User Manual PS 155 / Issue 1
8
2001 ASL Intercom, Utrecht, Holland.
12.0 PARTY LINE, TECHNICAL CONCEPT 13.0 TECHNICAL SPECIFICATIONS
ASL's Pro Series offers a complete two way ('full
duplex') communications system.
Users of the system are connected via a 'party line'.
Master stations (with built-in power supply), beltpacks
and power supplies are interconnected via standard
microphone cable. 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 the headphones.
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 which will be sensed by each station and
interpreted as a Call signal.
14.0 WARRANTY
This unit is warranted by ASL Intercom to the original
end-user purchaser against defects in workmanship
and materials in it's manufacture for a period of one
year from 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 it's
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
UTRECHT, HOLLAND.
Web site: http:///www.asl-inter.com
E-mail: info@asl-inter.com
POWER CONSUMPTION
current (at 30 V DC) 18 mA quiescent
INTERCOM LINE DRIVER
max. output current 3 mA rms
output impedance > 150 Kohms
SIDETONE
rejection 0 - 35dB adjustable
DIMENSIONS AND WEIGHT
width 90 mm
height 38 mm
depth 124 mm
weight 260 gramms
GENERAL SYSTEM SPECIFICATIONS
intercom line impedance 350 ohms (1kHz)
2.2 Kohms (DC)
intercom line audio level nom. -18 dBu
max. +4 dBu
dynamic range 80 dB
call send signal +2.8 mA
call receive signal threshold +2.4 V DC
supply voltage +30 V DC (12 V to 32 V)
Note : 0dBu = 775 mV into open circuit
ASL reserves the right to alter specifications without
further notice.
(9 pages)
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