Tektronix SignalScout RFM151 Instruction Manual page 69

Measurement Reference
Desired to Undesired Mode
Picture or data quality does not degrade for digital carriers until error
correction fails. Being able to estimate the operating margin of
digitally modulated carriers is critical to keeping a digital system
error free. The desired-to-undesired (D/U) measurement mode
measures the average power of a digitally modulated RF signal and
subtracts the calculated power of the noise in the specified channel
bandwidth. The difference is the D/U measurement.
Table 3-6 explains the key actions in this mode. All front-panel keys
are disabled during the D/U measurement except those provided for
interactive contro}! of the measurement, HELP, and the POWER key.
Table 3-6: Functions of active keys in D/U measurement mode
Key
Action
Menu keys
Enters selected menu. (Aborts a partial keypad entry.)
Function keys
Provides interactive control of the measurement via on-screen prompts.
Tunes the instrument to the preset frequencies. Overrides partial keypad
entry.
Knob In the out-of-service mode, blanks the measurement results. You must
then select a function key to initiate a D/U measurement. The knob is
disabled while making an out-of-service D/U measurement.
Numeric keypad
Keying either channel or frequency, followed by CHAN, MHz, or ENTER,
CHAN Terminates keypad entry as channel. Switches to channel entry mode.
MHz Terminates keypad entry as frequency, Switches to frequency entry
ENTER Terminates a keypad entry in the active entry mode (channel or
frequency, as outlined in the top line of the display),
ome Pressing backspace during a keypad entry erases the character
preceding the cursor. Backspacing 1 click after field is empty aborts
partial entry.
HELP Displays context-sensitive help screen; aborts a partial keypad entry.
Esc Aborts a partial keypad entry without changing the instrument setup.
SignalScout RFM151 RF Analyzer Instruction Manual 3-21