Wavetek 132 Spezifikationen PDF herunterladen (Seite 14)

the

student

who

is

unfamiliar

with

circuit

construction

in

mind.

For

those

students

who

are

familiar

with

circuit

construction,

completion

of

this

lab

will

still

be

beneficial.

A

summer

circuit

is

designed

using

a

/xA741

operational

amplifier

[Ref.

1].

The

circuit

provides

summation

of

two

signals

with

a

gain

of

two.

This

circuit

provides

for

the

demonstration

of

basic

circuit

construction

and

analysis.

Two

periodic

waveforms

are

applied

as

inputs

and

the

output

signal

is

analyzed.

The

input

and

output

signals

are

viewed

on

the

RAPIDS

oscilloscope

and

spectrum

analyzer

screens.

Signal

periods

and

amplitudes

are

measured.

The

student

is

able

to

exercise

Fourier

series

[Ref.

2]

and

Fourier

transform

[Ref.

3]

techniques

and

then

compare

the

results

to

the

RAPIDS

output.

Hard

copy

plots

from

the

RAPIDS

system

are

generated.

The

more

conventional

Tektronix

2445B

oscilloscope

is

also

introduced

in

an

effort

to

acquaint

the

student

with

more

common

equipment.

The

displayed

signal

on

the

T2445B

is

compared

to

that

displayed

on

the

RAPIDS

system

by

visualization

as

well

as

measurements.

This

demonstrates

the

differences

in

accuracy

and

friendliness

of

available

equipment.

C.

LABORATORY

2:

SAMPLING

AND

ANALOG-TO-DIGITAL

CONVERSION

The

concepts

of

sampling,

filtering

and

analog-to-digital

(A-D)

conversion

are

explored

in

Laboratory

2.

An

LF198

sample

and

hold

chip

is

used

to

construct

the

circuit.

The

circuit

was

designed

using

the

National

Semiconductor

LF198A

specifications

for

a

typical

'Output

Holds

at

Average

of

Sampled

Input'

application.

A

logic

input

is

applied

as

the

sample

pulse

as

specified.

The

circuit

is

first

used

to

perform

natural

sampling

on

a

DC

signal.

A

DC

signal

was

chosen

so

the

voltage

level

could

be

modified

by

hand

during

the

sample

pulse.

When

the

circuit

is

not

in

sample

mode,

the

output

is

zero,

and

varying

the

DC

voltage

has

no

effect.

A

sine

wave

is

then

sampled

above,

at

and

below

Nyquist

rate

and

recovered

at

each

instance

using

a

60dB/decade

lowpass

Butterworth

filter

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