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Diffstat (limited to 'Transceiver52M/radioInterfaceResamp.cpp')
| -rw-r--r-- | Transceiver52M/radioInterfaceResamp.cpp | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/Transceiver52M/radioInterfaceResamp.cpp b/Transceiver52M/radioInterfaceResamp.cpp new file mode 100644 index 0000000..8ae4aa1 --- /dev/null +++ b/Transceiver52M/radioInterfaceResamp.cpp @@ -0,0 +1,235 @@ +/* + * Radio device interface with sample rate conversion + * + * Copyright (C) 2011-2014 Free Software Foundation, Inc. + * Copyright (C) 2015 Ettus Research LLC + * + * Author: Tom Tsou <tom@tsou.cc> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program 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 Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * See the COPYING file in the main directory for details. + */ + +#include <radioInterface.h> +#include <Logger.h> + +#include "Resampler.h" + +extern "C" { +#include "convert.h" +} + +/* Resampling parameters for 64 MHz clocking */ +#define RESAMP_64M_INRATE 65 +#define RESAMP_64M_OUTRATE 96 + +/* Resampling parameters for 100 MHz clocking */ +#define RESAMP_100M_INRATE 52 +#define RESAMP_100M_OUTRATE 75 + +/* Universal resampling parameters */ +#define NUMCHUNKS 24 + +/* + * 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 Resampler *upsampler = NULL; +static Resampler *dnsampler = NULL; +static size_t resamp_inrate = 0; +static size_t resamp_inchunk = 0; +static size_t resamp_outrate = 0; +static size_t resamp_outchunk = 0; + +RadioInterfaceResamp::RadioInterfaceResamp(RadioDevice *wRadio, + size_t tx_sps, size_t rx_sps) + : RadioInterface(wRadio, tx_sps, rx_sps, 1), + outerSendBuffer(NULL), outerRecvBuffer(NULL) +{ +} + +RadioInterfaceResamp::~RadioInterfaceResamp() +{ + close(); +} + +void RadioInterfaceResamp::close() +{ + delete outerSendBuffer; + delete outerRecvBuffer; + + delete upsampler; + delete dnsampler; + + outerSendBuffer = NULL; + outerRecvBuffer = NULL; + + upsampler = NULL; + dnsampler = NULL; + + if (sendBuffer.size()) + sendBuffer[0] = NULL; + if (recvBuffer.size()) + recvBuffer[0] = NULL; + + RadioInterface::close(); +} + +/* Initialize I/O specific objects */ +bool RadioInterfaceResamp::init(int type) +{ + float cutoff = 1.0f; + + close(); + + sendBuffer.resize(1); + recvBuffer.resize(1); + convertSendBuffer.resize(1); + convertRecvBuffer.resize(1); + mReceiveFIFO.resize(1); + powerScaling.resize(1); + + switch (type) { + case RadioDevice::RESAMP_64M: + resamp_inrate = RESAMP_64M_INRATE; + resamp_outrate = RESAMP_64M_OUTRATE; + break; + case RadioDevice::RESAMP_100M: + resamp_inrate = RESAMP_100M_INRATE; + resamp_outrate = RESAMP_100M_OUTRATE; + break; + case RadioDevice::NORMAL: + default: + LOG(ALERT) << "Invalid device configuration"; + return false; + } + + resamp_inchunk = resamp_inrate * 4 * mSPSRx; + resamp_outchunk = resamp_outrate * 4 * mSPSRx; + + if (mSPSTx == 4) + cutoff = RESAMP_TX4_FILTER; + + dnsampler = new Resampler(resamp_inrate, resamp_outrate); + if (!dnsampler->init()) { + LOG(ALERT) << "Rx resampler failed to initialize"; + return false; + } + + upsampler = new Resampler(resamp_outrate, resamp_inrate); + if (!upsampler->init(cutoff)) { + LOG(ALERT) << "Tx resampler failed to initialize"; + return false; + } + + /* + * Allocate high and low rate buffers. The high rate receive + * buffer and low rate transmit vectors feed into the resampler + * and requires headroom equivalent to the filter length. Low + * rate buffers are allocated in the main radio interface code. + */ + sendBuffer[0] = new RadioBuffer(NUMCHUNKS, resamp_inchunk, + upsampler->len(), true); + recvBuffer[0] = new RadioBuffer(NUMCHUNKS * 20, resamp_inchunk, 0, false); + + outerSendBuffer = + new signalVector(NUMCHUNKS * resamp_outchunk); + outerRecvBuffer = + new signalVector(resamp_outchunk, dnsampler->len()); + + convertSendBuffer[0] = new short[outerSendBuffer->size() * 2]; + convertRecvBuffer[0] = new short[outerRecvBuffer->size() * 2]; + + return true; +} + +/* Receive a timestamped chunk from the device */ +int RadioInterfaceResamp::pullBuffer() +{ + bool local_underrun; + int rc, num_recv; + + if (recvBuffer[0]->getFreeSegments() <= 0) + return -1; + + /* Outer buffer access size is fixed */ + num_recv = mRadio->readSamples(convertRecvBuffer, + resamp_outchunk, + &overrun, + readTimestamp, + &local_underrun); + if (num_recv != (int) resamp_outchunk) { + LOG(ALERT) << "Receive error " << num_recv; + return -1; + } + + convert_short_float((float *) outerRecvBuffer->begin(), + convertRecvBuffer[0], 2 * resamp_outchunk); + + underrun |= local_underrun; + readTimestamp += (TIMESTAMP) resamp_outchunk; + + /* Write to the end of the inner receive buffer */ + rc = dnsampler->rotate((float *) outerRecvBuffer->begin(), + resamp_outchunk, + recvBuffer[0]->getWriteSegment(), + resamp_inchunk); + if (rc < 0) { + LOG(ALERT) << "Sample rate upsampling error"; + } + + /* Set history for the next chunk */ + outerRecvBuffer->updateHistory(); + return 0; +} + +/* Send a timestamped chunk to the device */ +bool RadioInterfaceResamp::pushBuffer() +{ + int rc; + size_t numSent; + + if (sendBuffer[0]->getAvailSegments() <= 0) + return false; + + /* Always send from the beginning of the buffer */ + rc = upsampler->rotate(sendBuffer[0]->getReadSegment(), + resamp_inchunk, + (float *) outerSendBuffer->begin(), + resamp_outchunk); + if (rc < 0) { + LOG(ALERT) << "Sample rate downsampling error"; + } + + convert_float_short(convertSendBuffer[0], + (float *) outerSendBuffer->begin(), + powerScaling[0], 2 * resamp_outchunk); + + numSent = mRadio->writeSamples(convertSendBuffer, + resamp_outchunk, + &underrun, + writeTimestamp); + if (numSent != resamp_outchunk) { + LOG(ALERT) << "Transmit error " << numSent; + } + + writeTimestamp += resamp_outchunk; + + return true; +} |