Bird-technologies 5000-EX Manual do Utilizador descarregar pdf (Página 29)

Operation

Selecting Measurement

The Bird Wideband Power Sensor can measure Aver-

age, Peak, and Burst power as well as Crest Factor

and CCDF. To select the measurement:

" Press SHIFT to display the second set of softkeys.

Type should be key 2 and Filter should be key 3.

" Press Type to cycle through the possible modes.

Video Filter

Except for average power and VSWR measurements,

all measurements use a variable video filter to

improve accuracy. This filter can be set to either

4.5 kHz, 400 kHz, or Full bandwidth. It should be as

narrow as possible while still being larger than the

demodulated signal bandwidth (video bandwidth).

Narrowing the filter limits the noise contribution from

interfering signals. Listed below are some common

modulation schemes and the appropriate video filter.

Video Filter Modulation Type

4.5 kHz CW Burst (Burst width > 150 µs), Voice

Band AM, FM, Phase Modulation, Tetra

400 kHz CW Burst (b.w. > 3 µs), GSM, 50 kHz AM,

DQPSK (¼π, symbol rate < 24 k/s)

Full Bandwidth CW Burst (b.w. > 200 ns), CDMA, WCDMA,

DQPSK (¼π, symbol rate < 200 k/s),

DAB/DVB-T

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Bird-technologies 5000-EX Manual do Utilizador Página 29