Video filter, Average mode, Peak mode – Bird Technologies 5000-XT-Manual User Manual

Page 30: Burst mode, Crest factor mode, Ccdf mode

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.

Note: 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.

Average Mode

This mode displays the average forward and reflected power.

Note: In average mode, the VSWR or system match can be displayed
instead of the reflected power.

Peak Mode

This mode displays the peak envelope power.

Burst Mode

This mode displays the average power in a burst. The burst’s duty cycle is mea-
sured by the DPM.

Crest Factor Mode

The crest factor is the ratio of the forward peak power and the forward average

power. It is measured in dB.

Note: There are no additional controls in this mode.

CCDF Mode

The CCDF measures the percentage of time the power level is above a thresh-
old. To set the power threshold:
1.

Press menu.

Select CCDF Limit from the Main Menu.

Enter new value.

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 (¼

, symbol rate < 24 k/s)

Full Bandwidth

CW Burst (b.w. > 200 ns), CDMA, WCDMA,
DQPSK (¼

, symbol rate < 200 k/s), DAB/DVB-T