Filtering noise on tip ring line
Filtering noise on tip ring line
(OP)
I have a floating tip ring line that is fed into a transformer on my telephone device. The output of the transformer is referenced to ground. I can filter the noise from the output side with an active bandpass filter. However...
My question is: How do I put the filter(s) on the floating side without messing up the line balance?
My question is: How do I put the filter(s) on the floating side without messing up the line balance?





RE: Filtering noise on tip ring line
You need to careful about idle current and return loss as well. It is not an easy thing to do if you haven't done it before. The phone companies are kind of picky when it comes to adding non authorised equipment to the line.
Even if you put a filter on the transformer secondary, you need to make sure that return loss is OK. Primary impedance usually gets upset when you terminate the transformer other than it was designed for.
Gunnar Englund
www.gke.org
RE: Filtering noise on tip ring line
I wonder if just bridging from tip to ring using capacitors or inductors (for 60Hz noise) would work? The signal is FSK. I know the 60Hz is common mode, and should cancel, but it's there on the output.
RE: Filtering noise on tip ring line
Why do you think that 60 Hz is a problem? Shouldn't be, considering the 300 - 3400 Hz bandwidth.
Gunnar Englund
www.gke.org
RE: Filtering noise on tip ring line
RE: Filtering noise on tip ring line
Gunnar Englund
www.gke.org
RE: Filtering noise on tip ring line
Sorry, just a side story this reminded me of... :)
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Filtering noise on tip ring line
RE: Filtering noise on tip ring line
RE: Filtering noise on tip ring line