QPSK encoder

Description

QPSK encoder with Root-raised-cosine filter reads data from stdin and prints encoded data to stdout.

Quadrature Phase Shift Keying is used for the input data encoding.

Output data format: <sample number, I, Q>, where I(t) and Q(t) are the modulating signals.

If benchmark mode is on, then the encoding speed (bit/s) is printed to stdout.

Parameters

The encoder parameters are set in qpsk_encoder.ini file :

[Options]
FilterWidth: 10
SymbolWidth: 4
Beta: 0.25
ReadBufferSize: 1
CsvRounding: 3
[Debug]
Benchmark: False

• FilterWidth - the number of samples to apply the filter.

• SymbolWidth - the number of samples per symbol.

• Beta - β, or the roll-off factor - the parameter for Root-raised-cosine filter.

• ReadBufferSize - the buffer size for data reading from stdin or file.

• CsvRounding - the number of decimal places for I and Q parameters rounding.

• Benchmark:

  • Benchmark: False - the encoding mode is on.
  • Benchmark: True - the benchmark mode is on. The input data from stdin is encoded, but only the encoding speed (bit/s) is printed to stdout.

Requirements

• Python 3

Usage

Run the encoder from the command line:

python3 qpsk_encoder.py < input.file > output.csv

Example

echo 1 | python3 qpsk_encoder.py

where

echo 1

prints '1' to stdout, and

| python3 qpsk_encoder.py

reads '1' from stdin and encodes it into 32 samples, as there are 8 bits in the input '1' character and each input bit is encoded into 4 samples as SymbolWidth parameter is set to 4.

The resulting output in `stdout` :

1,-0.046,-0.046
2,-0.113,-0.113
3,-0.150,-0.150
4,-0.111,-0.111
5,0.101,0.101
6,0.375,0.375
7,0.495,0.495
8,0.249,0.249
9,-0.523,-0.523
10,-1.604,-1.604
11,-2.526,-2.526
12,-2.778,-2.778
13,-2.098,-2.006
14,-0.651,-0.426
15,0.996,1.296
16,2.134,2.356
17,2.254,2.144
18,1.296,0.771
19,-0.344,-1.034
20,-2.025,-2.301
21,-3.145,-2.301
22,-3.559,-1.101
23,-3.393,0.667
24,-2.979,2.079
25,-2.646,2.319
26,-2.435,1.400
27,-2.435,-0.277
28,-2.646,-2.025
29,-2.887,-3.145
30,-3.168,-3.559
31,-3.259,-3.393
32,-2.922,-2.979

Author

Andrey Filonov, andrey.filonov@gmail.com

License

QPSK encoder is available under the MIT license. See the LICENSE file for more info.