WSJT-X/lib/qra/qra64/qra64.h
Joe Taylor 8390bcd798 Add code for QRA64 with fast fading.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7295 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2016-11-06 00:53:47 +00:00

270 lines
11 KiB
C

// qra64.h
// Encoding/decoding functions for the QRA64 mode
//
// (c) 2016 - Nico Palermo, IV3NWV
// ------------------------------------------------------------------------------
// This file is part of the qracodes project, a Forward Error Control
// encoding/decoding package based on Q-ary RA (Repeat and Accumulate) LDPC codes.
//
// qracodes is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// qracodes is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with qracodes source distribution.
// If not, see <http://www.gnu.org/licenses/>.
#ifndef _qra64_h_
#define _qra64_h_
// qra64_init(...) initialization flags
#define QRA_NOAP 0 // don't use a-priori knowledge
#define QRA_AUTOAP 1 // use auto a-priori knowledge
#define QRA_USERAP 2 // a-priori knowledge messages provided by the user
// QRA code parameters
#define QRA64_K 12 // information symbols
#define QRA64_N 63 // codeword length
#define QRA64_C 51 // (number of parity checks C=(N-K))
#define QRA64_M 64 // code alphabet size
#define QRA64_m 6 // bits per symbol
// packed predefined callsigns and fields as defined in JT65
#define CALL_CQ 0xFA08319
#define CALL_QRZ 0xFA0831A
#define CALL_CQ000 0xFA0831B
#define CALL_CQ999 0xFA08702
#define CALL_CQDX 0x5624C39
#define CALL_DE 0xFF641D1
#define GRID_BLANK 0x7E91
// Types of a-priori knowledge messages
#define APTYPE_CQQRZ 0 // [cq/qrz ? ?/blank]
#define APTYPE_MYCALL 1 // [mycall ? ?/blank]
#define APTYPE_HISCALL 2 // [? hiscall ?/blank]
#define APTYPE_BOTHCALLS 3 // [mycall hiscall ?]
#define APTYPE_FULL 4 // [mycall hiscall grid]
#define APTYPE_CQHISCALL 5 // [cq/qrz hiscall ?/blank]
#define APTYPE_SIZE (APTYPE_CQHISCALL+1)
typedef struct {
float decEsNoMetric;
int apflags;
int apmsg_set[APTYPE_SIZE]; // indicate which ap type knowledge has
// been set by the user
// ap messages buffers
int apmsg_cqqrz[12]; // [cq/qrz ? ?/blank]
int apmsg_call1[12]; // [mycall ? ?/blank]
int apmsg_call2[12]; // [? hiscall ?/blank]
int apmsg_call1_call2[12]; // [mycall hiscall ?]
int apmsg_call1_call2_grid[12]; // [mycall hiscall grid]
int apmsg_cq_call2[12]; // [cq hiscall ?/blank]
int apmsg_cq_call2_grid[12]; // [cq hiscall grid]
// ap messages masks
int apmask_cqqrz[12];
int apmask_cqqrz_ooo[12];
int apmask_call1[12];
int apmask_call1_ooo[12];
int apmask_call2[12];
int apmask_call2_ooo[12];
int apmask_call1_call2[12];
int apmask_call1_call2_grid[12];
int apmask_cq_call2[12];
int apmask_cq_call2_ooo[12];
} qra64codec;
#ifdef __cplusplus
extern "C" {
#endif
qra64codec *qra64_init(int flags);
// QRA64 mode initialization function
// arguments:
// flags: set the decoder mode
// QRA_NOAP use no a-priori information
// QRA_AUTOAP use any relevant previous decodes
// QRA_USERAP use a-priori information provided via qra64_apset(...)
// returns:
// Pointer to initialized qra64codec data structure
// this pointer should be passed to the encoding/decoding functions
//
// 0 if unsuccessful (can't allocate memory)
// ----------------------------------------------------------------------------
void qra64_encode(qra64codec *pcodec, int *y, const int *x);
// QRA64 encoder
// arguments:
// pcodec = pointer to a qra64codec data structure as returned by qra64_init
// x = pointer to the message to be encoded, int x[12]
// x must point to an array of integers (i.e. defined as int x[12])
// y = pointer to encoded message, int y[63]=
// ----------------------------------------------------------------------------
int qra64_decode(qra64codec *pcodec, float *ebno, int *x, const float *r);
// QRA64 mode decoder
// arguments:
// pcodec = pointer to a qra64codec data structure as returned by qra64_init
// ebno = pointer to a float where the avg Eb/No (in dB) will be stored
// in case of successfull decoding
// (pass a null pointer if not interested)
// x = pointer to decoded message, int x[12]
// r = pointer to received symbol energies (squared amplitudes)
// r must point to an array of length QRA64_M*QRA64_N (=64*63=4032)
// The first QRA_M entries should be the energies of the first
// symbol in the codeword; the last QRA_M entries should be the
// energies of the last symbol in the codeword
//
// return code:
//
// The return code is <0 when decoding is unsuccessful
// -16 indicates that the definition of QRA64_NMSG does not match what required by the code
// If the decoding process is successfull the return code is accordingly to the following table
// rc=0 [? ? ?] AP0 (decoding with no a-priori)
// rc=1 [CQ ? ?] AP27
// rc=2 [CQ ? ] AP44
// rc=3 [CALL ? ?] AP29
// rc=4 [CALL ? ] AP45
// rc=5 [CALL CALL ?] AP57
// rc=6 [? CALL ?] AP29
// rc=7 [? CALL ] AP45
// rc=8 [CALL CALL GRID] AP72 (actually a AP68 mask to reduce false decodes)
// rc=9 [CQ CALL ?] AP55
// rc=10 [CQ CALL ] AP70 (actaully a AP68 mask to reduce false decodes)
// return codes in the range 1-10 indicate the amount and the type of a-priori
// information was required to decode the received message.
// Decode a QRA64 msg using a fast-fading metric
int qra64_decode_fastfading(
qra64codec *pcodec, // ptr to the codec structure
float *ebno, // ptr to where the estimated Eb/No value will be saved
int *x, // ptr to decoded message
float *rxen, // ptr to received symbol energies array
const int submode, // submode idx (0=QRA64A ... 4=QRA64E)
const float B90, // spread bandwidth (90% fractional energy)
const int fadingModel); // 0=Gaussian 1=Lorentzian fade model
//
// rxen: The array of the received bin energies
// Bins must be spaced by integer multiples of the symbol rate (1/Ts Hz)
// The array must be an array of total length U = L x N where:
// L: is the number of frequency bins per message symbol (see after)
// N: is the number of symbols in a QRA64 msg (63)
//
// The number of bins/symbol L depends on the selected submode accordingly to
// the following rule:
// L = (64+64*2^submode+64) = 64*(2+2^submode)
// Tone 0 is always supposed to be at offset 64 in the array.
// The m-th tone nominal frequency is located at offset 64 + m*2^submode (m=0..63)
//
// Submode A: (2^submode = 1)
// L = 64*3 = 196 bins/symbol
// Total length of the energies array: U = 192*63 = 12096 floats
//
// Submode B: (2^submode = 2)
// L = 64*4 = 256 bins/symbol
// Total length of the energies array: U = 256*63 = 16128 floats
//
// Submode C: (2^submode = 4)
// L = 64*6 = 384 bins/symbol
// Total length of the energies array: U = 384*63 = 24192 floats
//
// Submode D: (2^submode = 8)
// L = 64*10 = 640 bins/symbol
// Total length of the energies array: U = 640*63 = 40320 floats
//
// Submode E: (2^submode = 16)
// L = 64*18 = 1152 bins/symbol
// Total length of the energies array: U = 1152*63 = 72576 floats
//
// Note: The rxen array is modified and reused for internal calculations.
//
//
// B90: spread fading bandwidth in Hz (90% fractional average energy)
//
// B90 should be in the range 1 Hz ... 238 Hz
// The value passed to the call is rounded to the closest value among the
// 64 available values:
// B = 1.09^k Hz, with k=0,1,...,63
//
// I.e. B90=27 Hz will be approximated in this way:
// k = rnd(log(27)/log(1.09)) = 38
// B90 = 1.09^k = 1.09^38 = 26.4 Hz
//
// For any input value the maximum rounding error is not larger than +/- 5%
//
// return codes: same return codes of qra64_decode (+some additional error codes)
// Simulate the fast-fading channel (to be used with qra64_decode_fastfading)
int qra64_fastfading_channel(
float **rxen,
const int *xmsg,
const int submode,
const float EbN0dB,
const float B90,
const int fadingModel);
// Simulate transmission over a fading channel with given B90, fading model and submode
// and non coherent detection.
// Sets rxen to point to an array of bin energies formatted as required
// by the (fast-fading) decoding routine.
// returns 0 on success or negative values on error conditions
int qra64_apset(qra64codec *pcodec, const int mycall, const int hiscall, const int grid, const int aptype);
// Set decoder a-priori knowledge accordingly to the type of the message to
// look up for
// arguments:
// pcodec = pointer to a qra64codec data structure as returned by qra64_init
// mycall = mycall to look for
// hiscall = hiscall to look for
// grid = grid to look for
// aptype = define the type of AP to be set:
// APTYPE_CQQRZ set [cq/qrz ? ?/blank]
// APTYPE_MYCALL set [mycall ? ?/blank]
// APTYPE_HISCALL set [? hiscall ?/blank]
// APTYPE_BOTHCALLS set [mycall hiscall ?]
// APTYPE_FULL set [mycall hiscall grid]
// APTYPE_CQHISCALL set [cq/qrz hiscall ?/blank]
// returns:
// 0 on success
// -1 when qra64_init was called with the QRA_NOAP flag
// -2 invalid apytpe (valid range [APTYPE_CQQRZ..APTYPE_CQHISCALL]
// (APTYPE_CQQRZ [cq/qrz ? ?] is set by default )
void qra64_apdisable(qra64codec *pcodec, const int aptype);
// disable specific AP type
// arguments:
// pcodec = pointer to a qra64codec data structure as returned by qra64_init
// aptype = define the type of AP to be disabled
// APTYPE_CQQRZ disable [cq/qrz ? ?/blank]
// APTYPE_MYCALL disable [mycall ? ?/blank]
// APTYPE_HISCALL disable [ ? hiscall ?/blank]
// APTYPE_BOTHCALLS disable [mycall hiscall ? ]
// APTYPE_FULL disable [mycall hiscall grid]
// APTYPE_CQHISCALL set [cq/qrz hiscall ?/blank]
void qra64_close(qra64codec *pcodec);
// Free memory allocated by qra64_init
// arguments:
// pcodec = pointer to a qra64codec data structure as returned by qra64_init
// ----------------------------------------------------------------------------
// encode/decode std msgs in 12 symbols as done in jt65
void encodemsg_jt65(int *y, const int call1, const int call2, const int grid);
void decodemsg_jt65(int *call1, int *call2, int *grid, const int *x);
#ifdef __cplusplus
}
#endif
#endif // _qra64_h_