[digitalradio] Re: ASCII ?
Related to the earlier question about amateur radio ASCII, there was also the occasion when the 60wpm limit was lifted and 100 wpm Baudot was allowed. This too never became popular because only the guys who had Model 28 machines could use it, and because the shorter bit length (13 ms. versus 22 ms.) was more sensitive to errors, both from increased bandwidth and from multipath propagation. I believe Navy MARS made some use of 100 wpm RTTY.
Re: [digitalradio] Re: ASCII ?
Well, what I meant (I don't remember the exact quote right now) is that the steering wheel and the pedals remain in the same place and react in a similar way, you don't have to learn anything basically new. Highways don't need to be modified, either... Jose, CO2JA Tom Tcimpidis wrote: > The CEO of GM once said that “What is good for GM is good for the country.” > > > > *From:* digitalradio@yahoogroups.com > [mailto:[EMAIL PROTECTED] *On Behalf Of *jhaynesatalumni > *Sent:* Thursday, October 02, 2008 8:47 AM > *To:* digitalradio@yahoogroups.com > *Subject:* [digitalradio] Re: ASCII ? > > > > --- In digitalradio@yahoogroups.com > <mailto:digitalradio%40yahoogroups.com>, "Jose A. Amador" <[EMAIL PROTECTED]> > wrote: > > > but there was a GM - Microsoft > > controversy that ended with a caustic reply from the GM's President > > that explained it too well. > > That's interesting, because I think it was GM that is generally > credited with inventing "planned obsolescence" and the annual > model change. > Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [digitalradio] Re: ASCII ?
The CEO of GM once said that "What is good for GM is good for the country." From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of jhaynesatalumni Sent: Thursday, October 02, 2008 8:47 AM To: digitalradio@yahoogroups.com Subject: [digitalradio] Re: ASCII ? --- In digitalradio@yahoogroups.com <mailto:digitalradio%40yahoogroups.com> , "Jose A. Amador" <[EMAIL PROTECTED]> wrote: > but there was a GM - Microsoft > controversy that ended with a caustic reply from the GM's President > that explained it too well. That's interesting, because I think it was GM that is generally credited with inventing "planned obsolescence" and the annual model change.
[digitalradio] Re: ASCII ?
--- In digitalradio@yahoogroups.com, "Jose A. Amador" <[EMAIL PROTECTED]> wrote: > but there was a GM - Microsoft > controversy that ended with a caustic reply from the GM's President > that explained it too well. That's interesting, because I think it was GM that is generally credited with inventing "planned obsolescence" and the annual model change.
Re: [digitalradio] Re: ASCII ?
jhaynesatalumni wrote: > I guess some people thought it was a Big Deal, but there were lots > of reasons why it didn't go anywhere. > > I'd say the overriding one is that with 60 wpm Baudot RTTY the bit > length is 22 milliseconds. With 100 wpm ASCII 110 baud the bit > length is 9 milliseconds. That means 2.4 times the bandwidth, and > correspondingly more noise sensitivity. Maybe for VHF local work > it wouldn't matter; but for HF that's a big penalty. And we were > already running 500 watts or so to get good copy on RTTY. One very important reason is (I)nter (S)ymbol (I)nterference, or ISI, when one delayed (by multipath) symbol steps on the following one, confusing the demodulator and creating lots of garbage. A long symbol may allow reflections to die and the demodulator to output some meaningful data, but a shorter one also has smaller probabilities of "hitting the nail on the head". The idea of longer symbols crafted for multipath environments is exploited in OFDM systems, together with some measure of FEC, if not using also ARQ, to assure the correct reception of "data", whatever the message content may be. 73, Jose, CO2JA
[digitalradio] Re: ASCII ?
I guess some people thought it was a Big Deal, but there were lots of reasons why it didn't go anywhere. I'd say the overriding one is that with 60 wpm Baudot RTTY the bit length is 22 milliseconds. With 100 wpm ASCII 110 baud the bit length is 9 milliseconds. That means 2.4 times the bandwidth, and correspondingly more noise sensitivity. Maybe for VHF local work it wouldn't matter; but for HF that's a big penalty. And we were already running 500 watts or so to get good copy on RTTY. Other reasons include the plentiful supply of old Baudot Teletype machines, versus having to buy a new one for ASCII, until CRT terminals came along. And so many guys can't even type 60 wpm that the ability to operate at 100 wpm wasn't interesting. And for rag chewing, contests, and DX, the upper case only Baudot character set is entirely sufficient. Of course the earlier ASCII Teletypes were also upper case only. And the lower cost ASCII Teletype, Model 33, had terrible keyboard touch compared with the older Baudot machines. ASCII was advantageous only for applications involving connection to computers, or for applications requiring upper and lower case characters. Teletype's original up/low machines, Model 37 and Model 38, were failures; so it was the CRT terminal business that really made ASCII practical. Jim W6JVE
Re: [digitalradio] Re: ASCII ?
--- On Wed, 10/1/08, hankvond <[EMAIL PROTECTED]> wrote: > From: hankvond <[EMAIL PROTECTED]> > Subject: [digitalradio] Re: ASCII ? > To: digitalradio@yahoogroups.com > Date: Wednesday, October 1, 2008, 8:30 PM > --- In digitalradio@yahoogroups.com, John Becker > <[EMAIL PROTECTED]> wrote: > > > > Why did ASCII fail to catch on? Just curious! > > > > 73, > > > > John, K9MM > > > > Hi John, > > Probably because ASCII requires separate equipment. The > standard TTY > would not do ASCII and the home computers of 1980 would > were a little > too "software challenged". > > Hank - KI4UMX > > The computers would handle rtty with no problem. I wrote a rtty program on an old 8080 computer mother board that only had about 2 K of rom and 1 K of ram to do the program. Could do 60 and 100 wpm. I was using a ST-6 to send the pulses to the computer and generate the tones. The old computers often used the 110 (think that is the speed) ASCII for the input/output hard copy. That same 8080 was used to decode the ascii from W1AW when they sent it. The old Comodore and Radio Shack computers could handle that slow speed with no problem. I am sure there were several reasons the ASCII did not make it. The slower 60 WPM Baudot gave fewer errors than the faster speeds. Most hams could not type 60 wpm or faster. There was already much Baudot equipment out. The mechanical ASCII devices cost a lot more.
[digitalradio] Re: ASCII ?
--- In digitalradio@yahoogroups.com, John Becker <[EMAIL PROTECTED]> wrote: > > Why did ASCII fail to catch on? Just curious! > > 73, > > John, K9MM > Hi John, Probably because ASCII requires separate equipment. The standard TTY would not do ASCII and the home computers of 1980 would were a little too "software challenged". Hank - KI4UMX
