98 G12 OEM Board & Sensor Reference Manual
Notes on smoothing:
• Code smoothing by the carrier is performed by a first-order complimentary
filter which band goes narrower with time.
• Code smoothing works with update interval corresponding to the POP
setting
• Maximum smoothing interval is controlled by the SMI setting; smoothing
constant is changed from 1 to 1/SMI from locking a satellite.
• After SMI sec passes, smoothing constant is kept as 1/SMI (steady state);
the corresponding value in MCA changes from 0 to SMI.
• After reacquisition, smoothing is reset.
• Smoothing may also be reset in case of a large jump in code-carrier value,
and if current smoothing correction exceeds a preset value.
Example: Set code measurement smoothing to 100 seconds:
$PASHS,SMI,100
$PASHQ,SMI,[c1]
The associated query command is $PASHQ,SMI,[c1], where c1 is the optional
output port.
$PASHR,SMI
The response message is in the form:
$PASHR,SMI,d*cc
where d is the smoothing interval in seconds.
SNR: Set Signal-to-Noise Ratio
$PASHS,SNR,s
Sets the algorithm used for computing signal-to-noise ratio, where s is a 3-character
algorithm identifier; algorithm identifiers are DBH and AMP. Default is AMP. When
set to DBH, the SNR is calculated in dB-Hz, and with AMP the SNR values are a
function of amplitude.
Example: Compute SNR using DBH algorithm:
$PASHS,SNR,DBH
DEFAULT SETTING
SMI smoothing interval: 100 seconds
G12RevD.book Page 98 Tuesday, April 2, 2002 4:33 PM
To Next Page
Loading...