[Asterisk-Users] Ring Voltage Supplied by Wildcard TDM400P REV E/F& AUTO FXS/DPO

[Jim Van Meggelen]

Rich Adamson wrote:
>>> I'm trying to connect a TDM400P with an FXS module to a Valcom
>>> V-9940 Paging adaptor. This port on the TDM400P was connected to a
>>> 2500 Set and was working I just re-connected it to the Valcom (which
>>> is known to work on a Telco POTS line) and its not picking up.  The
>>> Valcom docs say it need a minimum of 75 Volts at 20-30 Hz to
>>> recognize a call... So the question is what ring voltage does the
>>> FXS modules on a TDM400P put out?
>> 
>> Ultimately, that depends on how much current is being drawn, but my
>> multimeter reports about 70V on a 6 foot line cord. Generally, I'd
>> expect an FXS to put out more like 90-110V (that's what my TalkSwitch
>> supplies).
> 
> According to the Silicon Labs spec sheet, the 3210 chip can
> supply "ringing signals of up to 88v peak or more, enabling
> the ProSLIC to drive a 5 REN ringer load across loop lengths of 2000
> feet or more." 
> 
> The multimeter will be measuring rms voltage, not peak.


Adding boostringer=1 to the modprobe parameters convinced my DMM to
display the 89V promised.

But yeah, it's not a true RMS DMM I'm using (I suspect a typical
non-true RMS DMM would tend to be biased towards 60Hz and thus give odd
AC readings at different frequencies - I noticed that the detected
voltage would start at ~89V, but then drop as the ring phase of the
cycle continued - I'm figuring it's aliasing somehow)

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