Y'know, there is some relevance in a significantly asynchronous circuit with this stuff.
I think the correct label is "asymmetric" but many people call it "asynchronous"...
Put the High speed TX on the top of the mountain and have it push high speed frames in broadcast or multicast mode whilst the outlying stations listen to the stream and write down the packets relevant to them.
This is of course what I had in mind. We don't have any mountains here but we have a 3cm ATV repeater at 220m in a broadcast tower transmitting a DVB multiplex where we could use some bandwidth (or e.g. the bandwidth remaining after the several variable-rate encoded ATV channels have had their share) to transmit IP over DVB. Both broadcast/multicast traffic (like IPTV streams from the repeater) and traffic to a single endpoint (after all, we do not hide traffic from eachother). The return channel could be much slower indeed, depending on the kind of traffic and the required return traffic. Maybe even a 9600+ baud packet link, or one of those newly developed 70cm links of about 400kHz width. At the moment the repeater is not operating, but we are working on getting it back on the air.
Rob
Just remember, in the US, that 70cm data must fit in 100 kHz and be 56 kbauds (Same on the 219 Mhz band), but this is interesting work. 97.305(c) and 97.307(f)6
On Fri, Sep 1, 2017 at 9:11 AM, Rob Janssen pe1chl@amsat.org wrote:
Maybe even a 9600+ baud packet link, or one of
those newly developed 70cm links of about 400kHz width.
On Fri, Sep 1, 2017 at 9:26 AM, K7VE - John k7ve@k7ve.org wrote:
Just remember, in the US, that 70cm data must fit in 100 kHz and be 56 kbauds (Same on the 219 Mhz band), but this is interesting work. 97.305(c) and 97.307(f)6
John,
Isn't this rule moot when the data is multiplexed on an ATV transmission? That is the most interesting detail of this implementation to me.
Tom KD7LXL
Why do all new-technology discussions about the ham bands degenerate into arguments about USA rules? No wonder most innovation takes place in other countries. - Brian
On Fri, Sep 01, 2017 at 10:37:15AM -0700, Tom Hayward wrote:
On Fri, Sep 1, 2017 at 9:26 AM, K7VE - John k7ve@k7ve.org wrote:
Just remember, in the US, that 70cm data must fit in 100 kHz and be 56 kbauds (Same on the 219 Mhz band), but this is interesting work. 97.305(c) and 97.307(f)6
John, Isn't this rule moot when the data is multiplexed on an ATV transmission? That is the most interesting detail of this implementation to me. Tom KD7LXL
On Fri, Sep 1, 2017 at 10:46 AM, Brian Kantor Brian@ucsd.edu wrote:
Why do all new-technology discussions about the ham bands degenerate into arguments about USA rules? No wonder most innovation takes place in other countries. - Brian
Rhetorical? I'll answer anyway...
In the context of data emissions (like we would expect on this mailing list), it's because the USA rules are so limiting. Every new technology is an exercise in squeezing into the old rules. This method of packing data into an ATV transmission--which is the one exception for high bandwidth on 70cm--is engenius.
And yes, it is no wonder most innovation takes place in other countries given the limits imposed on lower frequency data transmissions in the US.
Tom KD7LXL
A few decades ago, I was one of a handful of people included in a Special Temporary Authority (STA) permitting the use of spread spectrum on the ham bands. It was astonishing to me how much opposition from the ham community itself we encountered trying to get that exception to the rules approved.
I think to a large extent we could get the FCC rules brought into at least the previous century, if not this one, by a concerted effort to get them changed. But in general, hams in the USA don't work together, and we have no national organization in favor of getting such changes made, so that is not going to happen.
Some day I would hope we would be able to do something about that.
In the meantime, both STAs and the Experimental Radio Service are legal ways around the stupid rules we have to contend with. Both require a lot of paperwork.
But that's enough of USA rules problems; this is an international mailing list and I'm often encouraged by what people elsewhere are doing. Keep up the good work, folks. - Brian
PS: in Southern California, 70cm is so eaten up by military radars and other transmission stuff that it's really not very usable for anything beyond FM voice repeaters anyway.
On Fri, Sep 01, 2017 at 10:55:11AM -0700, Tom Hayward wrote:
In the context of data emissions (like we would expect on this mailing list), it's because the USA rules are so limiting. Every new technology is an exercise in squeezing into the old rules. This method of packing data into an ATV transmission--which is the one exception for high bandwidth on 70cm--is engenius.
And yes, it is no wonder most innovation takes place in other countries given the limits imposed on lower frequency data transmissions in the US. Tom KD7LXL
On 2/09/2017 3:46 AM, Brian Kantor wrote:
Why do all new-technology discussions about the ham bands degenerate into arguments about USA rules? No wonder most innovation takes place in other countries.
Probably says a lot about the US rules. There seems to be a lot more restrictions on emission modes than most other countries these days, especially on HF.
On Fri, 1 Sep 2017 18:11:03 +0200, Rob Janssen pe1chl@amsat.org wrote:
Y'know, there is some relevance in a significantly asynchronous circuit with this stuff.
I think the correct label is "asymmetric" but many people call it "asynchronous"...
One could go with asymmetric but Aloha was tested in two modes, asynchronous-asymmetric where the Menehune was master of the output channel and terminals contended "asynchronously" on the input without being able to hear each other and slotted Aloha where Menehune assigned time slots to terminals and they sent their data isochronally. I believe there was one slot kept open where a previously idle terminal could contend for assignment of a slot. Slotted Aloha performed better than asynchronous Aloha.
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Brian Kantor -
Geoff Joy -KE6QH- -
K7VE - John -
Rob Janssen -
Tom Hayward -
Tony Langdon