04-05-2011 09:36 AM - edited 03-16-2019 04:20 AM
Is it any problem in connecting an analog phone to a VG224 with a 2,5 kilometres cable?
Thank you very much!
04-05-2011 11:08 AM
FXS Analog Voice Port Maximum Distance:-
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The maximum distance is established by a total allowable loop resistance, including the phone or terminal equipment, of 600 ohms. Our FXS interface meets OPS Class B specs. Specifically, we can source greater than 20ma to a resistive distance of up to 1100 ohms. The homework question is translating impedance to actual distance in meters in your customer's environment; which will depend on the gauge of the wire as well as how the wire is routed and punched-down. It will depend on the type of phone/equipment you are hooking on the line as well as to how well it will work.
Also found how to calculate the dc loop resistance:-
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Calculating dc loop resistance
LRi = CRi * SLi
where LRi= DC loop resistance for cable section
CRi= Conductor Resistance per unit length for the cable section ( used gauge 24 rj11 cable)
Sli= length of cable section
Lri =600ohms
CRi = 173 ohm/loopkm
SLi = ?
= 600 ohm/ 173 ohm/loopkm
= (600 / 173 ) loop KM
= 3.47KM
= 3470 * 3
= 11384 feet.
So the FXS on the VG 224 using a gauge 24 cable (RJ-11) would allow for a max loop distance of 10410 feet .
12-30-2012 03:04 PM
Hi,
In your calculation, the maximum distance is established by a total allowable loop resistance should be NOT including the phone or terminal equipment.
so the 600 ohms in total - 430 ohms of the phone = 170 ohm for line resistance
CRi = 173 ohm/loopkm
= (170 / 173 ) loop KM
=0.98 Km
12-30-2012 05:44 PM
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