Transceiver52M: Replace resampler with SSE enabled implementation
Replace the polyphase filter and resampler with a separate
implementation using SSE enabled convolution. The USRP2 (including
derived devices N200, N210) are the only supported devices that
require sample rate conversion, so set the default resampling
parameters for the 100 MHz FPGA clock. This changes the previous
resampling ratios.
270.833 kHz -> 400 kHz (65 / 96)
270.833 kHz -> 390.625 kHz (52 / 75)
The new resampling factor uses a USRP resampling factor of 256
instead of 250. On the device, this allows two halfband filters to
be used rather than one. The end result is reduced distortial and
aliasing effecits from CIC filter rolloff.
B100 and USRP1 will no be supported at 400 ksps with these changes.
Signed-off-by: Thomas Tsou <tom@tsou.cc>
diff --git a/Transceiver52M/radioInterfaceResamp.cpp b/Transceiver52M/radioInterfaceResamp.cpp
index c7f17ea..d3dc82e 100644
--- a/Transceiver52M/radioInterfaceResamp.cpp
+++ b/Transceiver52M/radioInterfaceResamp.cpp
@@ -1,8 +1,8 @@
/*
* Radio device interface with sample rate conversion
- * Written by Thomas Tsou <ttsou@vt.edu>
+ * Written by Thomas Tsou <tom@tsou.cc>
*
- * Copyright 2011 Free Software Foundation, Inc.
+ * Copyright 2011, 2012, 2013 Free Software Foundation, Inc.
*
* 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
@@ -22,6 +22,12 @@
#include <radioInterface.h>
#include <Logger.h>
+#include "Resampler.h"
+
+extern "C" {
+#include "convert.h"
+}
+
/* New chunk sizes for resampled rate */
#ifdef INCHUNK
#undef INCHUNK
@@ -30,303 +36,194 @@
#undef OUTCHUNK
#endif
-/* Resampling parameters */
-#define INRATE 65 * SAMPSPERSYM
-#define INHISTORY INRATE * 2
-#define INCHUNK INRATE * 9
+/* Resampling parameters for 100 MHz clocking */
+#define RESAMP_INRATE 52
+#define RESAMP_OUTRATE 75
+#define RESAMP_FILT_LEN 16
-#define OUTRATE 96 * SAMPSPERSYM
-#define OUTHISTORY OUTRATE * 2
-#define OUTCHUNK OUTRATE * 9
+#define INCHUNK (RESAMP_INRATE * 4)
+#define OUTCHUNK (RESAMP_OUTRATE * 4)
-/* Resampler low pass filters */
-signalVector *tx_lpf = 0;
-signalVector *rx_lpf = 0;
+static Resampler *upsampler = NULL;
+static Resampler *dnsampler = NULL;
+short *convertRecvBuffer = NULL;
+short *convertSendBuffer = NULL;
-/* Resampler history */
-signalVector *tx_hist = 0;
-signalVector *rx_hist = 0;
-
-/* Resampler input buffer */
-signalVector *tx_vec = 0;
-signalVector *rx_vec = 0;
-
-/*
- * High rate (device facing) buffers
- *
- * Transmit side samples are pushed after each burst so accomodate
- * a resampled burst plus up to a chunk left over from the previous
- * resampling operation.
- *
- * Receive side samples always pulled with a fixed size.
- */
-short tx_buf[INCHUNK * 2 * 4];
-short rx_buf[OUTCHUNK * 2 * 2];
-
-/*
- * Utilities and Conversions
- *
- * Manipulate signal vectors dynamically for two reasons. For one,
- * it's simpler. And two, it doesn't make any reasonable difference
- * relative to the high overhead generated by the resampling.
- */
-
-/* Concatenate signal vectors. Deallocate input vectors. */
-signalVector *concat(signalVector *a, signalVector *b)
+/* Complex float to short conversion */
+static void floatToShort(short *out, float *in, int num)
{
- signalVector *vec = new signalVector(*a, *b);
- delete a;
- delete b;
-
- return vec;
+ for (int i = 0; i < num; i++)
+ out[i] = (short) in[i];
}
-/* Segment a signal vector. Deallocate the input vector. */
-signalVector *segment(signalVector *a, int indx, int sz)
+/* Complex short to float conversion */
+static void shortToFloat(float *out, short *in, int num)
{
- signalVector *vec = new signalVector(sz);
- a->segmentCopyTo(*vec, indx, sz);
- delete a;
-
- return vec;
-}
-
-/* Create a new signal vector from a short array. */
-signalVector *short_to_sigvec(short *smpls, size_t sz)
-{
- int i;
- signalVector *vec = new signalVector(sz);
- signalVector::iterator itr = vec->begin();
-
- for (i = 0; i < sz; i++) {
- *itr++ = Complex<float>(smpls[2 * i + 0], smpls[2 * i + 1]);
- }
-
- return vec;
-}
-
-/* Convert and deallocate a signal vector into a short array. */
-int sigvec_to_short(signalVector *vec, short *smpls)
-{
- int i;
- signalVector::iterator itr = vec->begin();
-
- for (i = 0; i < vec->size(); i++) {
- smpls[2 * i + 0] = itr->real();
- smpls[2 * i + 1] = itr->imag();
- itr++;
- }
- delete vec;
-
- return i;
-}
-
-/* Create a new signal vector from a float array. */
-signalVector *float_to_sigvec(float *smpls, int sz)
-{
- int i;
- signalVector *vec = new signalVector(sz);
- signalVector::iterator itr = vec->begin();
-
- for (i = 0; i < sz; i++) {
- *itr++ = Complex<float>(smpls[2 * i + 0], smpls[2 * i + 1]);
- }
-
- return vec;
-}
-
-/* Convert and deallocate a signal vector into a float array. */
-int sigvec_to_float(signalVector *vec, float *smpls)
-{
- int i;
- signalVector::iterator itr = vec->begin();
-
- for (i = 0; i < vec->size(); i++) {
- smpls[2 * i + 0] = itr->real();
- smpls[2 * i + 1] = itr->imag();
- itr++;
- }
- delete vec;
-
- return i;
-}
-
-/* Initialize resampling signal vectors */
-void init_resampler(signalVector **lpf,
- signalVector **buf,
- signalVector **hist,
- int tx)
-{
- int P, Q, taps, hist_len;
- float cutoff_freq;
-
- if (tx) {
- LOG(INFO) << "Initializing Tx resampler";
- P = OUTRATE;
- Q = INRATE;
- taps = 651;
- hist_len = INHISTORY;
- } else {
- LOG(INFO) << "Initializing Rx resampler";
- P = INRATE;
- Q = OUTRATE;
- taps = 961;
- hist_len = OUTHISTORY;
- }
-
- if (!*lpf) {
- cutoff_freq = (P < Q) ? (1.0/(float) Q) : (1.0/(float) P);
- *lpf = createLPF(cutoff_freq, taps, P);
- }
-
- if (!*buf) {
- *buf = new signalVector();
- }
-
- if (!*hist);
- *hist = new signalVector(hist_len);
-}
-
-/* Resample a signal vector
- *
- * The input vector is deallocated and the pointer returned with a vector
- * of any unconverted samples.
- */
-signalVector *resmpl_sigvec(signalVector *hist, signalVector **vec,
- signalVector *lpf, double in_rate,
- double out_rate, int chunk_sz)
-{
- signalVector *resamp_vec;
- int num_chunks = (*vec)->size() / chunk_sz;
-
- /* Truncate to a chunk multiple */
- signalVector trunc_vec(num_chunks * chunk_sz);
- (*vec)->segmentCopyTo(trunc_vec, 0, num_chunks * chunk_sz);
-
- /* Update sample buffer with remainder */
- *vec = segment(*vec, trunc_vec.size(), (*vec)->size() - trunc_vec.size());
-
- /* Add history and resample */
- signalVector input_vec(*hist, trunc_vec);
- resamp_vec = polyphaseResampleVector(input_vec, in_rate,
- out_rate, lpf);
-
- /* Update history */
- trunc_vec.segmentCopyTo(*hist, trunc_vec.size() - hist->size(),
- hist->size());
- return resamp_vec;
-}
-
-/* Wrapper for receive-side integer-to-float array resampling */
- int rx_resmpl_int_flt(float *smpls_out, short *smpls_in, int num_smpls)
-{
- int num_resmpld, num_chunks;
- signalVector *convert_vec, *resamp_vec, *trunc_vec;
-
- if (!rx_lpf || !rx_vec || !rx_hist)
- init_resampler(&rx_lpf, &rx_vec, &rx_hist, false);
-
- /* Convert and add samples to the receive buffer */
- convert_vec = short_to_sigvec(smpls_in, num_smpls);
- rx_vec = concat(rx_vec, convert_vec);
-
- num_chunks = rx_vec->size() / OUTCHUNK;
- if (num_chunks < 1)
- return 0;
-
- /* Resample */
- resamp_vec = resmpl_sigvec(rx_hist, &rx_vec, rx_lpf,
- INRATE, OUTRATE, OUTCHUNK);
- /* Truncate */
- trunc_vec = segment(resamp_vec, INHISTORY,
- resamp_vec->size() - INHISTORY);
- /* Convert */
- num_resmpld = sigvec_to_float(trunc_vec, smpls_out);
-
- return num_resmpld;
-}
-
-/* Wrapper for transmit-side float-to-int array resampling */
-int tx_resmpl_flt_int(short *smpls_out, float *smpls_in, int num_smpls)
-{
- int num_resmpl, num_chunks;
- signalVector *convert_vec, *resamp_vec;
-
- if (!tx_lpf || !tx_vec || !tx_hist)
- init_resampler(&tx_lpf, &tx_vec, &tx_hist, true);
-
- /* Convert and add samples to the transmit buffer */
- convert_vec = float_to_sigvec(smpls_in, num_smpls);
- tx_vec = concat(tx_vec, convert_vec);
-
- num_chunks = tx_vec->size() / INCHUNK;
- if (num_chunks < 1)
- return 0;
-
- /* Resample and convert to an integer array */
- resamp_vec = resmpl_sigvec(tx_hist, &tx_vec, tx_lpf,
- OUTRATE, INRATE, INCHUNK);
- num_resmpl = sigvec_to_short(resamp_vec, smpls_out);
-
- return num_resmpl;
+ for (int i = 0; i < num; i++)
+ out[i] = (float) in[i];
}
RadioInterfaceResamp::RadioInterfaceResamp(RadioDevice *wRadio,
int wReceiveOffset,
int wSPS,
GSM::Time wStartTime)
- : RadioInterface(wRadio, wReceiveOffset, wSPS, wStartTime)
+ : RadioInterface(wRadio, wReceiveOffset, wSPS, wStartTime),
+ innerSendBuffer(NULL), outerSendBuffer(NULL),
+ innerRecvBuffer(NULL), outerRecvBuffer(NULL)
{
}
-/* Receive a timestamped chunk from the device */
+RadioInterfaceResamp::~RadioInterfaceResamp()
+{
+ close();
+}
+
+void RadioInterfaceResamp::close()
+{
+ RadioInterface::close();
+
+ delete innerSendBuffer;
+ delete outerSendBuffer;
+ delete innerRecvBuffer;
+ delete outerRecvBuffer;
+
+ delete upsampler;
+ delete dnsampler;
+
+ innerSendBuffer = NULL;
+ outerSendBuffer = NULL;
+ innerRecvBuffer = NULL;
+ outerRecvBuffer = NULL;
+
+ upsampler = NULL;
+ dnsampler = NULL;
+}
+
+/* Initialize I/O specific objects */
+bool RadioInterfaceResamp::init()
+{
+ float cutoff = 1.0f;
+
+ close();
+
+ /*
+ * With oversampling, restrict bandwidth to 150% of base rate. This also
+ * provides last ditch bandwith limiting if the pulse shaping filter is
+ * insufficient.
+ */
+ if (sps > 1)
+ cutoff = 1.5 / sps;
+
+ dnsampler = new Resampler(RESAMP_INRATE, RESAMP_OUTRATE);
+ if (!dnsampler->init(cutoff)) {
+ 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.
+ */
+ innerSendBuffer = new signalVector(INCHUNK * 20, RESAMP_FILT_LEN);
+ outerSendBuffer = new signalVector(OUTCHUNK * 20);
+
+ outerRecvBuffer = new signalVector(OUTCHUNK * 2, RESAMP_FILT_LEN);
+ innerRecvBuffer = new signalVector(INCHUNK * 20);
+
+ convertSendBuffer = new short[OUTCHUNK * 2 * 20];
+ convertRecvBuffer = new short[OUTCHUNK * 2 * 2];
+
+ sendBuffer = innerSendBuffer;
+ recvBuffer = innerRecvBuffer;
+
+ return true;
+}
+
+/* Receive a timestamped chunk from the device */
void RadioInterfaceResamp::pullBuffer()
{
- int num_cv, num_rd;
bool local_underrun;
+ int rc, num_recv;
+ int inner_len = INCHUNK;
+ int outer_len = OUTCHUNK;
- /* Read samples. Fail if we don't get what we want. */
- num_rd = mRadio->readSamples(rx_buf, OUTCHUNK, &overrun,
- readTimestamp, &local_underrun);
+ /* Outer buffer access size is fixed */
+ num_recv = mRadio->readSamples(convertRecvBuffer,
+ outer_len,
+ &overrun,
+ readTimestamp,
+ &local_underrun);
+ if (num_recv != outer_len) {
+ LOG(ALERT) << "Receive error " << num_recv;
+ return;
+ }
- LOG(DEBUG) << "Rx read " << num_rd << " samples from device";
- assert(num_rd == OUTCHUNK);
+ shortToFloat((float *) outerRecvBuffer->begin(),
+ convertRecvBuffer, 2 * outer_len);
underrun |= local_underrun;
- readTimestamp += (TIMESTAMP) num_rd;
+ readTimestamp += (TIMESTAMP) num_recv;
- /* Convert and resample */
- num_cv = rx_resmpl_int_flt(rcvBuffer + 2 * rcvCursor,
- rx_buf, num_rd);
+ /* Write to the end of the inner receive buffer */
+ rc = dnsampler->rotate((float *) outerRecvBuffer->begin(), outer_len,
+ (float *) (innerRecvBuffer->begin() + recvCursor),
+ inner_len);
+ if (rc < 0) {
+ LOG(ALERT) << "Sample rate upsampling error";
+ }
- LOG(DEBUG) << "Rx read " << num_cv << " samples from resampler";
-
- rcvCursor += num_cv;
+ recvCursor += inner_len;
}
-/* Send a timestamped chunk to the device */
+/* Send a timestamped chunk to the device */
void RadioInterfaceResamp::pushBuffer()
{
- int num_cv, num_wr;
+ int rc, chunks, num_sent;
+ int inner_len, outer_len;
if (sendCursor < INCHUNK)
return;
- LOG(DEBUG) << "Tx wrote " << sendCursor << " samples to resampler";
+ chunks = sendCursor / INCHUNK;
+ if (chunks > 8)
+ chunks = 8;
- /* Resample and convert */
- num_cv = tx_resmpl_flt_int(tx_buf, sendBuffer, sendCursor);
- assert(num_cv > sendCursor);
+ inner_len = chunks * INCHUNK;
+ outer_len = chunks * OUTCHUNK;
- /* Write samples. Fail if we don't get what we want. */
- num_wr = mRadio->writeSamples(tx_buf + OUTHISTORY * 2,
- num_cv - OUTHISTORY,
- &underrun,
- writeTimestamp);
+ /* Always send from the beginning of the buffer */
+ rc = upsampler->rotate((float *) innerSendBuffer->begin(), inner_len,
+ (float *) outerSendBuffer->begin(), outer_len);
+ if (rc < 0) {
+ LOG(ALERT) << "Sample rate downsampling error";
+ }
- LOG(DEBUG) << "Tx wrote " << num_wr << " samples to device";
- assert(num_wr == num_wr);
+ floatToShort(convertSendBuffer,
+ (float *) outerSendBuffer->begin(),
+ 2 * outer_len);
- writeTimestamp += (TIMESTAMP) num_wr;
- sendCursor = 0;
+ num_sent = mRadio->writeSamples(convertSendBuffer,
+ outer_len,
+ &underrun,
+ writeTimestamp);
+ if (num_sent != outer_len) {
+ LOG(ALERT) << "Transmit error " << num_sent;
+ }
+
+ /* Shift remaining samples to beginning of buffer */
+ memmove(innerSendBuffer->begin(),
+ innerSendBuffer->begin() + inner_len,
+ (sendCursor - inner_len) * 2 * sizeof(float));
+
+ writeTimestamp += outer_len;
+ sendCursor -= inner_len;
+ assert(sendCursor >= 0);
}