GW Instek GSP-730 Quick start guide - Manual (Page 15)

Using the numeric keypad:
When prompted to enter a parameter, use the number
keys (0~9), the decimal key (.) and the minus key (-) to
enter a value. After a value has been entered, the unit
keys can be used to select the units.
The value of the parameter is shown at the bottom of
the screen as it is edited.
Edited parameter
Ref:-30dBm
Back Space:
Use the backspace key to delete the last character or
number entered.
Using the scroll wheel:
Use the scroll wheel to alter the current value.
Clockwise increases the value, anti-clockwise
decreases the value. The scroll wheel is usually used
for values that highly variable, such as the center
frequency settings.
Directional arrows:
Use the directional arrows to select discrete parameters
or to alter values by a coarser resolution than the scroll
wheel. Left/down decreases the value, right/up
increases the value. The directional arrows are usually
used for values that are of a discrete nature, such as
selecting a memory location.