Table of Contents
Advertisement
AC75 Hardware Interface Description
Strictly confidential / Preliminary
4.1
Antenna Diagnostic
The antenna diagnostic allows the customer to check the presence and the connection
status of the antenna by using the AT^SAD command. A description of the AT^SAD
command can be found in [1].
To properly detect the antenna and verify its connection status the antenna feed point must
have a DC resistance R
12kΩ to 40kΩ gives an undefined result.
A positive or negative voltage drop (referred to as V
without having any impact on the measuring procedure and the measuring result. A peak
) of ≤ 0.8V from ground is acceptable.
deviation (V
disturb
V
(peak) = ± 0.8V (maximum); f
disturb
Waveform: DC, sinus, square-pulse, peak-pulse (width = 100µs)
R
= 5Ω
disturb
Figure 38: Resistor measurement used for
antenna detection
Table 18: Values of the AT^SAD parameter <diag> and their meaning
Antenna connection status indicated by AT^SAD
Normal operation, antenna connected (resistance at
feed point as required)
Antenna connector short-circuited to GND
Antenna connector is short-circuited to the supply
voltage of the host application, for example the vehicle's
on-board power supply voltage
Antenna not properly connected, or resistance at
antenna feed point wrong or not present
AC75_HD_V00.202
of 9kΩ (±3kΩ). Any lower or higher resistance from 1kΩ to 6kΩ or
ANT
= 0Hz ... 5kHz
disturb
Page 79 of 120
) on the ground line may occur
disturb
Antenna connector
9k±3k
V
5 Ohm
disturb
<diag>
Equivalent ranges
<diag>=0
R
<diag>=1
R
<diag>=2
max. 36V
<diag>=3
R
s
AC75
= 6kΩ...12kΩ
ANT
= 0...1kΩ
ANT
= 40kΩ...∞Ω
ANT
27.04.2006
Advertisement
Table of Contents
