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Glossary
Version 1.5
Operator's Manual
NMEA
National Marine Electronics Association. The NMEA electronics
interface specifications have been developed under the auspices
of the Association. The NMEA 0183 is an internationally recog-
nized specification for interfacing marine electronics. NMEA 0183
version 2.1 is identical to IEC 1162-1.
PARALLEL
The perimeter of a parallel plane in the earth's ellipsoid. The paral-
lels define latitude. A special case parallel is the equator, whose
latitude is 0 degrees and to which all other parallels are referenced.
PARI1YBIT
A bit added to, or subtracted from, a binary coded message for
parity checking purposes.
PARI1Y CHECK
A simple statistical operation performed by the software that moni-
tors binary coded data being transmitted to verify that the received
message is the same as the transmitted message.
PARI1Y CONVENTION
In checking message parity (refer to PARITY CHECK), the soft-
ware may be designed to check either odd parity or even parity.
The choice is called parity convention: either odd or even parity
convention. Under odd parity convention rule, the binary-coded
message has the parity bit set to make up an odd number of rnes-
sage bits. Under even parity convention rules, the binary-coded
message has the parity bit set to make up an even number of mes-
sage bits.
P-CODE
A limited-access signal broadcast by the NAVSTAR satellites cur-
rently available only to military users.
PDOP (Position Dilution of Precision)
An indicator of the accuracy in position (latitude, longitude, and
altitude). See DILUTION OF PRECISION.
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