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CX2SA > SATDIG 30.06.10 11:07l 1054 Lines 34137 Bytes #999 (0) @ WW
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Subj: AMSAT-BB-digest V5 285
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Sent: 100630/0851Z @:CX2SA.LAV.URY.SA #:3422 [Minas] FBB7.00e $:AMSATBB5285
From: CX2SA@CX2SA.LAV.URY.SA
To : SATDIG@WW
Today's Topics:
1. [Fwd: Uploaded Amsat Schedules] (Andrew Glasbrenner)
2. TM-D700 voicemodule. was: pass prediction (Kai Gunter Brandt)
3. Re: Echo-1 A (Bill Bordy, NJ1H )
4. question (Dads)
5. Re: question (Nigel Gunn G8IFF/W8IFF)
6. Re: question (Anthony Monteiro)
7. Re: question (Adrian Engele)
8. Samuel Morse (Bruce)
9. Re: HF Satellite Relay (i8cvs)
10. Rulo, Nebraska (EN20) - 30 Jun (Gail A Mcdaniel)
11. Re: Samuel Morse (Tony Langdon)
12. 13 Colonies Special Event Update (Dave Webb KB1PVH)
13. Re: HF Satellite Relay (Bob- W7LRD)
14. Alinco DJ-G7T as a full-duplex FM Sat rig? (dave@xxxxx.xxxx
15. Re: HF Satellite Relay (Tony)
----------------------------------------------------------------------
Message: 1
Date: Tue, 29 Jun 2010 15:34:35 -0400
From: Andrew Glasbrenner <glasbrenner@xxxxxxxxxx.xxx>
Subject: [amsat-bb] [Fwd: Uploaded Amsat Schedules]
To: Amsat-BB <amsat-bb@xxxxx.xxx>
Message-ID: <4C2A4ACB.6010306@xxxxxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Forwarded from the Sumbandila team:
Hi Guys,
The schedules below were uploaded to the satellite.
29/06/2010
North America
19:35
Brazil
23:37
30/06/2010
South Africa
07:00
North America
00:00
03:10
04:45
Brazil
01:10
------------------------------
Message: 2
Date: Tue, 29 Jun 2010 22:38:36 +0200
From: Kai Gunter Brandt <kai.brandt@xxx.xxx.xx>
Subject: [amsat-bb] TM-D700 voicemodule. was: pass prediction
To: bruninga@xxxx.xxx
Cc: amsat-bb@xxxxx.xxx
Message-ID: <4C2A59CC.8050603@xxx.xxx.xx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 06/29/2010 08:25 PM, Robert Bruninga wrote:
>> sending %HIGH to the TM-D710 is just spelling each letter :o/
>>
> There is a list of codes somewhere. To speak one of the pre-set
> words, you just include the text %XX where XX is a two byte HEX
> value of the word you want spoken. I guess you could just try
> all 256 codes and write down the words spoken? Should be the
> same voice chip as in the D700.
>
> Bob
> WB4APR
>
hmm ok then it doesn't work as i have tested this. i don't remember the URL.
Not sure if it's a TM-D710 bug or if it's not implemented.
Kai Gunter
LA3QMA
------------------------------
Message: 3
Date: Tue, 29 Jun 2010 16:58:12 -0400
From: "Bill Bordy, NJ1H " <nj1h@xxxxxxx.xxx>
Subject: [amsat-bb] Re: Echo-1 A
To: amsat-bb@xxxxx.xxx
Message-ID: <4C2A5E64.9090008@xxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I remember Echo very well. As Domenico stated it was very visible. I
remember my father taking my siblings and I outside to view. He
certainly had my attention then.
73,
Bill
NJ1H
On 6/29/2010 2:05 PM, i8cvs wrote:
> Hi Greg, KO6TH
>
> Echo-1 A was a passive communication satellite launched on 12 august 1960
> in a circular orbit at 1519 - 1687 km and it was a balloon 30.5 meters in
> diameter made of 0.0127 mm thick metallized mylar polyester film to reflects
> signals transmitted from the earth at 960 MHz and 2390 MHz
>
> Echo-1 A was also carrying two VHF TLM beacons at 108.000 and 108.03 MHz
> with a power of 45 mW and I was receiving both of them for several days
> using a homebrewed downconverter with two low noise triodes 6AN4 in a
> cascode input stage and a simple three elements yagi.
>
> At that epoch time the 108 MHz band was used only for aeronautical and space
> communications but not for FM broadcasting as novadays so that it was free
> of interfering signals and man made noise and the only existing noise was
> the galactic noise.
>
> By the way in the early 1960 it was my first received satellite signal and
> it was very exiting to receive the 45 mW beacons using only a three elements
> yagi and a downconverter with a noise figure at best of 6 dB while to see
> the balloon as a bright star by naked eye flying in the night.
>
> For more technical informations on ECHO-1 ,ECHO-1A and ECHO-2 look at
> the following web page:
>
> http://msl.jpl.nasa.gov/QuickLooks/echoQL.html
>
>
> 73" de
>
> i8CVS Domenico
>
> ----- Original Message -----
> From: "Greg D."<ko6th_greg@xxxxxxx.xxx>
> To:<bruninga@xxxx.xxx>;<amsat-bb@xxxxx.xxx>
> Sent: Tuesday, June 29, 2010 7:03 AM
> Subject: [amsat-bb] Re: HF Satellite Relay
>
>
>
------------------------------
Message: 4
Date: Tue, 29 Jun 2010 18:39:01 -0500
From: "Dads" <w0sat@xxx.xxx>
Subject: [amsat-bb] question
To: <amsat-bb@xxxxx.xxx>
Message-ID: <SNT125-DS20707D99E17E53843157C9E4CB0@xxx.xxx>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
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
------------------------------
Message: 5
Date: Tue, 29 Jun 2010 23:53:08 +0000
From: Nigel Gunn G8IFF/W8IFF <nigel@xxxxx.xxx>
Subject: [amsat-bb] Re: question
To: Dads <w0sat@xxx.xxx>
Cc: amsat-bb@xxxxx.xxx
Message-ID: <4C2A8764.3010705@xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Perhaps that's because it doesn't really matter which sideband you use on
the linear sats although I believe it's
customary to Tx USB.
On 29-Jun-10 23:39, Dads wrote:
>
> 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
>
>
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.829 / Virus Database: 271.1.1/2967 - Release Date: 06/27/10
18:35:00
>
--
Nigel A. Gunn, 1865 El Camino Drive, Xenia, OH 45385-1115, USA. tel +1 937
825 5032
Amateur Radio G8IFF W8IFF (was KC8NHF), e-mail nigel@xxxxx.xxx www
http://www.ngunn.net
Member of ARRL, GQRP #11396, QRPARCI #11644, SOC #548, Flying Pigs QRP
Club International #385,
Dayton ARA #2128, AMSAT-NA LM-1691, AMSAT-UK 0182, MKARS, ALC,
GCARES, XWARN.
------------------------------
Message: 6
Date: Tue, 29 Jun 2010 20:03:26 -0400
From: Anthony Monteiro <aa2tx@xxxxxxx.xxx>
Subject: [amsat-bb] Re: question
To: Nigel Gunn G8IFF/W8IFF <nigel@xxxxx.xxx>, Dads <w0sat@xxx.xxx>
Cc: amsat-bb@xxxxx.xxx
Message-ID: <201006300003.o5U03hcj014647@xxxxx.xxx>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Dear Friends,
For linear transponders, it is customary to receive in USB.
So, if the transponder is non-inverting, TX in USB. If it is
inverting, TX in LSB.
73,
Tony AA2TX
AMSAT VP Engineering
---
At 07:53 PM 6/29/2010, Nigel Gunn G8IFF/W8IFF wrote:
>Perhaps that's because it doesn't really matter which sideband you
>use on the linear sats although I believe it's
>customary to Tx USB.
>
>On 29-Jun-10 23:39, Dads wrote:
> >
> > 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
> >
> >
> >
> >
> > No virus found in this incoming message.
> > Checked by AVG - www.avg.com
> > Version: 9.0.829 / Virus Database: 271.1.1/2967 - Release Date:
> 06/27/10 18:35:00
> >
>
>--
>Nigel A. Gunn, 1865 El Camino Drive, Xenia, OH 45385-1115,
>USA. tel +1 937 825 5032
>Amateur Radio G8IFF W8IFF (was KC8NHF), e-mail
>nigel@xxxxx.xxx www http://www.ngunn.net
>Member of ARRL, GQRP #11396, QRPARCI #11644, SOC #548, Flying Pigs
>QRP Club International #385,
> Dayton ARA #2128, AMSAT-NA LM-1691, AMSAT-UK 0182,
> MKARS, ALC, GCARES, XWARN.
>
>_______________________________________________
>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: 7
Date: Tue, 29 Jun 2010 17:27:58 -0700 (PDT)
From: Adrian Engele <aa5uk@xxxxx.xxx>
Subject: [amsat-bb] Re: question
To: Dads <w0sat@xxx.xxx>, amsat-bb@xxxxx.xxx
Message-ID: <591687.87122.qm@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=us-ascii
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
------------------------------
Message: 8
Date: Tue, 29 Jun 2010 18:32:59 -0700 (PDT)
From: Bruce <kk5do@xxxx.xxx>
Subject: [amsat-bb] Samuel Morse
To: amsat-bb@xxxxx.xxx
Message-ID: <612102.1221.qm@xxxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=us-ascii
I could not resist forwarding this spam as I found it most amusing that
Samuel Morse is still alive and wanting my help to move money from a foreign
country. I removed the email address from the spam. Can you say spam in
morse code?
73...bruce
The Desk Of,
Mr. Samuel Morse
Fund Manager,
Fidelity
International, UK .
I feel quite safe dealing with you in this important business.Though, this
medium (Internet) has been greatly abused, I choose to reach you through it
because it still remains the
fastest medium of communication.
Do accept my sincere apologies if my mail does not meet your personal
ethics.I knew that this mail will come to you as a surprise, but please do
not be discouraged with my
proposal, it was due to how things are moving with me, then i decided to
write to you when I saw your contact information in a directory.
However, this correspondence is unofficial and private, and it should be
treated as such.At first I will like to assure you that this transaction is
100% risk and trouble free to both parties
My name is Mr. Samuel
Morse, a Fund Manager with Fidelity Investment, UK. I handle all our
Investors Capital Project Funds which enabled me to divert 1.2% of
Investors Excess Return Capital Funds to our Magellan Trust Funds
Account where anyone can be presented to claim the funds.
Total sum
of Fifteen Million, Seven Hundred and Forty Five Thousand British Pounds
(15.745.000)BP has been diverted, representing 1.2% of Excess Return
Capital Funds from the Investor Capital Project Funds for 2006/2007
fiscal year.
I need a reliable and trustworthy person with whom I can work this deal out
so that we can claim the funds as mentioned
above.
There is no risk attached and the funds in question can never
be dictated or traced.
Sincerely,
Mr. Samuel Morse
------------------------------
Message: 9
Date: Wed, 30 Jun 2010 03:52:57 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: "Bob Bruninga" <bruninga@xxxx.xxx>, "AMSAT-BB"
<amsat-bb@xxxxx.xxx>
Message-ID: <005d01cb17f6$f6e09c60$0201a8c0@xxx.xx>
Content-Type: text/plain; charset="iso-8859-1"
----- 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 vot 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: 10
Date: Tue, 29 Jun 2010 18:54:26 -0700 (PDT)
From: Gail A Mcdaniel <gmcdanl@xxxxxxxxx.xxx>
Subject: [amsat-bb] Rulo, Nebraska (EN20) - 30 Jun
To: AMSAT-BB@xxxxx.xxx
Message-ID: <424854.28250.qm@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=iso-8859-1
David and I will be working a few passes tomorrow afternoon from Rulo
Nebraska (EN20gb).? We will probably work from the Lewis and Clark Camp Site
on the Nebraska side of the Missouri River if it gives us a fairly clear
view of the passes.? We are planning on working the AO-27 pass @ 1922z,
SO-50 pass @ 1949z and AO-27 pass at 2102z.? If you are looking for a
Nebraska contact and can work on of these passes... just let one of us know
if you want a QSL card and we will get it in the mail asap- no SASE is
required.
73
David(KB0RZE)
Gail(KB0RZD)
------------------------------
Message: 11
Date: Wed, 30 Jun 2010 12:48:44 +1000
From: Tony Langdon <vk3jed@xxxxx.xxx>
Subject: [amsat-bb] Re: Samuel Morse
To: Bruce <kk5do@xxxx.xxx>
Cc: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Message-ID: <5C6132EF-62D7-44AF-A0C1-28AD76C18525@xxxxx.xxx>
Content-Type: text/plain; charset=us-ascii
>
> alive and wanting my help to move money from a foreign country. I removed
the email address from the spam. Can you say spam in morse code?
>
>
... .--. .- --
There you go. :D
------------------------------
Message: 12
Date: Wed, 30 Jun 2010 00:06:37 -0400
From: Dave Webb KB1PVH <kb1pvh@xxxxx.xxx>
Subject: [amsat-bb] 13 Colonies Special Event Update
To: AMSAT -BB <amsat-bb@xxxxx.xxx>
Message-ID:
<AANLkTinAfVFQTW84y2Be06JX7bfIuX6ntbkZ_F6plAgi@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Just a reminder about the upcoming 13 Original Colonies Special Event. It
runs from July 1 through July 6. Unfortunately, we lost NH due to work
commitments, so if there is another station that wants to represent NH, get
in touch with me ASAP at kb1pvh@xxxxx.xxx.
Here is the link for more info- http://www.13colonies.info/
Here are the calls to listen for
NY- Pete, WB2OQQ/K2A
VA- Steve, NL7VX/K2B ( Only available on July 1 and in the AM on the 2nd )
RI ---------------------------
CT- Paul, K1PL/K2D
DE ------------------------
MD- Bruce, WA3SWJ/K2F
GA- Tim, N3TL/K2G
MA- Dave, KB1PVH/K2H
NJ ----------------------
NC- Mark, N8MH/K2J
NH -------------------------
SC- Art, K4YYL/K2L
PA- Rich, K3BFS/K2M
Thanks,
Dave - KB1PVH
------------------------------
Message: 13
Date: Wed, 30 Jun 2010 04:51:21 +0000 (UTC)
From: Bob- W7LRD <w7lrd@xxxxxxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: i8cvs <domenico.i8cvs@xxx.xx>
Cc: AMSAT-BB <amsat-bb@xxxxx.xxx>
Message-ID:
<1193021497.49615.1277873481103.JavaMail.root@xxxxxxx.xxxxxxxxxx.xx.xxxx.xxxxx
xx.xxx>
Content-Type: text/plain; charset=utf-8
You gotta love this guy!? It takes me days to figure it out, but I always
learn something!
73 Bob W7LRD
----- Original Message -----
From: "i8cvs" <domenico.i8cvs@xxx.xx>
To: "Bob Bruninga" <bruninga@xxxx.xxx>, "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Sent: Tuesday, June 29, 2010 6:52:57 PM
Subject: [amsat-bb] Re: 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
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Message: 14
Date: Wed, 30 Jun 2010 00:08:26 -0700
From: dave@xxxxx.xxx
Subject: [amsat-bb] Alinco DJ-G7T as a full-duplex FM Sat rig?
To: amsat-bb@xxxxx.xxx
Message-ID:
<3417b6a65352641f6d84b81f53ac9150.squirrel@xxxxxxx.xxxxx.xxx>
Content-Type: text/plain;charset=iso-8859-1
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
------------------------------
Message: 15
Date: Wed, 30 Jun 2010 04:31:21 -0400
From: Tony <dxdx@xxxxxxxxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: AMSAT-BB <amsat-bb@xxxxx.xxx>, i8cvs <domenico.i8cvs@xxx.xx>
Message-ID: <4C2B00D9.8070007@xxxxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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 -- Mikx.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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End of AMSAT-BB Digest, Vol 5, Issue 285
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