4 reasons why we need more digital voice modes (not fewer)

A great topic - thank you for the post. It's interesting; even with the non-ham commercial digital DMR systems, there seems to be incompatibility in IP connectivity (over the Internet linking). As a Ham, I've made the transition to digital in DSTAR and C4FM for VHF/UHF, and about 90% of my operating is in digital modes on VHF/UHF. For ARES/RACES support, this technology provides messaging (ARRL radiogram, other formats) photography, position reporting and crystal clear audio; everything in one package.

In terms of interoperability I do support workable solutions. I draw the line, however, at integrating analog systems with digital, unless completely necessary for emergency support. The benefits of digital radio are obliterated in such networks and the digital users must contend with digitized noise and sub par audio. I'll be anxious to see how WIRES-X addresses the audio issue (and the propensity for digital audio to overwhelm the analog channel). Thank you for raising the discussion.

 

what over crowding, two meters is going the way of the gooey bird,
even the 50% (technician's) don't use it. so lets fill it with buzzing noises that need more complexity to decode, it might sound like HiFi (just what I need) , but probably in the long run won't provide any real improvement in reliability.

lets stick with modes that work, digital voice is nonsense

 

I would be far more likely to purchase a reasonably priced multimode rig than any dv one.Make SSB more ubiquitous on 2 meters.Better range than digital and excellent spectrum efficiency. SSB mobile 2 meter rigs that are affordable would be fantastic.

DV only makes sense if the long range goal is to produce a system that also accommodates data...ie internet over 2m.I am not only not interested in that....I oppose it.

SSB handhelds would rock too!

 

Ah, but I think you have a "chicken vs. the egg" situation there.

In some parts of the country, it does appear that there are groups of hams who, either in the name of public service, or just through crowd contagion, seem to have actively moved toward one or another DV mode. When you have groups willing to make the move, you generate the inertia to support an investment in a repeater as well as the associated needed mobiles and portables.

But in other areas...you have some experimentation taking place, with different folks trying out different modes based on their personal interest and perhaps availability of cheap or surplus equipment. And you have several of us who are waiting on the sidelines waiting to see if/how the dust settles before allocating a portion of our toy budget to one or more DV modes.

If there were more VHF/UHF activity in these areas...particularly more interesting VHF/UHF activity... perhaps band congestion would be sufficient to drive up interest in more spectrum-efficient modes (especially if inexpensive equipment were available).

But for now...in much of the US, the move towards DV is likely an exercise in cat-herding.

If data is a desired capability, remember that today, for relatively short text messages, DV is competing with packet, which while painfully slow, benefits from the wide availability of cheap equipment. There are still pockets of classic packet activity, and there are a boatload of packet-accessible Winlink nodes in many areas. Yes, it's painfully slow, but for the purposes of achieving critical mass... "cheap" and "already widely available" are key.

(Heck, in some parts of the country, getting average hams to think about communicating in anything other than voice is a hurculean effort.)

Personally, I think the ongoing development of amateur broadband in the 13cm, 9cm, and 5cm bands is more intriguing for text, image, and even video purposes. While there is some competition among modes here, the developers seem to be making some effort to support interoperability, and for most end users, IP is IP is IP. I imagine it wouldn't take too much effort to package something like a Raspberry Pi capable of bridging between amateur mesh and standard WiFi for less technically-inclined hams, opening the door to using a smartphone to generate voice, data, or image traffic at a public service event.

If a group sees enough value to spend money to build up text and image capabilities, mesh networking is may be the better investment (subject to the usual constraints of the area they see a need to serve, topography, etc.). If they don't want to commit the resources to building in that direction, they aren't going to be willing to spend the money to convert to DV either.

Thanks for that video; I had been wondering how Fusion sounded....and while it's not quite as harsh as D*STAR or DMR, there is still a definite "Donald Duck" quality to the audio. I think that's really my biggest gripe with DV -- it just sounds so nasty that I'm not going to leave a radio on in the background in the shack/office or the car.

If I want to put my brain to work making sense of noise that I'm hearing, I'll stick with chasing DX on sideband, or in listening to CW. If I want to listen to harsh sounds, at least RTTY is somewhat musical.

 

At what point does the DV mode race turn into just another cell-phone system? Why spend a thousand dollars on a radio that will be obsolescent overnight when you can get a cheaper cell phone that will be obsolesced overnight anyhow? I'm afraid I don't see what differentiates ham radio from cell phones if we go down that gopher hole? 2M DV to a repeater that links to the Internet to allow "long distance" ham radio? I can take out my smart phone and call anywhere I want and still play freecell and solitare.

Consider this: Years ago there was a big push on repeaters because cellphones weren't ubiquitous (yet). Now, there are scads of under-utilized repeaters wherever you go in this country. Is that because they aren't effective or that the value proposition evolved by the more efficient cellphone / tower proposition.

To me, pioneering efforts in amateur spread spectrum communications (for example) seems to push the evolutionary technological envelope far more than simply re-building a "toy" cell phone network based simply on the fond memories of "those golden times of yesteryear".

 

That $400 Yaesu was connected to an external antenna. My $40 Baofeng with a Diamond telescoping antenna hits my local repeater 10 miles away from the opposite end of inside my house (meaning I'm going through 2/3 of my house) just fine.

 

Originally Posted by KJ4RYP;3263812. Here's a "wee video" on YouTube that does a pretty good job of demonstrating the audio quality: [URL http://youtu.be/-VxoFMF9OTo?t=2m20s[/URL]
Watch the S-meter -- they're operating at the lowest power settings to demonstrate audio quality on the fringe. No static, no white noise, no repeater dropping in and out.

Look at the third in that series of demo vids where they show the distance display feature,

http://youtu.be/epiu95GZYiU

Although I also admit the quacky-audio isn't too bad, simplex between fixed base stations with external antennas at 25 to 38 KM is hardly fringe even at 100 mW! Let's see how that plays on an HT with a rubber-ducky walking along or mobile in motion.

I have serious apprehension about the range issues of DV. Picket-fencing, multipath and intermod QRM is bad enough with analog FM. And, FYI, analog SSB can be copied at or below an S meter reading of ZERO!

My county Public Service Department recently attempted to switchover an older trunked Motorola EDACS analog FM to DV. I don't know what all their objectives were, but certainly the police don't like being monitored by scanners. However, based on the complaints heard listening to everyday traffic they have also suffered from chronic poor coverage, especially HT's inside structures, mobiles in dead zones in rural areas, often worse on some trunked repeater frequencies versus others.

Consequently, the attempts of switching to DV were a complete disaster! Quality of coverage was WORSE! The tests only lasting a few days before they gave up! (and us scanner guys sighed in relief, LOL!)

I think the tough lessons they learned were,

1) don't believe everything the radio sales and marketing guys tell you, ie, like "Oh this new stuff will fix all your problems", and,

2) first put a lot more attention and that precious public funding into the basic RF infrastructure, ie, more-better remote receive sites, xmit antennas, etc etc etc, to improve SNR over the coverage area, before they would be able reap any benefits from any DV system.

If an analog FM system isn't workable for basic voice comm, I doubt (todays) DV is gonna work either!

 

Reply to post

I run DV on HF, which presents additional challenges. It works very well; in fact, I was surprised at how well, and I've worked phone DX across the pond using two different voice digital modes at 100W or less. Preceding these QSos I completed tests of digital vs. analog clarity, range and usability for VHF/UHF purposes. Why? I was determining where to place an analog Allstar system. I found digital to be AT LEAST equivalent in performance in my tests with more capability. For that location under test, however, I was planning Allstar as the locals are not familiar with digital - yet, and largely are very senior citizen, retired hams. At another location I run a roughly equivalent station on digital.

Digital modes offer QRM resistance, but decoding can be a challenge when two digital signals compete - Just like analog. The County, I'm sure, that you reference does the best it can. Even if your county had perfect funding, plenty of time and incredible vendor support, change-overs are never perfect. The EDACS system you're referring to, I think, is a digital system (not analog), and is being sent through a forced upgrade.

I'd like to ask you to stop attempting to make comparisons when your posts consist of your analog experiences and what you think you might have heard from the public sector. If you were local to me I'd loan you several radios, equivalent antennas, etc. so that you could test TX/RX and added capabilities.

 

Vendors and manufacturers should realize that especially today where any feature imaginable is just a matter of amending software, the cheapest system will by default become the choice of the mainstream. Once you have the bigger piece of the pie, business will boom. Look at what happened to the first packet communications on the market... Token ring was more efficient than TCP in terms of getting data across the network. TCP ( http://en.wikipedia.org/wiki/Transmission_Control_Protocol ) ... TCP fails when packet collisions rise to 30%... What happened? It became the prominent protocol today. The Beta format cassette video storage/player was mechanically more efficient than that of the VHS format... Beta was even smaller meaning you could hold more of these cassettes than the VHS cassettes in the same space. However, VHS became more accepted and main stream over the Beta format that later went away. Bottom line, price is what controls the market, not features. Thanks for sharing Carl... BillyG KH6JPL retired telecom sales engineer

 

I agree with aa9g and k0ip. I even quit psk31 because it was soooooooo boring. Cookie cutter qso's. Much, much more fun doing cw and ssb or am.

 

As I see it - digital mode should be a plugin to the radio, software or hardware module. That way equipment wouldn't grow old at a pace impossible to keep up with.

Even then - there are different layers in digital modes; modulation is one, encoding is another. Looking at PSK31 there's a lot of garbage in the transmitted data due to interference, QSB etc. Adding an encoding layer on top of it to provide error correcting codes (hamming coding) would improve the quality of the transferred data, lower the capacity and make incompatible with the "raw" PSK31.

The big deal with digital modes is the problem of being compatible since it's very much like Zymurgy's Law; "Once you open a can of worms, the only way to re-can them is to use a larger can!"

 

You're getting your network layers confused. I think you mean to compare Token Ring and Ethernet. TCP is at the transport layer two layers above those and could run on either Ethernet or Token Ring.

I think Ethernet won in the end when simple resistor network hubs were replaced with intelligent switches which eliminated collisions. Even though the switches cost more than hubs, the total cost was less than Token Ring and the connectors were more convenient. These days even the cheapest consumer grade network "hub" is really a switch.

 

Dmr does sound sort of like Stephen hawking because it's only using 1/3 of the width as regular fm. Also I would like to see all these systems integrated so I don't have to spend a fortune to get 3 types of radios to use 3 different systems.

 

Today, 02:58 AM
<!-- BEGIN TEMPLATE: memberaction_dropdown --> KB1RXA - "I'd like to ask you to stop attempting to make comparisons when your posts consist of your analog experiences and what you think you might have heard from the public sector."

WHOA! This comment caused me to investigate if other "public sector" agencies may have had similar problems to what I have heard. Go browse YouTube, it is a nationwide if not global issue!

There are many many reports of similar problems with conversion of pubic sector comms from analog voice to digital voice trunked systems going back many years now. Here are just a few found links:

http://youtu.be/H3y_eVmRbEA

http://youtu.be/8rm7W7zN3uQ

http://youtu.be/U-ib5mQOLJI

Further investigation about my local Manatee county in FL (we are more local then you may think ;-) indicates their experience to be similar, and like others they are now spending tens of million$ additionally to fix it, mainly just to enable the extra features, which I can see are valuable to such organizations; but, are those features that valuable to hams?

And to my original point many of the improvements are for upgraded RF-side infrastructure, which would have probably fixed a lot of the basic comm issues with the old analog FM too.

I have played with Free DV on 20 meters. Listened to others, called CQ till blue faced. Not many to talk to yet. Here is a good example of some of the HF and other propagation path issues I am concerned about,

http://youtu.be/fFCRwXMJ5K4

And that doesn't include on or adjacent channel QRM! I am not particularly looking forward to listening to a DX pileup of DV signals!!

Despite potential lower peak RF power requirements, because the DV xmtr duty cycle apparently is so high for to run all those continuous digi carriers, its more like running FM or AM, so I don't see energy conscious QRP HF backpackers adopting it much either!

BTW, one of our big local repeaters NI4CE allegedly now has NXDF capability, and I don't hear much going on with that. The daily nets seem to still be analog. Huh ...

Don't get me wrong!

I am all for experimentation with digital modes! And I don't mean to rain on anybodies parade, but again, with digital voice, for hams I don't see much benefit other then educational, a few rag chew nets, and some EMCOMM.

Digital modes other then VOCODER's have more applications all across the RF spectrum. Another reply post mentioned hams working with UHF broadband WAN's to enable alternative internet access, which I think is a great idea.

How about some amateur DTV UHF repeaters (with SAT links) ???