I am pleased that AMSAT-NA is going to move forward with a LEO CubeSat, single channel, analog FM transponder. If successful, it will be immensely popular worldwide. My hope is that it will help usher in a new, improved series of satellites with more advanced payloads. There is great potential in the ranks of AMSAT-NA and groups worldwide to achieve lofty goals. Look at what AMSAT-UK and others have already done in the CubeSat platform. The digital mode capabilities discussed here on the AMSAT-BB are just the tip of the iceberg to where technology can take us.
It's very easy to be a pessimist or a cynic. Very little risk is involved. It doesn't take any cojones to sit in a comfy chair and email snarky comments. If you are optimistic about a project and it fails, your peers may see your actions as a fool. Even worse, people may withdraw their financial support for future missions. Even after great success, the optimist may receive very little praise, especially in this field of voluntary amateur radio service.
AMSAT-NA is boldly entering the CubeSat world with the planned satellite series FOX-1. If you haven't noticed, there have been full-page advertisements soliciting volunteers in the AMSAT Journal. There is plenty of opportunity to serve and influence the direction of AMSAT-NA.
If we all threaten to leave and stop paying our dues when things don't go our way, what will we ever accomplish?
Please take a simple step to support amateur radio in space. Donate to the FOX-1C launch effort. http://www.amsat.org/?p=2957
73 Clayton W5PFG
On 07/21/2014 05:36 PM, Clayton Coleman wrote:
It's very easy to be a pessimist or a cynic. Very little risk is involved. It doesn't take any cojones to sit in a comfy chair and email snarky comments. If you are optimistic about a project and it fails, your peers may see your actions as a fool.
I absolutely agree, but I must ask you about something you said earlier:
I am pleased that AMSAT-NA is going to move forward with a LEO CubeSat, single channel, analog FM transponder. If successful, it will be immensely popular worldwide. My hope is that it will help usher in a new, improved series of satellites with more advanced payloads.
I'm confused. My understanding of the idiomatic expression "usher in" is that something new and presumably revolutionary is being introduced, e.g., to "usher in a new era".
What, exactly, will a new LEO, single channel, analog FM transponder satellite "usher in" that none of the previous LEO, single channel, analog FM satellites managed to usher in?
Will the tiny cubesat form factor (to which we've been relegated by the intense competition for launches from the small satellite revolution we pioneered) make the difference this time? If not, what will?
The most common argument I've seen for launching more analog FM LEO satellites is that they are needed to replace existing analog FM LEO satellites that are now failing. Is that "ushering in" something new?
--Phil
By usher in he was clearly referring to gaining technical abilities as a group to attack more complex satellites.
On Monday, July 21, 2014, Phil Karn [email protected] wrote:
On 07/21/2014 05:36 PM, Clayton Coleman wrote:
It's very easy to be a pessimist or a cynic. Very little risk is involved. It doesn't take any cojones to sit in a comfy chair and email snarky comments. If you are optimistic about a project and it fails, your peers may see your actions as a fool.
I absolutely agree, but I must ask you about something you said earlier:
I am pleased that AMSAT-NA is going to move forward with a LEO CubeSat, single channel, analog FM transponder. If successful, it will be immensely popular worldwide. My hope is that it will help usher in a new, improved series of satellites with more advanced payloads.
I'm confused. My understanding of the idiomatic expression "usher in" is that something new and presumably revolutionary is being introduced, e.g., to "usher in a new era".
What, exactly, will a new LEO, single channel, analog FM transponder satellite "usher in" that none of the previous LEO, single channel, analog FM satellites managed to usher in?
Will the tiny cubesat form factor (to which we've been relegated by the intense competition for launches from the small satellite revolution we pioneered) make the difference this time? If not, what will?
The most common argument I've seen for launching more analog FM LEO satellites is that they are needed to replace existing analog FM LEO satellites that are now failing. Is that "ushering in" something new?
--Phil _______________________________________________ Sent via [email protected] javascript:;. 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
In addition most cubsats just buy prebut of commercial modules (clydespace...) so those teams have to do little actual engineering. Those teams however are limited I. Their scope for the future whereas AMSAT-NA is developing the basic building blocks of heir own platform to build on. I. Addition to IP being generated (designs, test hardware and software, firmware, etc) volunteers old and especially the new generation of volunteers that have joined in the last several year are getting experience from the ground up. This is the first Cubesat for AMSAT NA and yes it is a tough form factor to build in with missions longer than a few months, actually I'd say AMSAT isone of the few if only developing a cubsat platform for 5+ mission years. It's a tough problem and may look "solved" already but it is not. ITAR also hinders this greatly.
To those of you even mildly interested in volunteering please do! We are ally are ushering in a new wave of amateur radio satellites that will start with FM birds but will certainly progress through more advanced functions such as digital data. You don't have to work in Aerospace to volunteer but when building a Cubesat that has to work you've got to cross your t's and dot your i's. One step at a time, we will get there and it will be a growing pace, fox-1 is the start, fox-1b and 1c are low hanging fruit to get launches and improve upon our platform. Fox-2 and over starts getting much more power, software defined radio transponders, etc... It's going to be fun!
Brent, KB1LQD
On Tuesday, July 22, 2014, Bryce Salmi [email protected] wrote:
By usher in he was clearly referring to gaining technical abilities as a group to attack more complex satellites.
On Monday, July 21, 2014, Phil Karn <[email protected] javascript:;> wrote:
On 07/21/2014 05:36 PM, Clayton Coleman wrote:
It's very easy to be a pessimist or a cynic. Very little risk is involved. It doesn't take any cojones to sit in a comfy chair and email snarky comments. If you are optimistic about a project and it fails, your peers may see your actions as a fool.
I absolutely agree, but I must ask you about something you said earlier:
I am pleased that AMSAT-NA is going to move forward with a LEO CubeSat, single channel, analog FM transponder. If successful, it will be immensely popular worldwide. My hope is that it will help usher in a new, improved series of satellites with more advanced payloads.
I'm confused. My understanding of the idiomatic expression "usher in" is that something new and presumably revolutionary is being introduced, e.g., to "usher in a new era".
What, exactly, will a new LEO, single channel, analog FM transponder satellite "usher in" that none of the previous LEO, single channel, analog FM satellites managed to usher in?
Will the tiny cubesat form factor (to which we've been relegated by the intense competition for launches from the small satellite revolution we pioneered) make the difference this time? If not, what will?
The most common argument I've seen for launching more analog FM LEO satellites is that they are needed to replace existing analog FM LEO satellites that are now failing. Is that "ushering in" something new?
--Phil _______________________________________________ Sent via [email protected] javascript:; javascript:;. 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] javascript:;. 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
On 07/22/2014 12:26 AM, Bryce Salmi wrote:
By usher in he was clearly referring to gaining technical abilities as a group to attack more complex satellites.
That's not how I read it. In any event, AMSAT has already built far more complex satellites; remember AO-40? (Maybe that one was *too* complex.)
Quite a few of the older and more experienced technical volunteers have simply drifted away from the organization due to a lack of interesting current projects.
Ao40 was not too complex. I work in the space industry, I've already have my electronics fly to orbit (not AMSAT), it's awesome and scary all In one. Watching it launch not too long ago was gut wrenching, the entire system is complex but I trusted in my testing, I trusted my coworkers testing, and I trusted that we all worked to do the best we could, if it didn't work and we knew it wasn't from nativity... I'm fine with that, it's a learning experience. Anyone willing to operate in space must be willing to accept defeat.
we like to refer to space vehicles/missions as binary. It works or it doesn't, space is unforgiving and by forging into it you must accept failure as an outcome but do everything to avoid it. There's no shame in that. It can and will still happen. Only those willing to risk it achieve what was once thought impossible.
Having a clear path to get flight heritage on a common design is an obvious way of mitigating future risk.
Bryce Kb1lqc
On Saturday, July 26, 2014, Phil Karn [email protected] wrote:
On 07/22/2014 12:26 AM, Bryce Salmi wrote:
By usher in he was clearly referring to gaining technical abilities as a group to attack more complex satellites.
That's not how I read it. In any event, AMSAT has already built far more complex satellites; remember AO-40? (Maybe that one was *too* complex.)
Quite a few of the older and more experienced technical volunteers have simply drifted away from the organization due to a lack of interesting current projects.
Sent via [email protected] javascript:;. 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
Nativity = autocorrect of "being naive" :) sorry about that
On Saturday, July 26, 2014, Bryce Salmi [email protected] wrote:
Ao40 was not too complex. I work in the space industry, I've already have my electronics fly to orbit (not AMSAT), it's awesome and scary all In one. Watching it launch not too long ago was gut wrenching, the entire system is complex but I trusted in my testing, I trusted my coworkers testing, and I trusted that we all worked to do the best we could, if it didn't work and we knew it wasn't from nativity... I'm fine with that, it's a learning experience. Anyone willing to operate in space must be willing to accept defeat.
we like to refer to space vehicles/missions as binary. It works or it doesn't, space is unforgiving and by forging into it you must accept failure as an outcome but do everything to avoid it. There's no shame in that. It can and will still happen. Only those willing to risk it achieve what was once thought impossible.
Having a clear path to get flight heritage on a common design is an obvious way of mitigating future risk.
Bryce Kb1lqc
On Saturday, July 26, 2014, Phil Karn <[email protected] javascript:_e(%7B%7D,'cvml','[email protected]');> wrote:
On 07/22/2014 12:26 AM, Bryce Salmi wrote:
By usher in he was clearly referring to gaining technical abilities as a group to attack more complex satellites.
That's not how I read it. In any event, AMSAT has already built far more complex satellites; remember AO-40? (Maybe that one was *too* complex.)
Quite a few of the older and more experienced technical volunteers have simply drifted away from the organization due to a lack of interesting current projects.
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
I would also vote AO40 was not to complex, it was failed by an accident. Not wishing to bring up bad memories, but two questions: Did anything other than the plug incident happen? (In other words, did any systems fail before the explosion?) Was there a backup bird built of the same design that just might be flyable if we could find a ride?
----- Original Message ----- From: "Floyd Rodgers" [email protected] To: [email protected]; "Phil Karn" [email protected] Cc: [email protected] Sent: Sunday, July 27, 2014 8:17 PM Subject: Re: [amsat-bb] I want this. I want that. Here comes another FM LEO sat.
I would also vote AO40 was not to complex,
I agree ! Not to complex to be operated.
it was failed by an accident.
Someone forgot to remove a red cap from a valv fuel and helium system.
Not wishing to bring up bad memories, but two questions: Did anything other than the plug incident happen? (In other words, did any systems fail before the explosion?)
NO !
Was there a backup bird built of the same design that just might be flyable if we could find a ride?
We got for years OSCAR-10 and OSCAR-13 in the Molnyia orbit very similar to that of AO40 but with lover apogee and different orbit inclination,
73" de i8CVS Domenico
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Op 27-07-14 om 20:17 schreef Floyd Rodgers:
Was there a backup bird built of the same design that just might be flyable if we could find a ride?
Not a backup for phase 3d but a satelite with simular spaceframe and capabiletie to get in the same orbit, phase 3e is capable of being flight test ready in a short time as it was intended to be launched around 2007 if I'm not mistaken.
it has a simpler IF system but the signals should be just as strong as ao-40 was.
73 de Andre PE1RDW
Hi Phil,
The new era I speak of is AMSAT-NA's foray into CubeSats. Certainly FM birds are nothing new. I'd like to see more efficient modes and methods in the future. Perhaps leverage a smartphone interface for the roving digital operator?
I am a firm believer in the direction of replenishing the FM satellite fleet. They are a great entry point into amateur satellite operations and experimentation for many. They aren't the only path but is something most hams can do since dualband HT's have become ubiquitous. I've also been using, with success, the FUNcube Dongle Pro+ to interest people in telemetry and digital.
73 Clayton W5PFG On Jul 22, 2014 12:40 AM, "Phil Karn" [email protected] wrote:
On 07/21/2014 05:36 PM, Clayton Coleman wrote:
It's very easy to be a pessimist or a cynic. Very little risk is involved. It doesn't take any cojones to sit in a comfy chair and email snarky comments. If you are optimistic about a project and it fails, your peers may see your actions as a fool.
I absolutely agree, but I must ask you about something you said earlier:
I am pleased that AMSAT-NA is going to move forward with a LEO CubeSat, single channel, analog FM transponder. If successful, it will be immensely popular worldwide. My hope is that it will help usher in a new, improved series of satellites with more advanced payloads.
I'm confused. My understanding of the idiomatic expression "usher in" is that something new and presumably revolutionary is being introduced, e.g., to "usher in a new era".
What, exactly, will a new LEO, single channel, analog FM transponder satellite "usher in" that none of the previous LEO, single channel, analog FM satellites managed to usher in?
Will the tiny cubesat form factor (to which we've been relegated by the intense competition for launches from the small satellite revolution we pioneered) make the difference this time? If not, what will?
The most common argument I've seen for launching more analog FM LEO satellites is that they are needed to replace existing analog FM LEO satellites that are now failing. Is that "ushering in" something new?
--Phil _______________________________________________ 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
I dont keep up with these things at all but what happen to the others? failed, dropped out of orbit, what?
One day someone is going to be saying "sorry, ghost rider the pattern is full"
JAB
Off the top of my head:
AO-51 - Battery failure (Problem fixed in Fox series - shorted batteries will be cut loose from the circuit and the satellite will operate when in the sun) AO-27 - Likely radiation damaged memory (Problem fixed in Fox series - IHU failure will cause it to become a dumb FM repeater) HO-68 - Failed relay (Problem fixed in Fox series I think - no relays)
73,
Paul, N8HM
On Tue, Jul 22, 2014 at 10:09 AM, John Becker [email protected] wrote:
I dont keep up with these things at all but what happen to the others? failed, dropped out of orbit, what?
One day someone is going to be saying "sorry, ghost rider the pattern is full"
JAB
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On 7/22/2014 9:21 AM, Paul Stoetzer wrote:
Off the top of my head:
AO-51 - Battery failure (Problem fixed in Fox series - shorted batteries will be cut loose from the circuit and the satellite will operate when in the sun)
This is an original conops for Fox-1 that did not make it to reality. In fact this requirement was removed over a year ago because it could not be suitably implemented to fit in the space available on the PCB. You see, at that time new inhibit requirements that were received from the launch providers caused us to have to re-engineer the battery board. Moving the battery fail feature to another board was not possible because we could not afford to be redesigning the whole satellite, moving things around from each board to another to find room, in the time left to delivery (at that point the launch had not yet slipped to 2015 and we were due to deliver in March 2014). The choice had to be made to cut the battery fail protection from the battery board in order to incorporate the inhibits, to make the launch. The removal of this feature was brought forth at the Symposium last year, but the tale lives on. Yes, it was an outstanding feature but as has been pointed out in some of the other emails going on right now, there is a real limit to what we can fit in a 1U CubeSat and in the time and under the provisions allowed by our rideshare. Don't think it didn't get cut without a fight! :-)
The Fox-1A Engineering Unit is sitting on the official AMSAT test table in my shack right now, having arrived FedEx this morning after some time "in the shop" for fixes to hardware that we found in the first round of EU testing and having a new IHU all installed. I'm getting ready to load new software with the latest DSP and flight features. Stay tuned...
Jerry Buxton, NØJY
Jerry,
Thanks for the clarification. It is unfortunate that it got removed, but understandable. Hopefully the batteries will last the entire 11 year lifetime of the orbit and, if not, that newer and better satellites will continually be launched!
Is the feature that allows the FM transponder to function in the event of IHU failure still on board?
73,
Paul, N8HM
On Tue, Jul 22, 2014 at 1:19 PM, Jerry Buxton [email protected] wrote:
On 7/22/2014 9:21 AM, Paul Stoetzer wrote:
Off the top of my head:
AO-51 - Battery failure (Problem fixed in Fox series - shorted batteries will be cut loose from the circuit and the satellite will operate when in the sun)
This is an original conops for Fox-1 that did not make it to reality. In fact this requirement was removed over a year ago because it could not be suitably implemented to fit in the space available on the PCB. You see, at that time new inhibit requirements that were received from the launch providers caused us to have to re-engineer the battery board. Moving the battery fail feature to another board was not possible because we could not afford to be redesigning the whole satellite, moving things around from each board to another to find room, in the time left to delivery (at that point the launch had not yet slipped to 2015 and we were due to deliver in March 2014). The choice had to be made to cut the battery fail protection from the battery board in order to incorporate the inhibits, to make the launch. The removal of this feature was brought forth at the Symposium last year, but the tale lives on. Yes, it was an outstanding feature but as has been pointed out in some of the other emails going on right now, there is a real limit to what we can fit in a 1U CubeSat and in the time and under the provisions allowed by our rideshare. Don't think it didn't get cut without a fight! :-)
The Fox-1A Engineering Unit is sitting on the official AMSAT test table in my shack right now, having arrived FedEx this morning after some time "in the shop" for fixes to hardware that we found in the first round of EU testing and having a new IHU all installed. I'm getting ready to load new software with the latest DSP and flight features. Stay tuned...
Jerry Buxton, NØJY
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Being involved in the power system, I personally am hoping to get this included in the near future on some of the next Fox's. We will see!
On Tue, Jul 22, 2014 at 10:19 AM, Jerry Buxton [email protected] wrote:
On 7/22/2014 9:21 AM, Paul Stoetzer wrote:
Off the top of my head:
AO-51 - Battery failure (Problem fixed in Fox series - shorted batteries will be cut loose from the circuit and the satellite will operate when in the sun)
This is an original conops for Fox-1 that did not make it to reality. In fact this requirement was removed over a year ago because it could not be suitably implemented to fit in the space available on the PCB. You see, at that time new inhibit requirements that were received from the launch providers caused us to have to re-engineer the battery board. Moving the battery fail feature to another board was not possible because we could not afford to be redesigning the whole satellite, moving things around from each board to another to find room, in the time left to delivery (at that point the launch had not yet slipped to 2015 and we were due to deliver in March 2014). The choice had to be made to cut the battery fail protection from the battery board in order to incorporate the inhibits, to make the launch. The removal of this feature was brought forth at the Symposium last year, but the tale lives on. Yes, it was an outstanding feature but as has been pointed out in some of the other emails going on right now, there is a real limit to what we can fit in a 1U CubeSat and in the time and under the provisions allowed by our rideshare. Don't think it didn't get cut without a fight! :-)
The Fox-1A Engineering Unit is sitting on the official AMSAT test table in my shack right now, having arrived FedEx this morning after some time "in the shop" for fixes to hardware that we found in the first round of EU testing and having a new IHU all installed. I'm getting ready to load new software with the latest DSP and flight features. Stay tuned...
Jerry Buxton, NØJY
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On 07/22/2014 06:49 AM, Clayton Coleman wrote:
Hi Phil,
The new era I speak of is AMSAT-NA's foray into CubeSats.
Well, I guess I could read that as "when all you have is lemons, make lemonade". AMSAT used to make spacecraft that, while small by commercial/military/scientific standards, dwarfed a cubesat. So I don't see cubesats as an advance.
Although miniaturization of electronics and improvements in solar cell efficiency do help us cram everything into the tiny form factor, the fact remains that we are now forced to pay far more to launch far less than we used to.
I guess that's a "new era" in the same way that the Arab Oil Embargoes of 1973 and 1979 launched a glorious new era in automobile transportation...
Sure, this is a fact of life that we can't do anything about, despite the supreme irony of AMSAT pioneering small satellites so well that we created a whole new industry with which we must now fiercely compete for launches. Economics says that when demand outstrips supply, prices go up. So they have. A lot.
Like it or not, we have to adapt to changing realities. We used to get launches for free or at nominal rates, so our main investment in each satellite was just the volunteer engineers' time and the cost of those components we could not beg, borrow or steal.
But now that the launch cost dominates the budget of everything we fly, it's time to take a very serious look at what we get from each one. Said another way, it's time to look at how much MORE we could get from our very substantial investment in each launch. Every launch of a FM cubesat depletes a very large chunk of AMSAT funds that cannot be spent on launching something else.
In other words, I'm encouraging people to look at the *opportunity cost* of every additional analog FM satellite we launch. People don't yet realize just how huge it is because they only know 1960s analog technology. They simply don't realize how much more could be done with 21st century technology. That's what I'm trying to change, so far without much success.
--Phil
Phil, You're missing the point. Do I personally think Fox-1 is pushing the bleeding edge of technology? No. Buts it's a great step to building a good foundation. I think your frustration with the lack of digital birds is overcoming an understanding of where AMSAT currently is and where it's going. No one disagrees with you on wanting more advanced and possibly digital modes. I for one am yearning for digital birds.
I got my ticket in high school in 2004. I didn't really use satellites until a few years later so I missed out on ao40 and others. My understanding now of amsats history may be skewed but it's the best I can summarize.
After ao40 it appears to me many of the original players were getting too old to keep volunteering and possibly got let down by the events of ao40. Understandably, some chose to stop. From what I can tell reading through email archives, eagle caused some problems and some left then too. Past is past, I'll highlight it. Throw ITAR into the mix and now we are here at Fox, AMSATS first series of satellites in decades.
AO51 seemed to be a collaboration of AMSAT and space quest, and suitsat and arissat were fun and neat projects. fox is amsats chance to get a base of solid engineering to build upon. The main payload is analog. There are experimental PCB slots. fox-2 will have even more space. I think digital modes will find their way on there eventually when AMSAT is ready.
Very launch of a fox-1 satellite is building flight heritage on the designs. I work in the spacecraft and launch industry, every rocket that flies and spacecraft that safely returns to earth is heritage on our designs. It's worth it's weight in gold so to speak.
AMSAT has enough volunteers with the right skills to build fox 1 satellites. I personally think all of us, including me, have some to learn before we attempt crazy ideas. Heck, fox-1 is brilliant in that it allows AMSAT to fulfill a baseline analog fm and transponder need in the cubesat form factor while allowing extra space for experiments whether they are gyros or digital modes. These experiments can succeed or fail and not harm the base satellite of done right. The only crappy part about a 1U cubesat is it's super tiny power budget. fox-2 will be the first really power capable satellite and I'm excited as hell for it.
I wrote this on my iPhone while riding into work. Sorry for any misspelling :)
Bryce
On Tuesday, July 22, 2014, Phil Karn [email protected] wrote:
On 07/22/2014 06:49 AM, Clayton Coleman wrote:
Hi Phil,
The new era I speak of is AMSAT-NA's foray into CubeSats.
Well, I guess I could read that as "when all you have is lemons, make lemonade". AMSAT used to make spacecraft that, while small by commercial/military/scientific standards, dwarfed a cubesat. So I don't see cubesats as an advance.
Although miniaturization of electronics and improvements in solar cell efficiency do help us cram everything into the tiny form factor, the fact remains that we are now forced to pay far more to launch far less than we used to.
I guess that's a "new era" in the same way that the Arab Oil Embargoes of 1973 and 1979 launched a glorious new era in automobile transportation...
Sure, this is a fact of life that we can't do anything about, despite the supreme irony of AMSAT pioneering small satellites so well that we created a whole new industry with which we must now fiercely compete for launches. Economics says that when demand outstrips supply, prices go up. So they have. A lot.
Like it or not, we have to adapt to changing realities. We used to get launches for free or at nominal rates, so our main investment in each satellite was just the volunteer engineers' time and the cost of those components we could not beg, borrow or steal.
But now that the launch cost dominates the budget of everything we fly, it's time to take a very serious look at what we get from each one. Said another way, it's time to look at how much MORE we could get from our very substantial investment in each launch. Every launch of a FM cubesat depletes a very large chunk of AMSAT funds that cannot be spent on launching something else.
In other words, I'm encouraging people to look at the *opportunity cost* of every additional analog FM satellite we launch. People don't yet realize just how huge it is because they only know 1960s analog technology. They simply don't realize how much more could be done with 21st century technology. That's what I'm trying to change, so far without much success.
--Phil _______________________________________________ Sent via [email protected] javascript:;. 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
They simply don't realize how much more could be done with 21st century technology. That's what I'm trying to change, so far without much success.
Phil, the technology you describe could equally well be used in cross-band terrestrial transponders. Has anyone yet developed it for terrestrial use ?
73 Trevor M5AKA
On Tuesday, 22 July 2014, 17:16, Phil Karn [email protected] wrote:
On 07/22/2014 06:49 AM, Clayton Coleman wrote:
Hi Phil,
The new era I speak of is AMSAT-NA's foray into CubeSats.
Well, I guess I could read that as "when all you have is lemons, make lemonade". AMSAT used to make spacecraft that, while small by commercial/military/scientific standards, dwarfed a cubesat. So I don't see cubesats as an advance.
Although miniaturization of electronics and improvements in solar cell efficiency do help us cram everything into the tiny form factor, the fact remains that we are now forced to pay far more to launch far less than we used to.
I guess that's a "new era" in the same way that the Arab Oil Embargoes of 1973 and 1979 launched a glorious new era in automobile transportation...
Sure, this is a fact of life that we can't do anything about, despite the supreme irony of AMSAT pioneering small satellites so well that we created a whole new industry with which we must now fiercely compete for launches. Economics says that when demand outstrips supply, prices go up. So they have. A lot.
Like it or not, we have to adapt to changing realities. We used to get launches for free or at nominal rates, so our main investment in each satellite was just the volunteer engineers' time and the cost of those components we could not beg, borrow or steal.
But now that the launch cost dominates the budget of everything we fly, it's time to take a very serious look at what we get from each one. Said another way, it's time to look at how much MORE we could get from our very substantial investment in each launch. Every launch of a FM cubesat depletes a very large chunk of AMSAT funds that cannot be spent on launching something else.
In other words, I'm encouraging people to look at the *opportunity cost* of every additional analog FM satellite we launch. People don't yet realize just how huge it is because they only know 1960s analog technology. They simply don't realize how much more could be done with 21st century technology. That's what I'm trying to change, so far without much success.
--Phil _______________________________________________ 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
On 07/22/2014 04:06 PM, M5AKA wrote:
Phil, the technology you describe could equally well be used in cross-band terrestrial transponders. Has anyone yet developed it for terrestrial use ?
Sure, there are several digital schemes now appearing for ham VHF/UHF voice use, such as D*Star (championed by Kenwood) and C4FM (championed by Yaesu).
But they have their drawbacks, including use of proprietary voice codecs, a lack of multi-vendor support, and a general apathy among hams towards anything invented or deployed after 1955 or so, when SSB started to take off in the military and hams followed.
I reserve judgment on C4FM because I haven't looked at it yet, but I was underwhelmed when I looked at D*Star some years ago. The design was quite old and not very efficient or ambitious, and in demonstrations it didn't seem to perform a whole lot better than FM. And that's pretty faint praise for a digital mode.
Also, terrestrial and satellite communications are very different problems with very different technical solutions at the physical layer. In satellite communications power efficiency is almost always paramount, so you try to use simple binary modulation schemes like BPSK with coherent detection and strong forward error correction. High symbol rates are okay because you usually have a line-of-sight path and multipath is seldom a problem.
In terrestrial communications, including ham repeaters and mobile phones, power is usually not much of an issue, at least on the forward (base station to mobile) link. But unlike satellites, interference, fading and multipath are the real problems because you almost never have a clean line-of-sight path.
So terrestrial and satellite communications tend to use very different and more complex modulation and error correction methods. Everybody seems to be converging on OFDM (Orthogonal Frequency Division Multiplex) because of its inherent resistance to multipath; it's used in everything from WiFi to DSL to terrestrial TV broadcasting (except in North America, which uses something else) to 4G mobile (LTE). OFDM divides a channel into a lot of low speed channels that are inherently less vulnerable to multipath. Each channel then uses a traditional digital modulation like BPSK or QPSK. Higher order schemes like QAM are common because, aside from multipath, you usually have a high SNR and can afford to cram more bits/sec into each hertz of valuable bandwidth.
Cable TV systems are different from both satellite and terrestrial radio as they have high SNRs and no multipath. Straight (non OFDM) QAM with very large signal constellations are standard. 256QAM, where each symbol carries 8 bits at once, is very common. That's something I would never run on a satellite unless I was extremely constrained on bandwidth and had DC power to burn.
Above the physical level there ought to be commonality between terrestrial and satellite systems to permit interoperability between them, but here we run into political problems. D*STAR uses a proprietary patented digital voice codec common in public service land mobile, and I think C4FM does too. In my opinion, proprietary technologies have no place in ham radio, and enough people felt that way that we now have an excellent non-proprietary alternative, CODEC2 by VK5DGR. While it has gotten a lot of use in open source digital voice packages for HF it doesn't seem to have gotten a lot of traction among the commercial manufacturers of VHF/UHF mobile ham gear.
--Phil
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