11
Using the
DGPS 53
The following sections describe the NMEA data
format of each sentence transmitted and received by the
DGPS 53. The baud rate selection and one-pulse-per-
second output interfaces are also described.
NMEA Received sentences
This section defines the sentences which can be
received by the DGPS 53. Null fields in the configuration
sentence indicate no change in the particular configuration
parameter.
All sentences received by the DGPS 53 must be
terminated with <CR><LF> (press ENTER), but do not
require the checksum *hh. The checksum is used for
parity checking data and it is recommended that the
checksum be used in environments containing high
electromagnetic noise. It is generally not required in
normal PC environments. Sentences may be truncated by
<CR><LF> after any data field and valid fields up to that
point will be acted on by the DGPS 53.
Almanac Information (ALM)
$GPALM<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>,<15>
*hh<CR><LF>
The $GPALM sentence can be used to replace the DGPS 53’s stored almanac information if
battery back-up has failed.
<1> Total number of ALM sentences to be transmitted by the sensor board during almanac
download. This field can be null or any number when sending almanac to the sensor board.
<2> Number of current ALM sentence. This field can be null or any number when sending
almanac to the sensor board.
<3> Satellite PRN number, 01 to 32
<4> GPS week number
<5> SV health, bits 17-24 of each almanac page
<6> Eccentricity
<7> Almanac reference time
<8> Inclination angle
<9> Rate of right ascension.
<10> Root of semi major axis
<11> Omega, argument of perigee
<12> Longitude of ascension node
<13> Mean anomaly
<14> af0 clock parameter
<15> af1 clock parameter
NMEA Received sentences:
GPALM
PGRMI
PGRMC
PGRMO
PSLIB
