Tektronix 2715, Руководство пользователя

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Getting Started
2–16
2715 User Manual
To specify a predetermined value, press [REF LEVEL] to place the reference
level in the immediate entry mode. The abbreviation REFL will appear at left
center of the screen.
The REFL indicator tells you that you can enter the reference level directly from
the keypad by typing a value followed by an appropriate terminator key.
NOTE
. In the spectral display mode, the abbreviation for the control last placed
in the immediate entry mode remains on screen until another control is chosen.
When a control is in the immediate entry mode, repeated settings for that control
can be entered without having to press [CHAN/FREQ], [SPAN/DIV], or [REF
LEVEL] again. Only primary controls can be placed in immediate entry mode.
6. Press [2] [0] [ ] [8] to set the reference level to 20.8 dBmV.
The numbers you type appear on screen to the right of REFL. If you make a
mistake, you can correct it by repeatedly pressing [BKSP] (the backspace
key) until the incorrect number disappears and then entering the correct
value.
7. Press [Y] after the correct number has been entered.
The Y key can represent units of kHz or +dB. Because you selected an entry
mode (immediate reference level entry) that requires decibels, and because the
factory-default unit is dBmV, the spectrum analyzer correctly interprets the
currently displayed entry as 20.8 dBmV. If the currently selected reference level
units had been dBm or dBW, the 2715 would have interpreted your entry
correctly when you pressed the terminator key.
The RF attenuation is reduced to 2 dB and the reference level readout indicates
the desired 20.8 dBmV. For the parameters established for this example, this
entry method enabled you to specify a reference level that could not be achieved
with the arrow keys unless you switched to the FINE mode. You can also enter
fractional reference levels to the nearest 0.1 dB with this method.
The spectrum analyzer is still in the MAX SPAN mode, which means that the
harmonics of the calibrator signal are barely more than one half division apart.
Spread them out by reducing the span/div. As in the case of the reference level,
the spectrum analyzer provides two direct entry methods.
8. Press [
b
] to the right of [SPAN/DIV] twice to reduce the span to 50 MHz/
division.
Notice that the readout now indicates 50 MHz/, and the harmonics are two
divisions apart.