Dear Trevor ( M5AKA )
I continue to ask one question about digital voice on HF.
When will Hams see a digital voice system that will be able to Handle a 20 meter pile up.
So far , the answers have been negative.
Would Trevor know of any system that could accomplish that feat.
My best
Joe K0VTY =============================== On Sun, 25 Feb 2007 21:15:13 +0000 (GMT) Trevor [email protected] writes:
In the next 10 years or so we can expect All Amateur voice communications to switch to Digital in preference to SSB or FM. It will be as traumatic a shift as the move from AM to SSB was back in the early 60's.
I don't expect that any of the different Digital Voice systems currently in iuse will be the ones eventually adopted for HF and VHF/UHF - rate of techonological progress can be rapid in this field. But whichever format eventually dominates there will be significant challenges for satellite operation.
When newcomers try out the satellites for the first time they don't use fully computerised doppler correcting set-ups, they compensate for doppler by hand.
Now the existing satellites modes - CW, SSB, FM are all relatively "frequency insensitive" - you can be offtuned by 300 Hz on a CW signal and a human operator will still be able to copy it just fine. SSB is the most critical of the three, but even that can still produce understandable audio even with a 150 Hz+ frequency offset.
All existing Amateur Digital Voice modes are very frequency sensitive, you need to stay within 50 Hz of the correct frequency to decode them and this would be problematic for a LEO sat where the operator is tuning manually.
What we need is a Digital Voice mode that occupies a bandwidth of less than 2.5 kHz, can be decoded with very low S/N ratios (<15 dB) and can tolerate tuning offsets of at least 150 Hz - a tall order but not impossible.
Satellite users need to give some thought to this because unless there is Amateur Satellite Community input to the development of Amateur Digital Voice we could end up with the situation where none of the commercially available Amateur Digital rigs (that's all they'll be in 10 years time) can use LEO Amateur Satellites !
73 Trevor M5AKA
--- Dave hartzell [email protected] wrote:
Interesting idea...
Doppler tracking might also be an issue....do these radios
support
incremental VFO adjustment via computer control?
73,
Dave NøTGD
On 2/23/07, Patrick Green [email protected] wrote:
Hi All,
I'm wondering if the GMSK modulation scheme in D-Star can be
inverted and
whether the Icom 91AD dualband HT can work full duplex for
satellite work.
D-Star uses a 6.25kc channel which is way better than the 15kc
needed for
standard FM but not as friendly as SSB and CW. Let me know. I
haven't
purchased this equipment but it's worth at least a debate.
73 de Pat --- KA9SCF. _______________________________________________ Sent via [email protected]. Opinions expressed are those of the
author.
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Sagan.
Sent via [email protected]. Opinions expressed are those of the
author.
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At 12:34 PM 2/26/2007, joseph Murray wrote:
Dear Trevor ( M5AKA )
I continue to ask one question about digital voice on HF.
When will Hams see a digital voice system that will be able to Handle a 20 meter pile up.
So far , the answers have been negative.
Would Trevor know of any system that could accomplish that feat.
History has shown that older systems will stay around if they are still useful to the ham community. CW is a perfect example, and AM still exists in niches. Similarly, analog SSB and FM will continue to exist and be used on air for decades. Furthermore, the next generation of radios are likely to be software defined, so there will be no problems maintaining backwards compatibility with the modes we enjoy today. If the radio doesn't have the mode we want, we will be able to either download a firmware upgrade or Google for the source code we need and install it ourselves.
73 de VK3JED http://vkradio.com
Hi, Joe,
Basically D-STAR (registered trademark) is designed to be used only in FM mode. (Has VO-52 a FM transponder ?)
Currentry only the ICOM supplies D-STAR comtatipble TRX on to the market. However, it seems that even the ICOM does not have suitable TRX for Sat communication on DV mode. For example, look their new mobile TRX, IC-2820. This radio is of course D-STAR compatible TRX. This radio can handle both 144/430MHz in FM and full duplex operation may be available. ( This radio may be able to use on the AO-51)
But, most important point is the radio has only One DV mode circuit and because of this reason, there is no possibility to enter duplex operation on DV mode. In another word, on DV mode, only simplex operation is avilable.
Please note above is current situation in Japan and may differ on the oversea market and of corse two years ahead or even one year ahead may be in different situation.
Toyo JA0CQP
At 05:32 PM 2/25/2007, Tony Langdon wrote:
At 12:34 PM 2/26/2007, joseph Murray wrote:
Dear Trevor ( M5AKA )
I continue to ask one question about digital voice on HF.
When will Hams see a digital voice system that will be able to Handle a 20 meter pile up.
So far , the answers have been negative.
Would Trevor know of any system that could accomplish that feat.
History has shown that older systems will stay around if they are still useful to the ham community. CW is a perfect example, and AM still exists in niches. Similarly, analog SSB and FM will continue to exist and be used on air for decades. Furthermore, the next generation of radios are likely to be software defined, so there will be no problems maintaining backwards compatibility with the modes we enjoy today. If the radio doesn't have the mode we want, we will be able to either download a firmware upgrade or Google for the source code we need and install it ourselves.
73 de VK3JED http://vkradio.com
Tony and all:
Not only will SDR permit legacy modulation modes, but permit changing into new modes as they are developed. One of the most difficult "growing pains" of new technology is the rapid obsolescense of equipment as a new mode matures into a new "standard" (e.g. 8-track/cassette/CD/... or Betamax vs VHS). The SDR allows all and anything, limits are your imagination!
Joeseph: this still doesn't answer your question :-)
73, Ed - KL7UW ====================================== BP40IQ 50-MHz - 10-GHz www.kl7uw.com 144-EME: FT-847, mgf-1801, 4x-xpol-20, 185w DUBUS Magazine USA Rep [email protected] ======================================
At 03:22 PM 2/26/2007, Edward Cole wrote:
Not only will SDR permit legacy modulation modes, but permit changing into new modes as they are developed. One of the most difficult "growing pains" of new technology is the rapid obsolescense of equipment as a new mode matures into a new "standard" (e.g. 8-track/cassette/CD/... or Betamax vs VHS). The SDR allows all and anything, limits are your imagination!
Indeed, we have already seen this with the "first generation SDRs" that exist today. You're using yours to read this message! ;) Yes, I'm talking about the PC/soundcard combination, which is commonly used as a SDR to run both legacy modes such as CW, RTTY and SSTV (and Baird style NBTV!), as well as new modes such as PSK-31, JT-44 and the wide array of PC based digital modes we are using today. Even digital voice is covered, with DRM being available on the PC (I'm yet to fire up DRM on the air, need to find some locals on HF).
Joeseph: this still doesn't answer your question :-)
The answer to that lies in how tolerant D-Star is of frequency errors (i.e. Doppler shift). Digital modes vary widely in their tolerance of frequency shift. Most of the ham modes are optimised for narrow bandwidth, and therefore they can be susceptible to Doppler. Another issue is whether the clock recovery is capable of dealing with a slightly non standard bitrate. This effect is also Doppler related, and was what nearly sunk the Huygens mission on Titan. Fortunately, one of the engineers insisted on testing the comms system while Cassini was en route to Saturn and they were able to find a workaround for that problem. The full write up is available on the Net and is a good read. Try Google. :)
Still no answer to the original question, I don't know much about D-Star, and it's unlikely to be commonplace here until the next generation of SDR hardware is commonplace (assuming D-Star will be available as a firmware upgrade from Icom or someone else). The existing hardware based implementations are too expensive for sufficient uptake with our low population density.
I'm more inclined to spend $1000 on a SDR that can be programmed to do whatever modes are flavour of the month relatively cheaply (plus good old AM/FM/SSB/CW/PSK/packet etc) than spend $1000 on a radio with a new mode that works well but no one else has.
73 de VK3JED http://vkradio.com
Does anyone know how if this digital mode will be immunized against interference as it was one of the main gain SSB was offering when implemented?
As many audio digital mode actually in operation they are needing a very good and stable carrier and no interference at the RX point. That's something an amateur radio transmission does not have too often.
D start system testing is now in his very early stages only on company is offering a five radio and a repeater package in a way to permits amateurs a way to experience it. and It is on 1.2 Ghz.
As any new communication mode as the numerous PSK's mode and the APRS, PACKET are offering new ways to communicate but they don't replace what it is available. SSB replace AM as there was real benefits is the same will also happen to audio digital technologies? It depends on how effective this mode will perform or not perform in a real QRM/QRN situation.
I think it will be as SSTV and ATV a new mode of communication but due to his present limitations SSB and FM will be harder and longer to replace in the actual science level.
"-" "It is not the class of license the amateur holds, but the class of the amateur that holds the license."
Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe WAC BASIC CW PHONE SATELLITE
The Icom IC-800 will work with some Doppler Error in Digital voice mode. I have been testing the IC-800 specifically to see how well it would work in theory with a 2-meter signal from a simulated LEO Orbit, such as ISS at 240 miles altitude. The results have been very promising on Earth.
The IC-800 will decode good Digital voice, with a frequency error of > 2.5 kHz. And this was at an indicated signal level of S1 on the radios S-Meter. At higher S-Signal levels the amount of frequency error the IC-800 can tolerate in digital voice mode is higher.
I setup a pair of IC-800 20 miles away. Then by using a combination of 5k channels on one radio and 6.25k channels on the other radio, i was able to simulate 2, 2.5k and 3k channel doppler errors. A beam antenna was used to Lower the indicated Signals levels until audio quality droped.
The lower the altitude the higher the Doppler (Frequency dependant too). The Doppler from ISS is approximately Plus and Minus 3.3 kHz. This means that If a LEO satellite is approaching on 2-meters, the frequency you will see on your radio will be up to 3.3 kHz higher for the first minute, then will quickly drop to zero Doppler for a few seconds at the 5 minute mark (assuming a 10 minute pass).
So, in theory, if the Doppler on a transponder based satellite is less than 3 kHz and you have signals stronger than 1 S-Unit, it should be possible for 2-way Leo satellite via digital voice. Anyone else have an IC-800 and want to test?
Miles WF1F
www.marexmg.org
____________________________________________________________________________________ Now that's room service! Choose from over 150,000 hotels in 45,000 destinations on Yahoo! Travel to find your fit. http://farechase.yahoo.com/promo-generic-14795097
When will Hams see a digital voice system that will be able to Handle a 20 meter pile up.
Or the uplink to a LEO bird. It seems I LEO-digital will only probably work in a closed system, where a protocol allows checkins and assigned slots. Then the hardware/software manages the TX times for each station...
Bob
So far , the answers have been negative.
Would Trevor know of any system that could accomplish that
feat.
My best
Joe K0VTY
On Sun, 25 Feb 2007 21:15:13 +0000 (GMT) Trevor
writes:
In the next 10 years or so we can expect All Amateur voice communications to switch to Digital in preference to SSB or FM. It will be as traumatic a shift as the move from AM to SSB was back in the early 60's.
I don't expect that any of the different Digital Voice
systems
currently in iuse will be the ones eventually adopted for HF and VHF/UHF
- rate
of techonological progress can be rapid in this field. But
whichever
format eventually dominates there will be significant challenges
for
satellite operation.
When newcomers try out the satellites for the first time
they don't
use fully computerised doppler correcting set-ups, they compensate
for doppler
by hand.
Now the existing satellites modes - CW, SSB, FM are all
relatively
"frequency insensitive" - you can be offtuned by 300 Hz on a CW signal
and a
human operator will still be able to copy it just fine. SSB is the
most
critical of the three, but even that can still produce understandable
audio even
with a 150 Hz+ frequency offset.
All existing Amateur Digital Voice modes are very frequency sensitive, you need to stay within 50 Hz of the correct frequency to decode them
and
this would be problematic for a LEO sat where the operator is tuning
manually.
What we need is a Digital Voice mode that occupies a
bandwidth of
less than 2.5 kHz, can be decoded with very low S/N ratios (<15 dB) and
can
tolerate tuning offsets of at least 150 Hz - a tall order but not
impossible.
Satellite users need to give some thought to this because
unless
there is Amateur Satellite Community input to the development of
Amateur
Digital Voice we could end up with the situation where none of the
commercially
available Amateur Digital rigs (that's all they'll be in 10 years
time) can
use LEO Amateur Satellites !
73 Trevor M5AKA
--- Dave hartzell [email protected] wrote:
Interesting idea...
Doppler tracking might also be an issue....do these radios
support
incremental VFO adjustment via computer control?
73,
Dave NøTGD
On 2/23/07, Patrick Green [email protected] wrote:
Hi All,
I'm wondering if the GMSK modulation scheme in D-Star
can be
inverted and
whether the Icom 91AD dualband HT can work full duplex
for
satellite work.
D-Star uses a 6.25kc channel which is way better than
the 15kc
needed for
standard FM but not as friendly as SSB and CW. Let me
know. I
haven't
purchased this equipment but it's worth at least a
debate.
73 de Pat --- KA9SCF. _______________________________________________ Sent via [email protected]. Opinions expressed are
those of the
author.
Not an AMSAT-NA member? Join now to support the amateur
satellite program!
Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
-- "It is far better to grasp the Universe as it really is
than to
persist in delusion, however satisfying and reassuring." -
Carl
Sagan.
Sent via [email protected]. Opinions expressed are those
of the
author.
Not an AMSAT-NA member? Join now to support the amateur
satellite
program!
Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
What kind of emailer are you? Find out today - get a free
analysis
of your email personality. Take the quiz at the Yahoo! Mail Championship. http://uk.rd.yahoo.com/evt=44106/*http://mail.yahoo.net/uk _______________________________________________ Sent via [email protected]. Opinions expressed are those of
the
author. Not an AMSAT-NA member? Join now to support the amateur
satellite
program! Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:
Will this still work on an inverting transponder?
On 2/26/07, MM [email protected] wrote:
The Icom IC-800 will work with some Doppler Error in Digital voice mode. I have been testing the IC-800 specifically to see how well it would work in theory with a 2-meter signal from a simulated LEO Orbit, such as ISS at 240 miles altitude. The results have been very promising on Earth.
The IC-800 will decode good Digital voice, with a frequency error of > 2.5 kHz. And this was at an indicated signal level of S1 on the radios S-Meter. At higher S-Signal levels the amount of frequency error the IC-800 can tolerate in digital voice mode is higher.
I setup a pair of IC-800 20 miles away. Then by using a combination of 5k channels on one radio and 6.25k channels on the other radio, i was able to simulate 2, 2.5k and 3k channel doppler errors. A beam antenna was used to Lower the indicated Signals levels until audio quality droped.
The lower the altitude the higher the Doppler (Frequency dependant too). The Doppler from ISS is approximately Plus and Minus 3.3 kHz. This means that If a LEO satellite is approaching on 2-meters, the frequency you will see on your radio will be up to 3.3 kHz higher for the first minute, then will quickly drop to zero Doppler for a few seconds at the 5 minute mark (assuming a 10 minute pass).
So, in theory, if the Doppler on a transponder based satellite is less than 3 kHz and you have signals stronger than 1 S-Unit, it should be possible for 2-way Leo satellite via digital voice. Anyone else have an IC-800 and want to test?
Miles WF1F
www.marexmg.org
Now that's room service! Choose from over 150,000 hotels in 45,000 destinations on Yahoo! Travel to find your fit. http://farechase.yahoo.com/promo-generic-14795097 _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (8)
-
Dave hartzell -
Edward Cole -
joseph Murray -
Komatsu -
Luc Leblanc -
MM -
Robert Bruninga -
Tony Langdon