Wavetek 3SR Spécifications télécharger pdf (Page 94)

5-2

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

held sweep receiver. The headend sweep transmitter (3ST/3HRV) 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 re-

ceiver 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 sweeping with a 3ST. If additional

receivers attempt to sweep, a message is displayed. Up to 10 differ-

ent technicians can sweep the reverse path using a 3HRV. The only

effect on receivers sweeping in the forward direction is a slightly

slower sweep time.

Ingress Detection and Troubleshooting (3HRV only)

The 3HRV provides feedback to the field as to the current condition

of noise and ingress in the headend. Even if the noise or ingress is

"swamping" the telemetry a "picture" of the headend noise/ingress is

sent out to the receiver via a special forward telemetry carrier for

display.

Easy To Read Noise/Ingress Display (3HRV only)

The headend instrument provides a continuous display of the noise/

ingress performance of the connected nodes. This provides a quick,

easy way for the headend technician to verify performance. In

addition, the current reverse testing activity can be monitored.

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 ampli-

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Wavetek 3SR Spécifications Page 94