Ladies and gentlemen:
I have been reading the comments regarding the Eagle S-band downlink decision. I herewith respond to some.
All along, the Eagle project has put a premium on hard science, rigorous peer review, and dispassionate analysis.
All along we knew there might or would be some changes to what we've been planning.
With several other issues on the move or decided, we took a few days in late June to hammer out, based on science, the transponder situation. We did multiple, independent link analyses, and all came to the same conclusion. We validated interference predictions with measurements that have been taken. The conclusion is that S-band is marginally useful as a downlink today (unusable in many locations), and by the time Eagle is launched, and through it's lifetime, will be unusable.
Personally, I do not like this decision. I have S-band equipment that I was looking forward to using.
Personally, I can live with this decision, and defend it to myself, let alone anyone else, because I am convinced that it is technically sound.
As one of you commented this evening, AO-40 wasn't exactly a rock crusher on S-band. It worked, and adequately, at least on CW, but was not great. As I reflect on my personal AO-40 experiences, I now understand that there are 2 reasons for my disappointment. Local noise was one, and transponder distortion was another -- the latter will be corrected by SDX. S-band on AO-40, by necessity not choice, got many of us out of our comfort zones and convinced us that microwaves really aren't that hard. Let's enter the realm of S up and C down with that same realization.
REMEMBER THAT AMSAT IS DEVELOPING THE GROUND STATION ALONG WITH THE SPACE SEGMENT.
You will not be left on your own to develop ground equipment. You will not be asked to mortgage your house; affordability by the masses is a key component of the design for the entire system.
Comparison with AO-51 is an "apples and oranges" thing. The path losses are much different. FM is very unlike CW/SSB or wideband digital modes. Remember that a goal of the Eagle system is that everything is on all the time. No more matrix switches, no more schedules. We need up and downlinks to be useful throughout the entire orbit.
Why did we "regress" to U/V? For one reason, many of you asked for it, and some of us worked hard to somehow incorporate that capability in response to member's desires. The foot in the door was the utility of a V-band beacon in case everything else goes sour. The forcing function was as follows. A goal of Eagle has always been some kind of hand-held or jump bag portable ground station capability for entry into the emergency area while the tsunami waters are receeding and the hurricane winds are down to gale force. Many of us thought we could take advantage of the gain in small antennas to do this on the microwaves. Rigorous link analysis led us to the conclusion that the best place to do this is U/V -- both from a RF/DC power perspective, and from a link standpoint. This leads to the digital and "traditiona"l transponder package for U/V, implemented in SDX.
Why not also include a (switchable) S-band downlink in parallel with the V-band? Remember, no switches. Also, we run into an antenna space problem. We've already increased the size of the spacecraft from where we started, and for many reasons, do NOT want to build something as large as AO-40.
A couple of you have commented this evening that perusing EaglePedia has not revealed the details of the decisions. That is because, while Bob McGwier (N4HY) and I have been working on the report of the meeting, it is not public. We've been working hard on it since June, in and around other AMSAT, ham radio, and life events. Shortly after I push send on this message, I'll begin my final look at that document prior to public release.
Before I go spend time with the spousal unit TONIGHT, I will finish it and publish it. I will send an announcement on the amsat-bb that it is public. To read the report, go to the EaglePedia main page, and select project index. From there, select Team and Meetings, and there will be several options, not all public. The San Diego meeting minutes will be obvious and public.
Several of you have commented, "If S-band is unusable, why is it flying on P3E?" Fair question, but I can't answer for AMSAT-DL. I DO know that the P3E system design is considerably older and farther along than Eagle. Eagle design decisions were made based on the best information in June of 2006.
Aspects of this discussion have been worthy of /dev/null. More aspects of this discussion have raised valid points and reasonable questions, deserving of response, which is why I've been composing this note for the last four hours or so.
A few have raised the old allegation of the builders doing what they want, without regard to users needs. This is not true. While the desire to advance the state of the art (part of amateur radio's justification for existence and allocation of valuable spectrum) leads to enthusiasm and study of potentially useful new techniques, this desire had no impact on our analysis-based decisions. We started with requirements and services, and explored what would deliver.
I thank all of you for your interest and support. Your Eagle team is working hard to develop a system that will serve our needs, as well as advance the state of the art. As promised, we are making decisions based on sound, peer-reviewed science, not anybody's opinions or desires.
Please read the report, study the spreadsheets, download the excel file and play with it. If you can, make your own measurements and put those numbers into the spreadsheet. I think you'll understand how these decisions were reached.
After contemplating the report, send me your questions. I'll either respond or forward to he who can best respond. Another fundamental tenet of the Eagle project is openness, so you have a right to a response to a rational question. Please recognize that we're volunteers too, and subject to the realities of day jobs, families, and a real life. Response may not be instantaneous.
Thanks again and very 73,
Jim
James A. Sanford, PE Eagle Project Manager [email protected]
Guess what, my Direct TV sat dish will not work in a heavy rain storm here. Microwaves don't get through the rain or my vast trees when the leaves are out. V band does, U band too. But S and C bands won't. I wonder if C band signals will be blocked by the wood in the trees even when the leaves are down?
If my highly pointed S band dish is on my roof and tracking the sat in the sky and my nearest neighbor is more than 150 feet from my antenna how can my neighbor's telephone, with very limited range knock out the signal from Eagle, when I am using my SSB preamp?
I guess I just don't get the science to this. The FCC seems to think that BPL signals going down my power lines are not a problem, so why is one telephone or computer network from my neighbor going to stop me from working P3E or Eagle (if it had S Band)?
And guess what no 2.4 ghz devices will get any closer to my antenna 5 or 10 or even 20 years from now unless i move. So that argument does not hold water for me.
Les W4SCO
At 09:40 PM 9/7/2006, you wrote:
Ladies and gentlemen:
I have been reading the comments regarding the Eagle S-band downlink decision. I herewith respond to some.
All along, the Eagle project has put a premium on hard science, rigorous peer review, and dispassionate analysis.
All along we knew there might or would be some changes to what we've been planning.
With several other issues on the move or decided, we took a few days in late June to hammer out, based on science, the transponder situation. We did multiple, independent link analyses, and all came to the same conclusion. We validated interference predictions with measurements that have been taken. The conclusion is that S-band is marginally useful as a downlink today (unusable in many locations), and by the time Eagle is launched, and through it's lifetime, will be unusable.
Personally, I do not like this decision. I have S-band equipment that I was looking forward to using.
Personally, I can live with this decision, and defend it to myself, let alone anyone else, because I am convinced that it is technically sound.
As one of you commented this evening, AO-40 wasn't exactly a rock crusher on S-band. It worked, and adequately, at least on CW, but was not great. As I reflect on my personal AO-40 experiences, I now understand that there are 2 reasons for my disappointment. Local noise was one, and transponder distortion was another -- the latter will be corrected by SDX. S-band on AO-40, by necessity not choice, got many of us out of our comfort zones and convinced us that microwaves really aren't that hard. Let's enter the realm of S up and C down with that same realization.
REMEMBER THAT AMSAT IS DEVELOPING THE GROUND STATION ALONG WITH THE SPACE SEGMENT.
You will not be left on your own to develop ground equipment. You will not be asked to mortgage your house; affordability by the masses is a key component of the design for the entire system.
Comparison with AO-51 is an "apples and oranges" thing. The path losses are much different. FM is very unlike CW/SSB or wideband digital modes. Remember that a goal of the Eagle system is that everything is on all the time. No more matrix switches, no more schedules. We need up and downlinks to be useful throughout the entire orbit.
Why did we "regress" to U/V? For one reason, many of you asked for it, and some of us worked hard to somehow incorporate that capability in response to member's desires. The foot in the door was the utility of a V-band beacon in case everything else goes sour. The forcing function was as follows. A goal of Eagle has always been some kind of hand-held or jump bag portable ground station capability for entry into the emergency area while the tsunami waters are receeding and the hurricane winds are down to gale force. Many of us thought we could take advantage of the gain in small antennas to do this on the microwaves. Rigorous link analysis led us to the conclusion that the best place to do this is U/V -- both from a RF/DC power perspective, and from a link standpoint. This leads to the digital and "traditiona"l transponder package for U/V, implemented in SDX.
Why not also include a (switchable) S-band downlink in parallel with the V-band? Remember, no switches. Also, we run into an antenna space problem. We've already increased the size of the spacecraft from where we started, and for many reasons, do NOT want to build something as large as AO-40.
A couple of you have commented this evening that perusing EaglePedia has not revealed the details of the decisions. That is because, while Bob McGwier (N4HY) and I have been working on the report of the meeting, it is not public. We've been working hard on it since June, in and around other AMSAT, ham radio, and life events. Shortly after I push send on this message, I'll begin my final look at that document prior to public release.
Before I go spend time with the spousal unit TONIGHT, I will finish it and publish it. I will send an announcement on the amsat-bb that it is public. To read the report, go to the EaglePedia main page, and select project index. From there, select Team and Meetings, and there will be several options, not all public. The San Diego meeting minutes will be obvious and public.
Several of you have commented, "If S-band is unusable, why is it flying on P3E?" Fair question, but I can't answer for AMSAT-DL. I DO know that the P3E system design is considerably older and farther along than Eagle. Eagle design decisions were made based on the best information in June of 2006.
Aspects of this discussion have been worthy of /dev/null. More aspects of this discussion have raised valid points and reasonable questions, deserving of response, which is why I've been composing this note for the last four hours or so.
A few have raised the old allegation of the builders doing what they want, without regard to users needs. This is not true. While the desire to advance the state of the art (part of amateur radio's justification for existence and allocation of valuable spectrum) leads to enthusiasm and study of potentially useful new techniques, this desire had no impact on our analysis-based decisions. We started with requirements and services, and explored what would deliver.
I thank all of you for your interest and support. Your Eagle team is working hard to develop a system that will serve our needs, as well as advance the state of the art. As promised, we are making decisions based on sound, peer-reviewed science, not anybody's opinions or desires.
Please read the report, study the spreadsheets, download the excel file and play with it. If you can, make your own measurements and put those numbers into the spreadsheet. I think you'll understand how these decisions were reached.
After contemplating the report, send me your questions. I'll either respond or forward to he who can best respond. Another fundamental tenet of the Eagle project is openness, so you have a right to a response to a rational question. Please recognize that we're volunteers too, and subject to the realities of day jobs, families, and a real life. Response may not be instantaneous.
Thanks again and very 73,
Jim
James A. Sanford, PE Eagle Project Manager [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
If my highly pointed S band dish is on my roof and tracking
the sat
in the sky and my nearest neighbor is more than 150 feet from
my
antenna how can my neighbor's telephone, with very limited
range
knock out the signal from Eagle, when I am using my SSB
preamp?
The answer is relatively easy to compute. The simple communication equation for power received at a receiver (PR) from a distant transmitter (PT) in dB is simply:
PR = PT + GT + GR -LI - LS
Where:
PR is power received PT is power of the transmitter (lets say 40 dBm (10W) GT is gain ot the TX antenna (Lets say 8 dB) GR is gain of the RX antenna (abt 25 dB for a 1m dish) LI is incidental losses (usually less than 3 dB) LS is the space loss due to distance between TX and RX
Computing space loss is basic physics and boils down to ((4 * Pi * R)/ wavelength) squared.
For a P3E satellite with a Range (R) of about 40,000 km and the wavelength of 2.4 Ghz being about .12 meters that loss term is about -192 dB. Add it all up and you get a received signal power of about -122 dBm which is just about exactly the minimum receive signal for a typical FM receiver.
Ok, now compare this signal to one from a 10 milliwatt 2.4 GHz neighbor's phone about 150 feet away:
PT is now 10 dBm GT is at worst 0 dB GR is say - 10 dB (35 dB worse than main lobe) LI is still about 3 dB
But now the space loss, LS is not 40,000 km away, but only 150 feet away. And this computes to be a loss of only - 74 dB. Adding it all up gives a power received of about - 77 dBm.
Notice that this neighbor's wireless phone is a full 45 dB STRONGER coming in from the back of the dish than the satellite coming in from the front, even though the satellite has 35 dB more dish gain in the main lobe.
For reference, this 45 dB stronger neighbor's phone is equivalent to a 32 Killowatt neighbor compared to a 1 Watt satellite signal. Even if you use a 3m dish, then this only changes the signal power from the satellite by 10 dB so now you have a 10W satellite signal competing with a 32 Kw neighbor. Still the neighbor wins...
Computing it backwards, the neighbor's off-axis signal won't be less than the satellite signal until the phone is more than 5 miles away. (Of course, that is if it was line of sight with nothing in the way. Given that each tree is worth about 10 dB at S'band, then you would really maybe need only a small 1 acre forest to block his signal sufficiently?
Bottom line, looking at the numbers, it does not seem to make sense to intentionally design a satellite downlink these days useable by most of the AMSAT membership that is that susceptible to off-the-shelf consumer devices known to cause interference... Which is beyond our control to remedy.
Just my 2 cents. Bob, WB4APR
Why are so many people (many being a relative number) enjoying S band if this is the case?
I listened to a tape of a guy on S-band, his corner reflector and downconverter laying on the roof of his car....
Color me confused....
de Tim, K4SHF
On Friday 08 September 2006 11:17, Robert Bruninga wrote:
If my highly pointed S band dish is on my roof and tracking
the sat
in the sky and my nearest neighbor is more than 150 feet from
my
antenna how can my neighbor's telephone, with very limited
range
knock out the signal from Eagle, when I am using my SSB
preamp?
The answer is relatively easy to compute. The simple communication equation for power received at a receiver (PR) from a distant transmitter (PT) in dB is simply:
PR = PT + GT + GR -LI - LS
Where:
PR is power received PT is power of the transmitter (lets say 40 dBm (10W) GT is gain ot the TX antenna (Lets say 8 dB) GR is gain of the RX antenna (abt 25 dB for a 1m dish) LI is incidental losses (usually less than 3 dB) LS is the space loss due to distance between TX and RX
Computing space loss is basic physics and boils down to ((4 * Pi
- R)/ wavelength) squared.
For a P3E satellite with a Range (R) of about 40,000 km and the wavelength of 2.4 Ghz being about .12 meters that loss term is about -192 dB. Add it all up and you get a received signal power of about -122 dBm which is just about exactly the minimum receive signal for a typical FM receiver.
Ok, now compare this signal to one from a 10 milliwatt 2.4 GHz
neighbor's phone about 150 feet away:
PT is now 10 dBm GT is at worst 0 dB GR is say - 10 dB (35 dB worse than main lobe) LI is still about 3 dB
But now the space loss, LS is not 40,000 km away, but only 150 feet away. And this computes to be a loss of only - 74 dB. Adding it all up gives a power received of about - 77 dBm.
Notice that this neighbor's wireless phone is a full 45 dB STRONGER coming in from the back of the dish than the satellite coming in from the front, even though the satellite has 35 dB more dish gain in the main lobe.
For reference, this 45 dB stronger neighbor's phone is equivalent to a 32 Killowatt neighbor compared to a 1 Watt satellite signal. Even if you use a 3m dish, then this only changes the signal power from the satellite by 10 dB so now you have a 10W satellite signal competing with a 32 Kw neighbor. Still the neighbor wins...
Computing it backwards, the neighbor's off-axis signal won't be less than the satellite signal until the phone is more than 5 miles away. (Of course, that is if it was line of sight with nothing in the way. Given that each tree is worth about 10 dB at S'band, then you would really maybe need only a small 1 acre forest to block his signal sufficiently?
Bottom line, looking at the numbers, it does not seem to make sense to intentionally design a satellite downlink these days useable by most of the AMSAT membership that is that susceptible to off-the-shelf consumer devices known to cause interference... Which is beyond our control to remedy.
Just my 2 cents. 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
Be careful about comparing HEOs and LEOs. HEOs a 40,000 km have an additional 34 dB of path loss compared to LEOs at 800 km.
73,
John KD6OZH
----- Original Message ----- From: "Tim Tapio" [email protected] To: [email protected]; [email protected] Sent: Saturday, September 09, 2006 00:24 UTC Subject: [amsat-bb] Re: Example of S-band interference
Why are so many people (many being a relative number) enjoying S band if
this
is the case?
I listened to a tape of a guy on S-band, his corner reflector and downconverter laying on the roof of his car....
Color me confused....
de Tim, K4SHF
On Friday 08 September 2006 11:17, Robert Bruninga wrote:
If my highly pointed S band dish is on my roof and tracking
the sat
in the sky and my nearest neighbor is more than 150 feet from
my
antenna how can my neighbor's telephone, with very limited
range
knock out the signal from Eagle, when I am using my SSB
preamp?
The answer is relatively easy to compute. The simple communication equation for power received at a receiver (PR) from a distant transmitter (PT) in dB is simply:
PR = PT + GT + GR -LI - LS
Where:
PR is power received PT is power of the transmitter (lets say 40 dBm (10W) GT is gain ot the TX antenna (Lets say 8 dB) GR is gain of the RX antenna (abt 25 dB for a 1m dish) LI is incidental losses (usually less than 3 dB) LS is the space loss due to distance between TX and RX
Computing space loss is basic physics and boils down to ((4 * Pi
- R)/ wavelength) squared.
For a P3E satellite with a Range (R) of about 40,000 km and the wavelength of 2.4 Ghz being about .12 meters that loss term is about -192 dB. Add it all up and you get a received signal power of about -122 dBm which is just about exactly the minimum receive signal for a typical FM receiver.
Ok, now compare this signal to one from a 10 milliwatt 2.4 GHz
neighbor's phone about 150 feet away:
PT is now 10 dBm GT is at worst 0 dB GR is say - 10 dB (35 dB worse than main lobe) LI is still about 3 dB
But now the space loss, LS is not 40,000 km away, but only 150 feet away. And this computes to be a loss of only - 74 dB. Adding it all up gives a power received of about - 77 dBm.
Notice that this neighbor's wireless phone is a full 45 dB STRONGER coming in from the back of the dish than the satellite coming in from the front, even though the satellite has 35 dB more dish gain in the main lobe.
For reference, this 45 dB stronger neighbor's phone is equivalent to a 32 Killowatt neighbor compared to a 1 Watt satellite signal. Even if you use a 3m dish, then this only changes the signal power from the satellite by 10 dB so now you have a 10W satellite signal competing with a 32 Kw neighbor. Still the neighbor wins...
Computing it backwards, the neighbor's off-axis signal won't be less than the satellite signal until the phone is more than 5 miles away. (Of course, that is if it was line of sight with nothing in the way. Given that each tree is worth about 10 dB at S'band, then you would really maybe need only a small 1 acre forest to block his signal sufficiently?
Bottom line, looking at the numbers, it does not seem to make sense to intentionally design a satellite downlink these days useable by most of the AMSAT membership that is that susceptible to off-the-shelf consumer devices known to cause interference... Which is beyond our control to remedy.
Just my 2 cents. 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
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
On 7 Sep 2006 at 21:40, Jim Sanford wrote:
The conclusion is that S-band is marginally useful as a downlink today (unusable in many locations), and by the time Eagle is launched, and through it's lifetime, will be unusable.
Personally, I do not like this decision. I have S-band equipment that I was looking forward to using.
AMSAT-NA should step forward here and rule out about EXPERIMENTING VS OPERATING. Nobody will be against experimenting that's always be the roots of amateur radio. But when "operating" need a relay "satellite" to achieve communication the first goal is to learn from the past and see what the "USERS" wants!
Your Eagle team is working hard to develop a system that will serve our needs, as well as advance the state of the art. As promised, we are making decisions based on sound, peer-reviewed science, not anybody's opinions or desires.
*****not anybody's opinions or desires***** Here is the problem The eagle team should not be let alone in theses decisions. The AMSAT-NA BOD should have a VETO here. All final decisions regarding the satellite construction should be validated by the BOD. It is a serious decision making flaw as there is no balance between the users desires and the technical builders because all the decisions regarding the construction are made by the builders. Its like to be the judge and the lawyer at the same time it is not sound. Remember theses words *****not anybody's opinions or desires*****
As one of you commented this evening, AO-40 wasn't exactly a rock crusher on S-band. It worked, and adequately, at least on CW, but was not great. As I reflect on my personal AO-40 experiences.
Those who makes like me more than a 1000 contacts on AO-40 in the U/S mode and they can affirm that near 70% of theses contacts where as good than all what can we hear actually with all the LEO including ECHO raise your hands. Yes there was problems LEILA RADAR bootleggers taxi fishing boat and so on but even with this i learn since 1971 the beginning of my Ham "career" that i should always try to have a station with at least the average equipment to be able to work and enjoy the "communication" Yes huge HF beam, a kilowatt, preamp and so on.
I am sorry to tell your personal AO-40 experiences are far away with my personnal experiences and if the EAGLE team based their reasoning this way it is urgent the BOD start to VETO the eagle team on their final decision.
A few have raised the old allegation of the builders doing what they want, without regard to users needs. This is not true. While the desire to advance the state of the art (part of amateur radio's justification for existence and allocation of valuable spectrum) We started with requirements and services, and explored what would deliver.
Fine but communicating is the ultimate goals for all the users. "Looking towards the desire to advance the state of the art" for technically incline amateur should not be done against the users
EG:> Why not also include a (switchable) S-band downlink in parallel with the
V-band? Remember, no switches.
Sure if there is an always on S band receiver the only one solution is to get rid of the S band TX simple maths here...and there is no concern about all the existing S band equipment that many of us hardly constructed with often very scarce financial ressources. As one said it is a terrible marketing error. Here again the BOD should act on this.
A goal of Eagle has always been some kind of hand-held or jump bag portable ground station capability for entry into the emergency area while the tsunami waters are receeding and the hurricane winds are down to gale force.
It is an utopy a fixation "the HT syndrome" how would you be able to sustain reliable communications when the power is out and the zone is devastated? Its good on papers and on the media but reality is quite different.
Mode S-U-V are as you said the bread and butter on the downlink and i agree with you. Eagle should keep theses mode but in this forcing the "experimenting" leads and the users loose. Will they be there tomorrow? question ask?
Please recognize that we're volunteers too, and subject to the realities of day jobs, families,
and a real life.
Yes we all but your involvment is not questionned here.
"-" The medium is the message...The content is the audience...;)
Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe
----- Original Message ----- From: "Jim Sanford" [email protected] To: [email protected] Sent: Friday, September 08, 2006 3:40 AM Subject: [amsat-bb] S-band on Eagle
Ladies and gentlemen:
As one of you commented this evening, AO-40 wasn't exactly a rock crusher on S-band. It worked, and adequately, at least on CW, but was not great.
Hi James, WB4GCS
Not true ! If one of us commented that AO40 was not great and only was usable at least on CW it means that his own station was not adeguate for it and not the satellite was responsible and one non able to fly swallow does not make a summer. By the experience of users majority the S-band downlink of AO40 was great and the best ever made by AMSAT
As I reflect on my personal AO-40 experiences, I now understand that there are 2 reasons for my disappointment. Local noise was one, and transponder distortion was another --
If local noise was a problem for you it was not a problem for the world wide majority of S-downlink users
Distorsion is not completely true ! Warbling and not distorsion was only present when RUDAK was operating so another swallow that not make a summer.
Thanks again and very 73,
Jim
James A. Sanford, PE Eagle Project Manager [email protected]
Best 73" de
i8CVS Domenico
Quite so, Dom.
Pre-launch predictions were way-off on AO-40 ground station requirements. We were told all one needed was a 16-turn helix and a downconvertor such as the "Drake". I found that the 24-inch BBQ with bare Drake was deaf.
But when I used a 33-inch offset feed dish (solen from my ku-band sat-TV) coupled with a good preamp before my unmodified Drake...I could copy the beacon out to squints of 49-degrees. That tranlates as nearly 5 s-units SNR for low squint angles (<10). I did spend a little more than the average BBQ dish user (I purchased the MKU-232 from db6nt for ~ $245, but made the system). I bought three Drakes in 1998 for $100 and modified one to 435 MHz IF. The other I received at 123 MHz totally unmodified. I gave the third as a door prize at a local hamfest.
My dish cost me $159 (for the 1-meter dish I had to buy for my TV system since I stold the 33-inch for ham radio). I built my own 5-turn helix for under $20. Everything else was left over from AO-10/13: FT-847, M2 UHF yagi, 2m yagi.
For mode-L, I bought a 45-element loop-yagi ($125) and DEMI 144/1268 Tx conv. ($450). There is the Yaesu B5400 and coax cables, etc. etc. ...but not counting that. You should guess what my 2m-eme station cost? So I have a lot of cash tied up in eme/sat ham radio (~ $10K), but not everyone need duplicate what I do.
To summarize, my mode-US station came real close to performing like my AO-10 mode-B station (in many ways it was superior).
Well I am glad that Amsat-DL chose to keep mode-L and S on P3E. You know my opinion regarding Eagle...disappointment. But I will reserve judgement till the day it is in orbit and operational...then ask me!
73's Ed - KL7UW
At 11:43 AM 9/8/2006 +0200, i8cvs wrote:
----- Original Message ----- From: "Jim Sanford" [email protected] To: [email protected] Sent: Friday, September 08, 2006 3:40 AM Subject: [amsat-bb] S-band on Eagle
Ladies and gentlemen:
As one of you commented this evening, AO-40 wasn't exactly a rock crusher on S-band. It worked, and adequately, at least on CW, but was not great.
Hi James, WB4GCS
Not true ! If one of us commented that AO40 was not great and only was usable at least on CW it means that his own station was not adeguate for it and not the satellite was responsible and one non able to fly swallow does not make a summer. By the experience of users majority the S-band downlink of AO40 was great and the best ever made by AMSAT
As I reflect on my personal AO-40 experiences, I now understand that there are 2 reasons for my disappointment. Local noise was one, and transponder distortion was another --
If local noise was a problem for you it was not a problem for the world wide majority of S-downlink users
Distorsion is not completely true ! Warbling and not distorsion was only present when RUDAK was operating so another swallow that not make a summer.
Thanks again and very 73,
Jim
James A. Sanford, PE Eagle Project Manager [email protected]
Best 73" de
i8CVS Domenico
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
73's, Ed - KL7UW ========================================= http://www.qsl.net/al7eb - BP40iq 144-EME: FT-847, mgf-1801/1402, 4xM2-xpol-20, 170w 432-EME: FT-847, mgf-1402, 1x21-ele (18.6 dBi), 60w =========================================
participants (8)
-
Edward R. Cole -
i8cvs -
Jim Sanford -
John B. Stephensen -
Luc Leblanc VE2DWE -
Robert Bruninga -
sco＠sco-inc.com -
Tim Tapio