Keypad; Vacuum Fluorescent Display (Vfd) - Comtech EF Data CDM-750 Installation And Operation Manual

CDM-750 Advanced High-Speed Trunking Modem
Front Panel Operation

5.1.2 Keypad

The function of the keypad is as follows:
Key
ENTER
CLEAR
◄ ►
(Left, Right)
▲ ▼
(Up, Down)

5.1.3 Vacuum Fluorescent Display (VFD)

a blue light, the brightness of which can be controlled by the user. Compared to a Liquid Crystal
Display (LCD), it has greatly superior viewing characteristics and does not suffer problems of
viewing angle or contrast.
On most menu screens, a flashing solid block cursor blinks at a once-per-second rate. This
indicates the currently selected item, digit, or field. Where it might obscure the item being edited
(e.g., a numeric field), the solid block cursor automatically changes to an underline cursor.
'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 '
IMPORTANT
Function
This key is used to select a displayed function or to execute a modem configuration change.
From the opening screen, pressing ENTER once takes the user to the SELECT: (Main) menu.
This key is used to back out of a selection or to cancel a configuration change which has not
been executed by pressing ENTER. Pressing CLEAR generally returns the display to the
previous selection or, if pressed repeatedly, to the opening screen. From the opening screen,
pressing CLEAR once takes the user to the SELECT: (Main) menu.
These arrow keys are used to move to the next selection or to move the cursor position. Space
permitting, most of the menus include arrow key hints (◄ ► ▲ ▼) to guide the user.
These arrow keys are used primarily to change configuration data (numbers), at the current
cursor position. Occasionally they may be used to scroll through a number of choices at the
current cursor position. Space permitting, most of the menus include arrow key hints to guide
the user.
Demod not locked
The keypad has an auto-repeat feature. When a key is
held down for more than 1 second, the key action will
repeat, automatically, at the rate of 15 keystrokes per
second. This is particularly useful when editing
numeric fields, with many digits, such as frequency or
data rate.
The CDM-750 features a Vacuum Fluorescent
Display (VFD). The VFD is an active display
showing two lines of 40 characters each. It produces
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
' or the circuit Eb/No value when
5–3
Revision 1
MN-CDM750