SIGNAL
CONDITIONING MODULE
The SCM
provides the system with a range of functions that are
ideal for EMC testing. All SCM functions are remotely
controlled from the Folnet Controller by easy-to-use
menu driven commands.
The SCM
provides the following:
-
0-45dB
attenuator in 3 dB steps
-
12dB
Low noise Pre-amplifier
-
Four
Switchable Inputs
-
Calibrate
Generator
-
Switchable
High Impedance Buffer
-
Maximum
link gain of 33dB
-
Maximum
link attenuation of -24dB
The
inclusion of the attenuators and pre-amplifier allows
the user to adjust the gain in 3 dB steps to adapt the
superb simultaneous dynamic range of the Sentinel II FOL
to match the signal levels being monitored.
OPTICAL
RECEIVER MODULE
The Optical
Receive Module (ORM) receives the signal from the OTM and
converts it from an optical to an electrical signal. The
ORM front panel contains a three colour LED, which gives
the user an immediate indication of the integrity of the
optical link.
The ORM is
plugged into a Folnet Controller, which provides power and
control. The Folnet Controller (see separate Data Sheet)
is available in either single channel Desktop (pictured
above) or five channel Rack mount version.
DYNAMIC
RANGE PERFORMANCE
The use of
a DFB Laser Diode has yielded a system with unparalleled
simultaneous dynamic range. Conventional laser and LED
based systems cannot match this performance. The Sentinel
II has a very low noise figure, and an output voltage
capability of 630mVp-p. The attenuators within the SCM
allow the monitoring of pulsed input signals as high as
+25dBm/11Vp-p, and the pre-amplifier permits the detection
of very low level signals. Refer to A pplication Note
AN003 “Dynamic Range, Noise and Linearity” for further
details.
BATTERY
MANAGEMENT
The
standard Battery Pack maintains full performance for up to
six hours of continuous operation. Alternatively, higher
capacity Battery Pack options are available. Advanced
power control circuitry within the OTM ensures that full
performance is maintained until the Battery Pack is fully
discharged. Once discharged, the Battery Pack may be
rapidly re-charged with one of a range of Fast Chargers.
Please
refer Datasheet for more information.
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OPTICAL
TRANSMIT MODULE
The OTM
contains an RF amplifier, Laser Diode and control
circuitry. Its purpose is to convert the electrical
input signal to an optical signal. It is connected to
the Optical Receive Module via the ruggedised Fibre
Optic Cable. Power is provided either by the removable
Battery Pack, a suitably filtered external DC supply
or a shielded mains supply. The OTM is paired up with
a Signal Conditioning Module to provide greater
functionality. Both units are shielded for operation
in intense electromagnetic fields.
OPTICAL
CABLE AND CONNECTORS
The
ruggedised Fibre Optic Cable contains two optical
fibres: a single-mode fibre for signal information
from the OTM to the ORM, and a multi-mode fibre for
control information from the ORM to the OTM.
Single-mode
fibre has been selected for the signal path due to its
superior performance and elimination of “modal noise”
and signal distortion, which are characteristic of
systems using multi-mode fibre.
The
surface finish of the cable has been designed to be
resistant to “snagging”, thereby minimising the
possibility of cable breaks.
High
tensile strength aramid fibres within the optical
cable are crimped to the optical connector housing
ensuring that any stress on the cable is transferred
directly to the mechanics. This guarantees that the
sensitive optical fibres and connectors are relieved
of stress.
The
optical contacts of the Lemo connector are recessed
inside the metal shell thus reducing the chance of
damage to the polished fibre face. The special design
allows for easy cleaning should the contacts become
contaminated. The Lemo connector offers superb
repeatability.
A
cleaning kit and comprehensive instructions are
provided for use should cleaning become necessary.
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