Hi Brian, At 08:29 AM 11/2/2007, you wrote: >I'm not trying to be a pain in the butt, honest. >
Neither is my reply meant to be anything other than pointing out the obvious. >We need narrower bandwidths not wider bandwidths for real progress >with the real life crowded bands. I think that is why PSK has worked >so well. Anybody pushing for wider bandwidths seems to be swimming >against the current. Patrick's efforts on FAE ARQ and ALE400 are an excellent example of taking Military communications standards and deriving solutions for Amateur Radio applications tailored to both the equipments being used by Radio Amateurs and within reason, to the parameters being demanded as well, he did not have to take the time and effort to provide ALE400 in response to those calling for narrower bandwidth, I certainly would not have bothered doing so, I applaud his efforts! For daily, casual Amateur Radio QSO's PSK and all modes down to CW ( which more new Amateurs should be using) are just fine, great actually, with two good CW ops if they can hear each other the message will be passed, but the top speeds under the best of conditions are pale in comparison to modern digital FEC and ARQ protocols. >I want to point out the old fashioned analog mode of SSB this weekend >had at least one station making 10,000 DX QSO's in a 48 hour period. >This was the bottom of the sunspot cycle with incredible QRM. For the given speed that a Phone SSB contact can be made, 1.8Khz band width is about as narrow as you can go and still be intelligent, for meaningful traffic passing and not DX contacts you would NEVER see 10,000 contacts in 48 hours on SSB, taking into account a typical ECOM message and band conditions, from a single operator based SSB Phone station, you would be really lucky to get off 600 and with shifts of changing operators. >It just seems to me that to replace existing technology, the newer >stuff has to be able to do all the old technology could do and much >more in the same or less bandwidth. I'm not seeing this in these >digital modes. Yep, laws of physics do tend to get in the way. Yes, for digital speed you need bandwidth, its that simple. SSB Phone and AM Phone take up a lot of bandwidth for very little in the way of speed, or for that matter accuracy and operator fatigue has a negative affect on both parameters during an ECOM event. >Those interested in what can be done if the bandwidth were available >should read the proceedings of the AMSAT meeting held this month in >Pittburgh. They are talking about a geosyncronous satellite with 6MHz >of bandwidth available. Supposedly being able to be reached with 5 >watts and a 60cm dish. They think this is the future of emergency >communications. All well and good, but the focus here is HF digital communications for ECOM, at least that is my focus and when you start talking about this aspect of ECOM we can of course any existing technology, however for the best throughput and error free delivery I can not see much less than 2Khz BW and ARQ protocols being used to achieve greater than 300 baud operation, the adaptive PSK ARQ stuff that I am work with in MARS exceeds 800 baud uncompressed already using the PC Sound Device Modem (PCSDM) within a 2Khz BW, wether those with a narrow BW focus come around or not, these wave forms on coming on the air from countries outside the U.S, here the out of date FCC rules need to change to bring it and other technology to the U.S. Amateur Radio bands to enable the U.S. Amateur Radio Service to benefit from the application of the PCSDM in support of ECOM and not continue regulate U.S. Amateurs to using expensive, proprietary hardware modems when we could be achieving desire results via the PCSDM. /s/ Steve, N2CKH >73 de Brian/K3KO
