# Difference between revisions of "Demod2"

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=== Operational constraints === | === Operational constraints === | ||

− | # The reference implementation uses 48 ksps. For other sample rates the filter coefficients in nyquist.c must be reworked<ref>dpsk.h line 58-61</ref>. It is therefore easier to | + | # The reference implementation uses 48 ksps. For other sample rates the filter coefficients in nyquist.c must be reworked<ref>dpsk.h line 58-61</ref>. It is therefore easier to resample to 48 ksps. |

== DSP library == | == DSP library == |

## Revision as of 01:44, 27 January 2011

Some random notes about the reference BPSK-1000 reference modem for ARISSat-1 by Phil Karn, KA9Q.

## Overview

The package contains a DSP lilbrary libdspfec.a and various utility programs for testing and demonstration purposes. The included Makefile will build the library and all executables.

### Operational constraints

- The reference implementation uses 48 ksps. For other sample rates the filter coefficients in nyquist.c must be reworked
^{[1]}. It is therefore easier to resample to 48 ksps.

## DSP library

libdspfec.a and dsfec.h

## Top level aplpications

### mod

Complete encoder and modulator.

Takes arbitrary data stream as input (LSB first according to HDLC standard), applies CRC and FEC, and outputs modulated baseband.

- Input: 500 bps arbitrary data; becomes 1000 symbols/sec with FEC (where does CRC and HDLC framing code go?)
- Output: 48 kHz 16-bit linear PCM little-endian

### demod

Complete demodulator and decoder.

- Input: 48 kHz 16-bit linear PCM little-endian
- Output: 500 bps data stream

## Utilities

### addcw

### addnoise

### async_hdlc_decode

### bplay

### byteorder

### dist

### gentestdata

### meter

## Test programs

### dotprod_test

### pack_unpack_test

### parity_test

### peak_test

### rand_test

### sq_test

### sub_test

### viterbi27_streamtest

### viterbi27_test

## References

- ↑ dpsk.h line 58-61