> My opinion is the RTTY contesting community should look toward moving
> to this higher speed.
Maybe the broader question should be whether 75 baud ASCII (75 8N2)
should replace 45.45 baud 5 bit codes (45.45 5N1.5) in general?
The bandwidth requirements are very similar: CCIR 328-5 puts 45.45
baud/170 Hz shift at 246 Hz vs. 262 Hz for 75 baud/170 Hz shift.
The NTIA (Annex J) puts 45.45 baud.170 Hz shift at 279 Hz vs. 350
Hz for 75 baud. Even with the added bits the 8 bit code is slightly
faster overall (146 ms/character vs, 165 ms) than 5 bit/45.45 baud.
For amateur use the 8 bit code has two other advantages - elimination
of the Figs/Letters shift and the ability to support non-English
alphabets. Amateur radio also seems to be the last user of five
bit codes - their long term support is far from certain (and more
of a problem than the lack of sub-300 baud support in newer hardware).
I'm sure Chen can provide the math for theoretical s/n differences
but since amateur detection methods are far from optimal in a lot
of cases, I doubt that there would be much practical difference
in that regard.
73,
... Joe, W4TV
On 6/13/2010 11:23 PM, Robert Chudek - K0RC wrote:
> Sure, I remember that contest! :-) It pretty much fizzled because I had
> looked for a "commercial sponsor" but was not having much success. Then
> family "issues" reared their ugly head and I was off the air for several
> years so the HSS fell into oblivion. I had talked to Ron K5DJ about it. He
> took over the contest weekend but decided upon a different contest format.
>
> Yesterday I decoded someone sending CQ HSS... and that put a smile on my
> face... apparently someone else remembered it too!
>
> This was the first time I have used two different decoders in a contest, the
> normal MMTTY soundcard software and my old Kantronics KAM Plus TNC. It was
> quite the circus act trying to get that KAM going on a laptop with only USB
> ports available, but I finally won that battle.
>
> I thought the KAM was a decent decoder "in its day", but having the two RX
> windows open side by side, the MMTTY engine was clearly the winner when
> signals would dive into the noise. My Icom Pro 3 also has the advantage of
> the Twin Passband Filters and this helped both decoders when a signal was
> too weak to copy normally. Turning on this filter creates a serious "noise"
> issue which is irritating to listen to for an extended period of time, so I
> only turn it on when necessary.
>
> There were stations I called who could not copy me. I was running 300 Watts
> which helped somewhat, but I think having the Twin Passband Filters in my
> receiver might have been another part of the problem of a one-way
> "connection". Other variables are the other station may have been running
> 1500 Watts and/or he did not have Twin Passband Filters in his rig. So it's
> really difficult to draw a conclusion without more information.
>
> I did not experience abnormal requests for repeats. But this is really
> subjective as well. It's tough to quantify with only one "Test" and the less
> than ideal propagation during the contest. I was keeping track... I asked
> for 3 repeats, and I was asked for 4 repeats. My repeats were to verify I
> got the serial number more than one time on my screen. These were mostly
> European stations and they were during QSB conditions. I was impressed how
> quickly the exchanges came across the screen when decoding normally.
>
> My opinion is the RTTY contesting community should look toward moving to
> this higher speed. As a SO1R operator, the first hour tested my skill to
> punch the right keys, log the contact, and settle into the faster routine. I
> can imagine the higher rates would even challenge the SO2R operators in the
> beginning. Maybe some SO2R operators can comment on this?
>
> 73 de Bob - KØRC in MN
>
>
> ----- Original Message -----
> From: "Kok Chen"<chen@mac.com>
> To: "RTTY Reflector"<RTTY@contesting.com>
> Sent: Sunday, June 13, 2010 12:00 PM
> Subject: Re: [RTTY] BARTG 75 Sprint
>
>
>> On Jun 13, 2010, at 6/13 6:52 AM, Don Hill AA5AU wrote:
>>
>>> That was a blast! I really enjoyed the 75 baud RTTY Sprint.
>>
>> Has everybody forgotten the High Speed Sprint (HSS) contest already?
>>
>> The same 75 baud, and similarly short contest. I have logs from 1997
>> through 2000. And then the contest appeared to have fizzled out.
>>
>> My first contact in 2000 was with an AA5AU :-). Followed in the log
>> by the usual suspects: WS7I, N8YYS, VE3WQ, W4JLS, W0ETC, and ta da...
>> W6/G0AZT, and more familiar call signs.
>>
>> KK5OQ, K0RC, K3MM, K5DJ, W7TI (remember him?) and ta da... VE6RAJ were
>> among calls my 1998 log.
>>
>> As I said, the usual suspects :-) :-).
>>
>> 73
>> Chen, W7AY
>>
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