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Diffstat (limited to 'Transceiver52M/radioInterfaceDiversity.cpp')
| -rw-r--r-- | Transceiver52M/radioInterfaceDiversity.cpp | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/Transceiver52M/radioInterfaceDiversity.cpp b/Transceiver52M/radioInterfaceDiversity.cpp new file mode 100644 index 0000000..8e921b1 --- /dev/null +++ b/Transceiver52M/radioInterfaceDiversity.cpp @@ -0,0 +1,248 @@ +/* + * SSE Convolution + * Copyright (C) 2013 Thomas Tsou <tom@tsou.cc> + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library 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 + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include <radioInterface.h> +#include <Logger.h> + +#include "Resampler.h" + +extern "C" { +#include "convert.h" +} + +/* Resampling parameters for 64 MHz clocking */ +#define RESAMP_64M_INRATE 20 +#define RESAMP_64M_OUTRATE 80 + +/* Downlink block size */ +#define CHUNK 625 + +/* Universal resampling parameters */ +#define NUMCHUNKS 48 + +/* + * Resampling filter bandwidth scaling factor + * This narrows the filter cutoff relative to the output bandwidth + * of the polyphase resampler. At 4 samples-per-symbol using the + * 2 pulse Laurent GMSK approximation gives us below 0.5 degrees + * RMS phase error at the resampler output. + */ +#define RESAMP_TX4_FILTER 0.45 + +static size_t resamp_inrate = 0; +static size_t resamp_inchunk = 0; +static size_t resamp_outrate = 0; +static size_t resamp_outchunk = 0; + +RadioInterfaceDiversity::RadioInterfaceDiversity(RadioDevice *wRadio, + size_t sps, size_t chans) + : RadioInterface(wRadio, sps, chans, 2), outerRecvBuffer(NULL), + mDiversity(false), mFreqSpacing(0.0) +{ +} + +RadioInterfaceDiversity::~RadioInterfaceDiversity() +{ + close(); +} + +void RadioInterfaceDiversity::close() +{ + delete outerRecvBuffer; + + outerRecvBuffer = NULL; + + for (size_t i = 0; i < dnsamplers.size(); i++) { + delete dnsamplers[i]; + dnsamplers[i] = NULL; + } + + if (recvBuffer.size()) + recvBuffer[0] = NULL; + + RadioInterface::close(); +} + +bool RadioInterfaceDiversity::setupDiversityChannels() +{ + size_t inner_rx_len; + + /* Inner and outer rates */ + resamp_inrate = RESAMP_64M_INRATE; + resamp_outrate = RESAMP_64M_OUTRATE; + resamp_inchunk = resamp_inrate * 4; + resamp_outchunk = resamp_outrate * 4; + + /* Buffer lengths */ + inner_rx_len = NUMCHUNKS * resamp_inchunk; + + /* Inside buffer must hold at least 2 bursts */ + if (inner_rx_len < 157 * mSPSRx * 2) { + LOG(ALERT) << "Invalid inner buffer size " << inner_rx_len; + return false; + } + + /* One Receive buffer and downsampler per diversity channel */ + for (size_t i = 0; i < mMIMO * mChans; i++) { + dnsamplers[i] = new Resampler(resamp_inrate, resamp_outrate); + if (!dnsamplers[i]->init()) { + LOG(ALERT) << "Rx resampler failed to initialize"; + return false; + } + + recvBuffer[i] = new signalVector(inner_rx_len); + } + + return true; +} + +/* Initialize I/O specific objects */ +bool RadioInterfaceDiversity::init(int type) +{ + int tx_len, outer_rx_len; + + if ((mMIMO != 2) || (mChans != 2)) { + LOG(ALERT) << "Unsupported channel configuration " << mChans; + return false; + } + + /* Resize for channel combination */ + sendBuffer.resize(mChans); + recvBuffer.resize(mChans * mMIMO); + convertSendBuffer.resize(mChans); + convertRecvBuffer.resize(mChans); + mReceiveFIFO.resize(mChans); + dnsamplers.resize(mChans * mMIMO); + phases.resize(mChans); + + if (!setupDiversityChannels()) + return false; + + tx_len = CHUNK * mSPSTx; + outer_rx_len = resamp_outchunk; + + for (size_t i = 0; i < mChans; i++) { + /* Full rate float and integer outer receive buffers */ + convertRecvBuffer[i] = new short[outer_rx_len * 2]; + + /* Send buffers (not-resampled) */ + sendBuffer[i] = new signalVector(tx_len); + convertSendBuffer[i] = new short[tx_len * 2]; + } + + outerRecvBuffer = new signalVector(outer_rx_len, dnsamplers[0]->len()); + + return true; +} + +bool RadioInterfaceDiversity::tuneRx(double freq, size_t chan) +{ + double f0, f1; + + if (chan > 1) + return false; + + if (!mRadio->setRxFreq(freq, chan)) + return false; + + f0 = mRadio->getRxFreq(0); + f1 = mRadio->getRxFreq(1); + + mFreqSpacing = f1 - f0; + + if (abs(mFreqSpacing) <= 600e3) + mDiversity = true; + else + mDiversity = false; + + return true; +} + +/* Receive a timestamped chunk from the device */ +void RadioInterfaceDiversity::pullBuffer() +{ + bool local_underrun; + int rc, num, path0, path1; + signalVector *shift, *base; + float *in, *out, rate = -mFreqSpacing * 2.0 * M_PI / 1.08333333e6; + + if (recvCursor > recvBuffer[0]->size() - resamp_inchunk) + return; + + /* Outer buffer access size is fixed */ + num = mRadio->readSamples(convertRecvBuffer, + resamp_outchunk, + &overrun, + readTimestamp, + &local_underrun); + if ((size_t) num != resamp_outchunk) { + LOG(ALERT) << "Receive error " << num; + return; + } + + for (size_t i = 0; i < mChans; i++) { + convert_short_float((float *) outerRecvBuffer->begin(), + convertRecvBuffer[i], 2 * resamp_outchunk); + + if (!i) { + path0 = 0; + path1 = 2; + } else { + path0 = 3; + path1 = 1; + } + + /* Diversity path 1 */ + base = outerRecvBuffer; + in = (float *) base->begin(); + out = (float *) (recvBuffer[path0]->begin() + recvCursor); + + rc = dnsamplers[2 * i + 0]->rotate(in, resamp_outchunk, + out, resamp_inchunk); + if (rc < 0) { + LOG(ALERT) << "Sample rate downsampling error"; + } + + /* Enable path 2 if Nyquist bandwidth is sufficient */ + if (!mDiversity) + continue; + + /* Diversity path 2 */ + shift = new signalVector(base->size(), base->getStart()); + in = (float *) shift->begin(); + out = (float *) (recvBuffer[path1]->begin() + recvCursor); + + rate = i ? -rate : rate; + if (!frequencyShift(shift, base, rate, phases[i], &phases[i])) { + LOG(ALERT) << "Frequency shift failed"; + } + + rc = dnsamplers[2 * i + 1]->rotate(in, resamp_outchunk, + out, resamp_inchunk); + if (rc < 0) { + LOG(ALERT) << "Sample rate downsampling error"; + } + + delete shift; + } + + underrun |= local_underrun; + readTimestamp += (TIMESTAMP) resamp_outchunk; + recvCursor += resamp_inchunk; +} |