Kaman Extreme Environment Sensors - Manual (Page 12)

High Temperature Displacement System
Importance of Oscillator Frequency
The Oscillator frequency used will vary depending on the sensor and type of target
used. The high temperature displacement systems generally operate at a lower
frequency than other Kaman transducers. The reason they operate at low
frequencies is to allow the transducer to "see through" the protective covering on the
sensor (normally Inconel) and to optimize the sensor output from a specific target
material. The lower frequencies are responsible for limitations in frequency response
of the system and how thin a target material can be. Minimum thickness of the
target material depends on the permeability, conductivity, and frequency of operation
but generally is not a factor for thickness of .5" or greater. Frequency response of the
system is generally set at least 10 times less than the oscillator frequency.
Synchronization
If you are using a multiple channel system or you have several single channel
systems with the sensors in close proximity, the modules will require synchronization
done at the factory. If you ordered a multichannel 8200 system the modules will
have been synchronized in either a daisy chain or parallel configuration. When the
modules are synchronized you will have one 'master' module and several 'slave'
modules which will be labeled accordingly on the side of the modules. The 'master'
module provides the oscillator frequency from its 'sync out' pin to the other 'slave'
modules 'sync in' pins. If it is a daisy chain configuration each successive module
provides the oscillator to the next module. This has the advantage of allowing more
modules to be tied together, but if any modules in the chain are disconnected, all of
the modules downstream from it won't work. The parallel configuration relies on one
module to have the master oscillator and all of the other modules get there oscillator
from that one master module. The parallel configuration will work only until there
are so many modules that one oscillator can no longer driver them adequately. The
system will drive up to eight modules in parallel. The 'master' module is normally
located in the leftmost slot in the chassis (next to the power supply if there is one).
In either case, if the master module oscillator is not functioning, no other modules in
the chassis will work.
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