User's Manual

MDS 05-2708A01, Rev. D MDS TransNET I&O Guide 21
Antenna SWR Check
It is necessary to briefly key the transmitter for this check by placing the radio
in the SETUP mode (Page 40) and using the KEY command. (To unkey the
radio, enter DKEY; to disable the SETUP mode and return the radio to normal
operation, enter Q or QUIT.)
The SWR of the antenna system should be checked before the radio is put into
regular service. For accurate readings, a wattmeter suited for 1000 MHz is
required. One unit meeting this criteria is the Bird Model 43 directional watt-
meter with a 5J element installed.
The reflected power should be less than 10% of the forward power
(≈2:1 SWR). Higher readings usually indicate problems with the antenna,
feedline or coaxial connectors.
Data Buffer Setting—Modbus Protocol
The default setting for the data buffer is OFF. This allows the radio to operate
with the lowest possible latency and improves channel efficiency. MODBUS
and its derivatives are the only protocols that should require the buffer to be
turned on. See “BAND [A, B, C]” on Page 30 for details.
Hoptime Setting
The default hop-time setting is 7 (7 ms). Alternate settings of 14 and 28 milli-
seconds can be used to increase throughput, but at the cost of increased
latency. A detailed explanation of the HOPTIME command can be found on
Page 34.
TotalFlow™ Protocol at 9600 with Sleep Mode
For reliable operation with TotalFlow meters, use the default settings for
9600 with the following alterations:
HOPTIME 28—Allows large data packets
FEC OFF—Improves store-and-forward performance for a large contin-
uous data stream
BUFF ON—Ensures “ungapped” 4-second polls if unit in sleep mode
Operation at 115200 bps
Burst throughput at 115200 bps is supported at all settings. The radio will
always buffer at least 500 characters. Sustained throughput at 115200 bps is
only possible when the data path is nearly error-free and the operating settings
have been properly selected. For sustained operation at 115200 bps, use the
following settings: SAF OFF, FEC OFF, REPEAT 0, RETRY 0, HOPTIME 28.