CHAPTER THREE
If the code into the TM7000 has normal Polarity, “NORM” should be selected. If the input code
is inverted, “INV” should be selected. When the direction of the input code is reversed, a
Polarity inversion takes place automatically to provide optimal translating capability.
The update rate of translated time on the LED Display is changed according to the code being
translated, and the rate (real time versus speed-up). This can cause a peculiar appearance of the
time display. If, for example, the seconds update ten times as fast as the display, they would not
appear to change. Changing the code speed slightly could cause the seconds display to
increment (or even decrement) at a slow rate. This phenomenon only occurs at rates much faster
than real time.
Pressing NEXT or PREV will change the LCD Display to the Warning Message screen, Figure
3.8.2, which forces the user to make a decision on whether to proceed or not to proceed. Making
the decision to Proceed “YES” returns the LCD Display to the Select Versatile Display Function
Menu, Figure 3.8.1 allowing the user to select the TM7000 operating mode in which to operate.
3.8.6 FILTERS
The Select Filters LCD Display as shown in Figure 3.8.6.1, provides for the enabling and
disabling of independent filters for the Envelope and Carrier of the input code.
When the “IN” below CARRIER FILTER is selected “IN” will be displayed in upper case letters
and “out “ will be displayed lower case letters.
The Carrier Filter is a band pass filter, implemented with a Phase Lock Tracking filter, designed
to remove extra, and/or supply missing carrier cycles.
The “COAST” switch enables/disables freewheeling during dropouts or loss (below the
threshold set by R132) of input code. If the carrier frequency is not precise (within 1%), disable
the carrier filter.
The Carrier Filter must be IN (enabled) for the “COAST” function to operate.
When “COAST” is displayed in upper case letters it is enabled. If “coast” is in lower case letters
it is disabled.
Note: When reading codes with more than one second between elements, adjust the threshold
for “space” cycles or enable “COAST” to prevent discontinuous translation.
3-24 TM7000 TymMachine TCG/T (Rev D) Symmetricom, Inc.
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