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CX2SA > SATDIG 01.07.10 13:29l 1158 Lines 38066 Bytes #999 (0) @ WW
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To : SATDIG@WW
Today's Topics:
1. AO-7 mode B (Bob- W7LRD)
2. Re: AO-7 mode B (Andrew Glasbrenner)
3. Re: AO-7 mode B (Patrick STODDARD (WD9EWK/VA7EWK))
4. Dual band "cheap yagi" question ( interlacing elements?)
(Michael Tondee)
5. Re: HF Satellite Relay (i8cvs)
6. Re: Dual band "cheap yagi" question ( interlacing elements?)
(Edward R Cole)
7. Michigan's Upper Peninsula Grid Activation EN65, EN66, and
EN76 July 3-5, 2010 (Doug Papay)
8. Re: HF Satellite Relay (Joe)
9. 13 Colonies update ( The last one ) (Dave Webb KB1PVH)
10. Re: HF Satellite Relay (Tony)
11. Re: HF Satellite Relay (Tony)
12. SO-67 1 June possible active passes (OZ1MY)
13. 13 Colonies (Dave Webb KB1PVH)
----------------------------------------------------------------------
Message: 1
Date: Wed, 30 Jun 2010 19:17:47 +0000 (UTC)
From: Bob- W7LRD <w7lrd@xxxxxxx.xxx>
Subject: [amsat-bb] AO-7 mode B
To: amsat-bb@xxxxx.xxx
Message-ID:
<1361214409.24778.1277925467049.JavaMail.root@xxxxxxx.xxxxxxxxxx.xx.xxxx.xxxxx
xx.xxx>
Content-Type: text/plain; charset=utf-8
AO-7 seems "stuck" in mode B.? This is not a bad thing.? Anyone know, how,
why etc.
73 Bob W7LRD
------------------------------
Message: 2
Date: Wed, 30 Jun 2010 16:02:02 -0400
From: Andrew Glasbrenner <glasbrenner@xxxxxxxxxx.xxx>
Subject: [amsat-bb] Re: AO-7 mode B
To: Amsat-BB <amsat-bb@xxxxx.xxx>
Message-ID: <4C2BA2BA.4060400@xxxxxxxxxx.xxx>
Content-Type: text/plain; charset=UTF-8; format=flowed
Bob- W7LRD wrote:
> AO-7 seems "stuck" in mode B. This is not a bad thing. Anyone know, how,
why etc.
>
> 73 Bob W7LRD
> _______________________________________________
> 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
>
Short eclipses or near-eclipses over the South Pole cause the power to
drop enough to reset the 24 hour mode change timer.
73, Drew KO4MA
------------------------------
Message: 3
Date: Wed, 30 Jun 2010 13:03:47 -0700
From: "Patrick STODDARD (WD9EWK/VA7EWK)" <amsat-bb@xxxxxx.xxx>
Subject: [amsat-bb] Re: AO-7 mode B
To: amsat-bb@xxxxx.xxx
Message-ID:
<AANLkTimuwExXWOd2OTamPposNLULYU59USB1CJyLsFXq@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Hi Bob!
> AO-7 seems "stuck" in mode B.? This is not a bad thing.? Anyone know, how,
why etc.
Stuck? It looks like it was in mode A yesterday, and - based on the
posts at http://oscar.dcarr.org/ - switched back to mode B around
2200-2300 UTC yesterday. In a few hours, we'll know if it goes back
to mode A or stays in B.
I wish it would stay in mode B for another week and a half, so it
would be available every day of my upcoming trip. ;-) But if it is
back to switching between modes A and B, I will work around
that. I'm open to schedules for contacts stretching the AO-7
footprint (as well as stretching HO-68 and FO-29 footprints) when
I'm up in Canada. Parts of Europe are possible from Vancouver
Island, and I'd like to see if I can improve on my personal best for
a long-distance satellite QSO (over 6700km, from an AO-7 QSO
in May between Dayton OH and OZ1MY).
73!
Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
------------------------------
Message: 4
Date: Wed, 30 Jun 2010 16:19:40 -0400
From: Michael Tondee <mat_62@xxxxxxxxxxxx.xxx>
Subject: [amsat-bb] Dual band "cheap yagi" question ( interlacing
elements?)
To: amsat-bb@xxxxx.xxx
Message-ID: <4C2BA6DC.8010001@xxxxxxxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I'm in the process of putting together a portable FM satellite station
and I intend to homebrew the antenna using the WA5VJB "cheap yagi"
design. In looking at a picture in the May/June 2007 AMSAT Journal I've
noticed that the so called "AMSAT demonstration antenna"
that is composed of two elements on two meters and five elements on
70cm has the 70cm antenna built completely ahead of the two meter
antenna on the boom. In other words, the elements for the two bands are
not interlaced with each other.
I'm planning to build a larger antenna with more elements as I will
use it on a tripod rather than holding it by hand and I'm wondering if I
can interlace the elements of the two antennas on the boom without
adversely affecting performance. To build the antenna I envision in the
fashion shown in the picture with one antenna built completely ahead of
the other on the boom would result in an unruly boom length.
Also, if I do interlace the elements, should I place them at 90
degrees orientation to each other as is done in the Arrow design? I
doubt it makes any difference but just to be clear, I will be using two
separate radios for TX and RX so no diplexer will be used.
Yagi antennas, especially dual band designs, are not exactly my forte so
I thought I'd ask this question just to be sure.
Tnx and 73,
Michael, W4HIJ
------------------------------
Message: 5
Date: Thu, 1 Jul 2010 00:11:27 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: "Tony" <dxdx@xxxxxxxxx.xxx>, "AMSAT-BB" <amsat-bb@xxxxx.xxx>,
<jh1krc@xxx.xxx.xx.xx>
Message-ID: <001001cb18a1$2fbce160$0201a8c0@xxx.xx>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: "Tony" <dxdx@xxxxxxxxx.xxx>
To: "AMSAT-BB" <amsat-bb@xxxxx.xxx>; "i8cvs" <domenico.i8cvs@xxx.xx>
Sent: Wednesday, June 30, 2010 10:31 AM
Subject: Re: [amsat-bb] Re: HF Satellite Relay
> Dominico,
>
> 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
>
Hi Tony, K2MO
I have heard the EME echoes on the 21 MHz EME test from JH1KRC and they
are very strong for a 6 element yagi claiming 18 dBi at 10? elevation and 1
KW output at the antenna but the moon was only 10.8? above the horizon for
JH1KRC so that he was advantaged by the gain of the ground at such low moon
elevation.
By the way on day 14 jan 2006 the moon was at a distance of 400.000 km from
the earth and at a range of 405.000 km from JH1KRC so that the elapsed time
from TXing to the echoes must be ( 405.000 x 2 ) / 300.000 = 2.7 seconds and
this by hears seems to be accordingly.
We know that the range from the Moon and JH1KRC was 405.000 km and we
know that the radius of the Moon is 1735 km or 1735 x 10^3 meters
Also we know that the reflectivity coefficient of the moon at 21 MHz is 7 %
The 21 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 21 MHz isotropic antenna = 1 in power ratio
Ar = Aperture of the isotropic antenna at 21 MHz in square meters.
R = Radius of a sphere wich distance from the earth is 405 x 10^6
meters i.e the distance from the Moon and the earth expressed
in meters.
Sigma = Surface of the Moon in square meters i.e. of the Moon as a
radar target like a disc multiplied by the reflectivity
coefficient of 7 %
Computing:
/ 2 2
/\ 14.3
Ar = ---------- = ----------- = 16.24 square meters
4 x 3,14 4 x 3,14
Sigma = (1735 x 10^3) ^2 x 3.14 x 0.07 = 6.62 x 10^11 square meters
1 x 1 x 16.24 x (6.62 x 10^11)
Pr = --------------------------------------- = 2.53 x 10^-24 watt
[(4 x 3.14 x ( 405 x 10^6)^2]^2
1
Round trip attenuation = 10 log ----------------- = 236 dB
2.53 x 10^-24
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 as that of JH1KRC the galactic noise is the limiting factor and
at 21 MHz the noise temperature is around 29.000 kelvin so that reducing
the Noise Figure belove 8 dB at 21 MHz do not improve the S/N ratio.
In addition during the 15mEME01 QRO test on CW JH1KRC claims to
have used a RX CW filter with a bandwidth of only 10 Hz as you can
read in his web page.
http://eme.dokidoki.ne.jp/sound/jh1krc/index.html
With the above data the noise floor of this receiver for CW into a
bandwidth of 10 Hz can be calculated as follows:
Noise Floor = KTB = 1.38 x 10^-23 ( 1539 + 29.000 ) x 10 = - 173.7 dBW
or - 142.6 dBm
Link budged calculation:
TX power 1000 watt.............................+30 dBW
TX Antenna gain....................................+18 dBi
-----------
Transmitted EIRP .................................+48 dBW
Round trip attenuation 1500 km..........- 236 dB
-----------
Received power Pr on isotropic
antenna on the earth ..............................-188 dBW
RX antenna gain....................................+ 18 dB
-----------
Available power at RX input............... - 170 dBW
RX noise floor...................................... - 173.7 dBW
-----------
Signal received with a S/N ratio.......... + 3.7 dB
So according with the above calculations the signal of JH1KRC is 3.7 dB
over the noise and so it is detectable very strong as recorded in the file
15m01142006_31qro in the following web page.
http://eme.dokidoki.ne.jp/sound/jh1krc/index.html
In addition since the test was made with the Moon at a very low elevation
of 10.8? we must add to 3.7 dB at least 1 or 2 dB or more due to the gain
of the ground.
Probably if a new test will be made at higher moon elevation the echoes
of file 15m01142006_31qro would be audible but not so spectacular.
Best 73" de
i8CVS Domenico
------------------------------
Message: 6
Date: Wed, 30 Jun 2010 15:35:51 -0800
From: Edward R Cole <kl7uw@xxxxxxxxx.xxx>
Subject: [amsat-bb] Re: Dual band "cheap yagi" question ( interlacing
elements?)
To: Michael Tondee <mat_62@xxxxxxxxxxxx.xxx>, amsat-bb@xxxxx.xxx
Message-ID: <201006302335.o5UNZqC7008062@xxxxxxx.xxxxxxxxx.xxx>
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 12:19 PM 6/30/2010, Michael Tondee wrote:
>I'm in the process of putting together a portable FM satellite station
>and I intend to homebrew the antenna using the WA5VJB "cheap yagi"
>design. In looking at a picture in the May/June 2007 AMSAT Journal I've
>noticed that the so called "AMSAT demonstration antenna"
> that is composed of two elements on two meters and five elements on
>70cm has the 70cm antenna built completely ahead of the two meter
>antenna on the boom. In other words, the elements for the two bands are
>not interlaced with each other.
> I'm planning to build a larger antenna with more elements as I will
>use it on a tripod rather than holding it by hand and I'm wondering if I
>can interlace the elements of the two antennas on the boom without
>adversely affecting performance. To build the antenna I envision in the
>fashion shown in the picture with one antenna built completely ahead of
>the other on the boom would result in an unruly boom length.
> Also, if I do interlace the elements, should I place them at 90
>degrees orientation to each other as is done in the Arrow design? I
>doubt it makes any difference but just to be clear, I will be using two
>separate radios for TX and RX so no diplexer will be used.
>Yagi antennas, especially dual band designs, are not exactly my forte so
>I thought I'd ask this question just to be sure.
>Tnx and 73,
>Michael, W4HIJ
>_______________________________________________
>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
Michael,
I definitely recommend you place the elements at right angles as
there is minimum interaction between the two antennas. Designing a
yagi pretty much requires antenna design software. You will find
considerable interaction doing interlacing and only come up with a
compromise instead of optimized antenna. Arrow and Gulf-Alpha both
use the right angle (or cross polar) design. You can use the simple
WA5VJB design with no fear of one affecting the other. Since you do
not plan to use a diplexer the 20+ dB isolation of this design is beneficial.
73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 144-600w, 432-100w, 1296-60w, 3400-fall 2010
DUBUS Magazine USA Rep dubususa@xxxxxxx.xxx
======================================
------------------------------
Message: 7
Date: Wed, 30 Jun 2010 19:46:45 -0400
From: Doug Papay <doug.papay@xxxxx.xxx>
Subject: [amsat-bb] Michigan's Upper Peninsula Grid Activation EN65,
EN66, and EN76 July 3-5, 2010
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Message-ID:
<AANLkTimG22p_lZ1qylirUieYNy0yn5mnOy1ymcLVLEN5@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
All,
I will be active via FM satellite (AO-51, SO-50, AO-27 and SO-67) from
the uncommon grid squares EN65, EN66, and EN76 in Michigan's Upper
Peninsula during the Independence Day holiday weekend (Saturday, July
3rd PM - Monday, July 5th AM). EN76 is my primary destination with
side trips for operations from EN65 and EN66. Look for me on from
EN76 on Saturday afternoon & Sunday and Monday mornings. I expect to
operate from EN65 and EN66 during the afternoon/evening passes on
Saturday and Sunday respectively coinciding with the location of the
local fireworks displays. I will attempt to work as many passes as
possible, family commitments prevailing.
Operating conditions at my EN76 destination are unknown; satellite
imagery shows heavy tree cover as is typical of most of northern
Michigan, but since we will be located across the road from a lake, I
should have good visibility to the south from the shore and/or dock.
I expect to operate from the Lake Michigan and Lake Superior
shorelines while in EN65 and EN66 respectively. My station consists of
a Kenwood TH-D7A and Arrow antenna.
If you are looking for EN74 or EN75, it is possible that I could
operate from either these grids on the journey north (Saturday AM) or
on the return trip (Monday AM/PM). Drop me an email with your request
and I'll try to accommodate.
As always, I will sign KD8CAO/P to indicate that I am portable and not
@ my home QTH. For all contacts, no QSL or SASE is required, just
send me an email request and I will send you a QSL card.
73,
Doug KD8CAO
------------------------------
Message: 8
Date: Wed, 30 Jun 2010 18:50:18 -0500
From: Joe <nss@xxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: i8cvs <domenico.i8cvs@xxx.xx>
Cc: AMSAT-BB <amsat-bb@xxxxx.xxx>
Message-ID: <4C2BD83A.4020801@xxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
The article by VJB makes it sound like this airplane scatter is just as
weak and any other weak signal mode.
That is not what I remember for two reasons.
1- we had full scale signals on 2 meter FM simplex.
2- Imagine how strong the reflected signal has to be off the plane to
totally cancel out a megawatt direct signal from a TV Transmitter? you
know arrive 180 deg out of phase so it take that mega watt STRONG signal
and makes it drop into the snow. That can't be no weak signal for sure!
Joe WB9SBD
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 6/30/2010 11:48 AM, i8cvs wrote:
> ----- 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: 9
Date: Wed, 30 Jun 2010 20:53:29 -0400
From: Dave Webb KB1PVH <kb1pvh@xxxxx.xxx>
Subject: [amsat-bb] 13 Colonies update ( The last one )
To: AMSAT -BB <amsat-bb@xxxxx.xxx>
Message-ID:
<AANLkTilE3LgAhzGZLFcn4EcTGzKeHhy61j84mDgLCPVl@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
We have NH represented again, thanks to Jack WA1ZDV!!
So hopefully for the last time, here are the satellite operators.
NY- Pete, WB2OQQ/K2A
VA- Steve, NL7VX/K2B ( only available July 1st and 2nd )
RI ---------------------------
CT- Paul, K1PL/K2D
DE ------------------------
MD- Bruce, WA3SWJ/K2F
GA- Tim, N3TL/K2G
MA- Dave, KB1PVH/K2H
NJ- John, K2ZA/K2I ***** NEW *****
NC- Mark, N8MH/K2J
NH- Jack, WA1ZDV/K2K ****** NEW *****
SC- Art, K4YYL/K2L
PA- Rich, K3BFS/K2M
I hope everyone has a good time!!
Dave - KB1PVH/K2H
Sent from my Verizon Wireless DROID
------------------------------
Message: 10
Date: Wed, 30 Jun 2010 21:45:16 -0400
From: Tony <dxdx@xxxxxxxxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: AMSAT-BB <amsat-bb@xxxxx.xxx>
Message-ID: <4C2BF32C.30804@xxxxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Joe,
> But how would you detect a doppler shift of something that lasts less
than a second? Joe WB9SBD
It may not last very long, but the Doppler is easily detected. It's
common to see frequency shifts of 500Hz or more on VHF over a period of
1/2 second or so. The reflections from the ionized trail left behind by
the meteor can last several seconds or more during a major shower.
The image found on the link below illustrates the Doppler caused by the
motion of the meteor and the duration of the reflected signal (steady
trace) after the trail was formed. Notice that the Doppler starts a few
hundred Hertz above the steady carrier.
http://www44.zippyshare.com/v/57215533/file.html
Tony -K2MO
> The Original Rolling Ball Clock
> Idle Tyme
> Idle-Tyme.com
> http://www.idle-tyme.com
>
> On 6/30/2010 12:55 PM, Tony wrote:
>
>> On 6/30/2010 10:35 AM, Joe wrote:
>>
>>
>>> 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.
>>>
>>>
>>>
>> Joe - It would seem that the plasma cloud in front of the meteor would
>> be moving at the same velocity as the meteor itself and would cause the
>> fast Doppler shift we see prior to the trail formation.
>>
>> Tony -K2MO
>>
>>
>>
>>
>>
>>
>>> 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
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>>>>>
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>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>> _______________________________________________
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> _______________________________________________
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------------------------------
Message: 11
Date: Wed, 30 Jun 2010 23:02:21 -0400
From: Tony <dxdx@xxxxxxxxx.xxx>
Subject: [amsat-bb] Re: HF Satellite Relay
To: amSAT-BB <amsat-bb@xxxxx.xxx>
Message-ID: <4C2C053D.2090707@xxxxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Dominico,
Thank you very much for the calculations. It would seem that it is
possible to work EME on the higher HF bands using WSJT modes under the
right conditions. But, I can see that it would take an exceptional HF
station to work CW on a regular basis. Of course there's the ionosphere
to contend with as well.
Thanks again.
Tony -K2MO
On 6/30/2010 6:11 PM, i8cvs wrote:
> ----- Original Message -----
> From: "Tony"<dxdx@xxxxxxxxx.xxx>
> To: "AMSAT-BB"<amsat-bb@xxxxx.xxx>; "i8cvs"<domenico.i8cvs@xxx.xx>
> Sent: Wednesday, June 30, 2010 10:31 AM
> Subject: Re: [amsat-bb] Re: HF Satellite Relay
>
>
>> Dominico,
>>
>> 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
>>
>>
> Hi Tony, K2MO
>
> I have heard the EME echoes on the 21 MHz EME test from JH1KRC and they
> are very strong for a 6 element yagi claiming 18 dBi at 10? elevation and 1
> KW output at the antenna but the moon was only 10.8? above the horizon for
> JH1KRC so that he was advantaged by the gain of the ground at such low moon
> elevation.
>
> By the way on day 14 jan 2006 the moon was at a distance of 400.000 km from
> the earth and at a range of 405.000 km from JH1KRC so that the elapsed time
> from TXing to the echoes must be ( 405.000 x 2 ) / 300.000 = 2.7 seconds and
> this by hears seems to be accordingly.
>
> We know that the range from the Moon and JH1KRC was 405.000 km and we
> know that the radius of the Moon is 1735 km or 1735 x 10^3 meters
> Also we know that the reflectivity coefficient of the moon at 21 MHz is 7 %
>
> The 21 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 21 MHz isotropic antenna = 1 in power ratio
>
> Ar = Aperture of the isotropic antenna at 21 MHz in square meters.
>
> R = Radius of a sphere wich distance from the earth is 405 x 10^6
> meters i.e the distance from the Moon and the earth expressed
> in meters.
>
> Sigma = Surface of the Moon in square meters i.e. of the Moon as a
> radar target like a disc multiplied by the reflectivity
> coefficient of 7 %
>
> Computing:
>
> / 2 2
> /\ 14.3
> Ar = ---------- = ----------- = 16.24 square meters
> 4 x 3,14 4 x 3,14
>
>
> Sigma = (1735 x 10^3) ^2 x 3.14 x 0.07 = 6.62 x 10^11 square meters
>
>
>
> 1 x 1 x 16.24 x (6.62 x 10^11)
> Pr = --------------------------------------- = 2.53 x 10^-24 watt
> [(4 x 3.14 x ( 405 x 10^6)^2]^2
>
>
> 1
> Round trip attenuation = 10 log ----------------- = 236 dB
> 2.53 x 10^-24
>
>
> 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 as that of JH1KRC the galactic noise is the limiting factor and
> at 21 MHz the noise temperature is around 29.000 kelvin so that reducing
> the Noise Figure belove 8 dB at 21 MHz do not improve the S/N ratio.
>
> In addition during the 15mEME01 QRO test on CW JH1KRC claims to
> have used a RX CW filter with a bandwidth of only 10 Hz as you can
> read in his web page.
>
> http://eme.dokidoki.ne.jp/sound/jh1krc/index.html
>
> With the above data the noise floor of this receiver for CW into a
> bandwidth of 10 Hz can be calculated as follows:
>
> Noise Floor = KTB = 1.38 x 10^-23 ( 1539 + 29.000 ) x 10 = - 173.7 dBW
> or - 142.6 dBm
>
> Link budged calculation:
>
>
> TX power 1000 watt.............................+30 dBW
> TX Antenna gain....................................+18 dBi
>
-----------
> Transmitted EIRP .................................+48 dBW
> Round trip attenuation 1500 km..........- 236 dB
>
-----------
> Received power Pr on isotropic
> antenna on the earth ..............................-188 dBW
> RX antenna gain....................................+ 18 dB
>
-----------
> Available power at RX input............... - 170 dBW
> RX noise floor...................................... - 173.7 dBW
>
-----------
> Signal received with a S/N ratio.......... + 3.7 dB
>
>
> So according with the above calculations the signal of JH1KRC is 3.7 dB
> over the noise and so it is detectable very strong as recorded in the file
> 15m01142006_31qro in the following web page.
>
> http://eme.dokidoki.ne.jp/sound/jh1krc/index.html
>
> In addition since the test was made with the Moon at a very low elevation
> of 10.8? we must add to 3.7 dB at least 1 or 2 dB or more due to the gain
> of the ground.
>
> Probably if a new test will be made at higher moon elevation the echoes
> of file 15m01142006_31qro would be audible but not so spectacular.
>
> Best 73" de
>
> i8CVS Domenico
>
>
>
>
>
>
>
> __________ Information from ESET NOD32 Antivirus, version of virus
signature database 5241 (20100630) __________
>
> The message was checked by ESET NOD32 Antivirus.
>
> http://www.eset.com
>
>
>
>
>
------------------------------
Message: 12
Date: Thu, 1 Jul 2010 10:14:19 +0200
From: "OZ1MY" <oz1my@xxxxxx.xx>
Subject: [amsat-bb] SO-67 1 June possible active passes
To: "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Message-ID: <000601cb18f5$67ac7280$6401a8c0@xxxxxx.xx>
Content-Type: text/plain; charset="iso-8859-1"
01/07/2010
Europe
07:53:00
09:07:00
North America
15:50:00
17:25:00
Brazil
11:20:00
73 OZ1MY
Ib
------------------------------
Message: 13
Date: Thu, 1 Jul 2010 07:07:15 -0400
From: Dave Webb KB1PVH <kb1pvh@xxxxx.xxx>
Subject: [amsat-bb] 13 Colonies
To: AMSAT -BB <amsat-bb@xxxxx.xxx>
Message-ID:
<AANLkTim700W36eKVMoY6vmS-UH92qX1X_G_V-BnKxFhk@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
We just picked up Fletch, N1RCN for Rhode Island on a limited basis. His
call will be N1RCN/K2C.
Dave - KB1PVH
Sent from my Verizon Wireless DROID
------------------------------
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Sent via amsat-bb@xxxxx.xxx. Opinions expressed are those of the author.
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