INTEGRUS | Digital Infra-red Language Distribution System
en |
17
BOSCH Security Systems | February 2003
20m
20m
30m
30m
R2
R5
R4
R3
R1
20m
Figure 1.26 System with five radiators and measured cable lengths
Table 1.1 Calculation of the cable signal delays
Radiator
number
Total cable
length [m]
Cable signal delay
per meter [ns/m]
Cable sgnal
delay [ns]
Signal delay
difference [ns]
Delay switch
position
1
30
5.6
30*5.6 = 168
280
-168 = 112
112/33 = 3.39 = 3
2
30+20 = 50
5.6
50*5.6 =
280
280
-280 = 0
0/33 = 0
3
20
5.6
20*5.6 = 112
280
-112 = 168
168/33 = 5.09 = 5
4
30
5.6
30*5.6 = 168
280
-168 = 112
112/33 = 3.39 = 3
5
30+20 = 50
5.6
50*5.6 =
280
280
-280 = 0
0/33 = 0
The used cable signal delay per meter is an example. Use the actual signal delay per meter in this calculation as specified by the
manufacturer.
1.5.1.2 Determining delay switch positions by using a delay measuring tool
The most accurate way to determine the cable signal delays is to measure the actual signal delay for each radiator as described in
the following procedure:
1. Disconnect the cable from a radiator output of the transmitter and connect this to a delay measurement tool.
2. Disconnect a radiator from this cable.
3. Measure the impulse response time (in ns) of the cable(s) between the transmitter and the radiator.
4. Reconnect the cable to the radiator and repeat steps 2 to 4 for the other radiators that are connected to the same
transmitter output.
5. Reconnect the cable to the transmitter and repeat step 1 to 5 for the other radiator outputs of the transmitter.
6. Divide the impulse response times for each radiator by two. These are the cable signal delays for each radiator.
7. Determine the maximum signal delay.
8. Calculate for each radiator the signal delay difference with the maximum signal delay.
9. Divide the signal delay difference by 33. The rounded off figure is the delay switch position for that radiator.
10. Add delay switch positions to radiators under a balcony, if applicable (see section 1.5.3)
11. Set the delay switches to the calculated delay switch positions.
: Turn the delay switches carefully to a new position until you feel that it clicks into position, to prevent that a switch is positioned
between two numbers, which would result in a wrong delay setting.
