HF digital use

[AlphaFive]

Just was reading another post that was asking about FM use on HF. It brought up another question to my mind, somewhat unrelated. If FM use is very limited other than 10 meters, then, is AM used in digital mode? Certainly FM above 30 Mhz is largely in that format, what about AM below 30? I truly do not mean to sound like a simpleton, but I really don't know, and I'm not ashamed to say I don't know. Is AM digital in use?

 

[nd5y]

Are you talking about amateur or commercial/government/military?
Are you talking about sending modem generated audio tones on double sideband AM?

In the ham world it's mostly direct FSK (RTTY) or sending audio tones on SSB.
Some of the modes like PSK don't have a constant amplitude but are not considered AM.

I have never heard of anybody using full carrier AM for digital on HF.
That would take up twice the bandwidth as the same signal on SSB.

The only time I have seen FM used for digital was back in the 80's some of us were running 1200 baud packet on 10m FM.

 

[AlphaFive]

Are you talking about amateur or commercial/government/military?
Are you talking about sending modem generated audio tones on double sideband AM?

I have never heard of anybody using full carrier AM for digital on HF.
That would take up twice the bandwidth as the same signal on SSB.

That one answered my question.. I should certainly have been more specific. I was really referring to voice modulation, either amateur use or some of the independent high power broadcasters that I read about. Like always, I appreciate your help, you provide an answer even I can understand, haaaa. Take care.

 

[nd5y]

I was really referring to voice modulation, either amateur use or some of the independent high power broadcasters that I read about.

Some Icom radios can operate D-STAR on HF but I don't know how popular it is.
AOR still sells these ARD9800 | OTHER PRODUCTS | AOR U.S.A., INC. Authority On Radio Communications but I don't think many people have them.

I'm not familiar with commercial HF.
Some broadcasters use DRM but I don't know much about it either.
Digital Radio Mondiale | The future of global radio
https://en.wikipedia.org/wiki/Digital_Radio_Mondiale

 

[AlphaFive]

Digital HF

Thank you for the links, I'll look it over..

 

[ka3jjz]

It's not really AM - the modulation is much more complex than that. And while DRM is used on HF, there are very few broadcasts actually aimed our way. But before we get to that...

DRM - The RadioReference Wiki

There are several ways to modify HF receivers (some, at least) to work with DRM, and a few SDRs also have this capability. The modifications are, in principle, very similar to what you would do to tap a scanner to get baseband audio for various decoding purposes.

Mike

 

[AlphaFive]

digital HF

Thank you for that. I have seen many references to DRM, have to admit I never took the time to read anything about it. Now I have, and will learn a little more also. Thanks muches, take care.

 

[edweirdFL]

I seldom operate or hear D Star on HF outside of the scheduled nets on Saturday and Sundays.

 

[ka3jjz]

No ham stuff here, edweird. There's another forum for that.

This is HF broadcasting we're talking about here...thanks Mike

 

[majoco]

DRM is almost a dead duck now. It was touted as "FM quality over shortwave radio" and indeed it was - the few times I managed to receive the only useable signal to me was from All India Radio. RNZ had a DRM transmission to the Pacific but I was too close of course. The cost of equipment to the broadcaster was too high as well so you'll be lucky to hear any HF broadcasts now. It also required a special receiver which put it out of reach of target audiences

DRM on ham bands - I very much doubt it - too much bandwidth required and specialised equipment.

 

[ka3jjz]

It's used on the ham bands, just not very much due, in part, to specialized gear. This it OT here, of course, but check out WinDRM

Mike

 

[unclejed613]

I have never heard of anybody using full carrier AM for digital on HF.
That would take up twice the bandwidth as the same signal on SSB.

actually there's a cuban numbers station (HM01) that uses a digital mode (RDFT) on an AM carrier. i thought it was the weirdest thing when i saw it in my SDR waterfall. there may be other stations/countries that do something like this, but the cuban one is the only one i've seen on the air.

 

[AlphaFive]

HF digital

That one is very interesting, and great information to put in a file. I ask the initial question about AM digital, because it will assist in my decision about obtaining my first actual receiver. The essential question being, "If below 30 Mhz is nearly exclusively AM, is there a need to obtain a modern receiver that would include AM digital modes"? I am learning now that there really is not widespread use of any particular system that is both digital and AM, as exists in the world of FM. All of the posts are very much appreciated, and very helpful to me. Thank you all, the day is getting much closer for me to have enough saved up to jump in the deep end... Can't wait.
I would add that at this point and time, my only interest exists in simple voice modulation, am not ready for, or have any interest yet in the world of decoding systems..

 

[ka3jjz]

This question really belongs in our HF equipment forum - and the discussion on this topic should be there...however...

There are only a few SDRs and rare portables that can cover DRM natively, so that shouldn't be a consideration. That's the only voice digital mode HF broadcasters use (there are a few others used by hams). And while AM is widespread, sideband use is equally widespread in the utilities and ham worlds. If you don't get something that is sideband capable - and you can do that easily with portables like the Tecsun PL660 - you will be short changing yourself when and if you find your interests change - and they often do in this hobby.

To be continued in our HF equipment forum...Mike

 

[AlphaFive]

AM

Thank you, glad your here to guide me in the right direction (forum)... haaa, take care
Reference the sideband availability. In researching receivers over a long period, it seems as though I rarely ran across a unit that wouldn't include sideband coverage. Anything I have marked in red on my "list of consideration" would certainly include the sideband coverage. I do find that interesting and would really like to delve into that also. Thanks for your help

 

[AlphaFive]

HF digital

I'll go ahead and toss this into the mix. I've already decided what's best for me, and my particular situation. I will be limited to my high and clear wooden attic, too many outdoor antennas already in the mix. I'm going with the Alinco DX R8T/E, and hooked up onto an SA7000 antenna. That will set me up for future expansion into a wider range receiver. Really enjoy the loop offerings. The SA7000 will allow me not to have to concern myself with null effects. I was, and still am trying to learn about AM and FM availability. I find the world of HF, SW MW and LW to be fascinating. Don't know much, but always wanting to learn. As always, thank you all for your help

 

[ka3jjz]

All right, to get this back on topic, I'm fairly sure there's a R8T Yahoo group out there somewhere- so if you get interested in DRM, those folks are likely to have the mod procedure

Good Luck..Mike