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transceiver: workaround for transmit testing with no clock reset

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Non-functional clock reset causes huge initial timing offset
between expected and received timestamps. Receive an initial
packet to 'set' the expected starting timestamp value for
both transmit and receive.

Signed-off-by: Thomas Tsou <ttsou@vt.edu>
This commit is contained in:
Thomas Tsou
2012-06-17 21:15:46 -04:00
committed by Alexander Chemeris
parent 77db43f380
commit 1bcd01c7c5
2 changed files with 17 additions and 4 deletions
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19
Transceiver52M/UHDDevice.cpp
View File

@@ -58,6 +58,8 @@ const double rx_smpl_offset = .00005;
const double rx_smpl_offset = .0000869;
#endif
static TIMESTAMP init_rd_ts = 0;
/** Timestamp conversion
@param timestamp a UHD or OpenBTS timestamp
@param rate sample rate
@@ -169,8 +171,8 @@ public:
bool setTxFreq(double wFreq);
bool setRxFreq(double wFreq);
inline TIMESTAMP initialWriteTimestamp() { return 0; }
inline TIMESTAMP initialReadTimestamp() { return 0; }
inline TIMESTAMP initialWriteTimestamp() { return init_rd_ts; }
inline TIMESTAMP initialReadTimestamp() { return init_rd_ts; }
inline double fullScaleInputValue() { return 32000 * tx_ampl; }
inline double fullScaleOutputValue() { return 32000; }
@@ -546,6 +548,17 @@ void uhd_device::restart(uhd::time_spec_t ts)
cmd = uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS;
cmd.stream_now = true;
usrp_dev->issue_stream_cmd(cmd);
uhd::rx_metadata_t md;
uint32_t buff[rx_spp];
usrp_dev->get_device()->recv(buff,
rx_spp,
md,
uhd::io_type_t::COMPLEX_INT16,
uhd::device::RECV_MODE_ONE_PACKET);
init_rd_ts = convert_time(md.time_spec, actual_smpl_rt);
}
bool uhd_device::start()
@@ -912,7 +925,7 @@ ssize_t smpl_buf::read(void *buf, size_t len, TIMESTAMP timestamp)
num_smpls = len;
// Starting index
size_t read_start = data_start + (timestamp - time_start);
size_t read_start = data_start + (timestamp - time_start) % buf_len;
// Read it
if (read_start + num_smpls < buf_len) {

2
Transceiver52M/radioInterface.cpp
View File

@@ -120,9 +120,9 @@ void RadioInterface::start()
LOG(INFO) << "starting radio interface...";
mAlignRadioServiceLoopThread.start((void * (*)(void*))AlignRadioServiceLoopAdapter,
(void*)this);
mRadio->start();
writeTimestamp = mRadio->initialWriteTimestamp();
readTimestamp = mRadio->initialReadTimestamp();
mRadio->start();
LOG(DEBUG) << "Radio started";
mRadio->updateAlignment(writeTimestamp-10000);
mRadio->updateAlignment(writeTimestamp-10000);