Terrestrial Crossband Linear Transponders

[g4tut]

Terrestrial Amateur Radio Crossband Linear Transponders

The widesread use by Radio Amateurs of terrestrial crossband linear transponders has, until now, been held back by dynamic range issues. Software Defined Transponders (SDX) look set to resolve this and help boost activity on the Microwave bands.

At the 2007 AMSAT-UK International Space Colloquium, AMSAT-NA President Rick Hambly W2GPS outlined his intention to get an SDX linear transponder on the air in his home state. Such a transponder could simultaneously handle dozens of SSB, CW or data contacts. It is hoped that others will follow suit and help re-populate our microwave bands.

Howard Long G6LVB first presented and demonstrated the STELLA software defined transponder to the AMSAT-UK Colloquium in July 2005. The 435 to 145 MHz transponder generated much interest and similar technology will now be used for transponders for the P3E, Eagle, ESEO and Suitsat 2 satellites.

Software Defined Cross Band Linear Transponder (July 2006)
http://www.southgatearc.org/news....der.htm (http://www.southgatearc.org/news/july2006/crossband_linear_transponder.htm)

STELLA page
http://www.g6lvb.com/Articles/stella/

STELLA document
http://www.g6lvb.com/Stella.zip

Software Defined Radio Working Group report to the ARRL
http://www.arrl.org/announc....oup.doc (http://www.arrl.org/announce/reports-2006/july/13b-Software%20Defined%20Radio%20Working%20Group.doc)

SuitSat 2
http://www.suitsat.org/

AMSAT-UK
http://www.uk.amsat.org/

AMSAT-UK publish OSCAR News which is full of Amateur Satellite information.
You can join online at https://secure.amsat.org.uk/subscription/





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Updated every day - 365 days per year

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[wa6itf]

Quote[/b] (g4tut @ July 25 2007,12:43)]Terrestrial Amateur Radio Crossband Linear Transponders

The widesread use by Radio Amateurs of terrestrial crossband linear transponders has, until now, been held back by dynamic range issues. Software Defined Transponders (SDX) look set to resolve this and help boost activity on the Microwave bands.

At the 2007 AMSAT-UK International Space Colloquium, AMSAT-NA President Rick Hambly W2GPS outlined his intention to get an SDX linear transponder on the air in his home state. Such a transponder could simultaneously handle dozens of SSB, CW or data contacts. It is hoped that others will follow suit and help re-populate our microwave bands.

Howard Long G6LVB first presented and demonstrated the STELLA software defined transponder to the AMSAT-UK Colloquium in July 2005. The 435 to 145 MHz transponder generated much interest and similar technology will now be used for transponders for the P3E, Eagle, ESEO and Suitsat 2 satellites.

Software Defined Cross Band Linear Transponder (July 2006)
http://www.southgatearc.org/news....der.htm (http://www.southgatearc.org/news/july2006/crossband_linear_transponder.htm)

STELLA page
http://www.g6lvb.com/Articles/stella/

STELLA document
http://www.g6lvb.com/Stella.zip

Software Defined Radio Working Group report to the ARRL
http://www.arrl.org/announc....oup.doc (http://www.arrl.org/announce/reports-2006/july/13b-Software%20Defined%20Radio%20Working%20Group.doc)

SuitSat 2
http://www.suitsat.org/

AMSAT-UK
http://www.uk.amsat.org/

AMSAT-UK publish OSCAR News which is full of Amateur Satellite information.
You can join online at https://secure.amsat.org.uk/subscription/





Daily Amateur Radio News Service: (http://www.southgatearc.org/)
Updated every day - 365 days per year

Get our News Headlines for your Website:
http://www.southgatearc.org/rss/index.htm

Send Us Your News Items:
http://www.southgatearc.org/news/your_news.htm
This is really nothing new. Giving proper credit where credit is due, Ed Tipler W6IRE (ex-WA6KYZ) and the late Jim Reiger WA6EZL had such a system operational from Ridgecrest, CA. almost a quarter of a century ago. It worked -- worked very well -- and should have been the motivation for similar systems worldwide. But it was not.

While the system operated flawlessly and was far more technologically advanced than anything to that date, it lacked one thing. "Ego." Unlike a repeater with its whomping carrier that in itself says "Im Here - Come Use Me" -- a linear translator is -- well -- just there. No big "come and use me" sign. Nothing to say "I can make your signal bigger and make it go further." Nothing to fulfill the human ego.

I learned this first hand when I wrote about it in 73 Magazine. The mail and comments ffrom repeater owners and poltential repeater owners was very negative. Not regarding the "technology" but rather the personal gratification of being able to point to that "whomping carrier" and the "ID" and say: "Thats mine!"

So it was that while repeaters continued to grow in number, the WA6KYZ/WA6EZL 2 meter linear transponder remained a one-of-a-kind in the USA. And for this writer it was definite awakening to the basic instinct of human nature that I can vividly remember to this day.

de
WA6ITF

[K0RGR]

I think that's the call of the in-band linear translator I remember in California many years ago. It made it easy to work tremendous distances using SSB mobiles. We could access it mobile from San Jose, and could work stations over the whole northern half of the state.

Here in the upper midwest, a very few well-placed translators of this kind could make it easy to make contacts with SSB or other narrowband modes over long distances.

A translator halfway between Minneapolis and Milwaukee should be workable from both ends.

The other thing I find interesting is that they are using the digitized signals received on one band and retransmitting them on another band. You can do other things with digitized signals. You can repeat them as many times as you want with little or no distortion of the signal. You could stuff the digital output of the receiver in a big pipe (a.k.a., the Internet) and ship it somewhere else where it will be repeated. You could also dump it into some kind of link transmitter to send it to another remote location.

We don't have to do this on 2 meters, at all. We could do the bulk of it at 902 or 1296 Mhz., so that we can use some truly tiny antennas that shouldn't scare any homeowner's association.

[W5HTW]

Quote[/b] (wa6itf @ July 25 2007,14:07)]The mail and comments ffrom repeater owners and poltential repeater owners was very negative. Not regarding the "technology" but rather the personal gratification of being able to point to that "whomping carrier" and the "ID" and say: "Thats mine!"
I think that is a major reason for a lot of the repeaters in our country anyway. Where I live, in a very rural area, I can hit six repeaters of a certain system, four VHF and two UHF, that are all hard-linked together. Bringing up one, brings them all up, along with a good many others. To me this is like having 13 channels on your TV but 8 of them are the same company broadcasting the same information. And it keeps other TV stations from coming on the air on those channels.

All our VHF repeater pairs here are already assigned. We asked about getting a local coverage, ARES repeater, and there are no frequencies available on VHF.

Today hundreds of repeaters across the nation sit silent except for an occasional ID. That is indeed an ego thing. "It's MY frequency, and I'm not letting it go." We scream about that on HF but it is the norm on VHF.

And they are probably going to get lonelier. Now many of the Techs who were stuck on VHF/UHF will upgrade easily to General, and wind up on HF. Yet how many of you have heard of a coordinated VHF pair being surrendered?

Ed

[WA3KYY]

Ed,

You could try putting up an uncoordinated repeater. Chose a pair where the coordinated machines are far enough away the interference is unlikley. If the repeters are unused, you would not be interfering with anyone anyway. The problem of course is the expense needed for this gamble.

I truely think it is time to force the coordinating bodies to evaluate the repeaters in their areas and ask each repeater owner to produce statistics showing their repeater is actually used. Decoordinate those that cannot show use. Infrequently used repeaters do not need to be coordinated since interference to another repeater on the same pair would be rare. Use of PL tones would reduce that even further. IMO, coordination only makes sense for active repeaters.

73,
Mike WA3KYY

[KG4RUL]

Quote[/b] (WA3KYY @ July 26 2007,01:18)]Ed,

You could try putting up an uncoordinated repeater. Chose a pair where the coordinated machines are far enough away the interference is unlikley. If the repeters are unused, you would not be interfering with anyone anyway. The problem of course is the expense needed for this gamble.

I truely think it is time to force the coordinating bodies to evaluate the repeaters in their areas and ask each repeater owner to produce statistics showing their repeater is actually used. Decoordinate those that cannot show use. Infrequently used repeaters do not need to be coordinated since interference to another repeater on the same pair would be rare. Use of PL tones would reduce that even further. IMO, coordination only makes sense for active repeaters.

73,
Mike WA3KYY
How do you objectively define an "unused" or "underutilized" repeater? Does one usage of a linked system count as a usage for each of the linked repeaters or just the one originating the traffic? Then we have to get the various coordinating bodies to agree (fat chance of that). This is one HUGE can of worms!

[w1jeq]

Here in Missouri its not really the under used repeaters (all of them are under-used compared to 10 years ago). Its the repeaters that are not even on the air that irk some of us. A club or repeater owner that lets their repeater fall into dismaintance due to lack of funds or lack of agreement in the club on what to do. They should techincally call the repeater council and inform them that the repeater is off the air. If unable to get the system functional in 30 days then thier coordination is invalid and removed. We have probably 30 such repeaters accross the state based on that they are in the repeater directory but I can never key them when I am in the repeater coverage area or from other amateurs that know the repeaters are down. Clearing these "on paper only" repeaters would make more room for new repeaters or to clear congestion on the most popular frequencies (146.625, 145.13 ....) where there are 5 repeaters on the same freq throughout the state and during band opening all become useless even with PL tones. I hope that linear transponders will be better maintained and I hope we never have to read about transponder owners on the FCC enforcement site or have massive interference issues from transponders on the same freq bands.
To all amateurs setting up transponders, thank you for the hard work, good luck and 73.

[ka5piu]

Hello.

Having used military crossband linear translators and repeaters on the same frequencies, I can tell you what little I know.
In an area where there are several repeaters and each having its own access tone and a LCT there can be trouble.
The LCT has no way of dealing with CTCSS, it is just a bent pipe.
This CAN be a real mess if the users are not careful.
LCT's are very common in both ground and satellite applications for most military of the world.
The advantage that a LCT has is that it is transparent, one can send CDMA with whatever code and data rate, it does not matter.
The disadvantage is that a LCT has no security, I can grab a Chinese SatCom, point it at a US LCT satellite and it will work, there is no real system to exclude me.

[K0RGR]

Quote[/b] (w1jeq @ July 26 2007,07:03)]Here in Missouri its not really the under used repeaters (all of them are under-used compared to 10 years ago). Its the repeaters that are not even on the air that irk some of us. A club or repeater owner that lets their repeater fall into dismaintance due to lack of funds or lack of agreement in the club on what to do. They should techincally call the repeater council and inform them that the repeater is off the air. If unable to get the system functional in 30 days then thier coordination is invalid and removed. We have probably 30 such repeaters accross the state based on that they are in the repeater directory but I can never key them when I am in the repeater coverage area or from other amateurs that know the repeaters are down. Clearing these "on paper only" repeaters would make more room for new repeaters or to clear congestion on the most popular frequencies (146.625, 145.13 ....) where there are 5 repeaters on the same freq throughout the state and during band opening all become useless even with PL tones. I hope that linear transponders will be better maintained and I hope we never have to read about transponder owners on the FCC enforcement site or have massive interference issues from transponders on the same freq bands.
To all amateurs setting up transponders, thank you for the hard work, good luck and 73.
I'm not sure 30 days is enough time for many people to get a repeater that's been hit by lightning, for example, back on the air.

The expense can be overwhelming, even for a well-healed radio club. Replacing a repeater system can easily run $5-6,000. We just replaced the long-suffering Cushcraft antenna we were using for our 2 meter machine. The professional grade replacement was $800, but that's not the big expense. The big expense was the professional tower climber we had to hire to do the job. Oh, and I'm glad our hardline tested good!

We had all three of our club's repeaters go south in the same year. The main one was hit by lightning. The backup succumbed to 'old age' - nobody in the club had any technical info on it, and it needed repairs. The UHF repeater was built from commercial transcievers, and one of the transmitters gave up.

We had a lot of fund raisers that year! Fortunately, we collected the money to replace the big machine, and a kind local organization donated the replacement for the backup and another one kicked in $1,000.
We were able to just swap the rigs around and get UHF back on the air. But even so, the club had to put out almost 6 G's.

[N0NB]

Terrestrial linear translators sound like an interesting device. #The problem I see with the bands above 450 MHz right now is the lack of a day-to-day usefulness especially out here in the sticks.

I find it frustrating when there is a tropo opening and I can hit a dozen repeaters but can't raise a soul. #Doesn't anyone run mobile any more? #http://www.qrz.com/iB_html/non-cgi/emoticons/sad.gif #I realize that most of us are busy making a living and can't be around the radio most of the time and out here one does need to be dedicated to monitor repeaters on a regular basis.

Why doesn't anyone monitor repeaters any more? #Even the evening hours are dead. I don't know for sure, but it does seem as though the activity on repeaters has declined as talk radio has gained in popularity. #Or, are people are so inundated with technology these days that yacking on a radio isn't the diversion it once was? #Whatever the reason, I believe the repeaters should be used and used a lot. #Everyone should be familiar with it's range and weak spots. #When the Big One hits is not the time to learn that your mobile can't hit the machine from lower Podunk. (BTW, I am monitoring the local repeaters despite typing on a Web forum!)

As I think about it. #A linear translator could be a real boon in a local emergency. #Imagine not being limited to one signal at a time as with a repeater. #It would seem as though the efficiency of local emergency communications could be increased significantly.

Interesting indeed.

[ai3v]

Hi!

I think that terrestrial liner translaters are a solution in search of a problem.

Back when I was active on uhf, we had a fellow experimenting with a lt in the pittsburgh area, the major problem was it "had" to use an omnidirectional antenna, almost any station using even a modest beam and amp could easly work twice as far on troposcatter ssb.

LT's make great sense in the satellite service, particuarly for geostationary #birds where the dynamic range problems can be worked out.

As far as making a crossband LT for terrestial work, for the same $ that it takes to "get on" 2 bands 144 and 432 ssb for instance with a puny signal that "needs" the LT, I can be legal limit loud on one band and talk further.

As far as linking radios thru the phone company(ILRP), thats just talking on the phone!!!

Rege/AI3V (just a couple grids away from vucc)

[n4cqr]

WA3KYY,July 26 2007,05:18]I truely think it is time to force the coordinating bodies to evaluate the repeaters in their areas and ask each repeater owner to produce statistics showing their repeater is actually used. #Decoordinate those that cannot show use.


I agree 100%. You would not believe the number of repeater pairs that are coordinated and not on the air. Some were never put on the air to begn with.

[wa6itf]

Quote[/b] (n4cqr @ July 27 2007,09:42)]WA3KYY,July 26 2007,05:18]I truely think it is time to force the coordinating bodies to evaluate the repeaters in their areas and ask each repeater owner to produce statistics showing their repeater is actually used. Decoordinate those that cannot show use.


I agree 100%. You would not believe the number of repeater pairs that are coordinated and not on the air. Some were never put on the air to begn with.
"Paper Repeaters" will alway be a problem. They were when I put up my first repeater back East in the late '60's. They were when I served with the Southern California Repeater Association in the 70's and '80s. And they remain so to this day. And there is a reason. Let me explain.

If you look up the meaning of "coordinate" it really means "to place or class in the same order, rank, division, etc." In the world of FM and repeaters it means to "recommend where to operate."

It is really up to the individual seeking coordination services whether or not to accept the coordinators recommendation based on the coordinators technical expertise. If he/she does, then the repeater is considered as "coordinated." If he/she does not, then the repeater -- if it comes to the air is considered as "uncoordinated." Thats where the coordinators responsibility really ends.

It does not mean that a coordinator has the authority to tell a repeater that goes out of operation -- or one that has yet to come to the air -- that it can't. Only the FCC or the federal courts can do that. In reality, the only thing a "coordinator" can do in these situations is to rescind its recommendation. If the paper repeater owner ignores the coordinators request, then the coordinator can do no more.

The bottom line: Having been there and done that as a coordinator -- with the exception of those rare instances where the FCC chooses to get involved because of mutual on-channel interference between a coordinated and an uncoordinated repeater there is no other way for a coordinator to deal with the issue of repeaters that operate without the coordinators blessing -- be it in relation to coordination itself or being off the air for a prolonged amount of time or of never coming on the air at all. Until such time as the FCC deems the issue of "paper repeaters" of of significance to warrant the agency's attention, the "paper repeater" will remain.

de
WA6ITF

[N5PVL]

N0NB asks:
Quote[/b] ]
Why doesn't anyone monitor repeaters any more?

In my case, I stopped monitoring the repeater because of long-winded, often repeated automated announcements.

If they would keep the crap off of it and get it down to just repeater ID's and hams talking, I'd go back to monitoring it again.

I will also blow off any repeater that has the EchoLink nonsense on it. - All those beeps, boops and "NOT CONNECTED" announcements get priority over live hams trying to communicate. - It's hard to imagine anything more ignorant and annoying, especially if you are trying to use the repeater as intended, for a local QSO.

Basically I do not like nonproductive noise, and will not monitor a repeater that has very much of it.

But that's just me! - Some folks it does not bother at all, and some even like it.