
Pathfinder DVL Guide
April
2018
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Page 159
Header information is the first item sent by the Pathfinder to the output buffer. The Pathfinder always
sends the Least Significant Byte (LSB) first.
Table 32:
Header Data Format
Hex Digit
Binary
Byte
Field
Description
1,2
1
HDR ID / Header
ID
Stores the header identification byte (7Fh).
3,4
2
HDR ID / Data
Source ID
Stores the data source identification byte (7Fh for the Pathfinder).
5-8
3,4
Bytes / Number
of bytes in en-
semble
This field contains the number of bytes from the start of the current
ensemble up to, but not including, the 2-byte checksum (Figure 43).
9,10
5
Spare
3-byte checksum offset, which would allow the output of a very
large data type in the PD0 message, although no data type can start
beyond the reach of a 16-bit offset word in the header.
11,12
6
No. DT / Num-
ber of Data
Types
This field contains the number of data types selected for collection.
By default, fixed/variable leader, velocity, correlation magnitude,
echo intensity, and percent good are selected for collection. This
field will therefore have a value of six (4 data types + 2 for the
Fixed/Variable Leader data).
13-16
7,8
Address Offset
for Data Type #1
/ Offset for Data
Type #1
This field contains the internal memory address offset where the
Pathfinder will store information for data type #1 (with this firm-
ware, always the Fixed Leader). Adding “1” to this offset number
gives the absolute Binary Byte number in the ensemble where Data
Type #1 begins (the first byte of the ensemble is Binary Byte #1).
17-20
9,10
Address Offset
for Data Type #2
/ Offset for Data
Type #2
This field contains the internal memory address offset where the
Pathfinder will store information for data type #2 (with this firm-
ware, always the Variable Leader). Adding “1” to this offset number
gives the absolute Binary Byte number in the ensemble where Data
Type #2 begins (the first byte of the ensemble is Binary Byte #1).
21-24 thru
2n+13 to
2n+16
11,12
thru
2n+5,
2n+6
Address Offsets
for Data Types
#3-n / Offset for
Data Type #3
through #n
These fields contain internal memory address offset where the
Pathfinder will store information for data type #3 through data
type #n. Adding “1” to this offset number gives the absolute Binary
Byte number in the ensemble where Data Types #3-n begin (first
byte of ensemble is Binary Byte) #1).