Goodbye FT8, Hello Olivia, The MAGIC Digital Mode For HF!

So what? I can disconnect my PC from the internet and communicate just fine with FT8. If the clock drifts off, I'll set it again using my watch and everything is just hunky dory.

 

Fair enough. What you are saying is that clock recovery wouldn't have worked well, so the only way to get the desired SNR values was to communicate the clock in some other fashion, because it couldn't be done in-channel at that SNR.

That may help you get the QSO over those data paths, but there's no way to compare that SNR with the SNR of another mode that did the hard work to recover the clock from the signal. Recovering the clock from the internet means that the modem didn't completely recover the signal from the remote transmitter. It recovered half of it (the data bits), and got the other half through the Internet or from WWV, or wherever. Hence, my comments about the modem only recovering half the transmission.

Coherent CW was a completely different animal. Coherent CW used in-phase and in-quadrature correlators to completely recover the signal. It was essentially a full-time matched filter, before DSPs became popular. Fldigi still implements it if you check the right box. Coherent detection has nothing to do with synchronizing clocks -- it has to do with using an optimal filter to recover signals better than other methods.

 

So the path for the clock signal for your QSOs is internet -> watch -> receiver, rather than just internet -> receiver. The principle is the same.

If you want to test what I'm saying, disconnect from the internet, then set your PC clock to a random time, seconds included, then try to make FT8 QSOs. Other modes can do that just fine. FT8 cannot.

 

The Internet has no involvement. My watch sets itself once a day via WWV. I am often disconnected from the Internet in my shack, and work FT8 just as well as can be.

 

A lot of restating the obvious but not addressing the assertion.

I stated "... communicating that clock data OTA (is) irrelevant..."

Of course that means each system must then be synced some way. Which can even occur, within tolerances, "coincidently" ie even by random chance. I wouldn't say it always has to be "communicated". Either way, IMO, not much to be gained being so hung up on the clock source (pun alert).

So not disputing mode-relative SNR comparisons either. Sure, that's not a fair playing field. But why is that an issue in regards to any modes usefulness in amateur radio?

Discussion on whether Schrödinger's cat is dead or alive are best left to another Zed thread in Ham Radio Discussions too,

https://forums.qrz.com/index.php?th...ur-ham-cat-thread.583339/page-13#post-4419128



73 de John - WØPV

 

I get almost if not just as much fun reading articles like this and the responses as getting on the air.

Who needs digital when I can read these forums with all the "expert" advice.

 

You are not wrong. However, most PSK31 QSOs (90% easily) are Macro exchanges. I just click what response I want to give (pretty much same as the FT8, just less info on FT8). PSK, Olivia, etc., are fine for a rag chew. OP is just trolling FT8 users. It's like the rag chewers on SSB complaining when a contest is going on.

 

Bingo.

 

Excellent point. So the data half of your FT8 QSOs is being synchronized and conveyed OTA by the really large 60kHz transmitter in Fort Collins.

 

Good, because that was really my main point.

It mostly matters because K1JT himself, and the users of his modes, claim unqualified SNR values for their operations that just aren't true -- at least not true to the extent that such things are measured in the industry for all other such uses. And that makes people erroneously believe that the JT/FT modes are accomplishing something that they are not.

 

Nope. By my squinting at my watch and my fumble fingered setting of my PC's clock.

 

I have no illusions about this. It's only useful when comparing one JT/FT signal against another.

 

You need to pick a story. Either your are using WWV(B) for your time source, or you are not.

If you transferred that clock data using your hands, it makes no difference. The clock synchronization was done, one way or another, through a data channel other than the one on which you are running FT8. If the original source was WWV(B), then you used another very powerful transmitter somewhere in the process of synchronizing your FT8 station with the other guys. That means your clock and their clock were aligned out-of-band, and not by the modem through reconstruction as other modes do.

 

See, perhaps we're not so far apart in the facts, just the interpretation and judgement.

Measurement and other definitions between amateur users and other industries are often different. Non-commercial innovations frequently break so called conventional rules. That doesn't automatically make a claim false.

SNR controversy notwithstanding, quite the contrary, FT / JT mode technology has accomplished a major disruption first in VHF and now HF ham radio operations.

73 de John - WØPV

 

Agreed. The human tendency to chase fads without respect to (or evaluation of) the value of the object of the fad is continually amazing.