First satellite QSO using D-STAR Digital Voice

First amateur satellite QSO using D-STAR digital voice

What is believed to be the first Amateur Satellite QSO using the new Digital Voice Mode D-STAR took place on July 1st between Michael N3UC and Robin AA4RC using the AO-27 Amateur Satellite.

This report from http://www.ao27.org/

On July 1st, 2007 during the 20:00 UTC pass over North America, AO-27 was again providing a new round of enjoyment for Amateur satellite experimenters.

Thirteen years ago, AO-27, which coined the term "Easy Sat" by employing an FM bent pipe in space, provided many hams the ability to use a satellite without the expense of multi mode radios.

This time around, AO-27 was used to provide the first D-Star via Satellite contact between Michael, N3UC, FM-18 in Haymarket VA and Robin, AA4RC, EM-73 in Atlanta GA. Signals were reported as strong and easy to copy.
Call signs were received digitally on both sides of the link. Communications were possible for most of the pass.
Both Robin and Michael were surprised at just how well thedigital link was received.

The Analogue repeater on-board AO-27 is well suited for D-Star work. The radios were designed to pass 1200-19200 baud GMSK data. The Analogue mode was not a primary mode of operation in the design. Using a free switch setting in the switching board, the design team hooked up the output of the receiver to the input the transmitter to create the Analogue mode. There is not the normal low frequency filtering that is found in normal FM Repeaters. This means the Analogue mode passes the low frequencies required by D-Star.

The equipment for the contact were IC-2200s on the Uplink at both N3UC and AA4RC, an IC-2820 on the downlink at N3UC, and an IC-91AD on the downlink at AA4RC. Doppler shift did prove to be a minor problem while using these radios.

The D-Star signal would decode out to about 1.5 KHz in frequency error. The IC-2820 would only tune on 5 KHz spacing (the 6.25 KHz channels did not fall in the right locations to help.) so at times we could not decode the digital signals.

For others that want to try D-Star via Satellite we have a few things to keep in mind.

1) Remember that the FM users can't hear you on the bird.
They hear a strong "noise" but can't decode you. So please keep the D-Star transmitting short.
If you can monitor the FM side, you can time your transmitting as to not step on them.
Please try to schedule with other D-Star users instead of calling CQ for the entire pass.

2) Watch the doppler, at times you may not be able to decode a signal even if the other station can decode you.
Keep your uplink on 145.850 for the entire pass. Program your radio call signs the same as for simplex, AO-27
does not have a D-Star call sign. You don't need to set up your radio for repeater use.

3) Before using other satellites besides AO-27, please check with the control operators of those satellites. Every
FM satellite may not pass the D-Star signal nor may the control operators wish to have D-Star traffic on the bird.

4) If you hear us on the Bird, please give us a call. We would love to have as many D-Star users on AO-27 as possible.

The AO-27 Control Operators fully support and encourage the use of D-Star via Satellite on AO-27.

A shout goes out to ICOM for creating Radios for this Fun new Amateur mode of operation. Without their radios we could not have made this contact.

Michael N3UC
AO-27 Control Operator

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AMSAT-UK will be holding their 22nd International Space Colloquium at the University of Surrey, Guildford, England from Friday 20th to Sunday 22nd July.
see http://www.uk.amsat.org/Colloquium/

AMSAT-UK publish a quarterly newsletter OSCAR News.
For membership information contact the secretary Jim Heck G3WGM
Tel: +44 (0)1258 453959
Email: g3wgm@amsat.org
Join online at https://secure.amsat.org.uk/subscription/

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Oh joyous rapture!

 

Expensive radios that dont work all the time on the Satellite? No thanks I'll stick with my IC-910h. It may be expensive but it doesnt drop out.

 

Congratulations guys!

 

Even with the Doppler induced drop-outs, it is a rather noble first time achievement. If anything, it shows that the terrestrial radio gear will need to be improved to that it can tune in smaller increments such as 100 Hz steps or such.

If satellite operation of D-Star become popular, then I suspect that Icom -- or some other manufacturer -- will bring out gear specific for this type of utilization. Another though far more costly solution would be to launch into geosynchronous orbit three "TDRS-like" satellites that could be linked together to permit terrestrial hams to "talk" or exchange "data" in real time from any spot on the globe to any other spot on the globe.

Right now the two biggest complaints I as a writer hear are that ham radio satellites require stations be equipped to track them and that they are not available 24 hours a day / 7 days a week. Once satellite operation comes of age to where a given terrestrial station need only have an antenna fixed to one location in the sky, I suspect that you will see many more -- if not most of the worlds radio amateurs give it a try.

Technology is ever moving forward, A good example is FM which did not come of age until the first repeaters came on the air back in the late 1960's. A decade later, almost every ham owned some sort of FM transceiver -- at least for 2 meters -- and there were some 3500 repeaters in operation in the USA. By 1990 there were about 9500 FM repeaters world-wide and growth did not level off until about 2002.

Whether or not D-Star will be a catylist that pushes the worlds various AMSAT groups to think in terms of providing the global ham radio community with a system of digital ready, interlinked geosynchronous ham radio utility communications "Easy Sats" I cannot say. Its just far to early to know. But in the big picture, this D-Star experiment -- and in reality is is just an "experiment" -- does open the "ham radio digital door" a bit wider. And is not "experimentation" that leads to "utility" really an important part of what ham radio is really all about?


de
WA6ITF

 

Absolutely! In spite of what a lot of posters on here say.

 

So true.

A little experimenting or Research, Development, Testing, and Evaluation (RDT&E) is always a good thing -- if only to find out what doesn't work.

73.

 

I think it's great that digital has come to ham radio but I do have a question.
Why aren't we using APCO Project 25 digital?  It's becoming the national standard for public safety comms.

It could get to a point that those of us who have public safety frequencies plugged into our FM  2 meter/440 radios will be out of luck. If we were using Project 25 as a digital standard that wouldn't be a problem--especially during an "emergency" when that 2 meter/440 radio is needed to communicate directly with first responders.

 

Because the royalties on it are totally rediculous. D-Star uses the AMBE vocoder, a second generation vocoder after IMBE (P-25) but they charge a very small fee for that one.

There are quite a few hams using P-25 and a number of repeaters out there. I don't know if anyone has used them through satellites? Perhaps someone will speak up.

 

Who cares.  Public Safety isn't ham radio.

If you want to be a fireman or an ambulance driver, then join the force.

Hams should stay off Public Service frequencies.  If you want to communicate directly with first responders, have them give you a radio.  It's probably encrypted anyway.

 

Several reasons. First is that APCO-25 is not a free format. To manufacture equipment for it means that the maker has to pay a royaltee fee which in turn gets passed onto the customer.

As such the next reason -- that fee along with full type acceptance as required by the FCC places APCO-25 compliant radios out of the reach of most hams. And ham manufacturers know that radio amateurs will not shell out $1000 for an HT or $2500 for a mobile radio. On the other hand, D-STAR -- which was developed by the Japan amateur Radio League i in the public domain and is royaltee free. Anyone can make and sell D-STAR compliant radios albeit only Icom has to date.

All Icom has to do is recoup its research and development costs whereas those making and selling APCO-25 radios have the ongoing expense of royaltee fees for each radio delivered. So from a business position, APCO-25 make very bad ham radio business sense.

de
WA6ITF

 

Wow, all that expensive equipment - all that time - for two people to communicate with each other. They must have money to burn. Wonder if either of them considered a less expensive investment of email (you don't even need your own computer can use one at a local public library - for free - using a yahoo or hotmail account - also free - to kepp in touch), pick up a phone and dial each other up (a decent Verizon plan is less expensive than the cost of amateur radio gear as I well know as I have such a plan), or the cost of a .41 cent stamp would do the job just as well.

Hey guys, since ya got cash to toss away how about sending some my way?

Chuck, AA1MN

 

D-Star would be a great tool for experimentation, but the initial cost is prohibitive for many, myself included.

While the kudos to those that have and use it are at hand, many can not justify the much higher cost of the equipment and therefore, have to forego the experimantal stages amost out of hand.

P25 is crap as well...expensive royalties to D.V.I to produce a CODEC, and regardless of what many may think, P25 is NOT interoperable throughout the nation as many locales can not afford such costly infrastructure, and have no real need as well.

P25 was billed as the end-all for everything, and in the 'end', most are finding out it's incapable of real world usage, given geographical constraints, simulcasting requirements and multiple repeater sites....it doesn't make financial/fiscal sense, same goes for D-Star.

The ID-1200 appeared to be a neat radio, UNTIL you saw the price!!

Not to mention how many 1.2Ghz systems are there in this country that are operational AND being used as well?

I'll bet there's less than FIVE.

Even the IC U-82 and V-82 were cheap in initial cost of purchase....UNTIL you decided to add the D-Star board, then the cost of that radio jumped from under $100.00 to over $300.00, with 80% of that cost being for the digital board!

Sorry, but D-Star is NOT worth that much to me for playing with, not when I can pick up an Astro Saber with IMBE vocoder for about the same cost, plus I have a radio that can be used for business PLUS amateur radio too.

If you have the $$ to toss around for D-Star and have a digital repeater in operation also, then why stop there.
Go commercial and pay big $$ for a Datron, or an XTS 3000/5000 or even the 2500 with FPP.

No wonder the big names build and sell $20,000.00 H.F rigs....there must be a lot of hams with money burning holes in their wallets, or they have a HUGE spending limit on their credit cards!

D-Star is no different...playing up to those willing to spend any amount on new toys, too bad they'll have nobody to talk to once they power it up.

Don't get me wrong, I LOVE the technology, it's just too far in its infancy to be of real value yet, maybe over the course of the next five years the cost to own them will drop to a level most will no longer find objectionable, but for now, it's pretty much a rich man's game, and that in itself is sad.

 

For some of us, there is another reason I'd prefer not to see APCO 25 in my radios.

Here in the People's Republic of Minnesota, we have the country's most anal-retentive anti-scanner law. While the law does exempt amateur radio transceivers, hams are required to show any officer who inquires their license. This means that if my wife or daughter drive my car, they may face a jail term.

Fortunately, our local police and sheriff's offices have moved over to APCO-25 trunked digital, and within a few years, the whole state should be that way. At that point, I will no longer have a radio 'capable of receving public safety transmissions', so I shouldn't have to worry about my ham rigs or any analog scanner. If the radio is DSTAR, it still won't matter.

Congrats on this 'first'!

 

Holy RF Batman!!!!!!!!!!!!!