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Mirror link please? (Oddly Google on Firefox Mobile doesn't appear to offer cache links) And IMO, the shot of adrenaline that ham radio needs is for the FCC t

Mirror link please? (Oddly Google on Firefox Mobile doesn't appear to offer cache links) And IMO, the shot of adrenaline that ham radio needs is for the FCC to take the gloves off of data modes on HF. 300 baud, are you kidding me? The same RF bandwidth that analog voice gets to use could deliver magnitudes more as a digital signal.

vvanders 9y ago
Yup, floored me when I came across that on the exam. Tons of other awesome stuff in countries that do a proper bandwidth limit as opposed to symbol limit.
brian-armstrong 9y ago
I thought this wasn't so much the FCC's doing as it was older hams who shun anything digital
- vvanders 9y ago
  I think that tide is turning, esp given the recent explosion of FT8.
kb1lqc 9y ago
Try again, website is back up. May still be slow.
VLM 9y ago
Its a weird case of legislating good engineering into political law. Its not needed; should be able to just quote FCC part 97.101(a) "In all respects not specifically covered by FCC Rules each amateur station must be operated in accordance with good engineering and good amateur practice" Google up "digital transmission on fading multipath channels" or similar and for example there's a nice whitepaper from National http://www.ni.com/white-paper/14931/en/ http://www.ni.com/white-paper/14931/en/ The ionosphere makes massive incredible multipath distortion causing intersymbol interference making anything over 100 or so symbols per second basically broadband noise aka jamming. Even if by some miracle a (short NVIS?) hop were decodable between hams X and Y, the ionosphere being what it is means everyone else on the band would be hearing distorted broadband noise. Most of the work recently (like last 30 years) has been in very low baud rate systems. From memory, doesn't FT8 run at 5.86 baud? It uses multi channel fsk and some FEC weirdness to push a remarkable number of bits per symbol. Like a decade ago I used to talk to people using Olivia mode which runs at 31.25 baud which frankly was too fast for conditions. Olivia also encoded quite a few bits per symbol. Generally symbol rates (baud rates) have been dropping while bits/sec has been increasing for a very long time. In the really old days like RTTY the baud rate was the bits/sec rate so the ratio of bits/baud was 1, it hasn't been that low in a long time. It was very frustrating and weird (an annoying!) to watch a waterfall display as multipath fading drifted thru a band and destroyed just the mark or just the space carrier of a RTTY signal. 45 baud rtty is probably the highest baud rate you'll see on HF digital ham radio.
- lightlyused 9y ago
  "Most of the work recently (like last 30 years) has been in very low baud rate systems. From memory, doesn't FT8 run at 5.86 baud? It uses multi channel fsk and some FEC weirdness to push a remarkable number of bits per symbol." It also makes communications possible where normal modes just don't work well. For example, six meter (50MHz) band contacts where the signal signal level is extremely weak and the opens very brief.

vvanders 9y ago

Yup, floored me when I came across that on the exam. Tons of other awesome stuff in countries that do a proper bandwidth limit as opposed to symbol limit.

brian-armstrong 9y ago

I thought this wasn't so much the FCC's doing as it was older hams who shun anything digital

vvanders 9y ago
I think that tide is turning, esp given the recent explosion of FT8.

kb1lqc 9y ago

Try again, website is back up. May still be slow.

VLM 9y ago

Its a weird case of legislating good engineering into political law. Its not needed; should be able to just quote FCC part 97.101(a) "In all respects not specifically covered by FCC Rules each amateur station must be operated in accordance with good engineering and good amateur practice" Google up "digital transmission on fading multipath channels" or similar and for example there's a nice whitepaper from National http://www.ni.com/white-paper/14931/en/ http://www.ni.com/white-paper/14931/en/ The ionosphere makes massive incredible multipath distortion causing intersymbol interference making anything over 100 or so symbols per second basically broadband noise aka jamming. Even if by some miracle a (short NVIS?) hop were decodable between hams X and Y, the ionosphere being what it is means everyone else on the band would be hearing distorted broadband noise. Most of the work recently (like last 30 years) has been in very low baud rate systems. From memory, doesn't FT8 run at 5.86 baud? It uses multi channel fsk and some FEC weirdness to push a remarkable number of bits per symbol. Like a decade ago I used to talk to people using Olivia mode which runs at 31.25 baud which frankly was too fast for conditions. Olivia also encoded quite a few bits per symbol. Generally symbol rates (baud rates) have been dropping while bits/sec has been increasing for a very long time. In the really old days like RTTY the baud rate was the bits/sec rate so the ratio of bits/baud was 1, it hasn't been that low in a long time. It was very frustrating and weird (an annoying!) to watch a waterfall display as multipath fading drifted thru a band and destroyed just the mark or just the space carrier of a RTTY signal. 45 baud rtty is probably the highest baud rate you'll see on HF digital ham radio.

lightlyused 9y ago
"Most of the work recently (like last 30 years) has been in very low baud rate systems. From memory, doesn't FT8 run at 5.86 baud? It uses multi channel fsk and some FEC weirdness to push a remarkable number of bits per symbol." It also makes communications possible where normal modes just don't work well. For example, six meter (50MHz) band contacts where the signal signal level is extremely weak and the opens very brief.