SXBlue GPS Reference Manual
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5.2.9 ZDA Data Message
The ZDA message contains Universal Time information. The table below breaks down
the ZDA data message into its components. This message has the following format:
$GPZDA,hhmmss.ss,dd,mm,yyyy,xx,yy*cc<CR><LF>
Table 5-11 ZDA Data Message Defined
Field
Description
hhmmss.ss
UTC time in hours, minutes, seconds of the GPS
position
dd
Day, dd = 0 to 31
mm
Month, mm = 1 to 12
yyyy
Year
xx
Local zone description in hours, xx = -13 to 13
yy
Local zone description in minutes, yy = 0 to 59
*cc
Checksum
<CR><LF>
Carriage return and line feed
5.2.10 RD1 Data Message
The RD1 message contains diagnostic information for SBAS operation. The table below
breaks down the RD1 data message into its components. This message has the
following format:
$RD1,SecOfWeek,WeekNum,FreqMHz,DSPLocked,BER-BER2,AGC,
DDS,Doppler,DSPStat,ARMStat,DiffStatus,NavCondition *cc<CR><LF>
Table 5-12 RD1 Data Message Defined
Field
Description
SecOfWeek
The second of GPS week (may be a couple of seconds old)
WeekNum
The GPS week number
FreqMHz
The L-band frequency in MHz (1475.4200 is used for SBAS)
DSPLocked
1 if DSPStat = 1B or 1F
BER-BER2
Bit error rate – bit error rates are given for both SBAS satellites being tracked
AGC
L-band Signal strength
DDS
0.0 for SBAS
Doppler
0 for SBAS
DSPStat
A status bit mask for the DSP tracking of SBAS
ARMStat
A status bit mask for the ARM GPS solution
DiffStatus
The SBAS PRN of the satellite in use
NavCondition
A series of hex character fields, which is read from right to left, with each field
representing the number of GPS satellites satisfying a certain condition, all of
which conditions are required if the satellite is to be used in the solution
*cc
Checksum
<CR><LF>
Carriage return and line feed