ashtech ZY-12 Information Supplement page 98

DBEN Message
DBEN messages contain differential correction data used for the carrier phase
differential (CPD). Each DBEN message represents one epoch of GPS pseudo-
range and carrier phase measurements. DBEN is a "packed", or compressed,
message. The size of a DBEN message depends on the number of satellites
being tracked. DBEN data includes time, satellites PRN, and pseudo-range and
carrier phase measurements for each satellite being tracked. Tables A.11 through
A.13 below outline the contents of DBEN messages.
The structure of the DBEN message is shown below:
$PASHR,RPC, <Data Length> <Packed Data> <Checksum>
Parameter
data length unsigned short
packed data unsigned char[]
ChkSum unsigned short
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Table 4.11. $PASHR,RPC
Type # of bytes
2
data length
2
Description
number of bytes in <packed data> part
see below
Accumulative unsigned short summation
of the <packed data>, after <data length>
before <ChkSum>
ZY-12 GPS Receiver