Aw C'mon guys, You don't really expect the b.o.d. to pay any attention to the opinions of those whom actually "operate" on amateur satellites - not to speak of the paying public with their "donations".
Be smart, tell 'em what you *don't* want - then maybe you'll get what you *do* want. (tongue in cheek).
Remember ... they know better than than you! what you want - as I've oft times been told - (by b.o.d. members)
(... and yes, I'm fully aware of the following "sound" reasons for some of the decisions).
1) We have to adhere to the "constructors and planners" wishes otherwise the org: will die. 2) This is Amsat-NA, we can't oblige 3rd world country wishes - (even if we DO accept their donations). 3) Cutting edge technology - (read: fewer and fewer participants/the affluent only). 4) Launch criteria has changed - (money, money, money).
I just wonder if the simple mode-A that actually worked v high tech that doesn't - (for whatever reason) - has sunk in yet ... apparently not.
In my opinion, RS-10 and FO-20 were the most popular and widely used amateur radio satellites (worldwide) - neither of which, incidentally, had anything to do with Amsat.
... and before you turn on the flame throwers, yes, I AM doing my bit for the amateur radio satellite fraternity ... and I AM entitled to an opinion - (though I am NOT asking you to agree with it) - it does appear however that there is a continuing conflict of interests between the "planners" and the "users".
73 John. [email protected]
The most requested transponder was U/V (especially among members outside the U.S.) and AMSAT did respond by increasing resources for it on Eagle.
73,
John KD6OZH
----- Original Message ----- From: "john hackett" [email protected] To: [email protected] Cc: [email protected] Sent: Friday, September 08, 2006 08:50 UTC Subject: [amsat-bb] S-band continued.
Aw C'mon guys, You don't really expect the b.o.d. to pay any attention to the opinions of those whom actually "operate" on amateur satellites - not to speak of the paying public with their "donations".
Be smart, tell 'em what you *don't* want - then maybe you'll get what you *do* want. (tongue in cheek).
Remember ... they know better than than you! what you want - as I've oft times been told - (by b.o.d. members)
(... and yes, I'm fully aware of the following "sound" reasons for some of the decisions).
- We have to adhere to the "constructors and planners" wishes otherwise
the
org: will die. 2) This is Amsat-NA, we can't oblige 3rd world country wishes - (even if
we
DO accept their donations). 3) Cutting edge technology - (read: fewer and fewer participants/the affluent only). 4) Launch criteria has changed - (money, money, money).
I just wonder if the simple mode-A that actually worked v high tech that doesn't - (for whatever reason) - has sunk in yet ... apparently not.
In my opinion, RS-10 and FO-20 were the most popular and widely used
amateur
radio satellites (worldwide) - neither of which, incidentally, had
anything
to do with Amsat.
... and before you turn on the flame throwers, yes, I AM doing my bit for the amateur radio satellite fraternity ... and I AM entitled to an
opinion -
(though I am NOT asking you to agree with it) - it does appear however
that
there is a continuing conflict of interests between the "planners" and the "users".
73 John. [email protected]
Sent via [email protected]. 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
What data are you basing this on?
At 08:17 PM 9/9/2006, John B. Stephensen wrote:
The most requested transponder was U/V (especially among members outside the U.S.) and AMSAT did respond by increasing resources for it on Eagle.
The preference for U/V is my recollection of what published in the AMSAT journal a couple of years ago.
In the San Diego meeting, there was discussion about using the V, U, L, S, C and X bands. The spacecaft is too small for a decent HF antenna and 24 and 47 GHz ground station equipment is too expensive. We also had a goal that Eagle be usable over 75% of its orbit with a minimal size ground station. This requires that Eagle have antennas that can cover approximately 90 degrees if the ground station is at the subsatellite point or approximately 120 degrees for ground stations at the Earth's limb. It can be done with simple antennas consisting of 2 or 3 dipoles having 3-5 dBic of gain at V and U band. At higher frequencies, the path loss is much higher so you must go to an electrically steerable array with just enough gain to cover the Earth at apogee (appx. 17 dBic). Gain must be as high as possible in order to make RF power requirements at the satellite low enough for AMSAT to afford.
The minimal size ground station antennas were defined as small commercially-available CP yagis at V and U band and a 2-foot diameter dish at higher frequencies. It was clear from published measurements and the experience of AMSAT members that S-band noise levels are increasing dramaticly at many locations and each 3 dB increase in noise floor doubles the power required at the satellite. The NTIA recently did a study of noise levels near the 136-138 MHz satellite band, found that they have decreased significantly, and this conforms the experience of hams on 2 meters. This tips the balance towards U/V for the main transponder serving class 0 (analog) and class 1 (low-speed digital) users. It was also the only combination that would allow the use of fixed antennas for class 1 users.
If the satellites are to be usable for emergency communications in the future, they must also support class 2 (medium-speed digital) and class 3 (high-speed digital) users. This also allows amateurs to experiment wth new modes such as digital voice and streaming video. Microwaves are required here because sufficient spectrum isn't avaialable below 450 MHz. Since the satellite is small, only one pair of steerable microwave antennas will fit. Since the satellite is very expensive, the two frequecies must be the best (and safest) possible choice for the 2010-2030 time frame. The uplink band must be one where RF power can be generated inexpensively on the ground. L was preferred, but is a probem as the EU is putting GPS in that band so S and C were the possible uplinks because of the ablity to use WiMax power amplier ICs. The downlink band must have as little noise as possible so that the cost of solar panels on the satellite is minimized. S has the same noise problem for digital or anaog signals, so C and X awere the possible downlinks. Luckly, WiFi is below the 5830-5850 MHz C-band downlink allocation. S/C leads to less expensive ground stations than C/X as less gain is required so antenna pointing is easier and semiconductor devices are less expensive and more efficient.
73,
John KD6OZH
----- Original Message ----- From: "Emily Clarke" [email protected] To: "John B. Stephensen" [email protected]; [email protected] Cc: [email protected] Sent: Sunday, September 10, 2006 03:39 UTC Subject: Re: [amsat-bb] Re: S-band continued.
What data are you basing this on?
At 08:17 PM 9/9/2006, John B. Stephensen wrote:
The most requested transponder was U/V (especially among members outside
the
U.S.) and AMSAT did respond by increasing resources for it on Eagle.
At 02:24 AM 9/10/2006, John B. Stephensen wrote:
The preference for U/V is my recollection of what published in the AMSAT journal a couple of years ago.
In the San Diego meeting, there was discussion about using the V, U, L, S, C and X bands.
John: thank you for that lucid summary!
Dave
In the San Diego meeting, there was discussion about using the V, U, L, S, C and X bands. The spacecaft is too small for a decent HF antenna...
I hate to suggest this low tech approach, but we do have plenty of uplink bandwidth in the 10 meter band if we could find a way to use it. I know that most of the future thinking AMSAT engineers abhor this idea.... But it is still something to think about.
While an HF -gain- antenna cannot fit on a HEO satellite, a simple 10m dipole could be deployed... The main advantage is the users can use high power on the uplink. Lets assume users with a 500W transmitter and the link equation:
PR = PT + GT + GR -LI - LS
PT - power transmitted on the ground is say 500W = 57 dBm
GT - Gain of transmitter Ant is say 6 dB? (3 element beam)
GR - Gain of satellite receive antenna is 0 dB?
LI - is say 3 dB to cover all losses in the system
LS - is (4Pi*R/wavelength) squared = -154 dB
PR - is then 57+6+0-3-154 = -94 dBm
That is a pretty strong signal, but it is the Signal to Noise ratio that counts. And the problem is the GALACTIC AND other NOISE... It's just as high up there as it is here, and That can be as high as 20 dB ??? Over the noise floor of the satellite receiver? (someone more knowledgible here please fill this in.). If it is 20 dB of galactic noise, then the receiver noise floor might be more like -105dbM and now we just barely have a 10 dB margin over noise.
I just don't know whether it is worth doing. We had hopped that the HF uplink on PCSAT2 would have given us good info. But the transponder failed and so we still have no experience with 10m uplinks. It would be nice to do some more expermeintating with the 10m uplink receiver on AO-51 some time...
But one thing is certain, NO ONE is targeting the 10m band for consumer electroncis devices other than all the ILLEGAL CB operations. I just don't know how bad that is. In the solar max, it will probably be a ZOO!!! But maybe they will stay down at 27 MHz and leave 10m alone. Especially if we go after the 10m interlopers with a vengence...
Maybe just like HAM radio, the "HF-ers" are finding it easier to just play on the internet than mess with all that "RF" stuff...
Just babbling and thinking out loud. Bob, WB4APR
Hi Bob,
I am tried to get 10 metres looked at again by the AMSAT team but my comments have gone unanswered. I have also tried to query Peter to get an understanding why 29 MHz was dropped on P3E but no answer there either.
I can assume that antenna size is the big negative but I have been researching and doing some preliminary experimentation on ferrite loaded loops and dipoles for 28 MHz with some encouraging results so far. It appears that a ferrite loaded receiving dipole can have a gain of -12 to -8 dBi (yes a loss!) but given the frequency (lower path loss) and the availability of high power on the ground (almost all HF transceivers have 100+ watts Pout) my calculations show a nice link can be established.
Perhaps the biggest plus is that a satellite receiver at 29 Mhz looks down on a world wide frequency allocation void of those pesky WiFi's, cordless phones, CCTV's etc. and no one is predicting it will be taken away from us.
Speaking of allocations being taken away, I just can't fathom the AMSAT decision to drop L-Band up because of the "Galileo Affair." Now that's a decision based on "crystal ball engineering" and not fact. I've even read that if Galileo ever was launched - and that appears in the latest press to be questionable" the US "would has threatened to shoot them down!"
Regards...Bill - N6GHz
-----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of Robert Bruninga Sent: Sunday, September 10, 2006 9:18 AM To: [email protected] Subject: [amsat-bb] 10m band kibitzing
In the San Diego meeting, there was discussion about using the V, U, L, S, C and X bands. The spacecaft is too small for a decent HF antenna...
I hate to suggest this low tech approach, but we do have plenty of uplink bandwidth in the 10 meter band if we could find a way to use it. I know that most of the future thinking AMSAT engineers abhor this idea.... But it is still something to think about.
While an HF -gain- antenna cannot fit on a HEO satellite, a simple 10m dipole could be deployed... The main advantage is the users can use high power on the uplink. Lets assume users with a 500W transmitter and the link equation:
PR = PT + GT + GR -LI - LS
PT - power transmitted on the ground is say 500W = 57 dBm
GT - Gain of transmitter Ant is say 6 dB? (3 element beam)
GR - Gain of satellite receive antenna is 0 dB?
LI - is say 3 dB to cover all losses in the system
LS - is (4Pi*R/wavelength) squared = -154 dB
PR - is then 57+6+0-3-154 = -94 dBm
That is a pretty strong signal, but it is the Signal to Noise ratio that counts. And the problem is the GALACTIC AND other NOISE... It's just as high up there as it is here, and That can be as high as 20 dB ??? Over the noise floor of the satellite receiver? (someone more knowledgible here please fill this in.). If it is 20 dB of galactic noise, then the receiver noise floor might be more like -105dbM and now we just barely have a 10 dB margin over noise.
I just don't know whether it is worth doing. We had hopped that the HF uplink on PCSAT2 would have given us good info. But the transponder failed and so we still have no experience with 10m uplinks. It would be nice to do some more expermeintating with the 10m uplink receiver on AO-51 some time...
But one thing is certain, NO ONE is targeting the 10m band for consumer electroncis devices other than all the ILLEGAL CB operations. I just don't know how bad that is. In the solar max, it will probably be a ZOO!!! But maybe they will stay down at 27 MHz and leave 10m alone. Especially if we go after the 10m interlopers with a vengence...
Maybe just like HAM radio, the "HF-ers" are finding it easier to just play on the internet than mess with all that "RF" stuff...
Just babbling and thinking out loud. Bob, WB4APR
_______________________________________________ Sent via [email protected]. 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
Bill, The big question is the galactic noise floor. When I looked at this years, ago, I was very excited at the link budget for 10 meters to GEO, but I was assuming that the NOISE level at 10 m was all "atmospheric and ionospheric". Someone set me straight that most of the noise on 10m is not just atmospheric and does extend in the magnetosphere all the way out to LEO. But I wouild sure like to see a NOISE FLOOR plot of typical 10m band. Quiet and noisey sun...
Bob
-----Original Message----- From: Bill Ress [mailto:[email protected]] Sent: Sunday, September 10, 2006 4:40 PM To: [email protected]; [email protected] Subject: RE: [amsat-bb] 10m band kibitzing
Hi Bob,
I am tried to get 10 metres looked at again by the AMSAT team
but my
comments have gone unanswered. I have also tried to query Peter to get an understanding why 29 MHz was dropped on P3E but no answer there either.
I can assume that antenna size is the big negative but I have
been
researching and doing some preliminary experimentation on ferrite loaded loops and dipoles for 28 MHz with some encouraging results so
far. It
appears that a ferrite loaded receiving dipole can have a gain of -12 to -8 dBi (yes a loss!) but given the frequency (lower path loss)
and the
availability of high power on the ground (almost all HF transceivers have 100+ watts Pout) my calculations show a nice link can be
established.
Perhaps the biggest plus is that a satellite receiver at 29 Mhz looks down on a world wide frequency allocation void of those pesky WiFi's, cordless phones, CCTV's etc. and no one is predicting it will be taken away from us.
Speaking of allocations being taken away, I just can't fathom the AMSAT decision to drop L-Band up because of the "Galileo Affair." Now that's a decision based on "crystal ball engineering" and not fact. I've even read that if Galileo ever was launched - and that appears in the latest press to be questionable" the US "would has threatened to shoot them
down!"
Regards...Bill - N6GHz
-----Original Message----- From: [email protected]
[mailto:[email protected]]On
Behalf Of Robert Bruninga Sent: Sunday, September 10, 2006 9:18 AM To: [email protected] Subject: [amsat-bb] 10m band kibitzing
In the San Diego meeting, there was discussion about using the V, U, L, S, C and X bands. The spacecaft is too small for a decent HF antenna...
I hate to suggest this low tech approach, but we do have
plenty
of uplink bandwidth in the 10 meter band if we could find a
way
to use it. I know that most of the future thinking AMSAT engineers abhor this idea.... But it is still something to
think
about.
While an HF -gain- antenna cannot fit on a HEO satellite, a simple 10m dipole could be deployed... The main advantage is the users can use high power on the uplink. Lets assume users with a 500W transmitter and the link
equation:
PR = PT + GT + GR -LI - LS
PT - power transmitted on the ground is say 500W = 57 dBm
GT - Gain of transmitter Ant is say 6 dB? (3 element beam)
GR - Gain of satellite receive antenna is 0 dB?
LI - is say 3 dB to cover all losses in the system
LS - is (4Pi*R/wavelength) squared = -154 dB
PR - is then 57+6+0-3-154 = -94 dBm
That is a pretty strong signal, but it is the Signal to Noise ratio that counts. And the problem is the GALACTIC AND other NOISE... It's just as high up there as it is here, and That can be as high as 20 dB ??? Over the noise floor of the satellite receiver? (someone more knowledgible here please
fill
this in.). If it is 20 dB of galactic noise, then the
receiver
noise floor might be more like -105dbM and now we just barely have a 10 dB margin over noise.
I just don't know whether it is worth doing. We had hopped
that
the HF uplink on PCSAT2 would have given us good info. But
the
transponder failed and so we still have no experience with 10m uplinks. It would be nice to do some more expermeintating
with
the 10m uplink receiver on AO-51 some time...
But one thing is certain, NO ONE is targeting the 10m band for consumer electroncis devices other than all the ILLEGAL CB operations. I just don't know how bad that is. In the solar max, it will probably be a ZOO!!! But maybe they will stay
down
at 27 MHz and leave 10m alone. Especially if we go after the 10m interlopers with a vengence...
Maybe just like HAM radio, the "HF-ers" are finding it easier
to
just play on the internet than mess with all that "RF"
stuff...
Just babbling and thinking out loud. Bob, WB4APR
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:
There are three disadvantages compared to the 70 cm band. The commercial amateur satellite transceivers are desgned for U/V. The 10 m band can have extremely high losses at low elevations and Eagle is designed for an equatorial orbit. The antenna has to be deployed so it is another possible failure mode.
73,
John KD6OZH
----- Original Message ----- From: "Robert Bruninga" [email protected] To: [email protected] Sent: Sunday, September 10, 2006 16:17 UTC Subject: [amsat-bb] 10m band kibitzing
In the San Diego meeting, there was discussion about using the V, U, L, S, C and X bands. The spacecaft is too small for a decent HF antenna...
I hate to suggest this low tech approach, but we do have plenty of uplink bandwidth in the 10 meter band if we could find a way to use it. I know that most of the future thinking AMSAT engineers abhor this idea.... But it is still something to think about.
While an HF -gain- antenna cannot fit on a HEO satellite, a simple 10m dipole could be deployed... The main advantage is the users can use high power on the uplink. Lets assume users with a 500W transmitter and the link equation:
PR = PT + GT + GR -LI - LS
PT - power transmitted on the ground is say 500W = 57 dBm
GT - Gain of transmitter Ant is say 6 dB? (3 element beam)
GR - Gain of satellite receive antenna is 0 dB?
LI - is say 3 dB to cover all losses in the system
LS - is (4Pi*R/wavelength) squared = -154 dB
PR - is then 57+6+0-3-154 = -94 dBm
That is a pretty strong signal, but it is the Signal to Noise ratio that counts. And the problem is the GALACTIC AND other NOISE... It's just as high up there as it is here, and That can be as high as 20 dB ??? Over the noise floor of the satellite receiver? (someone more knowledgible here please fill this in.). If it is 20 dB of galactic noise, then the receiver noise floor might be more like -105dbM and now we just barely have a 10 dB margin over noise.
I just don't know whether it is worth doing. We had hopped that the HF uplink on PCSAT2 would have given us good info. But the transponder failed and so we still have no experience with 10m uplinks. It would be nice to do some more expermeintating with the 10m uplink receiver on AO-51 some time...
But one thing is certain, NO ONE is targeting the 10m band for consumer electroncis devices other than all the ILLEGAL CB operations. I just don't know how bad that is. In the solar max, it will probably be a ZOO!!! But maybe they will stay down at 27 MHz and leave 10m alone. Especially if we go after the 10m interlopers with a vengence...
Maybe just like HAM radio, the "HF-ers" are finding it easier to just play on the internet than mess with all that "RF" stuff...
Just babbling and thinking out loud. Bob, WB4APR
Sent via [email protected]. 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
Hi John,
At 11:24 PM 9/9/2006, John B. Stephensen wrote:
The preference for U/V is my recollection of what published in the AMSAT journal a couple of years ago.
I was really only concerned with this answer, which is what my question was aimed at finding out. Thanks.
The rest is all very interesting. I have some comments about the U/V antenna design, but I will write you about that off line.
73,
Emily
participants (6)
-
Bill Ress -
David B. Toth -
Emily Clarke -
John B. Stephensen -
john hackett -
Robert Bruninga