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transceiver: fix energy threshold bug 

If no bursts were received over a long enough duration
then the threshold would roll into negative territory.
The energy detection is based on a comparison with the
squared threshold, so all handsets would become
effectively barred after a certain period of
inactivity.

In theory, this bug also exists in the mainline tree,
but there the daughterboard receive gain is fixed at
max, which always allows the ADC to generate sufficient
noise to trigger the energy dectector and keep the
system in a valid steady state.

To fix, simply add a negative value check like those
already in place for other locations.

Signed-off-by: Thomas Tsou <ttsou@vt.edu>
This commit is contained in:
Thomas Tsou 2011-05-25 19:56:15 -07:00
parent f398757fe6
commit 3896e7499f
2 changed files with 6 additions and 0 deletions
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3
public-trunk/Transceiver/Transceiver.cpp
View File

@ -301,6 +301,9 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime,
double framesElapsed = rxBurst->time()-prevFalseDetectionTime;
if (framesElapsed > 50) { // if we haven't had any false detections for a while, lower threshold
mEnergyThreshold -= 10.0;
if (mEnergyThreshold < 0.0)
mEnergyThreshold = 0.0;
prevFalseDetectionTime = rxBurst->time();
}
delete rxBurst;

3
public-trunk/Transceiver52M/Transceiver.cpp
View File

@ -303,6 +303,9 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime,
double framesElapsed = rxBurst->time()-prevFalseDetectionTime;
if (framesElapsed > 50) { // if we haven't had any false detections for a while, lower threshold
mEnergyThreshold -= 10.0/10.0;
if (mEnergyThreshold < 0.0)
mEnergyThreshold = 0.0;
prevFalseDetectionTime = rxBurst->time();
}
delete rxBurst;