HP Cable Box 8591C manual Setting Comments

M a k i n g M e a s u r e m e n t s U s i n g S p e c t r u m A n a l y z e r M a d e

Using the Time-Gated Spectrum Analyzer Capability Without the Gate Utility (Option 107 only)

Use the guidelines in 7Able 5-l when using time-gated spectrum analyzer capability to view a pulsed RF signal. These are only guidelines, and the spectrum analyzer settings can be changed if necessary.

Table 5-1.

Determining Spectrum Analyzer Settings for Viewing a Pulsed RF Signal

Spectrum Analyzer

Spectrum

Analyzer

Setting

Comments

Function

S w e e p T i m e

Set the sweep time to be 401 times greater

Because the gate must be on at least once

than the pulse repetition interval IPRII:

per trace point, the sweep time has to be

set to the pulse repetition interval times for

S w e e p

t i m e

> 4 0 1 x

PRI

every point of the trace . IEach trace has

401 points . )

Gate

Delay

The gate

delay

is

equal

to the

signal delay

The gate delay must be set so that the

plus half of the pulse width:

gating captures the pulse . If the gate delay

is too short or too long, the gating can mist

G a t e

D e l a y =

S i g n a l D e l a y

+

r/2

the pulse or include resolution bandwidth

transient

responses.

Gate

Length

The gate

length

is

equal

to

one - fourth the

If the gate length is too long, the signal

pulse

width:

display can include transients caused by the

spectrum

analyzer filters.

G a t e

l e n g t h =

r/4

Video

Bandwidth

S e t t h e

v i d e o

b a n d w i d t h t o

a

v a l u e g r e a t e r

T h e v i d e o

b a n d w i d t h m u s t b e w i d e e n o u g h

than 1 divided by the gate length:

so that the rise times of the video

bandwidth do not attenuate the signal .

V i d e o

B a n d w i d t h >

gate ,!englh

Resolution Bandwidth

Set the resolution bandwidth to a value

The resolution bandwidth must be wide

greater then 2 divided by the gate delay

enough so that the charging time for the

minus

the signal

delay:

resolution bandwidth filters is less than the

pulse width of the signal .

R e s o l u t i o n B a n d w i d t h >

2

G a t e D e l a y - S i g n a l D e l a y

5-39