[pskmail] Pskmail turbo charged. Was: 300 Baud Rate in the USA

From: John Douyere <vk2eta@xxxxxxxxx>
To: pskmail@xxxxxxxxxxxxx
Date: Tue, 7 Feb 2012 20:11:51 +1100
Hi Dave,

Thank you for the quick reply regarding the bandwidth. Do you remember what
was the lowest frequency transmitted approximately?

I think that within a week I could have some beta software to test.

Can you compile Fldigi from source?

If so, I could send you some alpha code this week.

If not, what O/S do you run?

Regards, John
 On 07/02/2012 7:04 PM, "David Kleber" <kb3fxi@xxxxxxxxx> wrote:

> I took part in testing of off the shelf amateur gear back around 2007 with
> a simple audio tone generator, and from what I recall, we found a pretty
> consistent and reliable audio response on FM audio band pass of about 4.5kh
> with pretty sharp drops at the edges. I think a 3.5 - 4k width would be
> well within the reasonable limits of most transceivers and repeaters.
>
> I'm very interested in the results of your testing and would be glad to
> help with any testing. I'd love to Software Jockey some of your
> experimental modes!
>
> -Dave, KB3FXI
> paNBEMS.org
>
>
>   ------------------------------
> *From:* John Douyere <vk2eta@xxxxxxxxx>
> *To:* pskmail@xxxxxxxxxxxxx
> *Sent:* Tuesday, February 7, 2012 2:51 AM
> *Subject:* [pskmail] Re: 300 Baud Rate in the USA
>
> Hello David and Pskmail operators,
>
> Just to give you a heads up.
>
> Following Dave's request on faster modes for VHF I had a lot of fun
> driving the digital mode equivalent of a Ferrari (well, maybe just a
> turbo-charged Porshe today).
>
> I tried various combinations of multiple carriers with PSK500 / PSK500R
> and PSK250 / PSK250R, up to 4 carriers and I have to say it works well.
>
> To the point where the slower of my two PCs could not handle the speed of
> characters coming in, but that can be fixed.
>
> So far my highest test has been 4 x PSK500, using approx 2.6KHz of
> bandwidth and producing speeds of around 3200 words per minute. By changing
> the coding to the MFSK varicode I should be able to get around 3500 words
> per minute.
>
> This can be used with Pskmail or the Flxxx series of message handling.
>
> Of course the signal to noise of the channel has to be better and better
> as we increase the bandwidth and speed but in a good FM channel it should
> be fine.
>
> In my initial tests I find that an extra 8dBs of s/n ratio is required for
> the PSK Robust modes using 4 carriers instead of 1  (for 4 x the speed),
>  and 15dBs extra required for the standard PSK modes when going from 1 to 4
> carriers.
>
> The PSK Robust modes give excellent results, with very good sensitivity
> but at half the rate of the PSK modes of course.
>
> More tests required, but impressive so far.
>
> More of interest to the HF Pskmail operators, I have also tested with
> great success a 2 carrier PSK250 and PSK250R which give the same speed as
> PSK500 / 500R respectively and use 600Hz of bandwidth. Since these are at
> only 250 baud they are allowed in the USA on HF. Are there other
> restrictions on the HF bands like bandwidth in North America?
>
> Also, I searched through the internet but I could not find references in
> regard to the actual audio bandwidth of Amateur transceivers in FM. Has
> anyone got some references in that regards?
>
> All the best,
>
> 73, John
>
>
> On Sat, Jan 28, 2012 at 2:45 AM, David Kleber <kb3fxi@xxxxxxxxx> wrote:
>
> Good point, Victor.
>
> I more likely scenario would be a major cyber attack that would have
> equally damaging results. And, of course, on the local level, any situation
> that has everyone trying to use the cellular system at the same time will
> result in service outages (same thing goes with public safety trunked radio
> systems).
>
> For emcomm on HF, I see amateur radio being useful for situational
> awareness bulletins, the movement of bulk messages and logistical data.
> But, I see much more value that we could add at the local level (which is
> where the action is). MT63 2k long FEC/nonARQ is serving us very well but
> we're only using 2k of the 4.5k usable audio spectrum that is typical of
> most traditional FM transceivers and repeaters. A 3-3.5K mode would fit
> nicely.  I like the nonARQ for our manned station ops and MT63 2k long is
> quite reliable, even on long transmissions. FLWRAP and FLMSG allows all the
> receiving stations to confirm 100% and MT63 2k long is very tolerant to
> poor conditions and will even tolerate up to almost a full second of lost
> audio without missing a beat. That's why my wish list includes a very heavy
> FEC mode and would tolerate a moderate amount of FEC delay for our purposes.
>
> On the other hand, I'd like to see a new 3.5k high speed mode with just a
> little FEC for ARQ with a local pskmail server for emcomm use. I think this
> could be of great value for local emergency communications.
>
> -Dave,  KB3FXI
>
>
>
>
[pskmail] Pskmail turbo charged. Was: 300 Baud Rate in the USA

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