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uhd: increase initial transmit latency and disable adaptive control 

The underrun behaviour of the USRP2 is different from the USRP1, and
the adaptive latency mechanism is not directly transferable. Instead,
fix the latency with a higher starting value, which effectively
buffers more samples on the host in front of the Ethernet interface.

An alternative may be to use the adaptive approach with USRP2
specific upper and lower bounds. For now, just use preprocessor
directives until a better solution comes around.

Signed-off-by: Thomas Tsou <ttsou@vt.edu>
This commit is contained in:
Thomas Tsou 2010-11-15 17:18:47 -05:00
parent af2ded3b01
commit 589dd9091e
2 changed files with 5 additions and 5 deletions
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8
public-trunk/Transceiver/Transceiver.cpp
View File

@ -29,12 +29,10 @@
*/
#include <stdio.h>
#include <cstdio>
#include "config.h"
#include "Transceiver.h"
#include <Logger.h>
#include <cstdio>
Transceiver::Transceiver(int wBasePort,
@ -696,6 +694,7 @@ void Transceiver::driveTransmitFIFO()
radioClock->wait(); // wait until clock updates
while (radioClock->get() + mTransmitLatency >
mTransmitDeadlineClock) {
#ifndef USE_UHD
// if underrun, then we're not providing bursts to radio/USRP fast
// enough. Need to increase latency by one GSM frame.
if (mRadioInterface->isUnderrun()) {
@ -717,6 +716,7 @@ void Transceiver::driveTransmitFIFO()
}
}
}
#endif
// time to push burst to transmit FIFO
pushRadioVector(mTransmitDeadlineClock);
mTransmitDeadlineClock.incTN();

2
public-trunk/Transceiver/runTransceiver.cpp
View File

@ -56,7 +56,7 @@ int main(int argc, char *argv[]) {
}
RadioInterface* radio = new RadioInterface(usrp,3);
Transceiver *trx = new Transceiver(5700,"127.0.0.1",SAMPSPERSYM,GSM::Time(2,0),radio);
Transceiver *trx = new Transceiver(5700,"127.0.0.1",SAMPSPERSYM,GSM::Time(3,0),radio);
trx->transmitFIFO(radio->transmitFIFO());
trx->receiveFIFO(radio->receiveFIFO());