Operation Instruction Manual Psiren Graphic EQ

Operation Instruction Manual
Psiren Graphic EQ and Ambient Noise Sensor (GANS)
Features
It complies with BS 5839 part 4 for use in voice alarm applications when correctly installed.
Graphic Equalization The GANS provides 28 constant-Q, minimum phase 1/3 octave combining filters on modified ISO
centres.
Ambient Noise Sensing (ANS) & Following Via one or two ANS microphones. When a change in ambient noise is
detected by the GANS it increases or decreases, as appropriate, the level of audio signal fed to the zone amplifier. The
GANS can follow changes in ambient noise through a range of 24dB.
Technical Description
The GANS is based on an 8/16-bit CPU. Audio on entering the unit is debalanced then split into two paths.
The main signal is feed through the main voltage controlled amplifier into the graphic equalization cells. The audio is
altered according to the control signals, passed out of the equalizer, summed with the output of the pink noise generator
(set-up only) and passed through the line balancing section to the line level output.
The second path is via an RMS to DC converter and then into a Lin to Log converter to give a voltage, which is
logarithmically related to the input level (in dB). This makes all calculations into simple additions and subtractions of
voltages, which relate directly to dB levels. The output is fed into the input of a comparator. The other input of the
comparator is fed from a digital to analogue converter controlled by the CPU and forms a delta sigma modulator, which
acts as a first order analogue to digital converter.
Two sense mic feeds (line level) are debalanced, passed into a VCA cell as above. The same delta sigma process as
above gives a linear voltage, which changes relative to the audio output from the PA system plus the ambient noise.
Because the audio input and ambient noise microphone signals are logarithmic they can be subtracted leaving a dB gain
difference that is fed directly into the graphic equalizer section to alter each band in half dB steps under control of the
CPU.
The DAC controlling the sense mic VCA is loaded with a constant from the CPU, which is determined at commissioning.
This sets the gain of the sense mics to suit the installation and biases the delta sigma ADC to its mid dynamic range
point.
Front
panel
features
1
2
3
4
5
6
Backlit 40x2 LCD display.
Rotary encoder.
Two membrane switches
Fault Led (yellow) lights in case of microprocessor fault.
Mains Led (green)
Battery Led (green)
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Block diagram
Rear panel features
1
3
5
7
Name
AC Input
Battery Input
Function / Description
6 Amp IEC 22 type inlet
2
4
Name
Switch
RS232 in
(male on unit)
Function / Description
Rocker switch for on-off
RS232 out
(female
on
unit)
6
Sence
mic
(1&2)
Audio in
Audio out
Sence mics (ANS)
Sence mic 1 & 2 are the inputs for the ambient noise sensing
microphones. In a small area, one sense mic is sufficient. In
a larger space, two are better, placed either centrally one
third and two thirds of the way along the space or over two
main crowd areas such as bars.
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Contact
(female
unit)
on
DocNo.DCP0001413 RnB 08/12/03 rev1
Installation
Upon receipt of the shipment, please inspect for any damage incurred in transit. If damage is found, please notify your
local representative and the transport company immediately. State date, nature of damage and whether any damage
was noticed on the shipping container prior to unpacking. Please give the waybill number of the shipping order.
The unit should not be placed in areas;
1
with poor ventilation
2
exposed to direct sunlight
3
with high ambient temperature or adjacent to heat generating equipment
4
with high humidity or dust levels
5
susceptible to vibration
AC power operation
For normal AC operation, plug the AC power supply cord in a wall outlet of 230V specified voltage. The unit complies
with BS415.
AC power cord
Wires in the mains lead supplied with the unit are coloured in accordance with the following code.
Green and Yellow
Earth
Blue
Neutral
Brown
Live
As the colours of the wires in the mains lead of this unit may not correspond with the coloured markings identifying the
terminals in your plug, please connect as follows.
Wire
Plug terminal
Green & Yellow
‘E’ mark
‘EARTH’ symbol mark
‘GREEN’ mark
‘GREEN and YELLOW’ mark
Blue
‘N’ mark
‘BLACK’ mark
‘BLUE’ mark
Brown
‘L’ mark
‘RED’ mark
‘BROWN’ mark
Caution
To prevent electric shock do not remove the cover.
Fault Monitoring
Fault monitoring is in accordance with BS5839:Part 4.At switch-on, the unit performs a self-test including ROM check,
RAM check and E2PROM check. The program is protected by a watchdog facility, which is not serviced from interrupt
routines. The watchdog is an asynchronous timer, which is reset by the CPU within every 600 milliseconds. Failure to
reset within this timer causes the watchdog to fire and reset the CPU. The watchdog is only accessed once within the
main code. This means that if the program has locked up in a subroutine for more than 600 milliseconds it is
automatically reset.
Whilst the processor is being reset it’s pins go high impedance, removing the current from the outputs and signaling a
fault through the protection circuit to the contact port. Faults are signaled down the RS232 by the failure of the GANS to
respond to being polled by the system.
The associated SS2N polls the unit through the RS232 link looking for an OK return. Absence of an OK indicates fault,
so if a program stays locked up, it stays in fault.
The ambient noise sensing inputs are not monitored. The GANS sits in the audio chain between a SigNET station and an
amplifier. The monitoring tone from the SigNET LS SS2N station or iXLS passes through the audio chain and if the unit
or interconnections fail, the amplifier will detect a fault.
Failure of internal digital control electronics causes a fail-safe bypass relay to connect the audio input straight to the
output. The fault is reported back via two open collector contact ports, one normally open and one normally closed.
Faults are also indicated by failure of the GANS to respond to polling of its RS232 port. A fault indicator on the front
panel lights in case of microprocessor fault.
Controller Options
Control of the graphic and ANS settings can be made under PIN control from the front panel via a 24 way rotary selector
with accept and cancel keys. Feedback is displayed on the 40-character two-line backlit LCD.
A GANS can also be locally connected to a PC via its RS232 serial port to provide the same control.
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On a SigNET network up to 250 GANS can be connected to the RS232 output of a SigNET SS2 station and controlled
from PC(s) connected anywhere on the site.
The serial output on each GANS is daisy chained to the serial input of the next GANS. Further GANSs can be connected
to separate RS232 busses on different SigNET stations. GANS that are connected to one RS232 bus do not have to be
used in the same acoustic zone.
LS and non LS configuration
Life safety mode
Life safety mode is selected from the front panel or from a remote configuration PC via the
RS232 port. When the sensing mics cause the gain of the main VCA to vary (by up to ± 12 dB), the filters at 16kHz and
22kHz compensate to keep the gain at 22kHz steady so that the 22.05 kHz monitoring tone passes through unchanged
and the fault monitoring circuit will not be affected by changes in the overall volume level. For example, a VCA boost of 3
dB results in a cut of 3 dB at 22 kHz caused by changes in the levels of the 16 and 22 kHz filters. This change is not
exactly 3 dB at both 16 and 22 kHz because the two filters interact. The exact change at each frequency is adjusted
according to a stored table of values to result in a precise change at 22 kHz.
Non-Life safety mode The system operates as above but the 16 and 22 kHz filters are not re-adjusted.
ANS Commissioning
The GANS should first be set up manually to give the best measured response.
The ANS is then set up using a built-in pink noise generator. Pink noise at -15 dB (Allowing 3 dB of system headroom) is
played into the acoustic area and picked up by the noise sensing microphone(s). The GANS first calibrates these
microphones to the gain set by the system. Then, knowing the input reference level, it measures the returning calibrated
signal to arrive at the offset and adjusts the output gain accordingly.
Pink noise is used rather than fixed frequencies as it is statistically random and avoids the null and peak points caused by
standing waves which could cause microphones to give false readings. The GANS will ignore the changes to signals
passed through it and therefore won’t allow runaway gain changes as the system tries to chase itself.
The set-up process allows a minimum PA System level to be set, below which the PA System will not fall even if the
ambient noise level is significantly reduced. This is referred to as the ‘Noise Floor’ and is selected through the menu
sysyem (PIN number controlled access). ‘MAX Gain’ refers to the ceiling beyond which the unit will not attempt to
compensate for noise levels. Normally this should be set to 0db, because although the unit can provide gain, in some
acoustic spaces this can lead to instabilities. ‘Headroom’ should be specified. This is the level above ambient that the
unit attempts to maintain volume, typically this will be 6dB.
Set-up stores
There are eight non-volatile set-up stores which can each be loaded with different EQ curves for BGM and paging. Each
can also be given one of the four operation modes. The modes are switched between via the contact or RS232 ports.
Internal Adjustments
The unit has no internal adjustments or user serviceable parts.
Specification
Dimensions
Power Supply
230 VAC 24mA
Weight
3.5Kg
24 VDC 200mA
Width
433mm
Heat dissipation
16 Watts
Height
44mm
Maximum control range
24 dB (-12 dB to + 12 dB)
Depth
195mm
Life safety mode control range ± 12 dB (in the graphic) to allow monitoring tone to pass
Averaging time
5 sec. to 18 min
Frequency response
20 Hz to 30 kHz +1 dB, -0 dB
THD + N
<0.05% THD, unity gain, 1kHz music into balanced output
Signal to noise ratio
>70 dB, ref. 0 dBu, unity gain (30 kHz noise bandwidth)
Audio Inputs
Electronically balanced (RF suppressed)
Audio Input impedance
20Kohms
SigNET Amplification & Control
Tower Road,
Glover Estate,
Washington,
Tyne & Wear, NE37 2SH
Tel: +44 (0) 191 417 4551
Fax: +44 (0) 191 417 0634
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