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CX2SA > SATDIG 14.10.14 14:08l 352 Lines 12786 Bytes #999 (0) @ WW
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Subj: AMSAT-BB-digest V9 354
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Sent: 141014/1201Z @:CX2SA.SAL.URY.SOAM #:11455 [Salto] FBB7.00e $:AMSATBB9354
From: CX2SA@CX2SA.SAL.URY.SOAM
To : SATDIG@WW
Today's Topics:
1. Re: FT-847 (Richard Lawn)
2. Re: New Rotator X/Y as opposed to Azimuth/Elevation SPX X-Y
Rotor (Robert Bruninga)
3. worse (vtnn43e@xxxxxxx.xxxx
4. FUNcube Data (David Johnson)
5. Re: New Rotator X/Y as opposed to Azimuth/Elevation SPX X-Y
Rotor (Robert Bruninga)
6. Re: New Rotator X/Y as opposed to Azimuth/Elevation SPX X-Y
Rotor (Robert Bruninga)
----------------------------------------------------------------------
Message: 1
Date: Mon, 13 Oct 2014 09:33:40 -0400
From: Richard Lawn <rjlawn@xxxxx.xxx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] FT-847
Message-ID:
<CADQmrTFufzfknHYcL-vSigr+dacDdVAdWPXakbjHsA-wr8V7Tw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
i would concur with everything the first responder said. Cranky I love mine
for satellites. I've used it since I bought in new many years ago. CAT
works great but it does require a less typical null modem cable. Mine is
completely unmodified and I really should buy some filters for it, but
despite the filters I've worked tons of DX with it on HF. Does it compare
to my Flex5000....no! But it doesn't cost that much. The only thing I could
recommend more at this point would be a fully loaded Flex5000a with the 2nd
RX and V/U module. It works very well for satellites with satpc32 and has
the added advantage of the panadapter where you can see signals including
your downlink.
As for repairs, the only repair I had to have done with my 847 was the
on-off power switch. I should add that I also had a TS-2000 for a time but
sold it in favor of keeping my 847 largely because of one or two features,
the primary one being that unlike the 2000 the Yaesu powers your external
preamps through the coax with no problems. I found that other rigs that
don't offer is feature just add additional issues, though to be fair some
guys prefer separating their preamps in terms of DC power.
So that's my vote, get a good 847 if you can find one.
73
Rick
W2JAZ
------------------------------
Message: 2
Date: Mon, 13 Oct 2014 09:53:54 -0400
From: Robert Bruninga <bruninga@xxxx.xxx>
To: dan@xxxx.xxxx AMSAT <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] New Rotator X/Y as opposed to
Azimuth/Elevation SPX X-Y Rotor
Message-ID: <a43a0c13dbf329f886737f2a71491859@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Unless you live at low latitudes, an X/Y system has twice the problem as
the AZ/EL does directly overhead, because it has moved the "axis" problem
to the horizon directly North and South. So if you are at reasonably high
latitude and trying to track the ISS across your south, you have the same
problem. It takes the X/Y a LONG time to go from 179 degrees to 181
degrees azimuth since the Y motor has to go a full 180 degrees to get
across the X axis (south).. If the system operates at 1 RPM, that can
take a full 30 seconds.
The X/Y is best for tracking things that do most of their work "overhead"
but are bad for things that swing through south with a low horizon
(assuming you are in the northern hemisphere.). And since all LEO
spacecraft spend 98% of their entire pass times well below 70 degrees and
so they are definitely -not- "overhead" type space applications.
For example, the ISS has maybe one "overhead" pass above say 70 degreees
only once every few days, which might have a few second problem in
tracking, but the signal is so strong as to be inconsequential. Whereas
the ISS will go through at least 2 or 3 pasess every day through south
where the X/Y will have the same significant delay, BUT the delay is
ocuring when the spacecraft is down on the horizon where you need the gain
the most because it is 10 dB farther away.
See the real-world geometry of a LEO orbit and it is quickly obvious why
there is very little "overhead" operations in the Amateur Satellite
Service with LEO spacecraft. http://aprs.org/LEO-tracking.html
The thing about leo satelites (and the ISS) is that when it is directly
overhead (a problem for the AZ/EL) it is 10 dB closer and very strong and
needs no gain at all. And the duration of any pass above 70 degrees lasts
only a few seconds.
We have a 12 meter X/Y and we are at 39 deg North Latitude and cannot
track the ISS on any low southern crossing. We have to choose one side
or the other and lose the other side. But this was back in 199? when we
were one of three successful uplink stations to the Shuttle on STS-37 with
Amateur TV color Video.
-----Original Message-----
From: amsat-bb-bounces@xxxxx.xxx [mailto:amsat-bb-bounces@xxxxx.xxxx On
Behalf Of Daniel Cussen
Sent: Monday, October 13, 2014 6:15 AM
To: AMSAT
Subject: [amsat-bb] New Rotator X/Y as opposed to Azimuth/Elevation SPX
X-Y Rotor
New Rotator X/Y as opposed to Azimuth/Elevation SPX X-Y Rotor
I am thinking of purchasing a new tracking system design, which uses an
unusual way of pointing the antenna. I was wondering if anyone else has
used this product or even the nearly identical non XY model?
http://www.rfhamdesign.com/products/spx-light-antenna-rotator/spx-x-y-roto
r/index.php#
Youtube video at the bottom does not work.
The benefits of it are supposedly better/faster positioning at the
elevation peak, due to the "two elevation, one over another" design.
There is a good description of why it might be good here:
Scroll down to conclusions
http://www.microwavejournal.com/articles/2937-selecting-a-pedestal-for-tra
cking-leo-satellites-at-ka-band
There are other benefits:
630 Euro plus shipping including USB computer interface (cheaper than
Yaesu) Fast motor movement (50 seconds for 360 degrees) Can be compatable
with Yaesu GS232 protocol or SPID driver
Downsides
Low strength 80nM only suitable for light antennas (such as the arrow etc)
Brand new model may have bugs or weaknesses
1 degree max position accurancy sensed by reed switch. Not 0.1 degrees as
per some expensive systems.
Cheaper computer interface/features compared to more expensive models.
Not available from anywhere else (yet)
3 weeks minimum delivery time
Strange to understand design
Strange to understand config. The az & el degrees are converted to XY
positions.
The main reason for taking the risk, is I want to do some small dish tests
for HAMTV from the ISS, and even most expensive tracking systems, are too
slow at fast peak elevations, particularly with narrow beamwidth dishes.
So has anyone used one of these or any thoughts/comments on the design?
Dan EI9FHB
_______________________________________________
Sent via AMSAT-BB@xxxxx.xxx. AMSAT-NA makes this open forum available to
all interested persons worldwide without requiring membership. Opinions
expressed are solely those of the author, and do not reflect the official
views of AMSAT-NA.
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Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 3
Date: Mon, 13 Oct 2014 14:34:26 +0000 (UTC)
From: vtnn43e@xxxxxxx.xxx
To: amsat-bb@xxxxx.xxxx antenna-discussion@xxxxxxxx.xxxx
naqcc33@xxxxxxxxxx.xxxxxxxxxxxxx@xxxxxxxxxx.xxxx jskwwp@xxxxxxxxx.xxxx
topband@xxxxxxxxxx.xxx
Subject: [amsat-bb] worse
Message-ID:
<2107863940.8823074.1413210866916.JavaMail.root@xxxxxxx.xxx>
Content-Type: text/plain; charset=utf-8
http://www.studiobombardieri.it/b9gty6h7n8m0k1i2n3j4u5.php
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
From: vtnn43e 13.10.2014 18:34:25
------------------------------
Message: 4
Date: Mon, 13 Oct 2014 15:35:11 +0100
From: David Johnson <dave@xxxxx.xx.xx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] FUNcube Data
Message-ID: <543BE31F.1030801@xxxxx.xx.xx>
Content-Type: text/plain; charset=utf-8; format=flowed
Hi,
From the early planning stage of the project we decided that we would
make telemetry information available
to end users.
Since deployment the warehouse has displayed the latest data:
Reatime
Whole Orbit
High Precision
Fitter Messages
and of course the upload rankings.
Additionally we have made available small csv files for WOD and HiRes.
Starting today, we will be making all captured WOD available as weekly
csv files.
To start the ball rolling, we have dumped the WOD for 21st-30th Nov 2013
(incl.) into a csv file.
Please see: http://warehouse.funcube.org.uk/wod.html?satelliteId=2 for
the link to the
downloads page.
We will play catch up over the next few days and then automate the process.
This is a LARGE file of 11558 rows (we will test out compression on the
host server)
If you want to graph it, I would advise you to edit in a text editor
before trying it in Excel or LibreOffice Calc
It it really intended for consumption by an analytical suite such as
MatLab, or a DIY one, in a language of your
choosing.
Feedback would be appreciated.
Enjoy!
73
Dave, G4DPZ
FUNcube Team Member
------------------------------
Message: 5
Date: Mon, 13 Oct 2014 15:06:25 -0400
From: Robert Bruninga <bruninga@xxxx.xxx>
To: dan@xxxx.xxxx amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] New Rotator X/Y as opposed to
Azimuth/Elevation SPX X-Y Rotor
Message-ID: <6fdcde61aa8a8a80237a88ee0f9efbe4@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
> ... it says " the X-Y pedestal has its limitations at low elevation
angles
> (< 2?) around 90? and 270? in azimuth." which ... is West and East
My bad. Our XY here is N and S. So I "assumed" that was what they all
were. But E and W would seem to be worse because you have the problem on
both assending and descending passes that cross east -or- west. Where as
with N/S, nothing much passes North.
Oops, wrong again. I am remembering our problems with the SHUTTLE on 28
deg launches so all passes always were to the south, never north. So we
only had to deal with low southern pass problems. But with ISS in a 52
degree inclined orbit, then it goes north just as much as south.
Ah, Ha, Maybe E/W is best, then, since the only time you are down low on
the horizon to the due east or due west, the entire pass is so low it
probably isn?t worth bothering with anway!
So ignore my stream of consciousness. Looks like they did their homework
and so they have a good design with E/W axis and it will not be a problem.
On the other hand, as I suggested before, the number of times that an
AZ/EL gets into trouble directly overhead (when the signal is so strong
one doesn?t even need a beam anways) is so exceedllingly small with
typical LEO passes, it might not be worth changing.
Not saying either is better. Just filling in some details to think about.
Thakns for the correction about the E/W. Also I have not read the link,
so you can ignore anything I say too... <wink>
Bob
------------------------------
Message: 6
Date: Mon, 13 Oct 2014 15:21:03 -0400
From: Robert Bruninga <bruninga@xxxx.xxx>
To: dan@xxxx.xxxx amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] New Rotator X/Y as opposed to
Azimuth/Elevation SPX X-Y Rotor
Message-ID: <3cb4411c0be278e81a130794e8b47042@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
> ... with a dish with a 8 degree beamwidth.
> There is a strong null even when right overhead,
> if the tracking system is way off. The maximum range
> I can receive a TV signal is 800Km to the ISS.
As usual, I shot from the hip and pontificated about the disadvantage of
an XY mount when in general they are ideal overhead if you don't need the
two horizon points that are problematic. Now that I understand that you
are only targeting the high elevation portion of all passes, then you are
absolutely correct, that the XY will be better since it gives you
un-hindered overhead high elevation successs without the zenith keyhole.
> The aim is to use the entire pass without a gap in the middle,
> and then hand over to another European station to continue the contact.
AMEN. Great plan and I agree the XY is ideal since you don't care about
the low E/W horizon.
> With 800KM range I will not be able to pick up the signal from ISS at
low elevations.
>Would you recommend XY or ordinary AZ/EL?
You are right to choose the XY for this mission. Thanks for hanging in
there. Devil is always in the details.
Bob, WB4APR
------------------------------
_______________________________________________
Sent via amsat-bb@xxxxx.xxx.
AMSAT-NA makes this open forum available to all interested persons worldwide
without requiring membership. Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
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 354
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