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3.7 Setting the radiator delay switches
As described in section 1.3.6, signals picked up by the
receiver from two or more radiators can cause black
spots due to delay differences.
Signal delays reasons:
Cable signal delay, caused by the cable
transporting the signal from the transmitter to the
radiator.
Radiation signal delay, caused by the air
transporting the signal from the radiator to the
receiver.
Transmitter signal delay, caused if two or more
transmitters are used in a Bypass configuration.
To compensate the signal delay differences, the delay
of each radiator can be increased. HCS-5100 radiator
has a digital display showing the current compensation
value. Signal delays can be set with the delay switch
situated at the side of the radiator. The switch can be
adjusted from “00” (“00” means no compensation) to
“99”. Compensation time is calculated by multiplying 25
ns with the switch set value. Thus compensation time
varies between 25ns and 2475 ns.
In most cases the cable signal delays can be
calculated manually using in addition the delay switch
calculation tool (available on the documentation
CD-ROM).
How to calculate the delay switch positions manually for
systems with one, two or more transmitters will be
described in the next sections. Refer to the delay switch
calculation tool for information how to do to get a
computed value for the delay switch position.
3.7.1 System with one transmitter
There are no cable signal delays in systems with only
one transmitter and radiators directly connected to the
transmitter with cables of identical length. The delay
switches on all radiators are to be set to zero.
Subsequently check whether to compensate for
radiation signal delay (see section 3.3.3).
If the cable lengths differ from radiator to radiator, the
delay switch parameter can be calculated with the
formula:
Take signal delay rate as 5.0 ns/m (value as an
example for calculation only, real value depends on
the cable type used)
X : delay compensation parameter, displayed on the
LCD
L
MAX
: maximum cable length in the considered chain.
For the most distanced radiator, L
MAX
and L are
identical.
L : cable length between transmitter and radiator
Use the following procedure to determine the delay
switch position based on cable lengths:
1
．
Measure the cable length L between the
transmitter and every single radiator;
2
．
Determine the maximum cable length L
MAX
;
3
．
For each radiator calculate the cable length
difference value L
MAX
- L;
4
．
To obtain the cable signal delays for each radiator;
multiply the cable length difference of each radiator
with the cable signal delay per meter;
5
．
Divide the calculated signal delay difference by 25.
The rounded off figure is the signal delay switch
position for the radiator;
6
．
If applicable, add delay switch positions for
radiators under a balcony, (see section 3.7.3);
7
．
Set the delay switches to the calculated switch
positions.
Figure 3.16 and table 3.1 illustrate the calculation of the
cable signal delay.
Figure 3.16 System with 6 radiators and measured cable
lengths
