RoyalTek REB-3000 - Manual (Page 42)

RoyalTek RGM-3000/REB-3000
GPS Module Operational Manual)
37
Phase Loss
Count: The number of time the phase lock fell below the threshold between the
present code phase sample and the previous code phase sample. This task is
performed every 20 ms (max count is 50).
Integration
Interval: The time in ms for carrier phase accumulation . This is the time difference (as
calculated by the user clock) between the Carrier Phase(current) and the
Carrier Phase(previous).
Track Loop
Iteration: The tracking Loops are run at 2 ms and 10 ms intervals. Extrapolation values
for each interval is 1 ms and 5 ms for range computations.
Calculation of Pseudo-Range
Measurements
The pseudo-range measurement in meters
can be determined from the raw track data
by solving the following equation:
Pseudo-range (PR) = {Received Tine
(RT) – Transmit Time (TT)} * C
where C = speed of light
The following variables from the raw track
data are required for each satellite:
Bit Number (BN) – 50 bits per second
Millisecond Number (MSN)
Chip Number (CN)
Code Phase (CP)
Receiver Time Tag (RTTag)
Delta Carrier Phase (DCP)
The following steps are taken to get the psr
data and carrier data for each measurement
epoch.
1. Computation of initial Receiver
Time(RT) in seconds. Note-Where the
initial arbitrary value chosen at start
up to make the PR reasonable
(i.e.,set equal to TT+70ms) and then
incriminated by one second for each
measurement epoch.
2. Computation of Transmit Time (TT) in
seconds.
3. Calculate Pseudo-range at a common
receiver time of the first channel of
the measurement data set. Note-All
channel measurements are NOT
taken at the same time. Therefore, all
ranges must be extrapolated to a
common measurement epoch. For
simplicity, the first channel of each
measurement set is used as the
reference to which all other
measurements are extrapolated.
4. Extrapolate the pseudo-range based
on the correlation interval to improve
precision.
5. Compute the delta range.
If the accumulation time of the Dalta Carrier
Phase is 1000 ms then the measurement is
valid and can be added to the previous Delta
Carrier Phase to get Accumulated Carrier
Phase data. If the accumulation time of the
Delta Carrier Phase is not equal to 1000 ms
then the measurement is not valid and the
accumulation time must be restarted to get
Accumulated Carrier Phase data.
Response :Software Version
String – Message I.D.6
Output Rate:Response to polling message
Example:
A0A20015 – Start Sequence and Payload
Length
0606312E322E30444B495431313920534
D0000000000-Payload
0382B0B3 – Message Checksum and End
Sequence