User Manual
MHX-920 Operating Manual: Chapter 4 Configuration 27
All units within a network
must use the same
encryption key.
Warning: Microhard Systems
strongly recommends changing the
Encryption Key to a value
different than the factory default
before deploying the network.
S Register 107 - Encryption Key
The Encryption Key provides a measure of security and privacy of
communications by rendering the transmitted data useless without the
correct key on the receiver. Valid Encryption Keys range from 0 to 65535.
Keep in mind that all units within the network must use the same key for
communications to succeed.
S Register 108 - Output Power Level
The Output Power Level determines at what power the MHX-920 transmits.
The MHX-920’s sensitive receiver can operate with very low power levels,
so it is recommended that the lowest power necessary is used; using
excessive power contributes to unnecessary “RF pollution”.
The allowable settings are:
0 1 mW
1 10 mW
*2 100 mW
3 1000 mW
Ideally, you should test the communications performance between units
starting from a low power level and working upward until the RSSI is
sufficiently high and a reliable link is established. Although the conditions
will vary widely between applications, typical uses for some of the settings
are described below:
Power Use
1 mW
For in-building use, typically provides a link up to 300 feet on the
same floor or up/down a level. Outdoors, distances of 10 km can be
achieved if high-gain (directional) antennas are placed high above
ground level and are in direct line-of-sight.
10 mW
200-500 ft indoors, 8-15 km* outdoors.
100 mW
400-800 ft indoors, 15-25 km* outdoors.
1000 mW
(1 W)
Typically provides communications up to a distance of 1000 feet or
more in-building on the same floor or up/down a few levels,
depending on building construction (wood, concrete, steel, etc.). In
ideal line-of-sight conditions, up to 30 km* or more can be
achieved. Note that only an antenna with a gain of no more than 6
dBi may be used. Any higher is a violation of FCC rules. See
IMPORTANT warning below.
* These outdoor distances assume antennas are mounted at least 100 ft
above ground level