Tektronix 2715, Руководство пользователя

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Dedicated Controls
4–4
2715 User Manual
12. Press [MAX] a second time to return to 20KHZ/.
Many of the keys on the 2715 are toggle action. The ability to undo an action by
pushing the same button that carried out the action is typical. MAX is a
toggle-action key taking you from the current span/div to 180 MHz/div and
back.
ZERO. The following example demonstrates the effects of using zero span.
13. Set the center frequency to 100 MHz.
Notice that the calibration signal is centered in the display.
14. Press [ZERO].
The signal is a straight, horizontal line.
In the zero span mode, the 2715 remains at a fixed frequency. What you see is
the variation in time of the signal power coming through the RBW filter at that
frequency. Since the calibration signal has constant amplitude, the display is
constant.
15. Turn the FREQ/MKRS knob to slowly increase the center frequency.
The signal amplitude decreases and the noise increases as you tune away
from the calibration signal. The noise generated internally by the 2715 has a
time-varying random amplitude.
In the zero span mode, the 2715 does not sweep the frequency spectrum. Rather,
the local oscillator remains at a fixed frequency so that the resolution bandwidth
filter brackets the designated center frequency. Because the display screen is still
swept, the span readout indicates sweep speed (time per division rather than
frequency per division). The word ZSPAN follows the sweep speed to denote
zero span operation. In a sense, you have turned your spectrum analyzer into an
oscilloscope.
16. Press [ZERO] to return to 20 MHz/div span.
The following procedures demonstrate two methods of entering a channel
selection.
Arrow Keys
. This procedure uses the arrow keys to select a channel from a
selected channel table:
1. Press [UTIL] [1] [1] to restore the factory defaults.
2. Press [
y
] adjacent to [CHAN/FREQ].
The channel selection steps to the next channel in the selected channel table.
Channel Entry