Agilent Technologies 22A Especificações descarregar pdf (Página 39)

In some cases, time-gating capability enables you to perform measurements

that would otherwise be very difficult, if not impossible. For example,

consider Figure 2-33a, which shows a simplified digital mobile-radio

signal in which two radios, #1 and #2, are time-sharing a single frequency

channel. Each radio transmits a single 1 ms burst, and then shuts off while

the other radio transmits for 1 ms. The challenge is to measure the unique

frequency spectrum of each transmitter.

Unfortunately, a traditional spectrum analyzer cannot do that. It simply

shows the combined spectrum, as seen in Figure 2-33b. Using the time-gate

capability and an external trigger signal, you can see the spectrum of just

radio #1 (or radio #2 if you wished) and identify it as the source of the

spurious signal shown, as in Figure 2-33c.

Figure 2-33a. Simplified digital mobile-radio signal in time

domain

Figure 2-33c. Time-gated spectrum of signal #1 identifies

it as the source of spurious emission

Figure 2-33b. Frequency spectrum of combined signals. Which

radio produces the spurious emissions?

Figure 2-33d. Time-gated spectrum of signal #2 shows it is

free of spurious emissions

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Agilent Technologies 22A Especificações Página 39