Specifications

Chapter 6 TR-08 Option
6-10
Channel Attenuation Options
As with normal FXS loop start or ground start interfaces on the Access Bank I, each channel on
the SPOTS 12 Channel Analog Card can be individually configured to attenuate the audio signal
in both the transmit and receive directions. The level of loss is selected via a 6-position DIP
switch for each channel (12 switches per card), and is measured in decibels (dB). Note that a
3dB loss (-3dB) implies the average power is reduced by 50%.
Table 7-3: Transmission Gain Options and Switch Settings for the SPOTS 12 Channel Analog
Cards (same as FXS)
Receive loss in dB
Switch Position
1 2 3
Switch Setting
ON 0 0 0
OFF -2 -3 -4
Transmit loss in dB
Switch Position
4 5 6
Switch Setting
ON 0 0 0
OFF -2 -3 -4
The loss introduced by each switch is additive. Therefore, it is possible to select the total loss in
dB between 0 and 9dB for both the transmit and receive directions by properly setting the
switches on each channel.Individual Channel Attenuation Examples
RCV GAIN = -9dB
XMT GAIN = -9dB
ON
1 2 3 4 5 6
RCV GAIN = -6dB
XMT GAIN = -3dB
RCV GAIN = 0dB
XMT GAIN = 0dB
ON
ON
1 2 3 4 5 6
1 2 3 4 5 6
Figure 7-8: Individual Analog Channel Attenuation Settings (same as FXS Card)