Plura RUBIDIUM Series, Руководство пользователя

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Functional Description and Specifications RUB SW Page 19
2.2.2 Measurement of Signal Level
The level is important for the “signal loss” detector. Only the peak -to-peak value should be
regarded, any DC offset will not be considered. SW sets the signal threshold to 62 % of the
level, approximately.
Signals within a pair should have the same level. Utilising one of the configuration tools, the
level of each signal pair can be selected. If “Auto” is selected, the thresh old depends on the
measured level.
Instead of “Auto” , a level can be selected in the range of 1.0 V to 6.0 V, with steps of 0.5 V.
The threshold will be calculated from the selected level.
Example: Level = 5.0 V
→
threshold = 3.1 V.
In both cases, the measured level will be presented at the status monitor.
SW measures the level non-recurring; the measurement only takes place after the following
events:
•
First detection of a signal.
•
“Error Reset“ via front key at th e module or via button at the configuration tool.
•
Any change of level set-up at the configuration.
It is recommended to manually set the level, if the expected level is known and if SW operates
in a redundant word clock system.
Error Signal Loss
If the signal level falls below the threshold, a “ signal loss ” error will be indicated.
This error will be classified as a major error, so this error will be considered for a
changeover.
The status monitor indicates these measurements and errors at Input 1 page or Input 2 page
resp.
2.2.3 Measurement of Signal Frequency
SW permanently measures the frequency of all word clock signals. Signals within a pair
should have the same frequency. Utilising one of the configuration tools, the frequency of
each signal pair can be selected. If this is done, SW checks each signal of differences between
measured and selected frequency. If “Auto” has been selected instead, each signal will be
check for a valid word clock frequency only.
A valid word clock frequency should be a multiple of one of the basic sample frequencies:
32 kHz, 44.1 kHz or 48 kHz. The factor can be out of 1, 2, 4, 8, 16, 32, 64, 128 or 256.
Example: 96 kHz will be measured or selected as 48 kHz x 2.
The measurement is able to distinguish between all the Pull-Up and Pull-Down frequencies:
NTSC Pull-Down (NTSC_PD) = x 1/1,001,
PAL Pull-Down (PAL_PD)
= x 24/25,
NTSC Pull-Up (NTSC_PU) = x 1,001,
PAL Pull-Up (PAL_PU) = x 25/24.