Wavetek 3ST Specifiche Scaricare il pdf (Pagina 84)

5-1

SECTION 5 REVERSE SWEEP OPTION

5.1 INTRODUCTION

This section provides detailed operation of the Model 3ST Reverse

Sweep Option. Included are detailed descriptions of how to perform

reverse sweeping as well as the various displays.

5.1.1 Wavetek Stealth Reverse Sweep Concept

With the reverse sweep option, a transmitter is built into the hand-

held sweep receiver. The headend sweep transmitter (3ST) is set up

to receive the reverse sweep sent from the field. When a reverse

sweep is activated from a field test point, the headend transmitter

receives the telemetry signal that indicates which receiver is sending

the sweep. The headend transmitter measures the sweep, and sends

the results, along with the serial number of the sending receiver via its

telemetry signal to the field. The field receiver with the tagged serial

number then displays the sweep response as measured in the headend

on its LCD. Only one receiver at a time can perform reverse sweep-

ing. If additional receivers attempt to sweep a message is displayed.

The only effect on receivers sweeping in the forward direction is a

slightly slower sweep time.

5.1.2 Basic Reverse Sweep Procedure

Sweeping the reverse path is a little different from sweeping the

forward path. Because the system is designed with appropriate spacing

for the forward high frequency range, the reverse path may not require

amplification at each station. The lower frequencies aren't attenuated

in cable as much as the higher frequencies. In sweeping the forward

path the amplifier is aligned such that its output is within certain

limits (the amplifier compensates for the cable behind it). However in

sweeping the reverse path the amplifier is aligned such that the

response at the headend is within certain limits from this amplifier

alignment point. So, in the reverse path the amplifier compensates for

loss characteristics in the cable in front of it.

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Wavetek 3ST Specifiche Pagina 84