Comtech EF Data CDM-600/600L - Manual (Page 79)

CDM-600/600L Open Network Satellite Modem Revision 3
Front Panel Operation MN/CDM600L.IOM
5–3
5.1.2 Front Panel Keypad
IMPORTANT
The keypad has an auto-repeat feature. If 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 keypad comprises six individual keyswitches, mounted directly behind a fully sealed
membrane overlay. They have a positive ‘click’ action, which provides tactile feedback. The user
enters data via the keypad, and messages are displayed on the VFD. The function of the keypad is
as follows:
KEY FUNCTION
[ENT]
(ENTER)
This key is used to select a displayed function or to execute a modem configuration
change.
[CLR]
(CLEAR)
This key is used to back out of a selection or to cancel a configuration change which
has not been executed using [ENT]. Pressing [CLR] generally returns the display to
the previous selection.
[
←] [→]
(Left, Right)
These arrow keys are used to move between selections or to move the cursor
functions. At times, they may also be used to move from one section to another.
[
↑] [↓]
(Up, Down)
These arrow keys are used primarily to change configuration data (numbers or
characters). At times, they may also be used to move from one section to another.
5.1.3 Front Panel Vacuum Fluorescent Display (VFD)
The CDM-600/600L features a Vacuum
Fluorescent Display (VFD). The VFD is
an active display showing two lines of 40
characters each. It produces 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, the user 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.
If the user were to display the same screen for weeks at a time, the display could become ‘burnt’
with this image. To prevent this, the unit has a ‘screen saver’ feature that activates after 1 hour.
The message moves from right to left across the screen, then wraps around. The top line of the
display shows the Circuit ID (which can be entered by the user). The bottom line shows the
circuit Eb/No value (if the demod is locked) followed by ‘Press any key....’.
Pressing any key will restore the previous screen.