Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!wuarchive!emory!dscatl!lindsay
From: lindsay@dscatl.UUCP (Lindsay Cleveland)
Newsgroups: comp.dcom.modems
Subject: Re: Modems with cellular telephones
Message-ID: <31805@dscatl.UUCP>
Date: 28 Oct 90 16:03:10 GMT
References: <9010262354.AA04244@alw.nih.gov>
Reply-To: lindsay@dscatl.UUCP (Lindsay Cleveland)
Distribution: usa
Organization: Digital Systems Co,  Atlanta, Ga
Lines: 44

In article <9010262354.AA04244@alw.nih.gov> RAF@CU.NIH.GOV ("Roger Fajman") writes:
>Some people here would like to use a laptop PC and modem with a celluar
>telephone for the purpose of giving demonstrations in various locations
>where a modular jack may not be available.  Can anyone recommend
>cellular telephones and adapters for this purpose?  We don't have a
>particular cellular telephone yet -- it would be purchased specifically
>for this.  The phone would be stationary, of course, while the
>demonstration is going on, but would be inside various buildings.

I have actually seen what you describe.  At a demo here in Atlanta
of the Telebit "Cellblazer", a digital still-camera was used to
take a person's picture.  It was then read into a lap-top which
then used a standard package to "crop" the photo and include it
into a "employee id" form, and then transmit the entire file from
the laptop's internal "Cellblazer" modem via a cellular telephone there
in the demo room, up to Chicago.  (Since I could see the number on 
the handset's read-out, I know it really was Chicago (-:  )

Next, he went over to another cellular phone which was connected to
a external "Cellblazer" modem hooked up to a regular PC.  He dialed
the Chicago computer, went through the proper login sequence, and
then down-loaded the same form and picture (in color!) to the PC.

I seem to recall the actual thru-put speed as being around 14KB.

>A related question is how well various modem technologies work over
>cellular telephones.  We are mainly interested in v.22bis (2400 bps)
>and V.32 (9600 bps) so that so special modem would be needed at the
>other end.  Is it important to have MNP or V.42 error correction?

At the demo, they mentioned that they had to put some very special
"smarts" into their program contained in the modem, and it handles
the problems of fading and reflections of the signal.  
The protocol they use is (I assume) a variant of the Telebit PEP
protocol.

Anyway...I was impressed!

Cheers,
  Lindsay

Lindsay Cleveland         Digital Systems Co.   Atlanta, Ga
  gatech!dscatl!lindsay     (404) 497-1902
                         (U.S. Mail:  PO Box 1149, Duluth, GA  30136)