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CX2SA > SATDIG 27.07.14 14:04l 434 Lines 16506 Bytes #999 (0) @ WW
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Subj: AMSAT-BB-digest V9 258
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To : SATDIG@WW
Today's Topics:
1. Re: I want this. I want that. Here comes another FM LEO sat.
(Phil Karn)
2. Re: I want this. I want that. Here comes another FM LEO sat.
(Bryce Salmi)
3. Re: I want this. I want that. Here comes another FM LEO sat.
(Bryce Salmi)
4. Re: going digital (Phil Karn)
5. Re: FM birds (Phil Karn)
6. Re: Digital Satellites Question (Phil Karn)
7. Re: Digital Satellites Question (Phil Karn)
8. Re: Inclusion (satcoms?) (Phil Karn)
9. Re: AMSAT where are we going for what it is worth. (Phil Karn)
10. Yaesu G-5500 AZ/EL rotor for sale (John / NS1Z)
----------------------------------------------------------------------
Message: 1
Date: Sat, 26 Jul 2014 21:44:31 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] I want this. I want that. Here comes another
FM LEO sat.
Message-ID: <53D483AF.9010805@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
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.
------------------------------
Message: 2
Date: Sat, 26 Jul 2014 22:05:55 -0700
From: Bryce Salmi <bstguitarist@xxxxx.xxx>
To: Phil Karn <karn@xxxx.xxx>
Cc: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] I want this. I want that. Here comes another
FM LEO sat.
Message-ID:
<CAN5j0srOUi1bJEB0m5g73eU6j6Yxve+PVK7k9UzoZ+0Py8sWng@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
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 <karn@xxxx.xxx> 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 AMSAT-BB@xxxxx.xxx <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
>
------------------------------
Message: 3
Date: Sat, 26 Jul 2014 22:06:55 -0700
From: Bryce Salmi <bstguitarist@xxxxx.xxx>
To: Phil Karn <karn@xxxx.xxx>
Cc: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] I want this. I want that. Here comes another
FM LEO sat.
Message-ID:
<CAN5j0sq9qO5VpkHutZEA50uJxEPRYd9iGHKoyDOMk=-hvYv_bA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Nativity = autocorrect of "being naive" :) sorry about that
On Saturday, July 26, 2014, Bryce Salmi <bstguitarist@xxxxx.xxx> 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 <karn@xxxx.xxx
> <javascript:_e(%7B%7D,'cvml','karn@xxxx.xxxxxx>> 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 AMSAT-BB@xxxxx.xxx. 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
>>
>
------------------------------
Message: 4
Date: Sat, 26 Jul 2014 22:12:21 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] going digital
Message-ID: <53D48A35.5040806@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/22/2014 07:27 AM, JoAnne Maenpaa wrote:
> When thinking of projects to enter into the digital communication
> world plan on building or buying that digital interface to connect
> your radio to the soundcard.
Soundcard interfaces to existing voice radios were a good start, but
it's time to move past them. I've designed several modulation and coding
schemes to fit existing radios, and their inherently limited bandwidth
is a major pain. For ARISSat-1 I agreed to cram everything through a SSB
filter, and I'm not doing that again.
Not only does the narrow bandwidth often limit the data rate to much
less than what the link budget could actually support, but it enormously
aggravates the Doppler problem. It doesn't help that there are no
industry-wide standards for SSB phase response or computer tuning, or
that every time you retune one (which is often) there is a poorly
characterized phase jump.
Doppler is much easier to handle at high data rates because it's the
ratio of the symbol rate to the Doppler that matters, not the absolute
amount of Doppler.
Now that we have a variety of "pure digital" radio front ends to choose
from, it's time to set aside the voice radio + soundcard model. Not only
do the SDRs support wider bandwidths but they tend to be considerably
smaller, lighter and easier to work with in software. Some, like the
Funcube dongle, are even considerably cheaper than conventional radios.
--Phil
------------------------------
Message: 5
Date: Sat, 26 Jul 2014 22:24:15 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] FM birds
Message-ID: <53D48CFF.2070001@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/22/2014 07:49 AM, wa4hfn@xxxxxxx.xxx wrote:
> SSB/CW birds are the only way to go and if you build it they will
> come .
Think about what it would be like to tune for Doppler while working SSB
through a LEO satellite on microwave.
Before you say "computer control", work out the effect of even a tiny
error in your clock or orbital elements on a high elevation pass and
remember that SSB has no carrier or pilot tone for closed-loop frequency
tracking.
Sure, you could have a second receiver track the satellite's beacon. But
if you're going to all that trouble, why not just have it track a
single high speed data stream from the satellite, one that's much less
affected by Doppler in the first place?
------------------------------
Message: 6
Date: Sat, 26 Jul 2014 22:58:17 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] Digital Satellites Question
Message-ID: <53D494F9.9030504@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/22/2014 08:41 AM, Dave Marthouse wrote:
> A digital satellite would imply loads of processing power on the
> satellite. I would assume that with this additional activity that there
> will be more
> hardware on the bird with more complexity as this won't be a bent pipe
> system.
Not necessarily. Yes, it will rely on onboard computers -- but so do the
many analog satellites that use them for command and control. When the
IHU memory on AO-10 failed after 3 years in a high radiation orbit, the
analog transponder continued to operate but there was no way to repoint
the antennas and solar panels or to change the operating mode or power
system setpoints.
> With more physical hardware of much more complexity in orbit what about
> the radiation hazards to this more complex and physical hardware heavier
> system? Wouldn't a software based system be prone to radiation induced
> hardware and software glitches?
> What about shielding etc?
Radiation usually isn't a serious problem in LEO, though relatively
simple precautions like error-corrected memory are still a good idea.
With 14-16 day-night cycles per day, the usual problem is battery wearout.
And for low altitude cubesats, atmospheric drag usually trumps
everything else. Small objects tend to have small ballistic coefficients
making them more susceptible to drag. Even ARISSat-1, which was larger
and heavier than a cubesat, decayed in only a few months. Most cubesat
launch opportunities are to low altitudes, partly because that's where
the ISS flies, and partly because of the increasing pressure to minimize
space debris by keeping them out of the longer-lived altitudes.
------------------------------
Message: 7
Date: Sat, 26 Jul 2014 23:11:41 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] Digital Satellites Question
Message-ID: <53D4981D.5070402@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/22/2014 08:50 AM, Douglas Phelps wrote:
> And, in a related question, wouldn't more proccessing demand more
> power from the batteries/solar panels? I know my PC cetainly draws a
> lot more power when the CPO is working hard.
Not really. The biggest load in a communications satellite, or almost
any robotic spacecraft for that matter, is almost always the downlink RF
power amplifier(s). Using them more efficiently can justify almost anything.
Also, even highly efficient digital modes tend to be easy to generate;
many spacecraft do (or did) so purely in hardware. Demodulating and
decoding them is more work so uplink and downlink modes are often
different, each optimized for its purpose.
--Phil
------------------------------
Message: 8
Date: Sat, 26 Jul 2014 23:31:51 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] Inclusion (satcoms?)
Message-ID: <53D49CD7.9000107@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/22/2014 11:05 AM, Robert Bruninga wrote:
> The value of ham radio is providing communications where other systems
> cannot. And of course, playing with toys just for fun.
I'd flip that around. With the Internet, mobile phones and other
ubiquitous communications, about the sole reason left for ham radio to
exist is **education**. And playing with toys just for fun is often
quite educational as well.
Ham radio provides a hands-on opportunity to teach and learn radio (and
electronics) technology, and you still can't find anything like it
anywhere else.
Emergency communications is still in there somewhere, but in all honesty
I now see it as a distant second.
And if one is to teach oneself communications and electronics technology
through ham radio, then ham radio really ought to use something like the
communications and electronics technologies that the outside world is
using today, not just those the world was using 40 years ago.
--Phil
------------------------------
Message: 9
Date: Sat, 26 Jul 2014 23:35:20 -0700
From: Phil Karn <karn@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] AMSAT where are we going for what it is worth.
Message-ID: <53D49DA8.2040309@xxxx.xxx>
Content-Type: text/plain; charset=windows-1252
On 07/22/2014 11:19 AM, Bryce Salmi wrote:
> All this requires much much much more power than a 1U satellite is
> currently capable of producing. At least for always on type operating.
> We'll get there eventually.
Only if you keep the analog modes since they hog nearly all the
available power and drive the spacecraft design in many other ways. Let
go of them, and many new things suddenly become possible for the first time.
------------------------------
Message: 10
Date: Sun, 27 Jul 2014 06:27:28 -0400
From: "John / NS1Z" <ns1zjohn@xxxxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Yaesu G-5500 AZ/EL rotor for sale
Message-ID: <835B1DBBB411490AB90CB32551430B5E@xxxxxx>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
This rotor is less than a year old. It works perfectly and is in very good
condition. Works with any
of the ST series interfaces (ST-1 and ST-3). Selling the rotor, control box,
Satellite serial port interfaces ST-3 and SAT668.
It really is Plug and Play
$450 plus shipping
Thanks
-----Original Message-----
From: Phil Karn
Sent: Sunday, July 27, 2014 1:12 AM
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] going digital
On 07/22/2014 07:27 AM, JoAnne Maenpaa wrote:
> When thinking of projects to enter into the digital communication
> world plan on building or buying that digital interface to connect
> your radio to the soundcard.
Soundcard interfaces to existing voice radios were a good start, but
it's time to move past them. I've designed several modulation and coding
schemes to fit existing radios, and their inherently limited bandwidth
is a major pain. For ARISSat-1 I agreed to cram everything through a SSB
filter, and I'm not doing that again.
Not only does the narrow bandwidth often limit the data rate to much
less than what the link budget could actually support, but it enormously
aggravates the Doppler problem. It doesn't help that there are no
industry-wide standards for SSB phase response or computer tuning, or
that every time you retune one (which is often) there is a poorly
characterized phase jump.
Doppler is much easier to handle at high data rates because it's the
ratio of the symbol rate to the Doppler that matters, not the absolute
amount of Doppler.
Now that we have a variety of "pure digital" radio front ends to choose
from, it's time to set aside the voice radio + soundcard model. Not only
do the SDRs support wider bandwidths but they tend to be considerably
smaller, lighter and easier to work with in software. Some, like the
Funcube dongle, are even considerably cheaper than conventional radios.
--Phil
_______________________________________________
Sent via AMSAT-BB@xxxxx.xxx. 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 amsat-bb@xxxxx.xxx. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 9, Issue 258
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