GE GFK-2489 - Manual (Page 150)

GFK-2489 Chapter 6 Installation 6-17
6
6. View the Radio Retries and No Ack counts at the point of maximum RSSI level. They
should be the same or lower than the previous reading.
(Main Menu > Performance Information > Packet Statistics > Wireless Packet Statistics)
If the RSSI peak results in an increase in the
Radio Retries
and
No Ack
counts, the
antenna may be aimed at an undesired signal source. Try a different antenna
orientation.
Tips for Improving Data Throughput
Some suggestions are offered below for maximizing the throughput of the radio system. It is
important to realize that an exact formula for every radio system cannot be given. Much
depends on the number of radios contained in the radio system, the size of data strings being
sent, the type of data being sent, zone quality (interference potential) and data speed. You
should find several items here, however, that can be applied to your radio system.
To Maximize Throughput of Data and Reduce Latency Time
▪ (AP only) Increment the Hop Time to the maximum of 28 msec. This lowers the overhead,
since it stays longer on a channel. The drawback is that if a particular channel becomes
blocked, it will take longer to hop to another channel.
(Main Menu>Radio Configuration>hop Time)
▪ Match the buffer sizes and hop times to accommodate the majority of message sizes. For
example, a 7 msec hop time is best suited to short data bursts, such as in telemetry
applications. A 28 msec hop time is better suited to large data strings, such as sending
Web pages over the radio link.
The following table offers suggested Hop Time settings for four different message sizes.
Hop Time FEC Status* Bytes per
(msec) Packet
28 OFF 325
ON 151
14 OFF 139
ON 59
7 OFF 45
ON 11
* FEC ON is generally not recommended if optimal throughput is desired. The
transceiver Repeat-Retry function is a more efficient means of ensuring message
delivery.
NOTE: Reprogramming does not work over the air when the settings Hop Time=7, FEC=On
and Encryption=On are used at the AP.