FM1 Firemans Microphone

FM1 Firemans Microphone
Operation Instruction Manual
FM1 Firemans Microphone
The FM1 has compressor, noise gate, equalisation
controls and optional chime (one to three note). The unit
is fully monitored and complies with BS5839 part4.
Operation is by Speak bar or push button on the fist
The FM1 is housed in a steel wall mounting case, with a
clear window and lockable door.
Technical Description
Microphone signals are passed to a voltage controlled
amplifier under control of a signal derived from rectifying
the stage output signals, providing 3:1 compression ratio.
The output of this stage is fed to an LED output level
display and a three-band equaliser (100 Hz, 1KHz, 10
Power is supplied at nominal 24 VDC via separate cabling,
the phantom power on the audio + and audio - being used
for fault detection only. A regulator circuit provides 15
VDC for powering the FM1 electronics.
Front Panel Features
The FM1 provides for the following LED indications:
Function / Description
1 OK
GREEN when no fault detected.
AMBER when fault detected.
GREEN when system ready for paging announcement, FLASHING GREEN when system busy.
4 VU
VU meter to show audio level. VU meter is constantly active and will light in sync with audio
peaks to indicate that the audio path to the input stage is intact. This occurs even when speak
bar is not pressed.
Block Diagram
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Unpacking Upon receipt of 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;
with poor ventilation
exposed to direct sunlight
with high ambient temperature or adjacent to heat generating equipment
with high humidity or dust levels
susceptible to vibration
The FM1 has been designed to offer a simple microphone input to the SigNET Digital Audio network, giving
global all call operation for the emergency services. This unit can also be used in the SigNET LinX voice
alarm systems.
The microphone console comprises of a fist microphone, speak bar and two status indicators, one for OK and
one for fault.
In order to page, the thumb switch on the microphone or the speak bar are pressed, and if the system is able
to accept paging, the speak bar will light solid green and paging may commence.
The speak bar LED indicator will flash if there is a busy input indicating that an equal or higher priority input to
the system is in use on one of the selected zones, or that access to one of the selected zones is excluded. If
the zone selection is valid, the busy in will permit the speak bar to illuminate steadily and the announcement
can be made.
Fault monitoring
The electret microphone capsule is monitored for impedance and current absorption. Any deviation from preset windows triggers the monitor circuit with the following results:
1. The OK LED is extinguished and the Fault LED illuminated.
2. The monitor circuit removes the 6K8 termination of the PTT. This puts an open circuit condition on the
PTT line, signalling a fault to external control equipment.
The audio lines are monitored by the phantom detect circuit which notifies any loss of the 15V phantom (due to
an open circuit or short circuit line) to the monitor circuit. The monitor circuit causes an open circuit condition
to be set on the PTT, signalling a fault to external control equipment.
DC power operation
The FM1 requires a 24V DC supply which enters the unit through the six core cabling (see page 4).
This unit must never be directly connected into a 230V AC power supply.
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Internal Adjustments
Chime select
The FM1 contains an optional chime, which can be set to a 1, 2 or 3 note chime dependant on the jumper
settings, (this feature is not to be used with SigNET SS2n systems, as the chime is set with the SS2n).
No chime
1 note chime
2 note chime
3 note chime
Mic monitoring
With the header in position the microphone capsule is monitored, this is the default setting and should not be
removed for life safety applications.
Removing the header disables mic monitoring and subsequent fault indication on front panel.
EQ controls
Bass, Mid and Treble controls are provided. Each provides –12dB of attenuation. Turn fully clockwise for max.
Master and Chime levels
Separate Audio and chime level controls are provided. Turn fully clockwise for max.
Output Connections
Connections are as follows:
A = +24V
B = Gnd
D = Busy
G = Audio +
H = Audio -
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SigNET AC Limited
6 Tower Road,
Glover Estate,
Tyne & Wear,
NE37 2SH.
Tel: 0191 417 4551
Fax: 0191 417 0634
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