Toa TS-910 Series Installation - Manual (Page 56)

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14.2. Design Examples
14.2.1. Example : When installing 4 TS-905 Infrared Transmitter/Receiver units using 4 coaxial cables
reaching from the Central unit:
Central unit
Infrared Transmitter/Receiver units
TS-905
L
1) Finding the maximum cable length using maximum allowable cable losses
Assuming that the type of coaxial cable used is RG-59/U,
Maximum cable length L = (Coaxial cable loss / its cable loss per 100 m )
= (20 dB / 3.3 dB) x 100 m
= 606 m
The following table shows the maximum allowable cable length for each type of coaxial cable.
2) Finding the maximum cable length using voltage drop
Since one TS-905 Infrared Transmitter/Receiver unit is connected per coaxial cable, the current that flows
through each coaxial cable is 0.1 A.
Assuming that the type of coaxial cable used is RG-59/U,
Maximum length L = { (Voltage drop 1 / Current 1) / Coaxial cable loop resistance 1 for 100 m }
= { (5 V / 0.1 A) / 16.82 Ω } x 100 m
= 297 m
The following table shows the maximum allowable cable length for each type of coaxial cable.
The table below shows the required maximum cable length for the example 1, the shorter length of the
calculation results (1) and (2) above.
RG-59/U 606 m
RG-6/U 740 m
RG-11/U 1000 m
RG-59/U 297 m
RG-6/U 390 m
RG-11/U 2083 m
RG-59/U 297 m
RG-6/U 390 m
RG-11/U 1000 m