Digital "voice" for HF (FM)?

[ka5lqj]

Afternoon, :wink:

I've been a ham for a long time doing a lot of 2m/70cm, & some HF work.
I'm real new at this. Is there a digital FM mode for HF? I know D-Star is
on 2/440 FM, but I'm unsure of which mode they use.

I've done a lot of work with SkyWarn and listened to the Gulf Coast/LA
Hurricane Nets on USB. But, when a storm is approaching, the lightning
sometime wipes out a voice communication. If FM mode and P-25 protocol
were used that should wipe out the lightning and noise associated with a
ssb &/or AM mode transmission.

If there is a digital mode for HF is it transmitted with vertical or horizontal
orientation?

Thanks for LQ^QKing,

GOD BLESS,
73,

Don/KA5LQJ

 

[mancow]

Here's one.

AOR ARD 9000 DIGITAL VOICE MODEM - DIGITAL SSB FOR HF!

 

[KB7MIB]

Wirelessly posted (Mozilla/5.0 (X11; Linux i686; U; en-US) Gecko/20081217 Vision-Browser/8.1 301x200 LG VN530)

IIRC, for Ham radio, FM is only allowed above 29MHz. There are however, a few commercial landmobile allocations in the 25 and 26MHz bands that use analog FM.
I recall reading about AOR's digital SSB voice system many years ago.

 

[prcguy]

I have had an AOR digital voice modem for several years and have yet to catch someone on the bands in that mode.

I also have several Harris military HF radios with a very common LPC-10 digital voice mode and had many conversations over HF with other military radio owners.

The Harris radios have an internal 39 tome modem and the BW of the LPC-10 signal is legal for use in the voice portion of the HF bands.
prcguy

 

[Token]

Wirelessly posted (Mozilla/5.0 (X11; Linux i686; U; en-US) Gecko/20081217 Vision-Browser/8.1 301x200 LG VN530)

IIRC, for Ham radio, FM is only allowed above 29MHz. There are however, a few commercial landmobile allocations in the 25 and 26MHz bands that use analog FM.
I recall reading about AOR's digital SSB voice system many years ago.

I believe there is no actual regulation that says no FM below 29 MHz. 97.307 (1) and (2) define the transmission modes and widths that can be used on most of the HF ham bands (except 60M). Excerpt of ONLY 1 and 2 below, there is a lot more to be found in 97.307.

97.307
(1) No angle-modulated emission may have a modulation index greater than 1 at the highest modulation frequency.
(2) No non-phone emission shall exceed the bandwidth of a communications quality phone emission of the same modulation type. The total bandwidth of an independent sideband emission (having B as the first symbol), or a multiplexed image and phone emission, shall not exceed that of a communications quality A3E emission.

It does not say no FM. But, with a modulation index of 1 the bandwidth used is about twice the highest audio frequency used, i.e. basically the highest frequency voice (or data) component. It says the signals (talking about non-phone, but may apply) must not exceed the width of a communications quality A3E emission, but never defines what that width is. Since wideband AM is often found on HF for communications purposes these days (at least in the ham bands) it would be easy for a narrow band FM signal to use less bandwidth than that found in such wide AM. And with correct adjustment of the deviation you could probably get an NBFM signal under the 9 kHz that was proposed as the AM limitation under the regulation-by-bandwidth proposal.

But yeah, no reason to stay with FM to do digital voice, there are many voice encryption techniques used on HF, by other than ham services, all of them fairly narrow (compared to an AM or FM signal) and many of them requiring digitizing the audio before it can be encrypted. Digital voice and SSB is not unheard-of outside the ham bands.

To address the OPs question, there is not a currently used and widely accepted digital voice mode used by hams on HF. That is not to say there have not been a few scattered experiments, but nothing is currently in regular use.

T!

 

[ka5lqj]

"Thanks", All

Thanks Everyone,

I'd like to experiment with digital FM just for fun to see what kind of results I get. I'm not sure where I'd find a couple of Harris Military units on the surplus market, but there is nothing like trying, LOL!

My whole quest was to test the possibilities and if doable, use that to send messages via HF to other hams within the United States during very severe weather (hurricanes, etc.) Since it would be FM and transmitted horizontally, that should give a perfect audio quality (No QRN) for those participating.

I'm an old-time radio man who cut his teeth on tubes and NOS parts, so experimenting comes naturally. :lol: It's a shame that parts manufacturers don't still make these parts to repair or experiment with these parts and the circuits could be adapted to the new surface mount parts. I also do antenna experimenting as well.

Soon, I hope to have a digital mode (PSK-64, BPSK, J-65, etc.) setup to try it out. I'll be using Debian 6 to start with.

Beautiful Sunday morning here, no clouds, humidity is gettng up there and we're SUPPOSED to be about 106ºF, I think. Welcome to the Swamp, LOL!

GOD BLESS,
73,

Don/KA5LQJ

 

[brandon]

MELPe Digital Voice Demonstration with DVP-200 - YouTube
Audio sample about 1:10 into clip
Thought it sounded pretty good. Similar to P25

 

[exkalibur]

That brings up a good point really. On VHF/UHF/800 frequencies, there exists a LOT of off-the-shelf options for digital (P25, ProVoice, AEGIS, ASTRO, MotoTRBO, NXDN, D-Star, etc...). For the most part, they work far better than analog in a weak signal type of environment. I would be curious to see how they'd work in the HF environment.

I tried using FM on 20m with a friend once - it worked and sounded fantastic, but when there was noise on the band it was virtually unusable where AM and SSB worked good enough.

 

[LtDoc]

FM on 20 meters? That's a 'no-no'. FM is not any advantage on HF at all.
- 'Doc

 

[acyddrop]

I thought FM on HF frequencies was a no go because of FCC bandwidth restrictions? So using FM on 20 meters would be a violation of FCC regulations on the use of the bandwidth. I might be wrong, but I'm still new. I just recall all the exams pushing SSB in either USB or LSB variants on HF and a particular question on the General exam about FM being restricted on HF because of the bandwidth.

 

[ka5lqj]

HF Digital FM.....

Hi Guys!

First things first. Yes, the F.C.C. rules do say that FM can be run on
anything but 60 & 30 meters. The Modulation Index can not exceed
"1". Sounds like lawyer-speak to me, they need to put it in ham-
speak, LOL!

Now, what I was thinking was it being controled by software or an
outboard TNC. That way the Op doesn't have to have a pile of
notebook paper with all the configurations on different bands. The
Ultimate Goal is to have QRM & QRN-free commucations over long
distances. A cell 'phone will do that but during a natural disaster,
cell towers in the effected area are blown down, leaving almost no
communications except local 2m/70cm nets.

When the wx is not bad in either area, it would be better than D-Star :twisted: where you're at the mercy of a SysOp or group that might put you in or not. Then you have to have the Secret Society code number for the ham you're trying to reach and the Society "hand-shake" to talk to
him. <====Bronx "cheer".

I see there have been some pointers to Websites on here, I "Thank You" for sending them to me. For the past month, I really have not
been on much, but rather fighting my health problems.

GOD BLESS,
73,
Don/KA5LQJ

 

[zz0468]

First things first. Yes, the F.C.C. rules do say that FM can be run on
anything but 60 & 30 meters. The Modulation Index can not exceed
"1". Sounds like lawyer-speak to me, they need to put it in ham-
speak, LOL!

They DID put it in hamspeak. Hams are supposed to be technical enough to know what that means.

 

[acyddrop]

FM as a mode is not ~specifically~ banned but the bandwidth is the restriction, here's the rule and the reason:

FCC Rule 97.307 F 1:
(f) The following standards and limitations apply to transmissions on the frequencies specified in §97.305(c) of this Part.

(1) No angle-modulated emission may have a modulation index greater than 1 at the highest modulation frequency.

Since FM has is an angle modulation and you're restricted to an angle modulation of 1 it is effectively banned on frequencies below 29MHz. After 29MHz the restriction of this section no longer applies.

Read up on Angle modulation here: http://en.wikipedia.org/wiki/Angle_modulation since FM carries an inherent modulation index of 1 or more it's a no-no.

 

[kb2vxa]

"If FM mode and P-25 protocol were used that should wipe out the lightning and noise associated with a ssb &/or AM mode transmission."

Here's a point worth considering. While the mode will wipe out audible noise, whatever noise is present on the RF signal will disrupt the data stream resulting in dropouts and/or garbled voice. There are many digital modes designed for HF but all carry text where errors (up to a point) are tolerable but voice is very finicky and best left to VHF and UHF where noise is just about nil to begin with.

I've seen considerable misinformation here especially with regards to "angle modulation" and modulation index but when the above is considered all else becomes moot. Digital voice FM or otherwise isn't heard on HF for good reason, it's impractical when it comes to effective communications.

 

[ka5lqj]

Back in 1981.....

Hi All, :wink:

Back in 1981, when I took MY General Class test, the only thing the F.C.C.
listed was, CW, AM, SSB, FM, PHASE, & PULSE modulation, LOL! I can only
guess the original digital modulation was Morse Code. Pulse modulation
was used when high wattage was needed above 10gHz, better known as
radar, LOL!

I'm a supporter of AM on HF, especially 160, 75, & 10 meters, but there is
always some 'wise-acre' that will start a ghost QSO on SSB, then tell us
AM'ers, HE was here first and to "get off my frequency", even thought it is
within the allotted AM portion of the band.

What I'm looking for is a digital protocol that other hams don't hear any of
the "screeches" or "tones" and does not interfere with their QSO's and at
the same time, travel distances, both "local" and "far off" that is oblivious
to lightning or electrical noises. This would require either software written
or a TNC with embedded program. Electronics and digital move so =fast, if
I don't have it, maybe soon someone will invent it, LOL!

GOD BLESS,
73,

Don/KA5LQJ

 

[kb2vxa]

"Pulse modulation was used when high wattage was needed above 10gHz, better known as radar, LOL!"

Back then a version of the venerable 6146 was a common pulse modulator. Now PAM and PWM are the basis of AM and known as Class E, you'll find it in common use by the AM Gangstas on 75. Drifting frequency a bit to AM broadcast, that system has supplanted not only the old standard modified Heising modulation but phase modulation as well. Kiss the old RCA BTA 50G Ampliphase transmitter goodbye.

"...there is always some 'wise-acre' that will start a ghost QSO on SSB, then tell us AM'ers, HE was here first and to "get off my frequency", even thought it is within the allotted AM portion of the band."

No problem, the Gangstas fixed that problem years ago. Timtron invented a unique modulation scheme that drives slopbucketeers nuts.

"What I'm looking for is a digital protocol that other hams don't hear any of the "screeches" or "tones" and does not interfere with their QSO's and at the same time, travel distances, both "local" and "far off" that is oblivious to lightning or electrical noises."

Look no farther than your land line fiber optic network. You can arrange skeds, roundtables, ATV, packet and so much more QRM and QRN free.

"I don't have it, maybe soon someone will invent it, LOL!"

Lucent is WAY ahead of you OM.

 

[kb2vxa]

"Pulse modulation was used when high wattage was needed above 10gHz, better known as radar, LOL!"

Back then a version of the venerable 6146 was a common pulse modulator. Now PAM and PWM are the basis of AM and known as Class E, you'll find it in common use by the AM Gangstas on 75. Drifting frequency a bit to AM broadcast, that system has supplanted not only the old standard modified Heising modulation but phase modulation as well. Kiss the old RCA BTA 50G Ampliphase transmitter goodbye.

"...there is always some 'wise-acre' that will start a ghost QSO on SSB, then tell us AM'ers, HE was here first and to "get off my frequency", even thought it is within the allotted AM portion of the band."

No problem, the Gangstas fixed that problem years ago. Timtron invented a unique modulation scheme that drives slopbucketeers nuts.

"What I'm looking for is a digital protocol that other hams don't hear any of the "screeches" or "tones" and does not interfere with their QSO's and at the same time, travel distances, both "local" and "far off" that is oblivious to lightning or electrical noises."

Look no farther than your land line fiber optic network. You can arrange skeds, roundtables, ATV, packet and so much more QRM and QRN free.

"I don't have it, maybe soon someone will invent it, LOL!"

Lucent is WAY ahead of you OM.

 

[zz0468]

Read up on Angle modulation here: Angle modulation - Wikipedia, the free encyclopedia since FM carries an inherent modulation index of 1 or more it's a no-no.

"Inherent"? You can have a modulation index of less than 1.

11K0F3 has a modulation index of around 0.83. That's a 3000 hz audio channel deviated 2.5 KHz. Carson's rule will give you an approximation on occupied bandwidth, but to make it easy, that's 11 KHz.

The problem with running on HF is, in order to occupy the same space as an AM signal, the deviation has to be less than 0.2 khz (modulation index 0.67). The signal to noise ratio would be horrible. There being nothing to be gained by that, no one does it. But it's legal.

 

[kb2vxa]

Maybe a moot point but you raise the question; why does it have to occupy the same bandwidth as AM? I'm under the impression the modulation index must be 1 or less to be legal or am I wrong?

 

[Token]

"Pulse modulation was used when high wattage was needed above 10gHz, better known as radar, LOL!"

Back then a version of the venerable 6146 was a common pulse modulator. Now PAM and PWM are the basis of AM and known as Class E, you'll find it in common use by the AM Gangstas on 75. Drifting frequency a bit to AM broadcast, that system has supplanted not only the old standard modified Heising modulation but phase modulation as well. Kiss the old RCA BTA 50G Ampliphase transmitter goodbye.

To the OP, pulsed radar was not, naturally, limited to above 10 GHz. Then, and today, pulsed radars are found all the way down into the 3 MHz range. Of course, what we think of as “normal” high power radar systems generally start above 40 MHz with most from 400 MHz up.

Also to the OP, why stuck on FM for digital voice on HF? If you want to do digital voice on HF why not try some mode that can be based on something like SSB?

Warren, as for a variant of the 6146 as a common pulse modulator, I assume you mean the 6293? It is a tube very similar to the 6146 but optimized for pulse modulator type applications. I have seen it applied to a very few radar systems as a medium to low power pulse amplifier, being good up to about the 1 kW pulsed power range if I remember right. It may be common in other areas requiring low to medium power pulse amplification, but it is not all that common to find in the radar world. Such a tube is just a tickler when you start talking about 100 kW to 10 MW pulsed applications. And recent trends are to solid state devices as switchers for pulsed transmitters, directly driven by low level pulse amplifiers.

T!