Audio compression

DSP acceleration

Website

Audio compression: ADPCM

Website for receivers

DSP acceleration

csdr

csdr

#!/bin/bash
rtl_sdr -s 2400000 -f 89300000 -g 20 -

csdr

#!/bin/bash
rtl_sdr -s 2400000 -f 89300000 -g 20 - | csdr convert_u8_f

csdr

#!/bin/bash
rtl_sdr -s 2400000 -f 89300000 -g 20 - | csdr convert_u8_f | \
csdr shift_addition_cc -0.085

csdr

#!/bin/bash
rtl_sdr -s 2400000 -f 89300000 -g 20 - | csdr convert_u8_f | \
csdr shift_addition_cc -0.085 | csdr fir_decimate_cc 10 0.05 HAMMING

csdr

#!/bin/bash
rtl_sdr -s 2400000 -f 89300000 -g 20 - | csdr convert_u8_f | \
csdr shift_addition_cc -0.085 | csdr fir_decimate_cc 10 0.05 HAMMING | \
csdr fmdemod_quadri_cf

csdr

#!/bin/bash
rtl_sdr -s 2400000 -f 89300000 -g 20 - | csdr convert_u8_f | \
csdr shift_addition_cc -0.085 | csdr fir_decimate_cc 10 0.05 HAMMING | \
csdr fmdemod_quadri_cf | csdr fractional_decimator_ff 5 | \
csdr deemphasis_wfm_ff 48000 50e-6 | csdr convert_f_s16 | \
mplayer -rawaudio samplesize=2:channels=1:rate=48000 \
-cache 1024 -quiet -demuxer rawaudio -

Signal path

Digital downconverter

Simple C version
Simple C version
Simple C version
Simple C version
NEON SIMD
(Inline assembly)
NEON SIMD
NEON SIMD
NEON SIMD
NEON SIMD
NEON SIMD
NEON SIMD
NEON SIMD
GPGPU (CUDA)
GPGPU (CUDA)
GPGPU (CUDA)
GPGPU (CUDA)
2122ms → 113ms

×18.7 speedup
Mark Borgerding, "Turning Overlap-Save into a Multiband Mixing, Downsampling Filter Bank",
IEEE Signal Processing Magazine, March 2006

Various other things

Digital modes

Hardware support

qtcsdr

Digital modes: RTTY

Hardware support

HackRF, AFEDRI SDR, SDRPlay,
gr-osmosdr, etc.

hpsdrtool

➜  ~ hpsdrtool
hpsdrtool <hpsdr_metis_ip> [--freq <freq_in_hz>]
	[--preamp] [--no-iq-output]
https://github.com/ha7ilm/hpsdrtool

qtcsdr

Software (CLI)

QRPi

https://www.tapr.org/kits_20M-wspr-pi.html

qtcsdr

RTL-SDR + RPITX = transceiver

qtcsdr (RX)

qtcsdr (TX)

qtcsdr

https://github.com/ha7ilm/qtcsdr