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Loop Adapter; Magnetic Loop; Specification; Reception Specifications - Nokia Loopset LPS-3 Technical Documentation Manual

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PAMS Technical Documentation
When there is no call going, AUXOUT is in high impedance state and XMIC
is pulled up. When loopset is connected, XMIC is pulled down. XMIC is
connected to HeadsetInt line (in MAD), so an interrupt is given due to both
connection and disconnection.
During a call there is bias voltage (1.5 V) in AUXOUT. The state of HeadsetInt
can't be sure. It is better to disable loopset interrupt during a call and poll from
EAD line (AD converter in CCONT) to see if loopset is disconnected. Actually
disconnection of a headset without remote control switch could be seen in
HookInt, but headset with the switch could not.

Loop Adapter

Connection resistance must be under 3mΩ.

Magnetic Loop

The magnet field is based on the IEC 118–4 and BS 6083 part 4 stan-
dard.

Specification

Reception Specifications

Type of Function
Impedance
Frequency responce
Magnetic field
Loop Current
Automatis Gain Control
Signal to Noise Ratio
Maximum Ratings
Determined as defined by IEC 268 using signal limited to frequency range
300 ... 3400 Hz.
Issue 1 12/99
Specification
100k ohm +/– 5 % at 1 kHz
See figure 1
100mA/m (RMS) 3dB ref.
1kHz=0dB
400mA/m +12dB,125 ms RMS–
peaks
700mA(RMS) 3dB ref. 1kHz
=>0dB
2,8A (RMS), 125 ms RMS
peaks
=>+12dB
Response time <35 ms
Resetting time 0,5–5dB/s
855 dB
E Nokia Mobile Phones Ltd.
-
Loopset LPS-3
Notes
The strength of the magnetic
field measured next to the
ear. (or measured in the hor-
izontal plate and 170mm trip
from the curve of the loop.)
nominal level (122 mVrms)/
1kHz
Page 7

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