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Re: [hylafax-users] MultiTech ZBA
On 2003.10.08 14:20 An Intrepid HylaFax User wrote:
I have a MultiTech ZBA V.92 super-duper ($$$$) modem coming in the
mail.
It claims to support Class 2.1 - is this something I should use?
The only significant advantage of Class 2.1 over Class 2.0 is V.34
support. I'd recommend you run some real-world tests to determine
which one will be better for your application.
I'd
like
to exploit 2-D MMR if possible as I imagine most modern business fax
equipment supports that.
Class 2.0 supports MMR, also.
How are these modems best driven for outbound fax reliability?
They've been good for me.
The
HylaFAQ
has Multitech all over it as a "recommended" modem - I hope I've not
picked
a turkey.
Most of my outbound fax destinations are overseas, where quality of
telephony may be marginal. Is ECM a hindrance or a boon to such
places?
It depends on your faxing goals. If you want to ensure the remote has
a perfect image at all costs then ECM is a must and V.34 should not be
used as CTC attempts are not allowed in V.34 calls. However, it will
almost always (except, perhaps with the benefit of MMR and/or V.34)
take longer to send than without ECM. If you're trying to send a lot
of faxes quickly, then you'll need to determine what is best for you.
ECM does have an option to "minimize" lengthy calls by eliminating CTC
attempts. This can cause some destinations to receive incomplete
images, when the line is very noisy, but it will only be to those
destinations which were having trouble receiving data properly. To
those destinations you'd have to send without ECM to make the
transmission quickly since it will likely accept more readily the data
with partial errors.
Anyway, you'll need to test.
Are there S-register settings for noise-floor and/or sensitivity that
might
benefit from some tuning?
The only one that you should need to consider is the AT+FRY command
which enables/disables CTC in ECM.
Lee.
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