Specifications

AC65/AC75 Hardware Interface Description
4.1 Antenna Diagnostic
s
AC65_AC75_HD_v01.002 Page 72 of 117 2006-10-30
Confidential / Released
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
ANT
of 9kΩ (±3kΩ). Any lower or higher resistance from 1kΩ to 6kΩ or 12kΩ to 40kΩ gives an undefined
result.
A positive or negative voltage drop (referred to as V
disturb
) on the ground line may occur without having any impact
on the measuring procedure and the measuring result. A peak deviation (V
disturb
) of < 0.8V from ground is accept-
able.
V
disturb
(peak) = ± 0.8V (maximum); f
disturb
= 0Hz … 5kHz
Waveform: DC, sinus, square-pulse, peak-pulse (width = 100µs)
R
disturb
= 5Ω
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 <diag> Equivalent ranges
Normal operation, antenna connected (resistance at feed point
as required)
<diag>=0 R
ANT
= 6kΩ…12kΩ
Antenna connector short-circuited to GND <diag>=1 R
ANT
= 0...1kΩ
Antenna connector is short-circuited to the supply voltage of the
host application, for example the vehicle’s on-board power sup-
ply voltage
<diag>=2 max. 36V
Antenna not properly connected, or resistance at antenna feed
point wrong or not present
<diag>=3 R
ANT
= 40kΩ...∞Ω
Antenna
connector
AC75
9k±3k
External
antenna
V
disturb
5 Ohm