Messages
Chapter 5
WAAS GUS Signal Generator User Guide Rev 1
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Table 14: L1/L5 Control Command Field
INITIALIZE RANGE FIELD
If this field (flag) is set, the Signal Generator, upon receiving the next 1-PPS pulse, starts the I and Q coders.
DISABLE PRN CODE (I) FIELD
If this field (flag) is set, the Signal Generator does not use the I PRN codes in modulation.
DISABLE MESSAGE (I) FIELD
If this field (flag) is set, the Signal Generator does not use the I message symbols in modulation.
SELECT BPSK OR QPSK MODULATION MODE FIELD
If this field (flag) is set, the Signal Generator operates in the QPSK mode of modulation. If this field is not set, the
Signal Generator operates in the BPSK mode of modulation.
DISABLE NH/MANCHESTER (Q) FIELD
If this field (flag) is set, the Signal Generator disables the NH code for dataless operation or Manchester Code for
data operation.
DISABLE NH/MANCHESTER (I) FIELD
If this field (flag) is set, the Signal Generator disables the NH code for dataless operation or for the L5 I channel
signal only, the Manchester Code for data operation. (Note that Manchester coding is not used on the L1 I channel
signal).
DISABLE MESSAGE (Q) FIELD
If this field (flag) is set, the Signal Generator does not use the Q message symbols in modulation.
DISABLE PRN CODE (Q) FIELD
If this field (flag) is set, the Signal Generator does not use the Q PRN codes in modulation.
For clarity, the I and Q channel modulation formats which result from different combinations of control commands
are tabulated below. Note that the I channel is always active so its data format does not depend on the D3 bit.
Table 15: Resulting
I
Modulation Format
Byte
[6]
D7
D6
D5
D4
D3
D2
D1
D0
MSB
LSB
D3
D1
D5
D2
PRN Code
Manchester
Code
Neumann-
Hoffman
Code
Symbols
N/A
0
0
0
Enable
L5 Enable
L1 Disable
Disable
Enable
N/A
0
0
1
Enable
Disable
Enable
Disable
N/A
0
1
0
Enable
Disable
Disable
Enable
N/A
0
1
1
Enable
Disable
Disable
Disable
N/A
1
0
0
Disable
L5 Enable
L1 Disable
Disable
Enable