Specifications

VP ONCORE COMMAND REFERENCE
6 CHANNEL SATELLITE RANGE DATA OUTPUT
MESSAGE (@@Bg)
continued
The user can accurately calibrate the code discriminator output by using
the fact that the long term average difference between subsequent code
discriminator measurements will be equal to 1 quantum. K5, the
calibration constant, varies slowly over time as a function of received
signal to noise ratio and multipath. Typical values of K5 are between 0.5
and 1.5. A simple low-pass filter can be used to generate K5 as follows:
diff = K3 * abs (CD
k
– CD
k-1
)
CD
k-1
= CD
k
LPF = LPF + beta * (diff - LPF) (initialize LPF = 10.4662 meters)
K5 = 10.4662 / LPF
The constant "beta" establishes the filter time constant. Typical values of
beta are 0.001 (maximum filtering) to 0.5 (minimum filtering). The Oncore
uses a constant of 0.05 internally.
OTHER FIXED CONSTANTS:
L1FO = 1,575,420,000.0 Hz (L1 carrier frequency)
SOL = 299,792,458.0 m/s (GPS value for the speed of light)
K1 = SOL / L1FO
K2 = K1 / 65536
K3 - (2
-11
) * SOL * 0.001 / 28644
K4 = 360 / 65536
88 Synergy Systems, LLC 05OCT01