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Line Attenuation – Port 1 Only, Switches 5 and 6
Shorter distances between the TNE1520 and remote modems require increasing T1
transmit line attenuation in order to prevent the T1 signal from becoming too strong for
repeaters, switches and other T1 transmission equipment that may be encountered
along the line. Increased line attenuation translates to decreased T1 transmit amplitude.
0 dB – Receivers on most newer T1 transmission equipment can automatically
adjust for incoming amplitude, allowing them to run at zero attenuation regardless
of distance.
–7.5 dB, –15 dB, –22.5 dB – Some older T1 transmission equipment cannot
automatically adjust for incoming amplitude and line attenuation must be set
accordingly.
Port 1 Configuration Switches 5 and 6 on the TNE1520 control the line attenuation of
both T1 links (Port 1 and Port 2); line attenuation for the two links cannot be configured
independently.
Table 6. Line Attenuation Settings
Switch 5
down
up
down
up
Timing – Port 1 Only, Switch 7: TNE1520-P Only
Timing refers to the clock source for T1 transmission links.
Local – Local clock source refers to timing derived from an oscillator onboard the
TNE1520-P.
Loop – Loop clock source refers to timing derived from an intermediate device.
Port 1 Configuration Switch #7 controls the timing of both T1 links (Port 1 and Port 2) on
the TNE1520-P; timing for the two links cannot be configured independently. The
TNE1520-S determines T1 timing via communication with its partner T1 provider unit.
Table 7. Timing Settings
Switch 7
down
up
Switch 6
Attenuation
down
down
up
up
Clock Source
Local
Loop
0 dB
–7.5 dB
–15 dB
–22.5 dB
8
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