AXYS
®
Octadrive DSP-DN User Manual rev 2.0
201703/ODSPDN_2.0
11
ANS/Paging Microphone
The microphone input supports either electret or dynamic
mic types and features software configurable open circuit
and short circuit detection thresholds. The DC impedance
of dynamic microphone types should be between 300 and
10k
Ω
to ensure proper capsule monitoring operation.
Connection is via a 5-pin 3.81 mm-pitch screw-terminal
connector [15]. A mating connector is supplied with the
unit (an ANS microphone only requires a 3-pin connection).
ANS features:
The Octadrive DSP-DN’s processor card includes an
Autogain algorithm which adjusts the gain through the
unit in response to ambient noise levels. To accomplish this,
an external Ambient Noise Sensing (ANS) microphone*
must be connected to the ANS mic input. Signal processing
as for paging purposes (low-cut filter etc.) does not affect
local Autogain operation.
An ‘unprocessed’ microphone signal is available as an
output and is transmitted on channel 17 of the Dante
™
interface.
Paging features:
A ‘processed’ microphone signal is available as an output
and is transmitted on channel 18 of the Dante
™
interface.
This signal has a low-cut filter, gain control and a limiter.
The gain of the signal is software configurable in 10 dB
steps (30, 40, 50 or 60 dB). The gain should be adjusted
so that the Mic level LED [11] lights green during normal
operation, occasional red (limiter active) allowed.
Connect PTT to GND to activate the ‘processed’ microphone
Dante
™
transmit channel. For monitored PTT operation, the
DC impedance between PTT and GND should be 10k
Ω
(activated) respectively 20k
Ω
(deactivated). PTT control by
network command is also supported, this operates when PTT
is unconnected.
PTT Switch
2 x 10k
Ω
resistors
fig.7: PTT Switch Monitoring Circuit.
The PTT switch operation can either be monitored or
un-monitored. When monitored, a failure will result in
activation of the ‘processed’ microphone output.
If microphone monitoring is enabled, a failure will result
in muting of the ‘processed’ microphone output channel.
Both the ‘unprocessed’ and ‘processed’ microphone
outputs do not directly support the addition of a pilot
tone for receiver monitoring purposes. A pilot tone can be
added by using a local Dante
™
loopback for both these
microphone outputs.
Failure Relay
The Octadrive DSP-DN includes a two-pole changeover
relay whose contacts are accessible on two 2-pole 3.81
mm-pitch screw-terminal connectors. The conditions under
which the relay operates are defined as part of the unit
configuration in WinControl.
One pole of the relay provides volt-free contacts (Contacts
1, [18]), the other (Contacts 2, [19]) has internal resistors
to allow the Octadrive DSP-DN to be connected directly to
impedance-sensing line monitoring equipment such as the
AXYS
®
Cerberus.
On Connector [18], the pins of Contacts 1 are short-circuit
in normal operation, and become open-circuit when a
failure condition arises.
* A suitable AXYS
®
microphone (combined with a temperature sensor) is available – Part No. 971181101 Ambient Mic and Temperature sensor. Refer to
“Ambient temperature sensor” on page 13.