Amron 2810E, Руководство пользователя

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MODEL 2810E USER MANUAL
2810E UM REV 7.0
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Amron Diver Communicators are designed with a special balanced circuit,
differential input and output amplifiers. In a balanced circuit, each wire in the
twisted pair carries an equal and opposite signal. Each wire generates an
electromagnetic field that is in opposition with the field of other wire. The net result
is that strength of the radiated electromagnetic field is significantly reduced if not
totally eliminated. In addition, any external fields, either from the other wire pair or
an external noise source, will be coupled to both wires equally creating a common-
mode signal. The differential microphone amplifier in Amron Diver Communicators
cancels the common-mode signal while amplifying the signal from the microphone.
Communicators without both differential input and output amplifiers cannot match
the performance of Amron Diving Communicators. This is an extreme simplification
of the common-mode coupling effect and common-mode signal rejection but
shows the power of Amron's Full Duplex (4-Wire) mode of operation.
7.2.2 ISN'T ROUND ROBIN THE SAME THING?
In Round Robin communication systems, each diver is connected using a 4-Wire
cable like the Amron Full Duplex (4-Wire) mode. This is where the similarities end.
In Round Robin systems all the microphones are connected together in parallel
and connected to the microphone input of the communicator. All the earphones are
also connected in parallel and connected to the earphone output of the
communicator. Each microphone is loaded by all the other microphones in the
system causing lower output. In a two diver setup where the diver microphones
have a typical impedance of 8 Ohms and the tender's microphone has an
impedance of 150 Ohm, the diver microphone output level will be reduced by
about 50% while the tender's microphone is attenuated by out 95%. On the
earphone side, the diver earphones commonly have an impedance of 8 Ohms
while the typical tender earphone impedance is around 175 Ohms. These two
factors combine to create a serious volume imbalance which requires higher
volume settings resulting in more noise and less system stability.
WHY FULL DUPLEX (4-WIRE)? 7.3
Amron Diver Communicator uses an independent microphone amplifier for each diver circuit
as well as for the tender. This allows Amron Diver Communicators to use the power of
common-mode rejection to cancel any coupled noise for each microphone as well as
providing less loading of the microphone than in 2-Wire mode. In 2-Wire mode, the diver
microphone is wired in parallel with the diver earphones. Assuming that the impedance of
the microphone is the same as the earphones, the signal from the microphone is attenuated
by 65%. By separating the microphone from the earphones, the output signal from the
microphone increases by 285%. With more signal, the volume level can be decreased
resulting in less noise and improved system stability for a significant improvement in overall
clarity.