Wavetek 132 Especificações descarregar pdf (Página 103)

Q:

Measure

the

frequencies

of

the

spectral

components

and

sketch

them.

You

will

have

to

alternate

between

FREQ

and

MKR

after

choosing

DELTA

Marker

to

measure

each

frequency.

Q:

What

is

the

bandwidth

of

each

signal?

Q:

What

is

the

bandwidth

of

the

two

signals

added

together?

Q:

What

is

the

AB

to

avoid

crosstalk?

Q:

Change

f^

to

50

kHz,

measure,

sketch

and

calculate

the

frequency

spacing

again.

While

viewing

the

300

kHz

signal

and

it's

sidebands,

lower

the

frequency

of

fj

and

watch

the

sidebands

come

into

view.

Q:

At

what

frequency

does

crosstalk

occur?

Why?

d)

Change

the

frequencies

of

^

and

f^

to

80

kHz

and

fj

to

500

kHz.

At

this

point

you

have

two

identical

messages

that

have

been

shifted

to

provide

frequency

separation.

Now

you

will

modulate

them

as

one

signal

on

a

1

MHz

carrier.

Move

the

two

signals

from

the

input

of

the

spectrum

analyzer

to

the

input

of

the

signal

generator.

Connect

RF

out

of

the

signal

generator

to

the

input

of

the

spectrum

analyzer.

Press

preset

on

the

spectrum

analyzer.

Press

RF

OFF

to

turn

the

RF

on.

Set

up

the

signal

generator

as

in

laboratory

3

for

30%

amplitude

modulation

on

a

1

MHz

carrier

with

a

-7dB

output

amplitude.

Q:

Using

the

same

techniques

as

outlined

in

part

a,

measure

the

frequencies

of

the

carrier

and

all

of

it's

sidebands

and

sketch

the

spectrum.

Annotate

the

theoretical

values

as

well

as

the

actual

values.

Change

the

frequencies

of

f^

and

f^

to

100

kHz.

Q:

Measure

all

the

frequencies

again

and

explain

the

output.

Part

2:

Time-Division

Multiplexing

Demonstration

a)

Construct

the

TDM

circuit

of

Figure

2.

The

CD4051

mulitplexor

in

this

circuit

provides

the

commutator

function.

The

commutator

combines

four

signals

into

a

TDM

signal.

The

TDM

inputs

are

four

signals:

triangle

wave

at

pin

14,

two

sine

waves

at

pins

12

and

5,

and

a

DC

voltage

at

pin

4.

Apply

a

5

Vpp,

30

Hz

sine

wave

to

Vin.

Q:

Using

Lab

4

Page

4

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