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