diff options
Diffstat (limited to 'Transceiver52M/Transceiver.cpp')
| -rw-r--r-- | Transceiver52M/Transceiver.cpp | 89 |
1 files changed, 83 insertions, 6 deletions
diff --git a/Transceiver52M/Transceiver.cpp b/Transceiver52M/Transceiver.cpp index c6042eb..c3446f8 100644 --- a/Transceiver52M/Transceiver.cpp +++ b/Transceiver52M/Transceiver.cpp @@ -25,6 +25,10 @@ #include "Transceiver.h" #include <Logger.h> +extern "C" { +#include "sch.h" +} + #ifdef HAVE_CONFIG_H #include "config.h" #endif @@ -405,6 +409,50 @@ bool Transceiver::detectSCH(TransceiverState *state, return false; } +#define SCH_BIT_SCALE 64 + +/* Decode SCH burst */ +bool Transceiver::decodeSCH(SoftVector *burst, GSM::Time *time) +{ + int fn; + struct sch_info sch; + ubit_t info[GSM_SCH_INFO_LEN]; + sbit_t data[GSM_SCH_CODED_LEN]; + + if (burst->size() < 156) { + std::cout << "Invalid SCH burst length" << std::endl; + return false; + } + + float_to_sbit(&(*burst)[3], &data[0], SCH_BIT_SCALE, 39); + float_to_sbit(&(*burst)[106], &data[39], SCH_BIT_SCALE, 39); + + if (!gsm_sch_decode(info, data)) { + gsm_sch_parse(info, &sch); + + std::cout << "SCH : Decoded values" << std::endl; + std::cout << " BSIC: " << sch.bsic << std::endl; + std::cout << " T1 : " << sch.t1 << std::endl; + std::cout << " T2 : " << sch.t2 << std::endl; + std::cout << " T3p : " << sch.t3p << std::endl; + std::cout << " FN : " << gsm_sch_to_fn(&sch) << std::endl; + + fn = gsm_sch_to_fn(&sch); + if (fn < 0) { + std::cout << "SCH : Failed to convert FN " << std::endl; + return false; + } + + time->FN(fn); + time->TN(0); + } else { + return false; + } + + return true; +} + + /* * Detect normal burst training sequence midamble. Update equalization * state information and channel estimate if necessary. Equalization @@ -491,19 +539,26 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI, SoftVector *bits = NULL; TransceiverState *state = &mStates[chan]; + GSM::Time sch_time, burst_time, diff_time; + /* Blocking FIFO read */ radioVector *radio_burst = mReceiveFIFO[chan]->read(); if (!radio_burst) return NULL; /* Set time and determine correlation type */ - GSM::Time time = radio_burst->getTime(); - CorrType type = expectedCorrType(time, chan); + burst_time = radio_burst->getTime(); + CorrType type = expectedCorrType(burst_time, chan); switch (state->mode) { case TRX_MODE_MS_ACQUIRE: type = SCH; break; + case TRX_MODE_MS_TRACK: + if (!gsm_sch_check_fn(burst_time.FN())) + goto release; + type = SCH; + break; case TRX_MODE_BTS: if ((type == TSC) || (type == RACH)) break; @@ -534,7 +589,7 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI, /* Detect normal or RACH bursts */ if (type == TSC) - success = detectTSC(state, *burst, amp, toa, time); + success = detectTSC(state, *burst, amp, toa, burst_time); else if (type == RACH) success = detectRACH(state, *burst, amp, toa); else if (type == SCH) @@ -551,10 +606,32 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI, if (equalize && (type != TSC)) equalize = false; - if (avg - state->mNoiseLev > 0.0) - bits = demodulate(state, *burst, amp, toa, time.TN(), equalize); + /* Ignore noise threshold on MS mode for now */ + if ((type == SCH) || (avg - state->mNoiseLev > 0.0)) + bits = demodulate(state, *burst, amp, toa, + burst_time.TN(), equalize); + + /* MS: Decode SCH and adjust GSM clock */ + if ((state->mode == TRX_MODE_MS_ACQUIRE) || + (state->mode == TRX_MODE_MS_TRACK)) { + + if (decodeSCH(bits, &sch_time)) { + if (state->mode == TRX_MODE_MS_ACQUIRE) { + diff_time = GSM::Time(sch_time.FN() - burst_time.FN(), + -burst_time.TN()); + mRadioInterface->adjustClock(diff_time); + state->mode = TRX_MODE_MS_TRACK; + + std::cout << "SCH : Locking GSM clock " << std::endl; + } else { + std::cout << "SCH : Read SCH at FN " << burst_time.FN() + << " FN51 " << burst_time.FN() % 51 << std::endl; + } + } + goto release; + } - wTime = time; + wTime = burst_time; RSSI = (int) floor(20.0 * log10(rxFullScale / avg)); timingOffset = (int) round(toa * 256.0 / mSPSRx); |