Leased Lines

[toolbox212121]

We have a few leased lines (dry pairs) from our local teleco from our main campus to some remote sites. We are always having issues with them and having to test them using TIMS (shooting tones). There is alot of discussion here about one circuit is a -10dbm and another is 0dbm. My question is what does that mean and why would you want a circuit to be at -10dbm?

I know we can send tones at different levels on the TIMS so the way I understand it is if side A sends at 0dbm on one side, side B should receive at -10dbm. Is this the definition of a -10dbm circuit?

Sorry if my question is confusing because I really don’t understand it. I've set levels on our own amplifier circuits we have in house and understand the concept and how to use a TIMS but the -10dbm confuses me. Any input in much appreciated. Thanks

 

[trvlr1]

All lines/transmissions have losses in them, typically measured in DB/DBM. The equipment you use on these lines will have built in acceptable losses before they get to the stage of not being able to communicate. There are formula, that will tell you exactly how much losses are involved in the measurements you are getting, but an easy way to calculate this is for every 3 db your power level will half, ie 3db losses on a 100watt signal give you 50watts, 6db losses gives you 25watts.
When you get a leased line like this, you need to know the levels you need to receive to make it work, then set your transmit levels to a point where the level is correct at the receiving equipment. If it is not possible to set your equipment at low enough output not to cause problems at the far end, you might want to use external influences to maintain the correct levels at the remote end, such as a line with a built in 10db loss.
There are of course many factors that go in to setting all this up correctly, but I hope this simple explaination works for you.

 

[SYQUEST]

It all depends upon what type of circuits were ordered in the beginning. Are the circuits all of the same type? 2-wire, 4-wire, voice or data grade or just vacant copper pairs? If they are all the same design and one of them is not performing the same, then it may be defective. You will then need to open a trouble ticket with the provide of the circuit for repair. You do need some basic understanding of voice transmission and circuits in order to measure and troubleshoot these things. What kind of TIMMS are you using?

....JIM....