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Is it possible for a fax transmission to be clogged to the point that multiple transmissions can end up being received all at once? I had a data request done and multiple copies of the same form kept streaming out, but the other end wasn't transmitting any more forms.

montypython wrote:Is it possible for a fax transmission to be clogged to the point that multiple transmissions can end up being received all at once?

No. This is even less likely than two people managing to call your phone at the same time, which is already pretty much impossible.

I had a data request done and multiple copies of the same form kept streaming out, but the other end wasn't transmitting any more forms.

Modern faxes buffer both incoming and outgoing transmissions in memory, so they don't have to stay on the line longer than necessary. If it wasn't supposed to be doing that, most likely someone keyed in the wrong number of copies, though I suppose it's possible you encountered a software bug.

Starglider wrote: Modern faxes buffer both incoming and outgoing transmissions in memory, so they don't have to stay on the line longer than necessary. If it wasn't supposed to be doing that, most likely someone keyed in the wrong number of copies, though I suppose it's possible you encountered a software bug.

If in case copies keep streaming in then for whatever reason, is it all right to shut down the receiving machine to stop further incoming copies?

montypython wrote:If in case copies keep streaming in then for whatever reason, is it all right to shut down the receiving machine to stop further incoming copies?

Of course. It's not like anything is going to explode.

Faxes run on POTS, and the spec doesn't even call for something terribly fast either (I think I remember hearing 300 baud in my digicomm class, but I could be wrong). Hanging up on your end has the exact same effect as hanging up on a recorded telemarketer: either they keep spewing with no-one listening, or they realize that you've hung up and they stop sending.

Braedley wrote:Faxes run on POTS, and the spec doesn't even call for something terribly fast either (I think I remember hearing 300 baud in my digicomm class, but I could be wrong).

That would be ridiculously slow; speeds like that haven't been in common use since the 1970s. I seem to recall the standard fax speed being 14.4 kbit/s (or at least it used to be when I was a student).

Actually I just checked and apparently the early ones started at 4800 baud. The latest ones can get up to 33.6 kbit/s, which isn't surprising as it's the most bandwidth you can get out of a standard analogue telephone line without cheating (56k modems only work at the advertised speed for download, if there is telco support, and your line isn't noisy).

No offence, but you're wrong. POTS doesn't support 4800 baud, as it operates beyond the cutoff frequency of the switcher. Yes, you can get 33.6kb/s, but the baud rate is still less than 2400 baud. The first fax machines used 300 baud, 16 bit PSK, resulting in 4.8kb/s, which oddly enough is pretty close to what I said. Also, you can easily get a data rate of 33.6kb/s at 300 baud, although you're much better off using 600 baud or faster because it's twice as error resilient (assuming the detector speed is more than up to the challenge).

So just to clarify for you, the baud rate can only be taken as the same as the data rate when you have 1 bit per baud. Most modems use either PSK (phase shift keying) or QAM (quadrature amplitude modulation) to increase the bits per baud. The theoretical bandwidth of a POTS channel is 4kHz, but a 10% safety margin was imposed, limiting the bandwidth of a channel to 3.6kHz, and consequentially, the baud rate to 3600 baud.

Braedley wrote:So just to clarify for you, the baud rate can only be taken as the same as the data rate when you have 1 bit per baud.

True, sorry, I forgot about the symbol rate/data rate distinction. While this is unforgivable, I am still going to blame the fact that so many other IT people I know make the same mistake. Because none of us have used modems for ten years or so I guess.