Comtech EF Data CDM-750 - Manual (Page 82)

CDM-750 Advanced High-Speed Trunking Modem Revision 2
Front Panel Operation MN-CDM750
5–4
5.1.3 Vacuum Fluorescent Display (VFD)
The CDM‐750 features a Vacuum Fluorescent Display (VFD). The VFD is an active display
showing two lines of 40 characters each. It produces a blue light with a user‐adjustable
brightness. Compared to a Liquid Crystal Display (LCD), it provides superior viewing
characteristics and does not suffer problems of viewing angle or contrast.
5.1.3.1 Opening Screen
The opening screen is displayed whenever power is
first applied to the unit. After turning on the prime
power, this VFD ‘splash’ display identifies the
product – i.e., ‘CDM‐750 Advanced High‐Speed Trunking Modem’ – and the version number of
the installed firmware.
On most menu screens, you will observe a flashing solid block cursor, which blinks at a once‐per‐
second rate. This indicates the currently selected item, digit, or field. Where this solid block
cursor would obscure the item being edited (e.g., a numeric field) the cursor will automatically
change to an underline cursor. Press any key to restore the previous screen.
You may access the opening screen from any location within the CDM‐750 menu structure by
pressing the [CLEAR] key repeatedly. Otherwise, press any key to access the top‐level SELECT:
(main) menu.
5.1.3.2 Screen Saver
If the operating unit is left displaying the same
screen for weeks at a time, the VFD could become
‘burnt’ with this image. To prevent such ‘burn‐in’ a
‘screen saver’ feature activates after 1 hour. The message moves from right to left across the
screen, and then wraps around.
The top line of the display shows the user‐definable Circuit ID. The bottom line displays the
demod lock status message (either
‘Demod not locked’ or the circuit Eb/No value when
the demod is locked) followed by ‘Press any key....’ Press any key to return to the
previous screen.