ASL INTERCOM PS 289, Руководство пользователя

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User manual PS 289 / Issue 1 © 2006 ASL Intercom, Utrecht, The Netherlands
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9.0 PARTY LINE, TECHNICAL CONCEPT 11.0 DESIGN CRITERIA
ASL's PRO Series offers a complete, two way ('full
duplex') communication system.
Users of the system are connected via a 'party line'.
Master stations (with built-in power supply), beltpacks,
speaker stations and power supplies are interconnected
via standard microphone cable (minimum cable size of 2
x 0.226 mm
²
(#24AWG)). One wire is used as an audio
line, one as a power line and the screen of the cable
functions as earth/return.
Current drive is used for signal transfer. Each station
utilises a current amplifier to amplify the microphone
signal and place it on the common audio line where, due
to the constant line impedance (situated in the power
supply between XLR pin 3 and 1), a signal voltage is
developed which can be further amplified and sent to
headphones or loudspeakers.
This principle has three advantages:
-
the use of a single audio line allows several stations
to talk and listen simultaneously.
- due to the high bridging impedance offered by each
station, the number of stations 'on line' has no
influence on the level of the communications signal.
- power and audio to the intercom stations use the
same cable.
The Call signal is also sent as a current on the audio
line. It develops a DC potential over the line impedance
that will be sensed by each station and interpreted as a
Call signal.
10.0 GUARANTEE
ASL Intercom warrants this unit to the original end-user
purchaser against defects in workmanship and materials
in its manufacture for a period of one year from the date
of shipment to the end-user.
Faults arising from misuse, unauthorised modifications
or accidents are not covered by this warranty. If the unit
is faulty, it should be sent in its original packing to the
supplier or your local ASL dealer, with shipping prepaid.
A note must be included stating the faults found and a
copy of the original suppliers invoice.
THIS PRODUCT WAS DESIGNED, DEVELOPED AND
MANUFACTURED BY:
ASL INTERCOM BV
UTRECHT, THE NETHERLANDS
Website: www.asl-inter.com
Email:
info@asl-inter.com
Applications / Environment of use
ASL Pro Series equipment is designed for use as a
wired communications system in theatres, in Radio/TV
production facilities, in factories, and in utilities
complexes such as airports, railway stations and coach
terminals.
ASL equipment can be used outdoors in normal
weather conditions. In conditions with excessive cold
(<-10° C), heat (>50° C) or humidity (>85%), ASL
equipment might not perform properly.
ASL equipment is not designed to be used under
water, or in situations where explosion safe equipment
is specified by authorities.
Emission
ASL Pro Series equipment does not generate high
frequency (HF) signals. An ASL power supply can
generate a weak magnetic field caused by the power
transformer. To avoid possible negative affects, keep
ASL power supplies at a safe distance from equipment
which is very sensitive to magnetic fields.
Immunity
ASL Pro Series is designed on the base of low
impedance signal transport. User stations and power
supplies are to be connected via low capacity cabling
with an overall screen (also see Cabling section).
Therefore, HF signals are adequately rejected to
maintain an intelligible communication, unless strong
electro-magnetic fields (exceeding 3 V/m) are in the
direct vicinity of the interconnecting cables.
ASL 19” rack mount units are housed in a 1 mm steel
enclosure (closed construction), which offers, by
nature, the highest possible rejection of electro-
magnetic fields
ASL speaker stations (PS 130/230/430) are housed in
an enclosure made of 1 mm steel with ABS side
panels, which offers adequate rejection of electro-
magnetic fields.
ASL beltpacks are housed in an ABS enclosure and
are slightly more sensitive to electro-magnetic fields.
Negative effects in the performance of beltpacks can
be avoided when keeping them at a safe distance from
equipment which might radiate strong electro-magnetic
fields, such as transmitters antennas and dimmers.