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CX2SA > SATDIG 23.07.14 14:03l 387 Lines 14198 Bytes #999 (0) @ WW
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Subj: AMSAT-BB-digest V9 253
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From: CX2SA@CX2SA.SAL.URY.SA
To : SATDIG@WW
Today's Topics:
1. Re: Re; Inclusion (Patrick STODDARD (WD9EWK/VA7EWK))
2. Re: Re; Inclusion (Gus)
3. ISS HAM TV Downlink Active 2395Mhz (Daniel Cussen)
4. Re: I want this. I want that. Here comes another FM LEO sat.
(Phil Karn)
5. Re: Round-world balloon approaching Noth America M0XER-3
(Nitin Muttin)
6. Re: Round-world balloon approaching Noth America M0XER-3
(John Mac)
----------------------------------------------------------------------
Message: 1
Date: Tue, 22 Jul 2014 16:11:06 -0700
From: "Patrick STODDARD (WD9EWK/VA7EWK)" <amsat-bb@xxxxxx.xxx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Re; Inclusion
Message-ID:
<CAN6TEUc8wGvj88KHsMiX3eO43-vEw-X4O+BuBx9PeGp8duLfyg@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Hi Gus!
You would have been happy with how AMSAT presented satellite
operating at the ARRL Centennial Convention that just concluded
in Hartford over the weekend. We had a day-long training seminar
last Thursday (17 July), and we touched on the extremes for stations
capable of satellite operating. We actually talked about the home
station first, complete with an IC-820 sitting in front of the
presenters' podium along with a laptop running SatPC32. We also had
a TS-790 in the room, copying the signals from the OSCAR I model that
ARRL allowed us to use for the weekend. Later on, we talked about
the minimimalist extreme for satellite operating, for both FM and SSB.
Unfortunately, we do not have audio or video recordings of the seminar,
as ARRL advised at the start of each presentation that Connecticut state
law forbade the audio or video recording of the presentations.
Outside the convention center, I had demonstrations of both FM and SSB
operating. The SSB demonstrations, using AO-7, went off very well. The
first demonstration came at the end of the day-long training seminar on
Thursday afternoon, and we were able to work stations from coast to
(almost) coast. The second SSB demonstration, on Saturday also using AO-7,
was working out to just as successful, until the satellite switched off at
mid-pass. The FM demonstration we attempted on Saturday with SO-50 was not
as successful. We could hear the satellite, but with only 5 watts we were
not successful in hearing ourselves or making any QSOs. I have audio
recordings
from the two AO-7 passes, and plan on making slideshow videos with photos
and
other information from the convention weekend to go along with the
satellite
audio. These demonstrations illustrated the minimalist approach to working
satellites, which also made the point that even working the (almost)
40-year-
old AO-7 didn't require a huge expenditure for equipment (I used two FT-817s
with my Elk log periodic antenna). Many hams still envision a station that
could work the previous HEO satellites as the minimum required today, even
with lots of presentations given by satellite operators and the YouTube and
other videos showing that it doesn't take a lot to do this.
An unexpected treat happened on Saturday morning. I had planned on being
outside the convention center for ISS passes, prepared to show off the ISS
digipeater, and - if a voice was heard on 145.800 MHz -
talk to an ISS
crewmember. The first of the three workable passes from Hartford came a
little while before the convention officially opened for the day at 0835
local/1235 UTC. The ISS was passing across the northern sky, with maximum
elevation of 25 degrees. I heard only packet on 145.825 MHz, and was able
to bounce a few packets through the ISS digipeater using a TH-D72A and Elk
dual-band log periodic antenna.
The next pass, around
1010 local/1410 UTC, was the best of the passes for
the morning - going across the southwestern sky with maximum elevation of
59 degrees. I had a radio listening to both 145.800 and
145.825 MHz. I
heard nothing on 145.825 MHz, but thought I heard something on
145.800 MHz.
I started calling for NA1SS using my TH-D72A/Elk combination, and Reid
Wiseman
(the same astronaut who was on for Field Day last month) answered my call.
My
audience went crazy, and I was happy to make contact and have a nice 3- to
4-
minute chat.
I asked Reid if he might be on the microphone for the next pass
over the eastern USA around 1200 local/1600 UTC. He said he would try, and
we were outside for that as well.
Once we told people in the hall of the successful contact, the ARRL
made sure
there was a larger crowd outside for this pass. Several
minutes before AOS,
I was out there again, this time answering lots of questions from different
people. After AOS, I started calling for NA1SS, but never heard anything
on
145.800 MHz during the shallow (maximum elevation 6 degrees) pass.
I'm sure more will be written about the convention, especially the AMSAT
effort
there. Based on feedback from those attending the day-long seminar, and
other
feedback throughout the convention, AMSAT did a great job showing off this
part
of amateur radio. The Thursday seminar and Friday afternoon forums (one
led
by AMSAT President Barry Baines WD4ASW discussing the current state of
AMSAT,
followed by a "how-to" session for working the FM satellites led by Peter
Portanova W2JV) were full, and all 3 sessions had audiences that were
engaged
and asking questions.
Now back to the different discussions about the extremes for stations to
work
satellites, and FM vs. digital (and anything else) via satellite, already
in
progress... :-)
73!
Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
> As far as doing demos for the uneducated, broomstick waving is an
> excellent introduction, highlighting the equipment simplicity and low cost.
> I do personally think that the shack-potato option might also appeal to
> /some/ of the audience, so I hope the other end of the operations spectrum
> is mentioned at least briefly.
>
>
------------------------------
Message: 2
Date: Tue, 22 Jul 2014 19:48:57 -0400
From: Gus <gus@xxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] Re; Inclusion
Message-ID: <53CEF869.4050801@xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 07/22/2014 07:11 PM, Patrick STODDARD (WD9EWK/VA7EWK) wrote:
> You would have been happy with how AMSAT presented satellite
> operating at the ARRL Centennial Convention that just concluded
> in Hartford over the weekend.
Sounds like a great party! I know it wouldn't have been easy to set up,
and for that reason (alas) every demo can't be as comprehensive. I do
believe that the most simplistic demo could at least mention the wider
spectrum of operating possibilities and leave the audience with that
Tip-of-the-Iceberg feeling.
Sorry you couldn't take video. Would have liked to have seen that!
--
Gus 8P6SM
The Easternmost Isle
------------------------------
Message: 3
Date: Wed, 23 Jul 2014 00:24:48 +0100
From: Daniel Cussen <dan@xxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] ISS HAM TV Downlink Active 2395Mhz
Message-ID:
<CAF3DnKg6Q19LyGo4OTi2SGvC340sTYJzs-jtigVn502MB_4Hvg@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
HAM video Blank Transmission from the ISS was activated again today
Tuesday July 22 at 9:55 UTC, which is 11:55 CEST. It will be switched
off again on
August 6th so make the most of the chance to receive and test equipment.
The Ham Video transmitter will stay on in Configuration 4 till August 6:
- 2.395GHz
- 2.00 MSym/sec
This is a high bandwidth digital downlink, so for all those into their
digital modes and all those calling for non FM downlinks here you go!
The downlink is type DVB-S MPEG2 compression.
Most of the details on how to set up to receive are included in the
bulletins here:
http://www.ariss-eu.org/
There is a dedicated mailing list for the system here:
https://ca.groups.yahoo.com/neo/groups/HamTV/info
I will be receiving the transmissions, will you?
Dan EI9FHB
------------------------------
Message: 4
Date: Tue, 22 Jul 2014 18:04:33 -0700
From: Phil Karn <karn@xxxx.xxx>
To: M5AKA <m5aka@xxxxx.xx.xx>, AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] I want this. I want that. Here comes another
FM LEO sat.
Message-ID: <53CF0A21.2040205@xxxx.xxx>
Content-Type: text/plain; charset=utf-8
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
------------------------------
Message: 5
Date: Wed, 23 Jul 2014 12:02:08 +0800
From: Nitin Muttin <vu3tyg@xxxxx.xx.xx>
To: Robert Bruninga <bruninga@xxxx.xxx>, "amsat-bb@xxxxx.xxxx
<amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Round-world balloon approaching Noth America
M0XER-3
Message-ID:
<1406088128.6627.YahooMailNeo@xxxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=utf-8
Bob,
Are these balloon's on 144.390
?
73
Nitin [VU3TYG]
>________________________________
> From: Robert Bruninga <bruninga@xxxx.xxx>
>To: amsat-bb@xxxxx.xxx
>Sent: Tuesday, 22 July 2014 10:27 PM
>Subject: [amsat-bb] Round-world balloon approaching Noth America M0XER-3
>
>
>Regarding real LOW Earth ?orbits?, G6UIM reports a Balloon launched in the
>UK is approaching Washington state from across Asia and the Pacific right
>now.
>
>See: http://spacenear.us/tracker/ look for Balloon B-63
>
>
>
>It is being well received by the APRS network in Canada, Washington and
>Oregon as it approaches Vancoover Island as shown here:
>
>http://aprs.org/balloons/M0XER-3.jpg
>
>
>
>That image from Lynn, author of APRSIS32.
>
>Bob, Wb4APR
>_______________________________________________
>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: 6
Date: Wed, 23 Jul 2014 20:08:57 +1000
From: John Mac <vk2fak@xxxxx.xxx>
To: Nitin Muttin <vu3tyg@xxxxx.xx.xx>
Cc: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Round-world balloon approaching Noth America
M0XER-3
Message-ID:
<CANiF7qN2EC7XyhRCPVbx1FYamg2igEB6mf4fOwXrQpJ75+ay4g@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Hi all...
Andy VK3YT has a pico balloon that was launched from Melbourne
Australia and was last spotted using APRS flying over Brazil, still
at over 8000m alt.......with any luck it may end up back in
Australia....by the weekend...
John
------------------------------
_______________________________________________
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 253
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