Loma IQ3, Руководство пользователя

Страница: 58 / 144

Installation
Two versions of remote user interface are available, one with an on-board power supply and one
without. The model with the on-board power supply must be used where the cabling between the
search head and user interface exceeds two metres in length.
Care must be taken when routing the cabling to the remote user interface to observe good EMC
practice – do not run with mains or high energy switching cables.
Installing a Serial Link
The main control electronics board must have the optional serial link board fitted.
In order to use any of the serial link options your detector will require a cable and connector assembly
which facilitates external connection to the on board serial link electronics. The connector is normally
located on the underside of the control box.
If a serial link option was ordered with your detector the necessary internal cables and external socket
complete with a blank mating external plug and connection diagrams will be supplied. If you wish to
add a serial link to an existing system please contact your local Service Centre who will be pleased to
assist. See the
Setting Up Serial Links Setting Up Serial Links section for further details.
Site Considerations
Electromagnetic Compatibility (EMC)
All Loma machines are designed, and tested, to operate under factory conditions and have been
tested to recognised international standards for Electromagnetic Compatibility (EMC), both in terms of
not emitting excessively and not being subject to undesirable operation in the presence of other
equipment whose emissions also meet the standards.
This approach allows Loma to offer stable operation, even in RF noisy environments, provided the
other equipment is to the same standards and the field wiring is suitably ‘hard’.
It is still necessary, however, to ensure that the machine is not subjected to excessive electrical noise
via its supply or airborne sources.
Selection of Frequency Band
If two or more metal detectors sited within the same area are operating at the same frequency, then
they will interfere with each other leading to false rejects and unstable operation.
To overcome this problem, the detectors can be set to operate on one of ten different bands through
the
Menus > Service > Configuration > Head menu Search Head Setup screen. It is therefore very
important to ensure that detectors operating near one another are set to operate at different bands.
See
Frequency Selection Frequency Selection for further details.
Other EMC considerations
Any signal I/O which is connected to the auxiliary connections should be in screened cable, grounded
at one end by a low impedance path to RF, and kept free from sources of electrical noise (e.g. mains
supplies for large electrical machines).
The metal detector is a highly sensitive RF measuring device, which is well screened from outside
interference and has excellent electronic discrimination against unwanted electromagnetic fields.
However, due to its sensitivity it is possible that other devices which emit high levels of RF noise at
the operating frequency of the detector could cause interference, thereby degrading the performance
of the detector.
It is therefore important to avoid siting the detector next to any devices which emit abnormally high
levels of RF interference if proper operation is to be maintained.
Radio Frequency Interference
A metal detector is, essentially, a Radio Frequency (RF) transmitter and receiver. As such it is
sensitive to RF noise in the general vicinity of the detector location. Whilst those frequencies not close
to the operating frequency of the detector will usually be filtered out (this includes most ‘walkie talkie’
48