Black Box MTU200-N64M, Руководство пользователя

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14
Standalone G-Converter
SALES: 0118 965 5100
External Clock
The G-Converters have the ability to use as its clock source a clock supplied from the
connected DTE. An external clock is supplied externally to the converter via the EXT clock
pins, of the 15 way D type connector (pins 7 and 14). Whenever an external clock is used,
the rightmost decimal point of the seven-segment display is illuminated.
The two external clock modes are :-
External Clock without Autobauding
This mode is selected by switching SW4,7 to On and SW5,4 to OFF. In this mode the
external clock being supplied must be 20/- 50 ppm and the jitter content compliant
with the requirements of TBR12 and PD 7024. The function of the G-Converter in this mode
is identical to operation with recovered clock (normal operation) with the exception that the
clock source is from the external clock and not the G.703/4 link.
In this mode, if the received clock
F requency is grossly O ut of spec (or absent) then the
letters “Fo” will be alternately flashed with the N value on the LED display. At all times the
assumption is made that the clock being supplied to the G-Converter from the G.703/4
network is as per TBR12/PD7024 requirement.
When this mode is selected and operating correctly, the display should be steady with the
rightmost decimal point flashing.
External Clock with Autobauding
This mode is selected by switching SW4,7 to On and SW5,4 to ON. In this mode the
external clock, being supplied must be Nx /- 50 ppm and the jitter content
compliant with the requirements of TBR12 and PD 7024. The function of the G-Converter in
this mode will measure the external clock and set the operation of the G-Converter to this
speed. In this mode, the unit will become a Local.
In this mode, if the received clock
F requency is grossly O ut of spec (or absent) then the
letters “Fo” will be alternately flashed with the N value on the LED display. The N value will
still be derived from the external clock and the data will be clocked out of the DCE with this
clock, however the G.703/4 link will be clocked from the G.703/4 recovered 2048Kbps
clock. At all times the assumption is made that the clock being supplied to the G-Converter
from the G.703/4 network is as per TBR12/PD7024 requirement.
When this mode is selected and operating correctly, the display should be steady (indicating
the external clock speed) with the rightmost decimal point flashing.