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Re: [hylafax-users] Incomplete outgoing faxes



On 2004.05.13 08:54 Tortoise@xxxxxxxxx wrote:
Hello!
I would like to solve my problem. With latest Hylafax and Class 1
faxmodem I am experiencing problems with outgoing faxes, because they
are incomplete.
Try to imagine that Letter or A4 page is divided into about six
horizontal stripes, like this:
+-------------+
|Stripe 1     |
+-------------+
|Stripe 2     |
+-------------+
|Stripe 3     |
+-------------+
|Stripe 4     |
+-------------+
|Stripe 5     |
+-------------+
|Stripe 6     |
+-------------+

What target fax receives looks like this:
+-------------+
|Stripe 1     |
+-------------+
|Stripe 3     |
+-------------+
|Stripe 5     |
+-------------+

What is especially annoying when some agreements were sent and because
were only some (whole) paragraphs missing (those on parts 2,4 and 6),
it didn't look incomplete!

I checked postscript files from the Hylafax queue and they are -
according to my expectations - complete and without problems. This
problem occurs always - no matter, which kind of fax device is on the
other side.

I would like to ask for following:
1. Is it known problem?

I've seen this happen (it's only possible in non-ECM faxing) when the modem didn't properly support the designated flow control (XON/XOFF) and the baud rate (ModemRate) was sufficiently higher than the negotiated baud rate that the DTE-to-DCE data actually overflowed the modem's buffer.


What modem (make, model) are you using?

If so, is somewhere posted solution how to fix
it?

In the cases where I've seen this I changed ModemFlowControl from xonxoff to rtscts and it worked fine. Note, that this may not be an option if you are running an external modem off of a non-standard multiport serial expander (i.e., Cyclades).


2. If it is not known problem, which debug parts I should turn on to
detemine where is the problem?

It was really nasty to debug. I had to enable tracing of all modem communications (set 'TracingMask: 0x11' and then 'SessionTracing: 0xFFF'), and then sent a fax from HylaFAX to another port on the same HylaFAX system. I then compared the two sets of data and found that portions were simply missing. Because the receiver only sees one corrupt scan line at each "break" it generally will accept the data as "acceptable".


When faxing legal documents, etc., I highly recommend using ECM, since it nearly guarantees that the data will be exactly as the original. Non-ECM faxing only requires an "acceptable" quality level. You can get ECM in Class 1 by using HylaFAX 4.2.0 (now 4.2.0beta2).

Lee.

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