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CX2SA > SATDIG 30.06.10 20:18l 1154 Lines 36212 Bytes #999 (0) @ WW
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Today's Topics:
1. SO-67 possible active passes 30 June (OZ1MY)
2. SO-67 on for the first time over Europe (OZ1MY)
3. Awesome photo of ISS (andy thomas)
4. Re: Alinco DJ-G7T as a full-duplex FM Sat rig? (Alan P. Biddle)
5. Re: question (Mark Lunday)
6. ISS APRS Packet Active (Mani VU2WMY)
7. Re: question (Adrian Engele)
8. Re: question (Mark Lunday)
9. Re: ISS APRS Packet Active (Roger Kolakowski)
10. Re: HF Satellite Relay (Robert Bruninga)
11. Re: HF Satellite Relay (Joe)
12. Re: HF Satellite Relay (Mark L. Hammond)
13. Re: HF Satellite Relay (i8cvs)
14. SO-67 Suggestions (John Papay)
----------------------------------------------------------------------
Message: 1
Date: Wed, 30 Jun 2010 10:57:54 +0200
From: "OZ1MY" <oz1my@xxxxxx.xx>
Subject: [amsat-bb] SO-67 possible active passes 30 June
To: "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Message-ID: <000601cb1832$5405f8a0$6401a8c0@xxxxxx.xx>
Content-Type: text/plain; charset="iso-8859-1"
30/06/2010
South Africa
08:29
Europe
09:46
Brazil
11:39
13:15
North America
14:35
16:10
17:45
73 OZ1MY
Ib
------------------------------
Message: 2
Date: Wed, 30 Jun 2010 12:29:36 +0200
From: "OZ1MY" <oz1my@xxxxxx.xx>
Subject: [amsat-bb] SO-67 on for the first time over Europe
To: "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Message-ID: <000501cb183f$23ba2880$6401a8c0@xxxxxx.xx>
Content-Type: text/plain; charset="iso-8859-1"
Hi all,
Just had a pass with AOS at 0946 UTC here
in Copenhagen.
It works as described on the page:
http://www.amsatsa.org.za/
It means that you do not need the PL-tone once
the transponder is started.
In fact do not set the tone ON. The transponder
sounds better without the tone.
As before use FMN on the uplink - and turn the AF gain
down until your modulation sounds good to yourself.
Use of high power also seems to distort the audio on
the downlink.
This is just the experience from one short pass :-)
The list on the homepage above may not be up to date
all the time. When we receive confirmed lists from
the control station we will publish on amsat-bb.
Depending upon the time of the day - may need to sleep
every now and again.
This week until Monday next week I have only asked for
morning passes over Europe.
Next week I will ask for afternoon passes as well
when the satellite is in Sun.
Please remember we are just passengers on Sumbandilasat.
If there are other tasks they take priority.
73 OZ1MY
Ib
------------------------------
Message: 3
Date: Wed, 30 Jun 2010 12:29:44 +0000 (GMT)
From: andy thomas <andythomasmail@xxxxx.xx.xx>
Subject: [amsat-bb] Awesome photo of ISS
To: amsat <amsat-bb@xxxxx.xxx>
Message-ID: <966283.87416.qm@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=utf-8
see (from the space education institute, Leipzig):
"this we photographed in our observatory yesterday:"
http://www.youtube.com/user/SpaceEducation#p/c/BC233E60895D1BE3/0/_JfnLuKsAzw
73 de andy G0SFJ
------------------------------
Message: 4
Date: Wed, 30 Jun 2010 07:39:00 -0500
From: "Alan P. Biddle" <APBIDDLE@xxxxxx.xxx>
Subject: [amsat-bb] Re: Alinco DJ-G7T as a full-duplex FM Sat rig?
To: <dave@xxxxx.xxx>, <amsat-bb@xxxxx.xxx>
Message-ID: <BE411696B1AE4D83860700619901E211@xxxxxx>
Content-Type: text/plain; charset="us-ascii"
Dave,
Those of us who bought it early on, including me, were very disappointed in
its satellite performance, and in some cases general quality. At least two
people I know had theirs brick for things like battery or transmitter
failure. Upgrading the firmware did result in some significant
improvements, but it never was more than marginally useful according to
most. If you look back in the archives, there were some quantitative
reports using lab equipment which compared it with the standards such as the
D-7. The performance issues were clear, even on the bench. I finally sold
mine to someone locally who is very pleased with it for terrestrial use.
Even with the latest firmware, is was demonstrably less sensitive than other
rigs with identical specs, and with poor full duplex performance. My own
experience, and some of the regular satellite rovers, was negative.
That having been said, I had seen a few reports from people who were VERY
pleased. That may be based on different levels of expectation, or the
traditional process where manufacturers make running changes in production
to address problems. Also, the iffy quality control may be a factor. I see
that Alinco has changed their US distributor, which may or may not be
relevant, and the rig has been on sale recently.
My suggestion is to see if you get any reports from people with recent
production.
Alan
WA4SCA
-----Original Message-----
From: amsat-bb-bounces@xxxxx.xxx [mailto:amsat-bb-bounces@xxxxx.xxxx On
Behalf Of dave@xxxxx.xxx
Sent: Wednesday, June 30, 2010 2:08 AM
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Alinco DJ-G7T as a full-duplex FM Sat rig?
It's been a while now since I've heard any discussion about this Alinco HT
since its debut just over a year ago. The first reviews were fairly
negative, with most comments pointing towards immature firmware. I know
that Alinco has sent out a number of updates of this HT's operating system
since then, but I don't know how important or effective these improvements
were.
A ham friend of mine bought one about six months ago, and tells me he is
very pleased with his, enjoying some 1.2 Gig SF Bay Area repeater systems.
He has never used the satellites, though, (yep, it's a pity!) so could
not tell me anything about how well this HT accomplishes full-duplex FM
sat operation.
So, my question to those of you that own this HT and have kept up with the
updates: Is this product worth another look? Has it matured
sufficiently? I'm probably most interested in how well it performs in
full-duplex mode for FM satellites, hence my reason for posting this
question here.
So what say ye, DJ-G7T owners? Worth it, or not? Is the full-duplex
sensitivity and functionality good, or do you have to accept some
degradation or other compromises?
73 es tnx in advance,
Dave - K7DAA
_______________________________________________
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: 5
Date: Wed, 30 Jun 2010 08:45:26 -0400
From: "Mark Lunday" <mlunday@xx.xx.xxx>
Subject: [amsat-bb] Re: question
To: "'Adrian Engele'" <aa5uk@xxxxx.xxx>, "'Dads'" <w0sat@xxx.xxx>,
<amsat-bb@xxxxx.xxx>
Message-ID: <006901cb1852$1d5f2270$581d6750$@xx.xxx>
Content-Type: text/plain; charset="us-ascii"
Adrian, I had a thread from December 2008 on this board that said the
following:
>> VO-52 is LSB on the uhf uplink and USB on the vhf downlink
>> FO-29 is LSB on the vhf uplink and USB on the UHF downlink.
>> AO-7 is LSB on the uhf uplink and USB on the vhf downlink. Mode B
>> AO-7 is USB on the vhf uplink and USB on the 10m downlink Mode A
Can you please comment?
-----Original Message-----
From: amsat-bb-bounces@xxxxx.xxx [mailto:amsat-bb-bounces@xxxxx.xxxx On
Behalf Of Adrian Engele
Sent: Tuesday, June 29, 2010 8:28 PM
To: Dads; amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: question
Jerry,
Linear satellites today use LSB for the Uplink and USB for the downlink by
general agreement.
Also by agreement:
CW is on the lower 1/3 of the downlink bandpass.
Mixed Modes are in the center 1/3 of the downlink bandpass.
SSB is in the top 1/3 of the downlink bandpass.
73, Adrian AA5UK
________________________________
From: Dads <w0sat@xxx.xxx>
To: amsat-bb@xxxxx.xxx
Sent: Tue, June 29, 2010 6:39:01 PM
Subject: [amsat-bb] question
Hi : I sent a couple friends that are interested to the AMSAT
website.
I told them to look at all the satellites.
They found the site had all satellites on it.
When they brought up the sats they didn,t put on the
sidebands on the linear birds, the up and downlinks
.
I mean the upper and lower sidebands for these birds.
So I sent them to the UK site and they were there.
They didn,t have Oscar 68 on there though.
Jerry w0sat
_______________________________________________
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-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 6
Date: Wed, 30 Jun 2010 18:17:43 +0530
From: Mani VU2WMY <wmy@xxxx.xxx.xx>
Subject: [amsat-bb] ISS APRS Packet Active
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Message-ID: <20100630181743.126847fa5y926sq7@xxxxxxxx.xxxx.xxx.xxx.xx>
Content-Type: text/plain; charset=UTF-8; DelSp="Yes"; format="flowed"
Just heard ISS APRS packet active over VU Land during 12:44 pass. Can
someone confirm?
Mani, VU2WMY
------------------------------
Message: 7
Date: Wed, 30 Jun 2010 05:59:39 -0700 (PDT)
From: Adrian Engele <aa5uk@xxxxx.xxx>
Subject: [amsat-bb] Re: question
To: Mark Lunday <mlunday@xx.xx.xxx>, Dads <w0sat@xxx.xxx>,
amsat-bb@xxxxx.xxx
Message-ID: <341294.17091.qm@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=us-ascii
Mark,
Both our responses are correct. I decided to leave AO-7 Mode A off from my
initial response to Jerry as few people use that mode these days. This is a
non inverting transponder, therefore USB-Up and USB-Down.
I was trying to address Jerry's request for helping our newcomers. Their
concentration would most likely be on FO-29, HO-68, AO7 (mode B) and VO52. All
four of these satellites are LSB Up and USB down as you indicated below.
A great web site where all this information is nicely detailed is at:
http://www.dk3wn.info/satellites.shtml See each satellite page.
73, Adrian AA5UK
________________________________
From: Mark Lunday <mlunday@xx.xx.xxx>
To: Adrian Engele <aa5uk@xxxxx.xxx>; Dads <w0sat@xxx.xxx>; amsat-bb@xxxxx.xxx
Sent: Wed, June 30, 2010 7:45:26 AM
Subject: RE: [amsat-bb] Re: question
Adrian, I had a thread from December 2008 on this board that said the
following:
>> VO-52 is LSB on the uhf uplink and USB on the vhf downlink
>> FO-29 is LSB on the vhf uplink and USB on the UHF downlink.
>> AO-7 is LSB on the uhf uplink and USB on the vhf downlink. Mode B
>> AO-7 is USB on the vhf uplink and USB on the 10m downlink Mode A
Can you please comment?
-----Original Message-----
From: amsat-bb-bounces@xxxxx.xxx [mailto:amsat-bb-bounces@xxxxx.xxxx On
Behalf Of Adrian Engele
Sent: Tuesday, June 29, 2010 8:28 PM
To: Dads; amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: question
Jerry,
Linear satellites today use LSB for the Uplink and USB for the downlink by
general agreement.
Also by agreement:
CW is on the lower 1/3 of the downlink bandpass.
Mixed Modes are in the center 1/3 of the downlink bandpass.
SSB is in the top 1/3 of the downlink bandpass.
73, Adrian AA5UK
________________________________
From: Dads <w0sat@xxx.xxx>
To: amsat-bb@xxxxx.xxx
Sent: Tue, June 29, 2010 6:39:01 PM
Subject: [amsat-bb] question
Hi : I sent a couple friends that are interested to the AMSAT
website.
I told them to look at all the satellites.
They found the site had all satellites on it.
When they brought up the sats they didn,t put on the
sidebands on the linear birds, the up and downlinks
.
I mean the upper and lower sidebands for these birds.
So I sent them to the UK site and they were there.
They didn,t have Oscar 68 on there though.
Jerry w0sat
_______________________________________________
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-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 8
Date: Wed, 30 Jun 2010 09:03:37 -0400
From: "Mark Lunday" <mlunday@xx.xx.xxx>
Subject: [amsat-bb] Re: question
To: "'Adrian Engele'" <aa5uk@xxxxx.xxx>, "'Dads'" <w0sat@xxx.xxx>,
<amsat-bb@xxxxx.xxx>
Message-ID: <007801cb1854$a798a770$f6c9f650$@xx.xxx>
Content-Type: text/plain; charset="us-ascii"
Thanks, Adrian. I wanted to make sure that my notes were correct, as I am
not very experienced and have made mistakes in using the wrong mode.
Fortunately, a polite ham would gently correct me on the air, without making
me feel too dumb J
And I appreciate your kind response as well, Adrian. Just one more reason
why I enjoy this hobby and AMSAT. Thanks, 73
From: Adrian Engele [mailto:aa5uk@xxxxx.xxxx
Sent: Wednesday, June 30, 2010 9:00 AM
To: Mark Lunday; Dads; amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] Re: question
Mark,
Both our responses are correct. I decided to leave AO-7 Mode A off from my
initial response to Jerry as few people use that mode these days. This is
a non inverting transponder, therefore USB-Up and USB-Down.
I was trying to address Jerry's request for helping our newcomers. Their
concentration would most likely be on FO-29, HO-68, AO7 (mode B) and VO52.
All four of these satellites are LSB Up and USB down as you indicated below.
A great web site where all this information is nicely detailed is at:
http://www.dk3wn.info/satellites.shtml See each satellite page.
73, Adrian AA5UK
_____
From: Mark Lunday <mlunday@xx.xx.xxx>
To: Adrian Engele <aa5uk@xxxxx.xxx>; Dads <w0sat@xxx.xxx>;
amsat-bb@xxxxx.xxx
Sent: Wed, June 30, 2010 7:45:26 AM
Subject: RE: [amsat-bb] Re: question
Adrian, I had a thread from December 2008 on this board that said the
following:
>> VO-52 is LSB on the uhf uplink and USB on the vhf downlink
>> FO-29 is LSB on the vhf uplink and USB on the UHF downlink.
>> AO-7 is LSB on the uhf uplink and USB on the vhf downlink. Mode B
>> AO-7 is USB on the vhf uplink and USB on the 10m downlink Mode A
Can you please comment?
-----Original Message-----
From: amsat-bb-bounces@xxxxx.xxx [mailto:amsat-bb-bounces@xxxxx.xxxx On
Behalf Of Adrian Engele
Sent: Tuesday, June 29, 2010 8:28 PM
To: Dads; amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: question
Jerry,
Linear satellites today use LSB for the Uplink and USB for the downlink by
general agreement.
Also by agreement:
CW is on the lower 1/3 of the downlink bandpass.
Mixed Modes are in the center 1/3 of the downlink bandpass.
SSB is in the top 1/3 of the downlink bandpass.
73, Adrian AA5UK
________________________________
From: Dads <w0sat@xxx.xxx>
To: amsat-bb@xxxxx.xxx
Sent: Tue, June 29, 2010 6:39:01 PM
Subject: [amsat-bb] question
Hi : I sent a couple friends that are interested to the AMSAT
website.
I told them to look at all the satellites.
They found the site had all satellites on it.
When they brought up the sats they didn,t put on the
sidebands on the linear birds, the up and downlinks
.
I mean the upper and lower sidebands for these birds.
So I sent them to the UK site and they were there.
They didn,t have Oscar 68 on there though.
Jerry w0sat
_______________________________________________
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-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 9
Date: Wed, 30 Jun 2010 09:26:21 -0400
From: Roger Kolakowski <Rogerkola@xxx.xxx>
Subject: [amsat-bb] Re: ISS APRS Packet Active
To: Mani VU2WMY <wmy@xxxx.xxx.xx>
Cc: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Message-ID: <4C2B45FD.6060702@xxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Good day Mani...
I can send you here to see what is happening on ISS for Packet...
http://www.ariss.net/
Roger
WA1KAT
Mani VU2WMY wrote:
> Just heard ISS APRS packet active over VU Land during 12:44 pass. Can
> someone confirm?
>
>
>
> Mani, VU2WMY
>
> _______________________________________________
> 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: 10
Date: Wed, 30 Jun 2010 09:45:42 -0400
From: "Robert Bruninga" <bruninga@xxxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: "'i8cvs'" <domenico.i8cvs@xxx.xx>, "'AMSAT-BB'"
<amsat-bb@xxxxx.xxx>
Message-ID: <04D31A4BC107419E872DCE4D4834B7E4@xxxxx.xxxx.xxx>
Content-Type: text/plain; charset="US-ASCII"
Domenico,
Thanks for the calculations.
You confirmed it will not work for Hams.
That is about what I was getting and I wanted to make sure
before I scratched the idea off the list of possibilities. I
just wanted to check-it-out since the purpose of the large
buckyball in space was for "HF REFLECTION", I wanted to see if
it had any possibilities for amateurs.
Apparentlly it will only be good for HF megawatt radars...
Thanks
Bob, WB4APR
> -----Original Message-----
> From: i8cvs [mailto:domenico.i8cvs@xxx.xxx
> Sent: Tuesday, June 29, 2010 9:53 PM
> To: Bob Bruninga; AMSAT-BB
> Subject: Re: [amsat-bb] HF Satellite Relay
>
> ----- Original Message -----
> From: "Robert Bruninga" <bruninga@xxxx.xxx>
> To: <amsat-bb@xxxxx.xxx>
> Sent: Monday, June 28, 2010 7:44 PM
> Subject: [amsat-bb] HF Satellite Relay
>
> > Heard today of a Passive HF relay satellite being proposed.
> > Wondered if Hams could relay off of it.
> >
> > It's a 10m diameter sphere.
> > I assumed a 10m signal and 1000 Watts
> > And antenna gains at both ends of 10 dB.
> > Unless I made a dumb error, it looks impossible?
> > I get a received signal of -170 dBm
> > Compared to a good HF receiver of -122 dBm
> > So its 48 dB down in the noise.
> > Going to narrow band, could improve things, but the Doppler
of
> > +/- 600 Hz would make that difficult.
> >
> > Anyway, if someone else wants to double check the link
budget
> > using the radar range equation, go for it.
> >
> > The beauty of this system is that it is perfectly spherical,
so
> > the reflection coefficient would be constant within 1 dB.
That
> > is the advantage over trying to use the ISS or other large
> > rocket body... They vary by 20 dB making communication by
> > reflection impossible.
> >
> > Oh, and it would be in space for 30 years or more. So with
> > something that reliable, it would be worth developing an
amateur
> > capability to use it.
> > It is not designed for comms, but as a calibration sphere
for
> > over the horizon radars that have LOTS more power and LOTS
more
> > gain than we do.
> >
> > Bob, Wb4APR
> >
>
> Hi Bob, WB4APR
>
> I have assumed that the altitude of the Passive HF relay
> satellite over the
> earth is 1500 km and as we know the diameter of the sphere is
> 10 meters.
> Also I assumed that the reflectivity coefficient of the sphere
is 50%
>
> The 28 MHz Round Trip Isotropic Attenuation using the concept
of Radar
> Equation is as follows:
>
> Pt x Gt x Ar x Sigma
> Pr = ------------------------------
> (4 x 3.14 x R^2)^2
>
> where :
>
> Pr = received power
>
> Pt = transmitted power = 1watt
>
> Gt = gain of a 28 MHz isotropic antenna = 1 in power ratio
>
> Ar = Aperture of the isotropic antenna at 28 MHz in square
meters.
>
> R = Radius of a sphere wich distance from the earth is 1500^3
i.e
> the distance from the Passive HF relay satellite and
> the earth
> expressed in meters.
>
> Sigma = Surface of the target in square meters i.e. of the
Passive
> HF relay satellite as seen as a radar target
> disc multiplied
> by the reflectivity coefficient of 50%
>
> Computing:
>
> / 2 2
> /\ 10.71
> Ar = ---------- = ----------- = 9.13 square meters
> 4 x 3,14 4 x 3,14
>
>
> Sigma = 5^2 x 3.14 x 0.5 = 39.2 square meters
>
>
>
> 1 x 1 x 9.13 x 39.2
> Pr = --------------------------------------- = 4.47 ^ -25 watt
> (4 x 3.14 x 1500000^2) ^2
>
>
>
1
> Round trip attenuation = 10 log --------------- = 243.5 dB
> 4.47^
-25
>
> Link budged calculation:
>
> Assuming that we are using a good HF receiver with a NF= 8 dB
> equivalent to 1539 kelvin we must consider in addition that
> the receiver
> sensitivity is limited by the external available noise
> power.For quiet,rural
> locations the galactic noise is the limiting factor and at 28
> MHz the noise
> temperature is around 29.000 kelvin so that reducing the
Noise Figure
> belove 8 dB at 28 MHz do not improve too much the S/N ratio.
>
> With the above data the noise floor of this receiver for SSB
into a
> bandwidth of 2500 Hz can be calculated as follows:
>
> Noise Floor = KTB = 1.38 x 10^-23 ( 1539 + 29.000 ) x 2500 = -
151dBW
> or - 121 dBm
>
> TX power 1000 watt.............................+30 dBW
> TX Antenna gain....................................+10 dBi
>
> -----------
> Transmitted EIRP .................................+40 dBW
> Round trip attenuation 1500 km..........- 243.5 dB
>
> -----------
> Received power Pr on isotropic
> antenna on the earth ..............................-203.5 dBW
> RX antenna gain....................................+ 10 dB
>
> -----------
> Available power at RX input............... - 193.5 dBW
> RX noise floor...................................... - 151 dBW
>
> -----------
> Signal received with a S/N ratio.......... - 42.5 dB
>
>
> So according with Bob calculations the signal is 42.5 dB
> under the noise and
> so it is not detectable.
>
> Best 73" de
>
> i8CVS Domenico
>
>
>
>
>
>
>
>
------------------------------
Message: 11
Date: Wed, 30 Jun 2010 09:35:44 -0500
From: Joe <nss@xxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: amsat-bb@xxxxx.xxx
Message-ID: <4C2B5640.4060709@xxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I agree,
It's not the meteor or even the ionized portion near the head that you
bounce signals off of, it's the inonized trail that it leaves behind.
and that can be many many miles long.
Now about reflecting off of odd shaped things. A buddy an myself used
to in the late 70's have fun on 2 meters just playing around. we were
too far apart for direct communication, I was in the northwest suburbs
of Chicago, he was down in central indiana.
We would point our 4 ele beams at eachother and run like a meteor
scatter transmission sequesnce. and would make a qso. it was flaky and
wide variations in signal strength. But what did we use?
It was all the Jets coming in to land at Ohare! between us was the main
route for all the jets to com in on. The route killed TV all the time
by making signals in phase and then out then in then out, so we thought
if it's strong enough reflection to cancel out a direct megawayy
signal, hmmm. so we tried and it worked and worked faily well. each
"Opening" lasted between 10 and 15 seconds. and would go most times from
s zero to peg the meter.
was fun
and thats an odd shaped reflector. that for me was ohhh 60 miles
away, and for him close to 100 miles.
Joe WB9SBD
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 6/30/2010 3:31 AM, Tony wrote:
> Dominico,
>
> Your path loss calculations were very interesting. At first glance, I
> assumed it would be possible to hear 28MHz echoes off of the 10M sphere
> since smaller targets such as the ionized head of a meteor can reflect
> such signals with enough signal power to be heard.
>
> But, I think this is one of those apples to oranges comparisons since:
> a. the ionization around the front of the meteor head is responsible for
> signal reflection, not the rock itself. And b. the diameter of the
> ionized atmosphere in front of the meteor may be a lot larger than one
> would imagine.
>
> The 10M sphere brought another question to mind -- Mike Wantanabe,
> JH1KRC, managed to hear his own EME echoes on the 21MHz using a KW and a
> 6 element Yagi. Details and recordings are on his website (see below). I
> was wondering how the path loss calculations compare with his EME results.
>
> http://eme.dokidoki.ne.jp/sound/jh1krc/index.html
>
> Thanks Dominico...
>
> Tony -K2MO
>
>
> On 6/29/2010 9:52 PM, i8cvs wrote:
>
>> ----- Original Message -----
>> From: "Robert Bruninga"<bruninga@xxxx.xxx>
>> To:<amsat-bb@xxxxx.xxx>
>> Sent: Monday, June 28, 2010 7:44 PM
>> Subject: [amsat-bb] HF Satellite Relay
>>
>>
>>
>>> Heard today of a Passive HF relay satellite being proposed.
>>> Wondered if Hams could relay off of it.
>>>
>>> It's a 10m diameter sphere.
>>> I assumed a 10m signal and 1000 Watts
>>> And antenna gains at both ends of 10 dB.
>>> Unless I made a dumb error, it looks impossible?
>>> I get a received signal of -170 dBm
>>> Compared to a good HF receiver of -122 dBm
>>> So its 48 dB down in the noise.
>>> Going to narrow band, could improve things, but the Doppler of
>>> +/- 600 Hz would make that difficult.
>>>
>>> Anyway, if someone else wants to double check the link budget
>>> using the radar range equation, go for it.
>>>
>>> The beauty of this system is that it is perfectly spherical, so
>>> the reflection coefficient would be constant within 1 dB. That
>>> is the advantage over trying to use the ISS or other large
>>> rocket body... They vary by 20 dB making communication by
>>> reflection impossible.
>>>
>>> Oh, and it would be in space for 30 years or more. So with
>>> something that reliable, it would be worth developing an amateur
>>> capability to use it.
>>> It is not designed for comms, but as a calibration sphere for
>>> over the horizon radars that have LOTS more power and LOTS more
>>> gain than we do.
>>>
>>> Bob, Wb4APR
>>>
>>>
>>>
>> Hi Bob, WB4APR
>>
>> I have assumed that the altitude of the Passive HF relay satellite over the
>> earth is 1500 km and as we know the diameter of the sphere is 10 meters.
>> Also I assumed that the reflectivity coefficient of the sphere is 50%
>>
>> The 28 MHz Round Trip Isotropic Attenuation using the concept of Radar
>> Equation is as follows:
>>
>> Pt x Gt x Ar x Sigma
>> Pr = ------------------------------
>> (4 x 3.14 x R^2)^2
>>
>> where :
>>
>> Pr = received power
>>
>> Pt = transmitted power = 1watt
>>
>> Gt = gain of a 28 MHz isotropic antenna = 1 in power ratio
>>
>> Ar = Aperture of the isotropic antenna at 28 MHz in square meters.
>>
>> R = Radius of a sphere wich distance from the earth is 1500^3 i.e
>> the distance from the Passive HF relay satellite and the earth
>> expressed in meters.
>>
>> Sigma = Surface of the target in square meters i.e. of the Passive
>> HF relay satellite as seen as a radar target disc
multiplied
>> by the reflectivity coefficient of 50%
>>
>> Computing:
>>
>> / 2 2
>> /\ 10.71
>> Ar = ---------- = ----------- = 9.13 square meters
>> 4 x 3,14 4 x 3,14
>>
>>
>> Sigma = 5^2 x 3.14 x 0.5 = 39.2 square meters
>>
>>
>>
>> 1 x 1 x 9.13 x 39.2
>> Pr = --------------------------------------- = 4.47 ^ -25 watt
>> (4 x 3.14 x 1500000^2) ^2
>>
>>
>> 1
>> Round trip attenuation = 10 log --------------- = 243.5 dB
>> 4.47^ -25
>>
>> Link budged calculation:
>>
>> Assuming that we are using a good HF receiver with a NF= 8 dB
>> equivalent to 1539 kelvin we must consider in addition that the receiver
>> sensitivity is limited by the external available noise power.For
quiet,rural
>> locations the galactic noise is the limiting factor and at 28 MHz the noise
>> temperature is around 29.000 kelvin so that reducing the Noise Figure
>> belove 8 dB at 28 MHz do not improve too much the S/N ratio.
>>
>> With the above data the noise floor of this receiver for SSB into a
>> bandwidth of 2500 Hz can be calculated as follows:
>>
>> Noise Floor = KTB = 1.38 x 10^-23 ( 1539 + 29.000 ) x 2500 = - 151dBW
>> or - 121 dBm
>>
>> TX power 1000 watt.............................+30 dBW
>> TX Antenna gain....................................+10 dBi
>>
-----------
>> Transmitted EIRP .................................+40 dBW
>> Round trip attenuation 1500 km..........- 243.5 dB
>>
-----------
>> Received power Pr on isotropic
>> antenna on the earth ..............................-203.5 dBW
>> RX antenna gain....................................+ 10 dB
>>
-----------
>> Available power at RX input............... - 193.5 dBW
>> RX noise floor...................................... - 151 dBW
>>
-----------
>> Signal received with a S/N ratio.......... - 42.5 dB
>>
>>
>> So according with Bob calculations the signal is 42.5 dB under the noise
and
>> so it is not detectable.
>>
>> Best 73" de
>>
>> i8CVS Domenico
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> 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
>>
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signature database 5238 (20100629) __________
>>
>> The message was checked by ESET NOD32 Antivirus.
>>
>> http://www.eset.com
>>
>>
>>
>>
>>
>>
> _______________________________________________
> 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: 12
Date: Wed, 30 Jun 2010 10:51:19 -0400
From: "Mark L. Hammond" <marklhammond@xxxxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: bruninga@xxxx.xxx
Cc: AMSAT-BB <amsat-bb@xxxxx.xxx>
Message-ID:
<AANLkTik_453MzB8eV5kwJ6Y9LCxI0pscfsS4gAfmB7St@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
What about the narrow band digital EME modes?
Mark N8MH
On Wed, Jun 30, 2010 at 9:45 AM, Robert Bruninga <bruninga@xxxx.xxx> wrote:
> Domenico,
>
> Thanks for the calculations.
> You confirmed it will not work for Hams.
>
> That is about what I was getting and I wanted to make sure
> before I scratched the idea off the list of possibilities. ?I
> just wanted to check-it-out since the purpose of the large
> buckyball in space was for "HF REFLECTION", I wanted to see if
> it had any possibilities for amateurs.
>
> Apparentlly it will only be good for HF megawatt radars...
> Thanks
> Bob, WB4APR
>
>> -----Original Message-----
>> From: i8cvs [mailto:domenico.i8cvs@xxx.xxx
>> Sent: Tuesday, June 29, 2010 9:53 PM
>> To: Bob Bruninga; AMSAT-BB
------------------------------
Message: 13
Date: Wed, 30 Jun 2010 18:48:09 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: "Joe" <nss@xxx.xxx>, "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Message-ID: <003a01cb1874$05d66240$0201a8c0@xxx.xx>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: "Joe" <nss@xxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Sent: Wednesday, June 30, 2010 4:35 PM
Subject: [amsat-bb] Re: HF Satellite Relay
> I agree,
> Now about reflecting off of odd shaped things. A buddy an myself used
> to in the late 70's have fun on 2 meters just playing around. we were
> too far apart for direct communication, I was in the northwest suburbs
> of Chicago, he was down in central indiana.
>
> We would point our 4 ele beams at eachother and run like a meteor
> scatter transmission sequesnce. and would make a qso. it was flaky and
> wide variations in signal strength. But what did we use?
>
> It was all the Jets coming in to land at Ohare! between us was the main
> route for all the jets to com in on. The route killed TV all the time
> by making signals in phase and then out then in then out, so we thought
> if it's strong enough reflection to cancel out a direct megawayy
> signal, hmmm. so we tried and it worked and worked faily well. each
> "Opening" lasted between 10 and 15 seconds. and would go most times from
> s zero to peg the meter.
>
> was fun and thats an odd shaped reflector. that for me was ohhh 60 miles
> away, and for him close to 100 miles.
>
> Joe WB9SBD
>
> The Original Rolling Ball Clock
> Idle Tyme
> Idle-Tyme.com
> http://www.idle-tyme.com
>
Hi Joe, WB9SBD
I agree that the QSO was possible because It was the reflection of all the
Jets coming in to land at Ohare! between you and your ham friend it was
the main route for all the jets to com in on.
For the above reason I have sent to you a zipped file of a very interesting
article on this matter titled "Aircraft Scatter" written by Kent Britain,
WA5VJB.
If someone is isterested on it drop me a request off line.
Best 73" de
i8CVS Domenico
------------------------------
Message: 14
Date: Wed, 30 Jun 2010 13:00:52 -0400
From: John Papay <john@xxxxxx.xxx>
Subject: [amsat-bb] SO-67 Suggestions
To: amsat-bb@xxxxx.xxx
Message-ID: <440808.50681.qm@xxxxxxx.xxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset="us-ascii"; format=flowed
SO-67 is in a mode whereby the uplink audio is
repeated as long as the transmitter is turned on.
If there is no PL on the uplink, repeated audio
will be reduced by about 10db compared to rx noise
when no satellite is in view. SO-67 is being turned
on for 15 minute periods as conditions permit.
If you transmit PL, the repeated audio level will
be 10db higher than with no PL, however the PL tone
level will also be very high. There is apparently no tone
filtering between the receiver and the transmitter.
Once you stop transmitting with PL, you will hear rx
noise at full deviation. After 2-1/2 seconds or so,
the repeated noise/audio level will once again be 10db down.
As mentioned in another post, the best way to operate
given this configuration is not to use PL and work with
the low audio. Since this bird is very strong, low audio
is not a big problem. If there are signals with PL, the
audio level will jump up 10db so watch your ears.
73,
John K8YSE
------------------------------
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Sent via amsat-bb@xxxxx.xxx. Opinions expressed are those of the author.
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