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Section 11 - Beacon receiver binary protocol
11.1 Beacon receivers (8800 series and 8900 series)
11.1.1 Binary
control messages
05/01/97 REV H
If your differential-ready GPS receiver is compatible with the Magnavox
MX-50R radio-beacon interface protocol, a subset of this command proto-
col can be used to control the 8800 DGPS receiver. These binary control
messages consist of a function byte followed by parameter bytes.
Like NMEA 0183 control messages, binary control messages are accepted
on either the monitor or control input ports; they aren't echoed. Any out-
put that's generated in response to a binary control message is directed to
the RTCM SC-104 output port where it's interspersed with the RTCM
SC-104 data bytes. (Since the bytes contain two-bit type flags, there isn't
any interference with normal RTCM SC-104 data processing.)
Frequency select
The frequency-select command consists of the hexadecimal byte CE fol-
lowed by a two-byte frequency-selection code. Divide the desired tuning
frequency by 100 Hz, then encode that number into two bytes: The first
byte is hexadecimal C0 plus the six most significant bits (msb6); the sec-
ond byte is C0 plus the six least significant bits (lsb6). The general format
for this command is:
For example, tune channel 1 to 304.5 kHz:
Commanding a frequency of zero returns the 8800 to its automatic mode.
For example, return the 8800 to automatic mode:
Bitrate select
An explicit bitrate for the received beacon signals must be specified when
using the binary control protocol. You may specify it either before or
after the frequency selection. Here are the hexadecimal bit-rate selection
codes:
D4 = select 25 bits per second (bps)
•
D5 = 50 bps
•
D6 = 100 bps
•
D7 = 200 bps
•
Section 11 - Beacon receiver binary protocol
CE C0+ msb6 C0+ lsb6
CE EF E5
CE C0 C0
PAGE 61
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