User manual

PAGE 7
User Manual PS 630 / Issue 2011 © ASL Intercom BV
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8.0 TECHNICAL SPECIFICATIONS PS 630
System
dynamic range: 80 dB
call send signal: +2.8 mA
call signal threshold (receive): +2.4 V DC
supply voltage: +30 V DC (12 - 32 V DC)
power interrupt time (mic mute): 0.1 sec
Intercom Line
Impedance: 350 Ω (1kHz), 2.2 kΩ (DC)
audio level: nom. -18 dBu, max. +4 dBu
Mic. Pre-amps
gooseneck mic: noise cancelling electret
headset mic. impedance: 200 Ω
gain: 40 - 60 dB (adjustable internally)
presence filter: +6 dB at 5 kHz
frequency response: 200 Hz - 13 kHz (-3 dB)
power to electret mic: +9 V DC
Side Tone
Rejection: 0 - 30dB adjustable
Buzzer
max. SPL: 85 dBA
Speaker Driver Amp
speaker impedance: 25 Ω
max. output power: 2.9 Wrms
Headphones Driver Amps
max. output level:
monaural: 14 Vrms @ 200 Ω
binaural: 2x 10.6 Vrms @ 400 Ω
max. output power:
monaural: 1 Wrms @ 200 Ω
binaural: 2x 0.28 Wrms @ 400 Ω
Program Audio Input
input impedance: 11 kΩ (balanced)
nominal input level: -12 to + 6 dBU
max. input level: +21 dBu
Direct Mic Output
output impedance: 50 Ω (balanced)
nominal Output Level: + 6 dBu
max. Output Level: +24 dBu
Power Consumption PS 630
current (at 30 V DC):
105 mA quiescent, 140 mA signaling
280 mA at max. output + signaling
Dimensions & Weight PS 630
width: 337mm / height: 87 mm
depth: 155 mm / weight: 2940 grams
0 dBu is defined as 775 mV into open circuit
ASL reserves the right to alter specifications without prior notice
9.0 PARTY LINE, TECHNICAL CONCEPT
User stations in an ASL intercom system are
connected via one or several 'party lines'. A party
line offers two way (‘full duplex’) communication and
consists of standard microphone (multi-pair) 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
utilizes 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 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
the party 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.