Specifications

page 40
[
StarServe Installers Guide
]
Impulse Noise Interference
Impulse noise from house appliances, vehicle ignitions or
overhead power lines may interfere with the reception of the
digital services, causing intermittent picture blocking or
freezing. The disturbance to sound may be of greater
annoyance. Both level and quality margins may be consumed
by the interference caused by impulse noise. If the interference
is not being received via the antenna, an increased signal
level (either by use of an amplifier or a higher gain antenna)
may reduce the problem.
Further improvement to reception quality may be provided by:-
a) Correct matching of the antenna cable to the antenna
balun.
b) Use of double or quad screened cables between the
antenna and outlet plate.
c) Use of double or quad screened fly-lead from the wall
outlet to the receiver.
Interference From Other Services
Interference from adjacent channels or co-channel broadcast
services may result in reduced margins. As experienced in
analogue reception, a reduction in the level of the interference
is the first approach to a solution.
Depending on the direction from which the interference is
originating, antenna repositioning or antenna type may provide
a solution. The performance of the receiver to these types of
interference varies between models and brands.
How To Measure Signal Strength
Professional installers have access to field strength meters.
However, for a rough guide on signal strength, a variable
attenuator can be used. These are available from most
electronic stores.
Attenuators are approximately linear devices and, by noting
the position of the dial, the attenuation can be estimated
within a few dB. Marking the attenuator will assist in
approximation. For example, if the attenuator is variable from
0dB to 20 dB then midway will be approximately 10dB.
Note:-
A.The attenuators do not come with 0-20dB markings.
B.The numbers refer to the amount that the signal is reduced.
C.Do not leave these units in a system permanently.