[asterisk-users] Help With Physical Layer

[Tony Kasule]

On Tue, Jun 30, 2015 at 2:15 PM, Duncan Turnbull <duncan at e-simple.co.nz>
wrote:

>
> Hi Tony
>
> I'm not familiar with the card you but 120 ohm is usually twisted pair,
> and 75 ohm is coax (usually). If it is changeable its usually done with
> jumpers on the card.
>

The new Digium cards have no jumpers anymore and I don't think they support
coaxial cables. The only changes we can make on the digium cards is to
switch between E1/T1 modes and that's done when loading it in the kernel
using modprobe.


> I have used RAD modems before and their cable will have a specific
> pinout that you need to match. I doubt your digium card by default matches
> the pins, but maybe, and perhaps maybe your alcatel did. There will be a tx
> pair and an rx pair and you need to make sure they connect to the rx and tx
> pairs on the digium preferably with the same polarity. If you are getting
> no signal I would think its that. You can use a multimeter to check for
> voltage on the pins.
>

I would doubt it's the pinout but it's possible. I have tried several
cables (cross-over, straight-through, E1) and both didn't work but
surprisingly, they do on the other RAD modem that comes to the same PBX.


>
> Once you get that sorted another catch maybe timing. You will need to take
> E1 timing from one or other of the Telco's, with one as the primary
> source. If they for some reason aren't synced you will get errors every so
> often
>

Thanks for the pointers.

I am going to keep trying several things and if I get a break through, I'll
definitely share the results.

For no, any more help is welcome.

thanks!
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