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

I have no interest in the various "contest modes" that don't allow a QSO. I did SITOR/AMTOR back in the day and kind of miss it. I found to be a very fun mode to work. The ARQ mode was really something with the old PK-232 lighting up like a disco
Sailors back in the day were connecting to commercial SITOR stations with ham gear often enough that the operators at WLO would tell you the correct offsets for common ham gear if you asked, the maritime convention was different and you would be off frequency if you used the published numbers. WLO has moved on to PACTOR now, not sure how much AMTOR/SITOR is even left except for all the NAVTEX stations.

 

Guess I am the worst then.

I don't do any digital form of so-call ham radio and think it's just plain asinine. It's anything BUT wireless.

Kids do it everyday over the internet playing games and don't get excited.

Why would you care how others feel think or say as long as you get to do your thing!

 

I do FT8 for fun, I couldn't care less about "awards".

 

I think that will go Over most heads here

 

Can we just get the facts next time on the OP --rather than a putdown of FT8? Why should I use Olivia over FT8?

BTW 'magic' in Tech is a code word for ' snake oil'....was that your intent?

 

I have to ask, i dont understand your comment.. Can you explain again? Thanks

 

I clearly explained in the video, why you would use Olivia over FT8..

 

...and thus missed the point.

Most of us don't see 'amateur radio news' as an ersatz YOUTUBE. If your 'news' headline and piece isn't appropriate to introducing the video--and here it is not-- many will not bother with the video. I didn't. Attacking FT8 was a real turn off for me investigating OLIVIA. Also leading with "MAGIC". Obviously I am not alone on this.

Why don't you make a small table of FT8 and OLIVIA so we can see the plusses and minuses? Here...on the thread...not the video.

73
Chip W1YW

 

It means you don't have to attack FT8 and be defensive to get people interested.

 

A couple of things come to mind after watching this:
1. FT-8 does seem to have taken over HF. I can tune through the HF bands during the day and find no (or very few) SSB QSO's - almost all I hear are nets; no PSK31, but FT-8 is going strong.
2. The comments about power are, in my opinion, incorrect. Increasing power should not increase distortion, unless your amplifier has problems, in which case ALL modes would be similarly affected. I have tried to make contacts with FT-8, especially in Europe, and it just is not happening with 10 watts. I can call all day and not be heard, but when I go to 50 or 75 watts, suddenly they can hear me, and the signal reports are not high values - they are typically similar to what I am hearing from them.
3. I have had many nice QSO's with PSK31; even with macros in DM-780, I can still add "personal" notes to the transmission. Watching the Olivia QSO on the video was excruciating - much too slow for me. Also, it seemed (from what I could see) that there were many decoding errors in Olivia, and this may have been my misunderstanding of what was actually being sent. I'd much rather use PCK31 or 63 for an actual conversation.
4. The author forgot to mention that you have to specifically "attach" the RSID to your macros in DM-780 - it isn't automatic. I add RSID to just the beginning of the CQ macros, not to the others (report, station info, etc.). If the operator hasn't added RSID to their CQ macro, then no one will know they are calling CQ if the signal level is below the noise.
5. I suppose you could make a good case for FT-8 being only good for awards, but for me, it has allowed me to work stations that I would never have been able to work with PSK or SSB, as the noise levels at my location are so high (S7-S9 pretty much always below about 18-20 MHz) that other modes are unusable most of time, unless the other station is using a lot of power/gain antenna. I have called CQ on SSB portions for extended periods of time on the HF bands with almost zero results, but FT-8 will pretty much always get a reply.
6. I might give Olivia a try again (I think I actually have made perhaps one or two Olivia contacts the past 10 years) and see how it works out.

 

Every base-band data signal has two components. One is the data itself (the high and low bit states), and the other is the clock, which is used to position the bit transitions in time.

The performance of any digital mode demodulator depends on recovering both of these signals from the incoming signal + noise. If the clock recovery algorithm is good, the data recovery algorithm can be near-optimal in its ability to operate in low SNR conditions. If the clock recovery algorithm is poor, the SNR performance of the data recovery will also be poor, because it will be looking for bit state in the wrong locations.

This is something that every modem designer has to deal with.

But the JT-* modes and its various brethren don't do clock recovery -- at all. They depend on receiving clock data directly from the system clock, which must be disciplined to a government station, either via NTP, or hand-synchronization through WWV, CHU, or some other means that is not the radio channel from which the data is being taken. In fact, K1JT called this out explicitly in one of his papers on the subject -- he didn't implement clock recovery. The clocks of the end stations have to be pre-synchronized through one of these methods.

So whereas demodulators for Olivia, RTTY, PSK, and pretty much every other data mode including CW do the entire task of recovering the signal from the HF channel, the JT modes only recover half (the data), and they must get the other half (the clock) from a non-ham communications channel.

As a result, there is no way to meaningfully compare the SNR performance of JT65 with any other digital mode, because the JT65 SNR reports are based on the assumption that the JT65 demodulator has perfect out-of-band clock transition information, which artificially lowers the SNR threshold by using the Internet or other means to transfer half the channel data.

Go read the papers K1JT wrote on the subject. It's very clear. He worked around one of the hardest problems in modem design by simply not solving it at all, and taking that part of the transmission from another communications mode.

You raise a good point, which is disconnected operation. Technically, this changes nothing, because in order for your modem to work properly, you had to pre-synchronize your local system clock to an NTP, WWV, CHU or other government-sourced clock signal prior to operation, and that one-time act means that you and the other station used a non-ham communication channel to bring your modem clocks into alignment prior to the QSO. Whether your clocks were synchronized during or before the QSO is irrelevant. 100% of the modem clock information was communicated outside the HF channel, and the modem cannot function without this information being communicated in this way.

Every other digital mode can recover the clock information from the received tones on the HF channel, and their minimum SNR thresholds are dependent (among other things) on the quality of the clock recovery algorithms they use. JT-65 and its siblings cannot, nor do they even try, to do clock recovery, so the reported SNR numbers are artificially optimistic by comparison. And this is why you can't compare JT65 or FT8 SNR threshold values to Olivia. It is at least as different as apples and oranges. It's like comparing an apple to half (at most) of an orange.

 

Eric

Let me tell you about the advantages of AM Radio and my Johnson Viking !!!!!!!!!!!!!!!!!!!!!!!

Ian

 

Tinchy pogo

 

If I wanted to ragchew I'd get on phone. FT8 suits me just fine.

 

I didn't watch the video either after reading the biased intro text. I have used both modes and have a feel for the trade-offs.

Glad to see KD6UY call out the erroneous notion that FT / JT modes only send "half the (QSO) data over the radio channel". This seems to be a mistaken "fake-news" type notion that won't go away.

FT / JT are NOT "half internet" modes, ie, IRLP, EchoLink, or even PACTOR-WinLink. The notion of any "assitance" of the actual data comm'ed over the radio is facitious. It probably originates by the common and widespread use of the internet to set the clock on a home-shack PC to sync FT / JT xmsns. But use of the internet is only one of several available methods to accomplish that task.

The DX Cluster, email, etc can assists in locating stations OTA for awards hunting and contests. But, if used ethically, it's not communicating OTA QSO data. Of course, there have always been cheaters, even when post-mail was the only way to confirm contacts, and some responsible parties have been convicted.

Even before the internet made scheduling faster and more convenient, synchronized "blind" transmissions have been used by hams to communicate basic short info on classic modes for decades. Check out how meteor-scatter sequence analog QSO's was / are accomplished. This scheduling and "pre-synchronizing" of shack clocks enables being at the right place at the right time to hear the "pings" and in effect decreasing the perceived SNR. Does this method invalidate those QSO's?

The non-trivial and highly significant things Joe T. and Steve F. have done is automate the process while adding sophisticated DSP signal acquisition for detection and decoding.

73 de John - WØPV