Wavetek MS1300 Spezifikationen PDF herunterladen (Seite 96)

D-2

SETUP

The frequency and level of the predictable “leak” should be given

careful consideration, to avoid interfering with any off-air service or

allowing an off-air service to affect the measurement. This leak

should be generating a signal only during calibration and discon-

nected at all other times.

A bandpass cable drop may be used as the leak signal, with a

calibrated dipole as the source antenna. (A fixed dipole or a WWG

HD-1 may be used as the source antenna.) Be sure the dipole is set to

the proper length for the chosen monitoring frequency, and that the

antenna is mounted with the proper polarization to correspond with

the monitoring antenna to be used. Ideally, the calibration antenna

should be mounted on a wooden post at the same level as the vehicle-

mounted antenna. If a vertical monopole antenna is to be used, the

source dipole should also be vertical. The drop should be fed through

a bandpass filter and an attenuator for adjusting the leak to the correct

calibration level.

Set the leak as follows:

Using a CLI-1450 or other calibrated receiver and a dipole (1/2 λ),

stand at least 10 feet from the leak reference source. With the

antenna 10 feet off the ground and oriented with the proper polar-

ization to the source antenna, adjust the drop attenuator until the

level on the calibrated receiver matches the desired calibration

reference level. (It may be desirable to set the calibration higher

than 20 µV/m, if the calibrated reference receiver is not sensitive

enough to read a 20 µV/m leak).

NOTE:

The calibration area should be as free from obstructions and

conductive reflecting surfaces as possible.

1. The following considerations should be taken into account when

establishing a reference leak source:

a. Potential reference leak source: system signals fed through a

source frequency bandpass filter and attenuator.

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Wavetek MS1300 Spezifikationen Seite 96