\qquad 下面是HD-GR GNSS导航软件的BDS B1I信号捕获和跟踪实现代码，入口函数b1i_track_channels(…)：
// b1i_accum_task.c -- BDS B1I signal carrier and code tracking.
/*
* Copyright (C) 2005 Andrew Greenberg
* Distributed under the GNU GENERAL PUBLIC LICENSE (GPL) Version 2 (June 1991).
* See the "COPYING" file distributed with this software for more information.
*/
/* Namuru GPS OpenSource receiver project
* Original : tracking.c
* Modes : Some code has been modified for adaption to the Namuru HW by Peter Mumford
*
* In general, the original code has been commented out and
* replaced (with peters initials (pjm) on the new code lines).
* The Namuru HW is different from the GP4020 / 2021 in the following points:
* 1) early, prompt and late correlators, each separated by 0.5 chips
*
* version : V1.0
* date : 21st/Dec/2006
*/
/*
* HD-GR GNSS receiver project
* Modes : Inherited the code of tracking.c in the Namuru GPS receiver project
* V1.0 and made necessary adjustments to adapt to the new HW, RTOS and
* functions.
* version : V1.0
* date : xx/xx/2015
*/
#include <io.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include "includes.h"
#include "system.h"
#include "altera_avalon_pio_regs.h"
#include "alt_types.h"
#include "sys/alt_irq.h"
#include "main_allocate.h"
#include "b1i_accum_task.h"
#include "b1i_message.h"
/*******************************************************************************
* #defines
******************************************************************************/
// m_B1I_CH[ch].ef_out = m_B1I_CH[ch].ef_out/(2*PI_SHIFT14*T), T=0.02 s
// m_B1I_CH[ch].ef_out = m_B1I_CH[ch].ef_out/((20-2)*B1I_CARR_FREQ_RES)
#define B1I_PULLIN_EFOUT_COF (int)(0.5+0.72*PI_SHIFT14*B1I_CARR_FREQ_RES)
/*******************************************************************************
* Global variables
******************************************************************************/
b1i_chan_t m_B1I_CH[B1I_MAX_CHANNELS] __attribute__ ((section(".isrdata.rwdata")));
unsigned short m_D1SecCode[20] __attribute__ ((section(".isrdata.rwdata"))) =
{
0,0,0,0,0,1,0,0,1,1,0,1,0,1,0,0,1,1,1,0};
//
// ACCUM
//
/*******************************************************************************
* Static (module level) variables
******************************************************************************/
short m_B1iCarrSrchStep __attribute__ ((section(".isrdata.rwdata"))); // carry search step length
static unsigned short B1iCarrSrchWidth __attribute__ ((section(".isrdata.rwdata"))); // carry search width
static short B1iPullInTime __attribute__ ((section(".isrdata.rwdata")));
static short B1iPhaseTest __attribute__ ((section(".isrdata.rwdata")));
/*******************************************************************************
* 以下环路滤波参数未初始化。引用该源文件代码可在此将它们初始化为适合目标基带模块参数的值。例如：
* static long B1i_Pull_Carr_C0 __attribute__ ((section(".isrdata.rwdata"))) = 910;
*
* date: 17st/Sep/2021
******************************************************************************/
static long B1i_Pull_Code_TtwoTone __attribute__ ((section(".isrdata.rwdata")));
static long B1i_Pull_Code_DtTone __attribute__ ((section(".isrdata.rwdata")));
static long D1_Lock_Code_TtwoTone __attribute__ ((section(".isrdata.rwdata")));
static long D1_Lock_Code_DtTone __attribute__ ((section(".isrdata.rwdata")));
static long D2_Lock_Code_TtwoTone __attribute__ ((section(".isrdata.rwdata")));
static long D2_Lock_Code_DtTone __attribute__ ((section(".isrdata.rwdata")));
static long B1i_Pull_Carr_C0 __attribute__ ((section(".isrdata.rwdata")));
static long B1i_Pull_Carr_C1 __attribute__ ((section(".isrdata.rwdata")));
static long B1i_Pull_Carr_C2 __attribute__ ((section(".isrdata.rwdata")));
static long B1i_Lock_Carr_C0 __attribute__ ((section(".isrdata.rwdata")));
static long B1i_Lock_Carr_C1 __attribute__ ((section(".isrdata.rwdata")));
static long B1i_Lock_Carr_C2 __attribute__ ((section(".isrdata.rwdata")));
/*******************************************************************************
* Prototypes (Local visible functions)
******************************************************************************/
static void b1i_backto_acquire( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
static void b1i_enter_pull_in( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
static void b1i_check_signal( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
static void b1i_dll( unsigned short ch, long dcode_freq, long TtwoTone, long DtTone) __attribute__ ((section(".isrcode.txt")));
static void b1i_pll1( unsigned short ch, long dcarr_phase, long dcarr_freq, long c0, long c1, long c2) __attribute__ ((section(".isrcode.txt")));
static void b1i_acquire( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
static void b1i_confirm( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
static void b1i_freq_pull( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
static void b1i_pull_in( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
static void b1i_lock( unsigned short ch) __attribute__ ((section(".isrcode.txt")));
#ifdef B1I_FALSE_PHASE_LOCK_DETECTOR
static short b1i_cd1sec_FPLD(unsigned short ch) __attribute__ ((section(".isrcode.txt")));
#endif // B1I_FALSE_PHASE_LOCK_DETECTOR
/*******************************************************************************
* Write 32 bits to the code DCO rate and carrier DCO rate registers
*
* Modified by Peter Mumford for namuru HW (2006)
* Modified by Cheng Huaide for HD-GR GNSS (2015)
******************************************************************************/
inline void b1i_set_code_dco_rate( unsigned short ch, unsigned long freq)
{
write_to_correlator( (B1I_CH00_BASE + ch * CH_BASE_STEP + CODE_NCO), freq );
}
inline void b1i_set_carrier_dco_rate( unsigned short ch, unsigned long freq)
{
write_to_correlator( (B1I_CH00_BASE + ch * CH_BASE_STEP + CARRIER_NCO), freq );
}
/*
* False Phase Lock Detector (FPLD)
*/
#ifdef B1I_FALSE_PHASE_LOCK_DETECTOR
// FPLD defines
#define FPLD_G_THRESHOLD (PI_SHIFT14 / 12) // 15 deg.
static short b1i_cd1sec_FPLD(unsigned short ch)
{
signed long i_now = m_B1I_CH[ch].i_p_20 >> 4;
signed long q_now = m_B1I_CH[ch].q_p_20 >> 4;
signed long i_old = m_B1I_CH[ch].i_p_20_1 >> 4;
signed long q_old = m_B1I_CH[ch].q_p_20_1 >> 4;
signed long C = i_old*q_now - q_old*i_now;
signed long D = i_old*i_now + q_old*q_now;
if (m_B1I_CH[ch].cnt_fpld == 0) {
m_B1I_CH[ch].c_fpld = 0;
m_B1I_CH[ch].d_fpld = 0;
}
m_B1I_CH[ch].cnt_fpld ++;
m_B1I_CH[ch].c_fpld += (C - m_B1I_CH[ch].c_fpld)/m_B1I_CH[ch].cnt_fpld;
m_B1I_CH[ch].d_fpld += (D - m_B1I_CH[ch].d_fpld)/m_B1I_CH[ch].cnt_fpld;
if (m_B1I_CH[ch].cnt_fpld == 50) {
m_B1I_CH[ch].cnt_fpld = 0;
C = fix_atan2(m_B1I_CH[ch].c_fpld, m_B1I_CH[ch].d_fpld);
if (labs(C) > FPLD_G_THRESHOLD) {
return C;
}
}
return 0;
}
#endif // B1I_FALSE_PHASE_LOCK_DETECTOR
/******************************************************************************
* Need to set up m_B1I_CH[] structure and initialize the loop dynamic parameters.
******************************************************************************/
void b1i_initialize_tracking( void)
{
unsigned short ch;
// Why are these a good choices?
B1iCarrSrchWidth = 40; // search 20 frequency steps on either side
m_B1iCarrSrchStep = (short)(400./B1I_CARR_FREQ_RES); // 400Hz (CHD)
B1iPullInTime = 1000; // 1 second
B1iPhaseTest = 500; // last 1/2 second of pull in, start phase test
for (ch = 0; ch < B1I_MAX_CHANNELS; ch++) {
m_B1I_CH[ch].state = CHANNEL_OFF;
}
}
static void b1i_backto_acquire( unsigned short ch)
{
m_B1I_CH[ch].state = CHANNEL_ACQUISITION;
// flag the message_thread that the past subframes are no longer valid
b1i_clear_messages(ch);
m_B1I_CH[ch].codes = 0;
m_B1I_CH[ch].code_freq = B1I_CODE_REF;
b1i_set_code_dco_rate(ch, m_B1I_CH[ch].code_freq);
// Clear sync flags
m_B1I_CH[ch].bit_sync = 0;
}
void b1i_enter_pull_in( unsigned short ch)
{
m_B1I_CH[ch].state = CHANNEL_PULL_IN;
m_B1I_CH[ch].ch_time = 0;
m_B1I_CH[ch].th_rms = 0;
m_B1I_CH[ch].bit_sync = 0;
m_B1I_CH[ch].dcode_freq_1 = 0;
m_B1I_CH[ch].dcarr_phase_1 = 0;
m_B1I_CH[ch].dcarr_phase_2 = 0;
// Some garbage data
m_B1I_CH[ch].ms_sign = 0x12345;
m_B1I_CH[ch].ms_count = 0;
m_B1I_CH[ch].ms_count_20 = 0;
m_B1I_CH[ch].tang = 0;
}
static void b1i_check_signal( unsigned short ch)
{
// Amplitude Tang decider, exit if the amplitude is always small.
if (m_B1I_CH[ch].p_mag<TANG_THRESHOLD) {
m_B1I_CH[ch].tang-=3;
}
else if (m_B1I_CH[ch].tang<90) {
m_B1I_CH[ch].tang+=1;
}
if (m_B1I_CH[ch].tang<-30) {
b1i_backto_acquire(ch);
}
}
static void b1i_dll( unsigned short ch, long dcode_freq, long TtwoTone, long DtTone)
{
long ddf = (dcode_freq - m_B1I_CH[ch].dcode_freq_1) * TtwoTone;
m_B1I_CH[ch].code_freq += (dcode_freq * DtTone + ddf) >> 14;
b1i_set_code_dco_rate( ch, m_B1I_CH[ch].code_freq);
m_B1I_CH[ch].dcode_freq_1 = dcode_freq;
}
static void b1i_pll1( unsigned short ch, long dcarr_phase, long dcarr_freq, long c0, long c1, long c2)
{
long ddcar = dcarr_phase*c0 + m_B1I_CH[ch].dcarr_phase_1*c1 + dcarr_freq*c2;
m_B1I_CH[ch].carrier_freq += ddcar >> 14;
b1i_set_carrier_dco_rate( ch, m_B1I_CH[ch].carrier_freq);
m_B1I_CH[ch].dcarr_phase_1 = dcarr_phase;
}
/******************************************************************************
FUNCTION b1i_acquire( unsigned short ch)
RETURNS None.
PARAMETERS
ch char // Which correlator channel to use
PURPOSE to perform initial b1i_acquire by searching code and frequency space
looking for a high correlation
Original function : acquire
WRITTEN BY
Clifford Kelley
Modified by Peter Mumford for namuru HW (2006)
Modified by Cheng Huaide for HD-GR GNSS (2015)
******************************************************************************/
static void b1i_acquire( unsigned short ch)
{
// Search carrier frequency bins
if (abs(m_B1I_CH[ch].n_freq) <= B1iCarrSrchWidth) {
long power;
power = m_B1I_CH[ch].e_mag + m_B1I_CH[ch].p_mag + m_B1I_CH[ch].l_mag;
if (power > ACQ_THRESHOLD) {
m_B1I_CH[ch].state = CHANNEL_CONFIRM;
m_B1I_CH[ch].n_confirm = 0;
m_B1I_CH[ch].m_thresh = 0;
return;
}
// No satellite yet; try delaying the code DCO 1/2 chip
// accumulators[ch].write.code_slew_counter = 1;
write_to_correlator(B1I_CH00_BASE + ch * CH_BASE_STEP + CODE_SLEW, 1);
// Keep count of how many code phases we've searched
m_B1I_CH[ch].codes++;
// if (m_B1I_CH[ch].codes > 2044) // PRN code length in 1/2 chips
// All code offsets have been searched; try another frequency bin
if (m_B1I_CH[ch].codes > 4091) {
// reset code phase count
m_B1I_CH[ch].codes = 0;
// Move to another frequency bin
// Note the use of carrier_corr, this is meant to be a correction
// for estimated TCXO frequency error, currently set to zero.
// See the comment in cold_allocate_channel()
// Generate a search sequence: 0, 1, -1, 2, -2, ...
// This can be re-written to avoid the multiply.
if (m_B1I_CH[ch].n_freq & 1) {
// Odd search bins map to the "right"
m_B1I_CH[ch].carrier_freq = B1I_CARRIER_REF + m_B1I_CH[ch].carrier_corr +
m_B1iCarrSrchStep * (1 + (m_B1I_CH[ch].n_freq >> 1));
}
else {
// Even search bins are to the "left" of B1I_CARRIER_REF
m_B1I_CH[ch].carrier_freq = B1I_CARRIER_REF + m_B1I_CH[ch].carrier_corr -
m_B1iCarrSrchStep * (m_B1I_CH[ch].n_freq >> 1);
}
// Set carrier DCO
b1i_set_carrier_dco_rate(ch, m_B1I_CH[ch].carrier_freq);
m_B1I_CH[ch].n_freq++; // next time try the next search bin
}
}
else {
// End of frequency search: release the channel. A mainline thread will
// eventually allocate another satellite PRN to this channel
m_B1I_CH[ch].state = CHANNEL_OFF;
}
}
/*******************************************************************************
FUNCTION b1i_confirm(unsigned short ch)
RETURNS None.
PARAMETERS
ch char channel number
PURPOSE to b1i_lock the presence of a high correlation peak using an n of m
algorithm
Original function : confirm
WRITTEN BY
Clifford Kelley
Modified by Peter Mumford for namuru HW (2006)
Modified by Cheng Huaide for HD-GR GNSS (2015)
*******************************************************************************/
static void b1i_confirm( unsigned short ch)
{
long power;
// count number of b1i_confirm attempts
m_B1I_CH[ch].n_confirm++;
power = m_B1I_CH[ch].e_mag + m_B1I_CH[ch].p_mag + m_B1I_CH[ch].l_mag;
if (power > ACQ_THRESHOLD) {
// count number of good hits
m_B1I_CH[ch].m_thresh++;
}
// try "n" b1i_confirm attempts
if (m_B1I_CH[ch].n_confirm > 10) {
// confirmed if good hits >= "m"
if (m_B1I_CH[ch].m_thresh >= 8) {
m_B1I_CH[ch].state = CHANNEL_FREQ_PULL;
m_B1I_CH[ch].ch_time = 0;
m_B1I_CH[ch].th_rms = 0;
m_B1I_CH[ch].bit_sync = 0;
m_B1I_CH[ch].dcode_freq_1 = 0;
m_B1I_CH[ch].dcarr_phase_1 = 0;
m_B1I_CH[ch].dcarr_phase_2 = 0;
// Some garbage data
m_B1I_CH[ch].ms_sign = 0x12345;
m_B1I_CH[ch].ms_count = 0;
m_B1I_CH[ch].tang = 0;
m_B1I_CH[ch].ef_out = 0;
m_B1I_CH[ch].ef_max = -0x7fffffff;
m_B1I_CH[ch].ef_min = 0x7fffffff;
}
else {
// Keep searching - assumes search parameters are still ok
m_B1I_CH[ch].state = CHANNEL_ACQUISITION;
// Clear sync flags
m_B1I_CH[ch].bit_sync = 0;
}
}
}
/*******************************************************************************
FUNCTION b1i_freq_pull(unsigned short ch)
RETURNS None.
PARAMETERS
ch char channel number
PURPOSE to adjust the frequency of the acquired signal using a FLL.
*******************************************************************************/
static void b1i_freq_pull( unsigned short ch)
{
b1i_check_signal(ch);
if (m_B1I_CH[ch].state != CHANNEL_FREQ_PULL) {
return;
}
// Calculate frequency error
signed long C = m_B1I_CH[ch].i_p_1*m_B1I_CH[ch].q_p - m_B1I_CH[ch].q_p_1*m_B1I_CH[ch].i_p;
signed long D = m_B1I_CH[ch].i_p_1*m_B1I_CH[ch].i_p + m_B1I_CH[ch].q_p_1*m_B1I_CH[ch].q_p;
signed long df = fix_atan2(C, D);
// Accumulate frequency error
m_B1I_CH[ch].ef_out += df;
if (m_B1I_CH[ch].ef_max < df) m_B1I_CH[ch].ef_max = df;
if (m_B1I_CH[ch].ef_min > df) m_B1I_CH[ch].ef_min = df;
m_B1I_CH[ch].ms_count ++;
if (m_B1I_CH[ch].ms_count == 20) {
// Set carrier NCO
df = (m_B1I_CH[ch].ef_out - (m_B1I_CH[ch].ef_max + m_B1I_CH[ch].ef_min))/B1I_PULLIN_EFOUT_COF;
m_B1I_CH[ch].carrier_freq += df;
b1i_set_carrier_dco_rate( ch, m_B1I_CH[ch].carrier_freq);
b1i_enter_pull_in(ch);
}
}
/*******************************************************************************
FUNCTION b1i_pull_in( unsigned short ch)
RETURNS None.
PARAMETERS
ch char channel number
PURPOSE
pull in the frequency by trying to track the signal with a
combination FLL and PLL
it will attempt to track for xxx ms, the last xxx ms of data will be
gathered to determine if we have both code and carrier b1i_lock
if so we will transition to track
Original function : pull_in
WRITTEN BY
Clifford Kelley
Modified by Peter Mumford for namuru HW (2006)
Modified by Cheng Huaide for HD-GR GNSS (2015)
*******************************************************************************/
static void b1i_pull_in( unsigned short ch)
{
b1i_check_signal(ch);
if (m_B1I_CH[ch].state != CHANNEL_PULL_IN) {
return;
}
signed long C, D, M;
signed long i_sum, q_sum;
signed long dcode_freq, dcarr_phase, dcarr_freq;
unsigned short check_bit_sync = 0;
// This branch is probably almost always taken, so maybe skip the test?
// If both zero the correction is not zero (2nd order) except this test
// makes it so, which is a kink in the transfer function. Is this right?
if ((m_B1I_CH[ch].e_mag != 0) || (m_B1I_CH[ch].l_mag != 0)) {
dcode_freq = ((m_B1I_CH[ch].e_mag - m_B1I_CH[ch].l_mag)<<14) /
(m_B1I_CH[ch].e_mag + m_B1I_CH[ch].l_mag);
if (m_B1I_CH[ch].ch_time <= 2) {
m_B1I_CH[ch].dcode_freq_1 = dcode_freq;
}
else {
b1i_dll(ch, dcode_freq, B1i_Pull_Code_TtwoTone, B1i_Pull_Code_DtTone);
}
}
// dcarr_phase is a measure of phase error
i_sum = m_B1I_CH[ch].i_p + m_B1I_CH[ch].i_e + m_B1I_CH[ch].i_l;
q_sum = m_B1I_CH[ch].q_p + m_B1I_CH[ch].q_e + m_B1I_CH[ch].q_l;
if (i_sum || q_sum) {
dcarr_phase = fix_atan(q_sum, i_sum);
}
else {
dcarr_phase = m_B1I_CH[ch].dcarr_phase_1;
}
// Increase 1 ms epoch counter modulo 20 or 2
m_B1I_CH[ch].ms_count++;
if (m_B1I_CH[ch].ms_count > m_B1I_CH[ch].ms_maxval) {
m_B1I_CH[ch].ms_count = 0;
}
m_B1I_CH[ch].ms_count_20++;
if (m_B1I_CH[ch].ms_count_20 > 19) {
m_B1I_CH[ch].ms_count_20 = 0;
}
// Check if the last 20 ms (2 ms) have the same sign and this dump
// is different: if so, then we just had a bit edge transition
if (!m_B1I_CH[ch].bit_sync) {
unsigned long ms_sign;
unsigned short bit_sign = (i_sum < 0) ? 1:0;
if (IS_D1_NAVMESSAGE(m_B1I_CH[ch].prn)) {
// 剥离二次编码
ms_sign = (m_B1I_CH[ch].ms_sign ^ D1_SECONDARY_CODE);
// 如果符号发生变化且ms_sign的20位符号不变
if ((bit_sign != (ms_sign & 1)) &&
(ms_sign == 0 || ms_sign == 0xfffff)) {
check_bit_sync = 1;
}
}
else {
// 如果符号发生变化
if (bit_sign != (m_B1I_CH[ch].ms_sign & 1)) {
// 计算差分值: 如果所有奇数位为0，则位同步
ms_sign = m_B1I_CH[ch].ms_sign ^ (m_B1I_CH[ch].ms_sign << 1);
if ((ms_sign & 0xaaaaa) == 0) {
check_bit_sync = 1;
}
}
}
}
// Shift sign buffer to left
m_B1I_CH[ch].ms_sign = ((m_B1I_CH[ch].ms_sign << 1) & 0xfffff);
// Set the LSB bit if negative
if (i_sum < 0) {
m_B1I_CH[ch].ms_sign |= 1;
}
if (check_bit_sync) {
// Test if last two sums were within 1/4 radian of pi/2
// 4096 correponds to 1/4 of radian or aobut 14 degree. This is a strict
// requirement, since we could accept up to 20 degree phase error.
// 20 degree corresponds to 5719
if ((labs( dcarr_phase) < 5719) && // 4096
(labs( m_B1I_CH[ch].dcarr_phase_1) < 5719)) {
// 4096
// Let the world know we're synced to the satellite message bits
m_B1I_CH[ch].bit_sync = 1;
// sync the ms count to the bit stream
m_B1I_CH[ch].ms_count = 0;
m_B1I_CH[ch].ms_count_20 = 0;
// set the flag that tells tracking() to set the 1ms epoch counter
// after the accumulator registers are read: this will sync the
// epoch counter with the bit stream (and the ms_count, too).
m_B1I_CH[ch].load_1ms_epoch_count = 1;
}
}
// Near the end of pull in, start the phase test
if (m_B1I_CH[ch].ch_time > (B1iPullInTime - B1iPhaseTest)) {
m_B1I_CH[ch].th_rms += (dcarr_phase * dcarr_phase) >> 14;
}
// b1i_pull_in Carrier tracking loop
if (m_B1I_CH[ch].ch_time <= 5) {
m_B1I_CH[ch].dcarr_phase_2 = m_B1I_CH[ch].dcarr_phase_1;
m_B1I_CH[ch].dcarr_phase_1 = dcarr_phase;
}
else {
C = (m_B1I_CH[ch].i_p_1*m_B1I_CH[ch].q_p - m_B1I_CH[ch].q_p_1*m_B1I_CH[ch].i_p);
D = (m_B1I_CH[ch].i_p_1*m_B1I_CH[ch].i_p + m_B1I_CH[ch].q_p_1*m_B1I_CH[ch].q_p);
M = lmag(C,D);
dcarr_freq = (D >= 0) ? (C<<14)/M:-(C<<14)/M;
b1i_pll1(ch, dcarr_phase, dcarr_freq, B1i_Pull_Carr_C0, B1i_Pull_Carr_C1, B1i_Pull_Carr_C2);
}
m_B1I_CH[ch].ch_time++;
// Done with pull in. Wait until the end of a data bit.
// Are we sure we even think we're data-locked now?
// A bit transition will happen at the next dump.
if ((m_B1I_CH[ch].ms_count == m_B1I_CH[ch].ms_maxval) &&
(m_B1I_CH[ch].ch_time >= B1iPullInTime)) {
// Calculate the mean square value of phase error. Because of the function
// fix_sqrt enlarges the root result by 2^7, so the unit of the mean square
// value is still 1 radian = 16384, and the subsequent mean square error
// 12000 is about 40 degrees.
// m_B1I_CH[ch].th_rms = fix_sqrt( m_B1I_CH[ch].th_rms / B1iPhaseTest);
// Sufficient signal, transition to tracking mode
// (12000*12000 >> 14) = 8789.0625
// if (m_B1I_CH[ch].bit_sync && m_B1I_CH[ch].th_rms < 12000) {
if (m_B1I_CH[ch].bit_sync && m_B1I_CH[ch].th_rms < (8789*B1iPhaseTest)) {
// Bit edge was detected.
// Sufficient signal, transition to tracking mode
m_B1I_CH[ch].i_p_20 = 0;
m_B1I_CH[ch].i_e_20 = 0;
m_B1I_CH[ch].i_l_20 = 0;
m_B1I_CH[ch].q_p_20 = 0;
m_B1I_CH[ch].q_e_20 = 0;
m_B1I_CH[ch].q_l_20 = 0;
#ifdef B1I_CODE_LOOP_20MS_RATE
#endif // B1I_CODE_LOOP_20MS_RATE
#ifdef B1I_FALSE_PHASE_LOCK_DETECTOR
m_B1I_CH[ch].i_p_20_1 = 0;
m_B1I_CH[ch].q_p_20_1 = 0;
m_B1I_CH[ch].c_fpld = 0;
m_B1I_CH[ch].d_fpld = 0;
m_B1I_CH[ch].cnt_fpld = 0;
m_B1I_CH[ch].tot_fpld = 0;
#endif // B1I_FALSE_PHASE_LOCK_DETECTOR
// Officially switch modes
m_B1I_CH[ch].state = CHANNEL_LOCK;
}
else {
// We lost the pullin. Eventually, do a nice transition back to
// b1i_confirm and/or b1i_acquire. For now, to be paranoid, just kill
// the channel.
b1i_backto_acquire(ch);
}
}
}
/*******************************************************************************
FUNCTION b1i_lock( unsigned short ch)
RETURNS None.
PARAMETERS char ch , channel number
PURPOSE track carrier and code, and partially decode the navigation message
(to determine TOW, subframe etc.)
Original function : lock
WRITTEN BY
Clifford Kelley
added Carrier Aiding as suggested by Jenna Cheng, UCR
Modified by Peter Mumford for namuru HW (2006)
Modified by Cheng Huaide for HD-GR GNSS (2015)
*******************************************************************************/
static void b1i_lock( unsigned short ch)
{
b1i_check_signal(ch);
if (m_B1I_CH[ch].state != CHANNEL_LOCK) {
return;
}
signed long C, D, M;
signed long i_sum, q_sum;
signed long dcode_freq, dcarr_phase, dcarr_freq;
unsigned short D1Msg = IS_D1_NAVMESSAGE(m_B1I_CH[ch].prn);
// Check and correct ms_count_20 according to epoch_codes
if (m_B1I_CH[ch].epoch_codes < m_B1I_CH[ch].ms_count_20 && m_B1I_CH[ch].ms_count_20 != 19) {
m_B1I_CH[ch].ms_count_20 = 19;
}
else {
m_B1I_CH[ch].ms_count_20 = m_B1I_CH[ch].epoch_codes;
}
// Increment the time, in 20ms, since the week began. Used in the measurement
// thread. Also set to the true time of week when we get the TOW from a valid
// subframe in the messages thread.
if (m_B1I_CH[ch].ms_count_20 == 19) {
m_B1I_CH[ch].time_in_bits++;
if (m_B1I_CH[ch].time_in_bits >= BITS_IN_WEEK_50HZ)
m_B1I_CH[ch].time_in_bits -= BITS_IN_WEEK_50HZ;
}
// Update ms_count
m_B1I_CH[ch].ms_count = D1Msg ? (m_B1I_CH[ch].ms_count_20):(m_B1I_CH[ch].epoch_codes & 1);
// Carrier loop
i_sum = m_B1I_CH[ch].i_p + m_B1I_CH[ch].i_e + m_B1I_CH[ch].i_l;
q_sum = m_B1I_CH[ch].q_p + m_B1I_CH[ch].q_e + m_B1I_CH[ch].q_l;
if ((i_sum != 0) || (q_sum != 0)) {
C = (m_B1I_CH[ch].i_p_1*m_B1I_CH[ch].q_p - m_B1I_CH[ch].q_p_1*m_B1I_CH[ch].i_p);
D = (m_B1I_CH[ch].i_p_1*m_B1I_CH[ch].i_p + m_B1I_CH[ch].q_p_1*m_B1I_CH[ch].q_p);
M = lmag(C,D);
dcarr_freq = (D >= 0) ? (C<<14)/M:-(C<<14)/M;
dcarr_phase = sgn(i_sum) * (q_sum << 14) / lmag( i_sum, q_sum);
b1i_pll1(ch, dcarr_phase, dcarr_freq, B1i_Lock_Carr_C0, B1i_Lock_Carr_C1, B1i_Lock_Carr_C2);
}
// 20ms or 2ms accumulator
if (D1Msg && m_D1SecCode[m_B1I_CH[ch].ms_count]) {
m_B1I_CH[ch].i_p_20 -= m_B1I_CH[ch].i_p;
m_B1I_CH[ch].i_e_20 -= m_B1I_CH[ch].i_e;
m_B1I_CH[ch].i_l_20 -= m_B1I_CH[ch].i_l;
m_B1I_CH[ch].q_p_20 -= m_B1I_CH[ch].q_p;
m_B1I_CH[ch].q_e_20 -= m_B1I_CH[ch].q_e;
m_B1I_CH[ch].q_l_20 -= m_B1I_CH[ch].q_l;
}
else {
m_B1I_CH[ch].i_p_20 += m_B1I_CH[ch].i_p;
m_B1I_CH[ch].i_e_20 += m_B1I_CH[ch].i_e;
m_B1I_CH[ch].i_l_20 += m_B1I_CH[ch].i_l;
m_B1I_CH[ch].q_p_20 += m_B1I_CH[ch].q_p;
m_B1I_CH[ch].q_e_20 += m_B1I_CH[ch].q_e;
m_B1I_CH[ch].q_l_20 += m_B1I_CH[ch].q_l;
}
#ifndef B1I_CODE_LOOP_20MS_RATE
// Code tracking loop @ 1ms rate
dcode_freq = m_B1I_CH[ch].e_mag + m_B1I_CH[ch].l_mag;
if (dcode_freq != 0) {
dcode_freq = ((m_B1I_CH[ch].e_mag - m_B1I_CH[ch].l_mag)<<14)/dcode_freq;
b1i_dll(ch, dcode_freq, B1i_Pull_Code_TtwoTone, B1i_Pull_Code_DtTone);
}
#endif // B1I_CODE_LOOP_20MS_RATE
// Code tracking loop @ 20ms rate
if (m_B1I_CH[ch].ms_count == m_B1I_CH[ch].ms_maxval) {
/* Deleted by CHD -- 2020.4.29
if (!m_B1I_CH[ch].bit_sync) {
b1i_backto_acquire(ch);
return;
}
Deleted by CHD -- 2020.4.29 */
#ifdef B1I_CODE_LOOP_20MS_RATE
// Code tracking loop @ 20ms rate
signed long e_mag_20 = lmag( m_B1I_CH[ch].i_e_20, m_B1I_CH[ch].q_e_20);
signed long l_mag_20 = lmag( m_B1I_CH[ch].i_l_20, m_B1I_CH[ch].q_l_20);
dcode_freq = e_mag_20 + l_mag_20;
if (dcode_freq != 0) {
dcode_freq = ((e_mag_20 - l_mag_20) << 14)/dcode_freq;
if (D1Msg) {
b1i_dll(ch, dcode_freq, D1_Lock_Code_TtwoTone, D1_Lock_Code_DtTone);
}
else {
b1i_dll(ch, dcode_freq, D2_Lock_Code_TtwoTone, D2_Lock_Code_DtTone);
}
}
#endif // B1I_CODE_LOOP_20MS_RATE
// Data bit
// m_B1I_CH[ch].bit = ((m_B1I_CH[ch].i_e_20 + m_B1I_CH[ch].i_l_20 + m_B1I_CH[ch].i_p_20) > 0);
if ((m_B1I_CH[ch].i_e_20 + m_B1I_CH[ch].i_l_20 + m_B1I_CH[ch].i_p_20) > 0) {
g_channel_bits |= (1 << ch);
}
// Flag that this bit is ready to process (written to the message_flag
// in the tracking() function after we've gone through all the channels
#ifdef B1I_SYNC_PROCESS_FRAME_SYNC
if (m_messages[ch].frame_sync) {
g_channels_with_bits |= (1 << ch);
}
else {
// sync_frame(ch, m_B1I_CH[ch].bit);
sync_frame(ch, (g_channel_bits & (1 << ch)) ? 1:0);
}
#else
g_channels_with_bits |= (1 << ch);
#endif // B1I_SYNC_PROCESS_FRAME_SYNC
#ifdef B1I_FALSE_PHASE_LOCK_DETECTOR
if (D1Msg) {
m_B1I_CH[ch].tot_fpld ++;
if (m_B1I_CH[ch].tot_fpld > 50) {
dcarr_phase = b1i_cd1sec_FPLD(ch);
if (dcarr_phase != 0) {
m_B1I_CH[ch].carrier_freq += (dcarr_phase>0) ? (25/B1I_CARR_FREQ_RES):-(25/B1I_CARR_FREQ_RES);
b1i_set_carrier_dco_rate( ch, m_B1I_CH[ch].carrier_freq);
}
}
m_B1I_CH[ch].i_p_20_1 = m_B1I_CH[ch].i_p_20;
m_B1I_CH[ch].q_p_20_1 = m_B1I_CH[ch].q_p_20;
}
#endif // B1I_FALSE_PHASE_LOCK_DETECTOR
// Clear coherent accumulations
m_B1I_CH[ch].i_p_20 = 0;
m_B1I_CH[ch].i_e_20 = 0;
m_B1I_CH[ch].i_l_20 = 0;
m_B1I_CH[ch].q_p_20 = 0;
m_B1I_CH[ch].q_e_20 = 0;
m_B1I_CH[ch].q_l_20 = 0;
}
}
/*******************************************************************************
FUNCTION b1i_accum_newdata(unsigned long new_data)
RETURNS None.
PARAMETERS unsigned long new_data channel new data flags
PURPOSE Grab new accumulation data for each BDS channel.
*******************************************************************************/
void b1i_accum_newdata(unsigned long new_data)
{
unsigned short ch, ch_index;
// top of correlator block register map
ch_index = B1I_CH00_BASE;
// Sequentially check each channel for new data.
for (ch = 0; ch < B1I_MAX_CHANNELS; ch++) {
// if (new_data & (1 << ch))
if (new_data & (1 << ch)) {
m_B1I_CH[ch].i_p_1 = m_B1I_CH[ch].i_p;
m_B1I_CH[ch].q_p_1 = m_B1I_CH[ch].q_p;
// The built-in function IORD is used to maintain thread-safe operations. (pjm)
#ifdef ENABLE_32BIT_ACCUMULATOR
m_B1I_CH[ch].i_e = (signed long)(read_from_correlator( ch_index + I_EARLY ));
m_B1I_CH[ch].q_e = (signed long)(read_from_correlator( ch_index + Q_EARLY ));
m_B1I_CH[ch].i_p = (signed long)(read_from_correlator( ch_index + I_PROMPT ));
m_B1I_CH[ch].q_p = (signed long)(read_from_correlator( ch_index + Q_PROMPT ));
m_B1I_CH[ch].i_l = (signed long)(read_from_correlator( ch_index + I_LATE ));
m_B1I_CH[ch].q_l = (signed long)(read_from_correlator( ch_index + Q_LATE ));
#else // ENABLE_32BIT_ACCUMULATOR
m_B1I_CH[ch].i_e = (signed short)(read_from_correlator( ch_index + I_EARLY ));
m_B1I_CH[ch].q_e = (signed short)(read_from_correlator( ch_index + Q_EARLY ));
m_B1I_CH[ch].i_p = (signed short)(read_from_correlator( ch_index + I_PROMPT ));
m_B1I_CH[ch].q_p = (signed short)(read_from_correlator( ch_index + Q_PROMPT ));
m_B1I_CH[ch].i_l = (signed short)(read_from_correlator( ch_index + I_LATE ));
m_B1I_CH[ch].q_l = (signed short)(read_from_correlator( ch_index + Q_LATE ));
#endif // ENABLE_32BIT_ACCUMULATOR
// If the last dump was the first dump in a new satellite
// message data bit, then b1i_lock() sets the load_1ms_epoch_flag
// so that we can set the 1m epoch counter here. Why here?
// GP4020 Baseband Processor Design Manual, pg 60: "Ideally,
// epoch counter accesses should occur following the reading of
// the accumulation register at each DUMP." Great, thanks for
// the tip, now how 'bout you tell us WHY?!
if (m_B1I_CH[ch].load_1ms_epoch_count) {
// Load 1 ms epoch counter
write_to_correlator( ch_index + EPOCH_LOAD, 1 );
m_B1I_CH[ch].epoch_codes = 1;
m_B1I_CH[ch].load_1ms_epoch_count = 0;
}
else {
m_B1I_CH[ch].epoch_codes = read_from_correlator( ch_index + EPOCH_CHECK ) & 0x1F;
}
// To sync the 20ms epoch counter (the upper bits) we wait until
// we get a signal from the message thread that we just got the
// TLM+SOW words.
if (m_B1I_CH[ch].sync_20ms_epoch_count) {
unsigned long epoch_temp;
// 对于D1电文, 我们希望1ms epoch counter在信号失锁之前, 总是保持
// 同步的. 当我们获得TLM+SOW字时, 刚好位于当前子帧的第60-bits,
// 所以将它余50得10, 再左移5位得0x140.
if (IS_D1_NAVMESSAGE(m_B1I_CH[ch].prn)) {
epoch_temp = m_B1I_CH[ch].epoch_codes | 0x140;
}
// 对于D2电文, 1ms epoch counter的起点在位同步时只对齐了D2电文的
// 2ms-位, 并没有与20ms(时钟)起点对齐, 此时才有机会完成它.
// 1.当我们获得TLM+SOW字时, 刚好获得了当前页的第60-bits, 对应第
// 120ms, 为20ms的倍数;
// 2.如果对帧同步进行同步处理(在跟踪过程中直接调用sync_frame函数且这
// 之后没有丢失累积数据), 则本次处理对应的是设置帧同步参数
// (sync_20ms_epoch_count)后的第1个累积数据, 因此应有：
// (1) 1ms epoch counter = 0;
// (2) 20ms epoch counter = (sync_20ms_epoch_count % 50) << 5.
else {
epoch_temp = ((m_B1I_CH[ch].sync_20ms_epoch_count % 50) << 5);
m_B1I_CH[ch].epoch_codes = 0;
}
write_to_correlator( ch_index + EPOCH_LOAD, epoch_temp);
m_B1I_CH[ch].sync_20ms_epoch_count = 0;
}
// lmag approximates sqrt(i^2 + q^2) for long's
m_B1I_CH[ch].e_mag = lmag(m_B1I_CH[ch].i_e, m_B1I_CH[ch].q_e);
m_B1I_CH[ch].p_mag = lmag(m_B1I_CH[ch].i_p, m_B1I_CH[ch].q_p);
m_B1I_CH[ch].l_mag = lmag(m_B1I_CH[ch].i_l, m_B1I_CH[ch].q_l);
}
// increment channel index to top of next channel map
ch_index += CH_BASE_STEP;
}
}
/*******************************************************************************
FUNCTION b1i_track_channels(unsigned long new_data)
RETURNS None.
PARAMETERS unsigned long new_data channel new data flags
PURPOSE BDS channel signal acquisition and tracking main routine。
*******************************************************************************/
void b1i_track_channels(unsigned long new_data)
{
unsigned short ch;
// Finally, in a second (slower) loop, track each channel that dumped. Note
// that channels which are CHANNEL_OFF will be allocated satellites to
// track in a mainline thread.
for (ch = 0; ch < B1I_MAX_CHANNELS; ch++) {
// if( (new_data & (1 << ch)) && (m_B1I_CH[ch].state != CHANNEL_OFF))
// We already checked for dumped channels above, can we somehow
// avoid checking this again??
if ((new_data & (1 << ch)) && (m_B1I_CH[ch].state != CHANNEL_OFF)) {
// namuru (PJM)
switch (m_B1I_CH[ch].state) {
case CHANNEL_ACQUISITION:
b1i_acquire( ch);
break;
case CHANNEL_CONFIRM:
b1i_confirm( ch);
break;
case CHANNEL_FREQ_PULL:
b1i_freq_pull( ch);
break;
case CHANNEL_PULL_IN:
b1i_pull_in( ch);
break;
case CHANNEL_LOCK:
if (m_B1I_CH[ch].backto_pull_in) {
m_B1I_CH[ch].backto_pull_in = 0;
b1i_enter_pull_in(ch);
b1i_pull_in( ch);
}
else {
b1i_lock( ch);
}
break;
default:
// TODO: assert an error here
break;
}
}
// If the channel is off, set a flag saying so
if (m_B1I_CH[ch].state == CHANNEL_OFF) {
g_channels_to_allocate |= (1 << ch);
}
}
}