Prism
Operation Manual Issue 2.00
Page 6.9
To return to the `Carrier Tests' level of the menu system, press [EXIT].
Note: The Eye Closure measurement is closely related to the 'Intersymbol'
measurement in the version 1.0 firmware. However, the new Eye Closure
measurement is more 'worst-case' (and so generally measures higher) since it also
takes into account the effect of any fs jitter in narrowing the eye. It is therefore
compatible with the eye width as discussed in the interface standard, if the 200mV
threshold is used. The zero-crossing threshold is provided for compatibility with version
1.0 firmware.
6.1.6.
Errors (menu 1.6.)
This selection displays a count of biphase violations since the last acquisition of lock.
The result can be cleared to zero by pressing the [EDIT/CLEAR] key when this sub-
menu is selected.
Errors = 132
since last CLEAR
The interface standard dictates that transitions of the carrier always occur at certain
times, and never at certain other times. The presence or absence of extra transitions
embodies the varying data. A biphase error occurs when a transition of the incoming
carrier occurs where none is allowed, or when a compulsory transition is missed.
A sub-frame parity error is a type of biphase error since each sub-frame is required to
end in the opposite state to which it began, but a biphase error does not necessarily
imply a parity error.
To return to the `Carrier Tests' level of the menu system, press [EXIT].
