Specifications

SB-P-06-4066
sepura
Mobile & Gateway Accessory i/f
specification
30th July 2012
Page 23 of 39
Issue 7c
© Sepura plc 2011
Pin
Number
Signal
Name
Input/
Output
Description
Comment
Internal 47k pull up to 5V
7
MIC_SIG
I
Microphone
input
Console & AIU mk. 1, 2, 3
Sensitivity at ―normal‖ setting = 100 mVpp for
max. modulation.
Sensitivity at default ―high‖ setting = 10 mVpp for
max. modulation.
DC bias via internal 2.2 kΩ pull-up to 3 V when
microphone enabled; floating when microphone
muted. Zin = 2.2 kΩ.
AIU mk. 2 1, 3
Sensitivity at default ―normal‖ setting =
150 mVpp for max. modulation.
Sensitivity at default ―high‖ setting = 15 mVpp for
max. modulation.
DC bias via internal 4.4 kΩ pull-up to 3 V.
Zin = 1 kΩ.
If microphone resistance < 100 Ω, “high” sensitivity
is selected. Sensitivity = 15 mVpp for max.
modulation.
8
MIC_GND
-
Microphone
return
-
9
EAR_SIG
O
Earpiece output
32 ohms, power capability = approx 100 mW max.
(See note 7 below)
10
EAR_GN
D
-
Earpiece return
-
Notes:
1. Transceiver gain set to reference level, see section 6.5
2. The AIU Mk1 has been superseded by the AIU Mk2.
3. There are two audio gain settings: ―normal‖ intended for handheld microphones and
―high‖ intended for remote microphones. If the audio accessory identification resistor
(see section 6.3) is 10 kΩ, or greater, the ―normal‖ gain setting is selected. ―High‖
gain (20 dB higher than ―normal‖ gain) is always selected when the audio accessory
identification resistor is 0 Ω, i.e., ACC_ID is connected to ground.
4. AIU Mk2 only If the microphone resistance is < 100 Ω, the gain will be ―high‖. This
functionality is intended to allow dynamic microphones to operate with this interface
— as used in certain motorcycle helmet installations.