s ${RATE} -F char &

# Start rtl_sdr
rtl_sdr -f ${INTER_FREQ} -s ${RATE} -g ${GAIN} ${FIFO}