User's Guide

16
RADIO MODULE MACHINE (RMM)
Cable side exit and rear exit versions are available
RMM RADIO ANTENNA
The RMM receives radio signals from the probe, and
passes the signals via a 10m (32ft) coaxial cable to
the MI16 interface.
Two RMM units are supplied with each system.
The system can operate with a single RMM,
but there may be areas where the radio signal is
weak. This is a characteristic of all radio systems.
The second RMM is positioned to provide good
reception over the probes full working area.
SIGNAL TRANSMISSION ENVELOPE
Radio signals can be transmitted and recieved up
to distance of 3 metres (9.8ft), in any direction.
Distances greater than this may be achievable under
certain circumstances.
Line of sight between the RMP3 and the RMM
is not required and the signal can still be received
with the RMP3 fully enclosed in a bore.
Systems operating on the same channel should
be seperated by a distance of 100m (328ft), to
avoid interference with each other.
OPERATING ENVIRONMENT
It is important that the environment is free from
interference at the chosen transmission frequency.
Devices that may make operation difficult include
arc welders, pagers, remote control keys, mobile
phones or another radio probe operating on the
same channel.
An audio monitoring facility is provided to
diagnose causes of interference - see page 18.
RMM MOUNTING
Select a flat, metallic surface, ideally away from
corners and bulkheads.
The base of each RMM incorporates five perma-
nent magnets to allow temporary attachment to a
metal surface.
Alternatively three clearance holes are provided
within the base for M4 fixing screws -10mm long
for permanent installation.
RMM POSITIONING
Each RMM must be installed with care in order to
receive as strong and reliable a signal as possible
from the probe/RMP3 transmission module.
To guarantee reliability, the MI16 Interface has
two independent reception circuits, each support
one antenna (RMM). Radio waves are a coherent
form of energy, and reflected signals may add or
subtract to the performance, resulting in no signal
in some positions. To avoid this, a second RMM
is recommended.
Commence by connecting a single RMM to the
MI16 interface. Position the RMM as close as
possible to the working envelope. Activate the
probe/RMP3.
The strength of the radio transmission signal is
observed using the MI16 interface front panel
Rx signal display - see page 18 item 6. Move the
probe around the working envelope and observe
the RX signal display. Identify positions in the
working envelope where the signal is weak or
disappears. A satisfactory signal is indicated by
the RX display signal bars remaining green.