QPSK-mod-demod-libs

C-libraries for QPSK modulation and demodulation

▼ include
butterworth_filter.h	Butterworth Filter implementation for filtering continues signal Original code from: https://github.com/filoe/cscore
bytes_symbols_converter.h	Methods to convert array of bytes to symbols and back
pll.h	Numerically-controlled Phase locked loop
qpsk_demodulator.h	QPSK demodulator (decoder)
qpsk_modulator.h	QPSK modulator (encoder)
rrc_filter.h	Root raised cosine (RRC) filter implementation by Fern Lane for filtering continues signal
▼ src
butterworth_filter.c	Butterworth Filter implementation for filtering continues signal Original code from: https://github.com/filoe/cscore
bytes_symbols_converter.c	Methods to convert array of bytes to symbols and back
pll.c	Numerically-controlled Phase locked loop
qpsk_demodulator.c	QPSK demodulator (decoder)
qpsk_modulator.c	QPSK modulator (encoder)
rrc_filter.c	Root raised cosine (RRC) filter implementation by Fern Lane for filtering continues signal

Generated by

1.9.8

qpsk_modulator.c File Reference

Functions
qpsk_modulator_s *	qpsk_modulator_init (float sample_rate, float carrier_frequency, float bandwidth, uint16_t halfcycles_per_symbol, float amplitude_peak)
	Initializes QPSK demodulator.

uint32_t	qpsk_modulator_calculate_samples_chunk_length (qpsk_modulator_s *qpsk_modulator, uint32_t symbols_chunk_length)
	Calculates the size of the array of sample after modulation.

void	qpsk_modulator_modulate_chunk (qpsk_modulator_s qpsk_modulator, uint8_t symbols_chunk, uint32_t symbols_chunk_length, float *samples_chunk, uint8_t debug_messages)
	Modulates chunk of symbols.

void	qpsk_modulator_reset (qpsk_modulator_s *qpsk_modulator)
	Resets QPSK modulator to the initial state.

void	qpsk_modulator_destroy (qpsk_modulator_s *qpsk_modulator)
	Frees all memory allocated by QPSK modulator.

Detailed Description

QPSK modulator (encoder)

Author: Fern Lane

Version: 1.0.0

Date: 2023-09-26

Copyright: Copyright (c) 2023

Copyright (C) 2023 Fern Lane, QPSK modulator / demodulator libraries Licensed under the GNU Affero General Public License, Version 3.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.gnu.org/licenses/agpl-3.0.en.html Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Definition in file qpsk_modulator.c.

Function Documentation

◆ qpsk_modulator_calculate_samples_chunk_length()

uint32_t qpsk_modulator_calculate_samples_chunk_length	(	qpsk_modulator_s *	qpsk_modulator,
		uint32_t	symbols_chunk_length
	)

Calculates the size of the array of sample after modulation.

Parameters

qpsk_modulator	QPSK modulator's struct
symbols_chunk_length	number of symbols

Returns: uint32_t number of samples

Definition at line 104 of file qpsk_modulator.c.

◆ qpsk_modulator_destroy()

void qpsk_modulator_destroy

(

qpsk_modulator_s *

qpsk_modulator

)

Frees all memory allocated by QPSK modulator.

Parameters

qpsk_modulator

QPSK modulator's struct

Definition at line 252 of file qpsk_modulator.c.

◆ qpsk_modulator_init()

qpsk_modulator_s * qpsk_modulator_init	(	float	sample_rate,
		float	carrier_frequency,
		float	bandwidth,
		uint16_t	halfcycles_per_symbol,
		float	amplitude_peak
	)

Initializes QPSK demodulator.

Parameters

sample_rate	Sampling rate (in Hz)
carrier_frequency	Carrier frequency (in Hz)
bandwidth	Output signal required bandwidth (in Hz)
halfcycles_per_symbol	Rate of symbols in carrier halfcycles (2 halfcycles = 1 full carrier wave cycle)
amplitude_peak	Amplitude of modulated signal (peak value)

Returns: qpsk_modulator_s* QPSK modulator's struct

Definition at line 44 of file qpsk_modulator.c.

◆ qpsk_modulator_modulate_chunk()

void qpsk_modulator_modulate_chunk	(	qpsk_modulator_s *	qpsk_modulator,
		uint8_t *	symbols_chunk,
		uint32_t	symbols_chunk_length,
		float *	samples_chunk,
		uint8_t	debug_messages
	)

Modulates chunk of symbols.

Parameters

qpsk_modulator	QPSK modulator's struct
symbols_chunk	Array of symbols
symbols_chunk_length	Length of array of symbols
samples_chunk	Allocated array of samples (size must be qpsk_modulator_calculate_samples_chunk_length * sizeof(float))
debug_messages	Enable printf() debug messages (greatly affects performance)

Definition at line 120 of file qpsk_modulator.c.

◆ qpsk_modulator_reset()

void qpsk_modulator_reset

(

qpsk_modulator_s *

qpsk_modulator

)

Resets QPSK modulator to the initial state.

Parameters

qpsk_modulator

Definition at line 232 of file qpsk_modulator.c.

Generated by

1.9.8

qpsk_demodulator.c File Reference

Functions
float	clampf (float value, float min, float max)
	Clamps float value to a range.

qpsk_demodulator_s *	qpsk_demodulator_init (float sample_rate, float lo_frequency, float bandwidth, uint16_t halfcycles_per_symbol, float carrier_start_threshold, float carrier_lost_threshold, float pll_lock_threshold, float pll_lock_time)
	Initializes QPSK demodulator.

void	qpsk_demodulator_demodulate_chunk (qpsk_demodulator_s qpsk_demodulator, float samples_chunk, uint32_t samples_chunk_size, uint8_t *symbols_chunk, uint8_t debug_messages)
	Demodulates one chunk of samples into symbols.

void	qpsk_demodulator_reset (qpsk_demodulator_s *qpsk_demodulator)
	Resets QPSK demodulator to the initial state.

void	qpsk_demodulator_destroy (qpsk_demodulator_s *qpsk_demodulator)
	Frees all memory allocated by QPSK demodulator.

Detailed Description

QPSK demodulator (decoder)

Author: Fern Lane

Version: 1.0.0

Date: 2023-09-26

Copyright: Copyright (c) 2023

Definition in file qpsk_demodulator.c.

Function Documentation

◆ clampf()

float clampf	(	float	value,
		float	min,
		float	max
	)

Clamps float value to a range.

Parameters

value	Value to clamp
min	Range minimum value
max	Range maximum value

Returns: float Clamped value

Definition at line 42 of file qpsk_demodulator.c.

◆ qpsk_demodulator_demodulate_chunk()

void qpsk_demodulator_demodulate_chunk	(	qpsk_demodulator_s *	qpsk_demodulator,
		float *	samples_chunk,
		uint32_t	samples_chunk_size,
		uint8_t *	symbols_chunk,
		uint8_t	debug_messages
	)

Demodulates one chunk of samples into symbols.

Parameters

qpsk_demodulator	QPSK demodulator's struct
samples_chunk	Aarray of samples
samples_chunk_size	Length of array of symbols
symbols_chunk	Allocated array of symbols (size equal to samples_chunk_size) 0xFF - no symbol decoded at current sample, 0b00, 0b01, 0b10, 0b11 - decoded symbols at specific samples
debug_messages	Enable printf() debug messages (greatly affects performance)

Definition at line 153 of file qpsk_demodulator.c.

◆ qpsk_demodulator_destroy()

void qpsk_demodulator_destroy

(

qpsk_demodulator_s *

qpsk_demodulator

)

Frees all memory allocated by QPSK demodulator.

Parameters

qpsk_demodulator

QPSK demodulator's struct

Definition at line 481 of file qpsk_demodulator.c.

◆ qpsk_demodulator_init()

qpsk_demodulator_s * qpsk_demodulator_init	(	float	sample_rate,
		float	lo_frequency,
		float	bandwidth,
		uint16_t	halfcycles_per_symbol,
		float	carrier_start_threshold,
		float	carrier_lost_threshold,
		float	pll_lock_threshold,
		float	pll_lock_time
	)

Initializes QPSK demodulator.

Parameters

sample_rate	Sampling rate (in Hz)
lo_frequency	Carrier frequency (local oscillator) (in Hz)
bandwidth	Input signal bandwidth (in Hz)
halfcycles_per_symbol	Rate of symbols in carrier halfcycles (2 halfcycles = 1 full carrier wave cycle)
carrier_start_threshold	Signal must be above this threshold to start PLL locking and demodulating (in dBFS RMS)
carrier_lost_threshold	Signal must be below this threshold to stop PLL locking and demodulating (in dBFS RMS)
pll_lock_threshold	PLL's input (IQ error) should't change during pll_lock_time more than this value
pll_lock_time	PLL's input (IQ error) should't change during this time (in seconds) more than pll_lock_threshold

Returns: qpsk_demodulator_s* QPSK demodulator's struct

Definition at line 61 of file qpsk_demodulator.c.

◆ qpsk_demodulator_reset()

void qpsk_demodulator_reset

(

qpsk_demodulator_s *

qpsk_demodulator

)

Resets QPSK demodulator to the initial state.

Parameters

qpsk_demodulator

QPSK demodulator's struct

Definition at line 449 of file qpsk_demodulator.c.

Generated by

1.9.8

A failed attempt to build a case of QPSK modulation and demodulation case

I tried to use these functions to build a QPSK modulation and demodulation case, but the demodulation results and the input data are very different, the main program is as follows, I think it is the function parameter setting problem, hope the author can point out the error or provide a correct QPSK modulation and demodulation case, thank you very much!

`#include <stdlib.h>
#include <stdint.h>
#include <math.h>
#include "butterworth_filter.h"
#include "rrc_filter.h"
#include "qpsk_modulator.h"
#include "bytes_symbols_converter.h"
#include "file_reader.h"
#include "qpsk_demodulator.h"
#include "pll.h"
#include "butterworth_filter.h"

int main() {

read_file();
uint32_t bytes_length = file_len;
uint32_t start_silence_length = 10;
uint32_t preamble_length = 10;
uint8_t add_iq_sync_byte = 1;
uint32_t end_silence_length = 10;

uint8_t* symbols = bytes_to_symbols(file_buf, bytes_length, start_silence_length, preamble_length, add_iq_sync_byte, end_silence_length);

uint32_t symbols_length = bytes_to_symbols_calculate_length(bytes_length, start_silence_length, preamble_length, add_iq_sync_byte, end_silence_length);

//初始化QPSK调制器
qpsk_modulator_s* qpsk_modulator = qpsk_modulator_init(10000,5000,2000,2,100.0);

// 计算所需的样本数
uint32_t samples_length = qpsk_modulator_calculate_samples_chunk_length(qpsk_modulator, symbols_length);

// 为 IQ 样本序列分配内存
float* samples_chunk = malloc(samples_length * sizeof(float));

// 调制符号
qpsk_modulator_modulate_chunk(qpsk_modulator, symbols, symbols_length, samples_chunk, 1);

// 初始化 QPSK 解调器
uint8_t* symbols_demodulate = malloc(samples_length * sizeof(uint8_t));

qpsk_demodulator_s* qpsk_demodulator = qpsk_demodulator_init(10000, 5000, 2000, 2, -1, 1, 1e4, 1e-6);

qpsk_demodulator_demodulate_chunk(qpsk_demodulator, samples_chunk, samples_length, symbols_demodulate, 1);

uint8_t* symbols_demodulate2 = malloc(symbols_length * sizeof(uint8_t));

symbols_demodulate2 = symbols_remove_empty(symbols_demodulate2, symbols_length);

symbols_demodulate2 = symbols_to_bytes(symbols_demodulate, symbols_length);

return 0;

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