Bell System bellview - Page 41

Bell View Video System
Page 2 of 5
11 - 60 Way Single Door Systems
Cable Requirement (Refer to diagrams 4a, 4b and 4c.)
Cable types (solid core)
0.5 mm Twisted pair, e.g. BT spec CW1308
1.0 mm 1.0 mm
2
‘Twin & Earth’
1.4 mm 1.5 mm
2
‘Twin & Earth’
Co-ax 75 Ohm, RG59 or equivalent
Video phones (each group of 10)
Total Cable Length Video Power (+,-) Other connections
(N = no. of video phones)
Video Signal
Basic Functions
25 m 9+N @ 0.5 mm [double +, -] 75 Ohm Co-ax
50 m 2 @ 1.0 mm 5+N @ 0.5 mm 75 Ohm Co-ax
100 m 2 @ 1.4 mm 7+N @ 0.5 mm [double V, O] 75 Ohm Co-ax
Basic Functions + Door Monitor Facility
25 m 10+N @ 0.5 mm [double +, -] 75 Ohm Co-ax
50 m 2 @ 1.0 mm 6+N @ 0.5 mm 75 Ohm Co-ax
100 m 2 @ 1.4 mm 8+N @ 0.5 mm [double V, O] 75 Ohm Co-ax
e.g. 30 Video phones, with basic functions, and a maximum cable distance of 50 m required for each group of 10
phones;
2 common cables @ 1.0 mm, 5 common cables @ 0.5 mm and 10 individual call lines @ 0.5 mm.
Notes
A junction box MUST be placed within 2 metres of the power supply to split the common telephone wiring up into groups of 10
(video cables are already grouped by the VDC6 Video distributor) .
Assumes only 1 video phone is active at a time and the phones are distributed evenly along the cable run.
Loop the coaxial cable from phone to phone (daisy-chain wiring). Do not run a separate cable from each video phone back to
a common junction (star wiring). Where possible (for optimum speech clarity), a twisted-pair should be used for ‘R’ and ‘O’
connections to the video phone.
Entrance
Connections No. of Cores Max
Length
Solid Core
Diameter
Camera + Speech unit 6 + 75 Ohm Co-ax 50 m 0.5 mm
Push Buttons 1 per phone 50 m 0.5 mm
Lock Release (up to 0.5 A) 2 25 m
100 m
0.5 mm
1.0 mm
Trades button (optional) 1 50 m 0.5 mm
Exit button or Fire switch (optional) 2 100 m 0.5 mm
Door monitor switch (optional)
No. of Phones 20 2 50 0.5 mm
60 2 20
50
0.5 mm
1.0 mm