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CX2SA > SATDIG 15.09.11 20:04l 382 Lines 14291 Bytes #999 (0) @ WW
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From: CX2SA@CX2SA.LAV.URY.SA
To : SATDIG@WW
Today's Topics:
1. Re: Good mobile antennas to use (Bob Bruninga)
2. Re: Good mobile antennas to use (John Geiger)
3. Re: SDR For Satellite Use (Alan P. Biddle)
4. Re: ARISSAT telemetry - no kursk frames (Burns Fisher)
5. Re: Good mobile antennas to use (Bob Bruninga)
6. Thanks for certificate Arissat-1 (andy thomas)
----------------------------------------------------------------------
Message: 1
Date: Thu, 15 Sep 2011 13:07:44 -0400
From: "Bob Bruninga" <bruninga@xxxx.xxx>
To: "'Ng, Peter'" <Peter.Ng@xxxxx.xx>, "'AMSAT-BB'"
<amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Good mobile antennas to use
Message-ID: <012401cc73c9$fc8b9a90$f5a2cfb0$@xxx>
Content-Type: text/plain; charset="us-ascii"
Peter,
I donno. The only 1/4 19.5" antenna I ever used I just drilled into the
roof above the dome light and installed an NMO mount and simple whip. For
conversion of an existing mount, if it is a 5/8's wave vertical (most
mobiles are) then there is a matching network in the base.
The little tiny micro whips are ideal, but most of them now are being made
as "dual band" which then destroys their 7 dBi gain above the horizon.
No easy answers here.
Bob
-----Original Message-----
From: Ng, Peter [mailto:Peter.Ng@xxxxx.xxx
Sent: Thursday, September 15, 2011 12:47 PM
To: 'Bob Bruninga '; AMSAT-BB
Subject: RE: [amsat-bb] Re: Good mobile antennas to use
<snip>
But this is not what a 19.5" whip does. The 1/4 (3/4) wave 19.5" whip does
not have gain on the horizon (so it is rarely used for terrestrial mobile)
but its pattern is ideal for satellite work on high passes. It does NOT
then have a null in its pattern that causes the "crappy" contacts, and it
does have plenty of gain above about 25 degrees.... and it is a smooth
pattern.... not like the multi lobes of a standard mobile gain antenna.
</snip>
Hi Bob,
This is off topic and didn't want to start something on the list... :), but
can I convert my current magmount gain antenna simply by replacing the whip
or is the "gain" stuff in the magmount itself? If so, would any thin steel
rod do? I'd really like to give this a try!
73's Peter VE7NGP
------------------------------
Message: 2
Date: Thu, 15 Sep 2011 12:34:35 -0500
From: John Geiger <aa5jg@xxxxxxx.xxx>
To: Bob Bruninga <bruninga@xxxx.xxx>
Cc: AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Good mobile antennas to use
Message-ID:
<CAFq43LZcUovj+Xr6=ya6fF4T-jTRA7-qHw9D1jauVciGqpLuTQ@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Thanks for the plots Bob. The 2m havewave appears to do well on 70cm above
30 degrees, and fairly poor below that elevation. The 70cm 1/4 wave appears
to suffer from no real nulls except at the very high elevations. It is
about 5 DB down from the 2m 1/4 wave, but is also much more usable on the
below 30 degree passes.
So, would a dualband that is 1/4 wave on each band cover things pretty
well? It appears like it would.
73s John AA5JG
On Thu, Sep 15, 2011 at 12:07 PM, Bob Bruninga <bruninga@xxxx.xxx> wrote:
> Peter,
> I donno. The only 1/4 19.5" antenna I ever used I just drilled into the
> roof above the dome light and installed an NMO mount and simple whip. For
> conversion of an existing mount, if it is a 5/8's wave vertical (most
> mobiles are) then there is a matching network in the base.
>
> The little tiny micro whips are ideal, but most of them now are being made
> as "dual band" which then destroys their 7 dBi gain above the horizon.
>
> No easy answers here.
> Bob
>
> -----Original Message-----
> From: Ng, Peter [mailto:Peter.Ng@xxxxx.xxx
> Sent: Thursday, September 15, 2011 12:47 PM
> To: 'Bob Bruninga '; AMSAT-BB
> Subject: RE: [amsat-bb] Re: Good mobile antennas to use
>
> <snip>
> But this is not what a 19.5" whip does. The 1/4 (3/4) wave 19.5" whip does
> not have gain on the horizon (so it is rarely used for terrestrial mobile)
> but its pattern is ideal for satellite work on high passes. It does NOT
> then have a null in its pattern that causes the "crappy" contacts, and it
> does have plenty of gain above about 25 degrees.... and it is a smooth
> pattern.... not like the multi lobes of a standard mobile gain antenna.
> </snip>
>
> Hi Bob,
>
> This is off topic and didn't want to start something on the list... :), but
> can I convert my current magmount gain antenna simply by replacing the whip
> or is the "gain" stuff in the magmount itself? If so, would any thin steel
> rod do? I'd really like to give this a try!
>
> 73's Peter VE7NGP
>
> _______________________________________________
> 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: 3
Date: Thu, 15 Sep 2011 12:46:20 -0500
From: "Alan P. Biddle" <APBIDDLE@xxxxxx.xxx>
To: "'Joel Black'" <w4jbb@xxxxxxx.xxx>, "'Amsat BB'"
<AMSAT-BB@xxxxx.xxx>
Subject: [amsat-bb] Re: SDR For Satellite Use
Message-ID: <D7CAD06803A74A6895CA2043724299F8@xxxxxx>
Content-Type: text/plain; charset="us-ascii"
Joel,
I have a Flex VU5K, and it is coming along nicely as a satellite rig. It is
fun, and even useful, to be able to look at the ARISSat-1 downlink. You can
copy telemetry while watching the transponder passband to see if anyone is
on. On Fo-29 and similar linear birds, you don't need to tune around
looking for other stations. They are just there. Click, and QSO!
The Flex can respond to the Kenwood TS-2000 CAT commands, mostly, so it
works with SATPC32 and HRD. There are a few loose ends not implemented, so
you need to set a couple of things manually which would be set automatically
with a real TS-2000. However, there is nothing which prevents you from
using the Doppler control, etc. No doubt the rough edges will be fixed over
time.
73s,
Alan
WA4SCA
-----Original Message-----
From: amsat-bb-bounces@xxxxx.xxx [mailto:amsat-bb-bounces@xxxxx.xxxx On
Behalf Of Joel Black
Sent: Thursday, September 15, 2011 6:06 AM
To: Amsat BB
Subject: [amsat-bb] SDR For Satellite Use
I have successfully built and operated my G59 transceiver with GPA10 10W
amp (http://www.genesisradio.com.au/) for 40m JT65a contacts to VK2, 75m
voice contacts in the States, and everything in between.
At some point in the past, some group (TAPR?) had a 2m SDR transceiver.
I have no idea where that information might be.
Does anyone here use SDR for their satellite operation? Maybe using
Flex radios or something else? I don't know that it would matter on the
FM birds, but it would be nice to be able to see the spectrum on the
linear birds.
Thanks,
Joel - W4JBB
_______________________________________________
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: Thu, 15 Sep 2011 13:50:06 -0400
From: Burns Fisher <burns@xxxxxx.xx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: ARISSAT telemetry - no kursk frames
Message-ID:
<CABX7KxUeU-NBefHm3AkuiocNHbB4EbpHwPXQkDoQRH4z9=iPkA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Don't I recall correctly that the Kursk experiment requires an entire orbit
of data? I think I heard this in t context of low-power operation had to
keep Kursk running.
But in any case, now that the battery is history and we only get power
for the non-eclipse part of each orbit, I'd think that would mean that Kursk
is not doing much. I don't know what the IHU should do with the Kursk tlm
in that case, but 0 is not unreasonable.
Burns, W2BFJ
> Subject: [amsat-bb] Re: ARISSAT telemetry - no kursk frames
> Message-ID: <Yy4z1h0014ltuWb05y4zTa@xxxxx.xxx>
> Content-Type: text/plain; charset="us-ascii"
>
> Mike,
>
> Had it just come out of eclipse? I have seen no Kursk frames when it just
> came on just after eclipse...I think the Kursk Experiment isn't running
> quite yet, so no frames to xmit.
>
> So yes, I saw this yesterday :)
>
> Also, to confirm W5RKN---I have seem some "all 0" frames too...you can hear
> hear it on the audio actually :)
>
> Mark N8MH
>
> At 08:23 AM 9/15/2011 +0200, you wrote:
> >Hi all,
> >I had a 1 deg pass this morning and could grab 18 telemetry frames (!).
> Interesting was that I received no one KURSK frame.
> >Can someone confirm this?
>
------------------------------
Message: 5
Date: Thu, 15 Sep 2011 14:20:25 -0400
From: "Bob Bruninga" <bruninga@xxxx.xxx>
To: "'John Geiger'" <aa5jg@xxxxxxx.xxx>
Cc: 'AMSAT-BB' <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Good mobile antennas to use
Message-ID: <012e01cc73d4$23fa77e0$6bef67a0$@xxx>
Content-Type: text/plain; charset="iso-8859-1"
> Thanks for the plots Bob (http://aprs.org/astars.html 85% down the page).
Remember, ALL plots are for 70cm performance, even though some of them are
made using "2m" antennas to show how they perform as a dual band satellite
antenna.
> The 2m 1/4 wave appears to do well on 70cm above
> 30 degrees, and fairly poor below that elevation.?
> The 70cm 1/4 wave appears to suffer from no real
> nulls except at the very high elevations.? It is
> about 5 DB down from the 2m 1/4 wave (70cm 3/4),
> but is also much more usable on the below 30 degree passes.
?
> So, would a dualband that is 1/4 wave on each band
> cover things pretty well?? It appears like it would.?
I agree. That would be the ideal coverage. But it depends on the
definition of "cover" and "pretty well". Yes, you will have COVERAGE, but
can you hear anything "pretty well" at 2400 miles and 6 dB farther away at
that low elevation angle? Much less even see the horizon in a mobile. I
personally don?t think so.
Sometimes we focus too much on the "antenna coverage" and ignore the
GEOMETRY of a pass which has a full 10 dB difference between the horizon and
overhead. Please look at the scale drawing of the geometery of a LEO pass
shown on http://aprs.org/rotator1.html.
It all depends on what an individual considers "Good enough" and what is the
minimum signal to hear anything at all. If we assume that 3 dB of gain on
the horizon is good enough to hear a LEO satellite at the horizon, (I do
not) then the best combination is to start with a 5/8 wave 70cm vertical.
At 15 degree elevation, switch to a 1/4 wave 70cm and with that combination
and with the up to 6 to 10 dB improvement as the satellite gets closer, then
you have good no-null coverage from the horizon to overhead.. But remember,
to do this now you have two UHF omni antennas, and a diplexer plus a
separate VHF uplink antenna (again, maybe 2 to avoid nulls) and you have to
know where the satellite is.
But, if you believe that there is no LEO currently on the air, that you can
hear on the horizon with only 3 to 4 dBi gain, (like I do) then, write off
that area of coverage since you wont hear it anyway and take the +5dB
performance imnprovement of the 3/4 wave vertical (19.5" whip) which is dual
band and optimized for the higher elevation and gives no nulls and does give
strong signals (but only for 1/3rd of all passes).
I'll be the first to admit that I do not have enough actual experience to
know what is the minimum gain needed to actually hear the leo at the greater
distances (lower angles) on an omni. Looking at the gain plots, as you say,
if you can actually hear a LEO at say 15 degrees on a 1/4 wave whip, then it
is the best antenna because it will be useable lower and the poorer
performance higher up will be made up by the reduced range.
Good luck.
Bob, WB4APR
On Thu, Sep 15, 2011 at 12:07 PM, Bob Bruninga <bruninga@xxxx.xxx> wrote:
Peter,
I donno. ?The only 1/4 19.5" antenna I ever used I just drilled into the
roof above the dome light and installed an NMO mount and simple whip. ?For
conversion of an existing mount, if it is a 5/8's wave vertical (most
mobiles are) then there is a matching network in the base.
The little tiny micro whips are ideal, but most of them now are being made
as "dual band" which then destroys their 7 dBi gain above the horizon.
No easy answers here.
Bob
-----Original Message-----
From: Ng, Peter [mailto:Peter.Ng@xxxxx.xxx
Sent: Thursday, September 15, 2011 12:47 PM
To: 'Bob Bruninga '; AMSAT-BB
Subject: RE: [amsat-bb] Re: Good mobile antennas to use
<snip>
But this is not what a 19.5" whip does. ?The 1/4 (3/4) wave 19.5" whip does
not have gain on the horizon (so it is rarely used for terrestrial mobile)
but its pattern is ideal for satellite work on high passes. ?It does NOT
then have a null in its pattern that causes the "crappy" contacts, and it
does have plenty of gain above about 25 degrees.... and it is a smooth
pattern.... not like the multi lobes of a standard mobile gain antenna.
</snip>
Hi Bob,
This is off topic and didn't want to start something on the list... :), but
can I convert my current magmount gain antenna simply by replacing the whip
or is the "gain" stuff in the magmount itself? ?If so, would any thin steel
rod do? ?I'd really like to give this a try!
73's Peter VE7NGP
_______________________________________________
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: Thu, 15 Sep 2011 19:56:54 +0100 (BST)
From: andy thomas <andythomasmail@xxxxx.xx.xx>
To: amsat <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Thanks for certificate Arissat-1
Message-ID:
<1316113014.46025.YahooMailNeo@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=iso-8859-1
Great to receive this morning the certificate for the Russian secret word!
Many thanks!
?
73 de andy G0SFJ
------------------------------
_______________________________________________
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 6, Issue 523
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