[amsat-bb] OZ7SAT? Off the air?
Does anybody (Ib ;) ) know if OZ7SAT is off the air? I haven't seen any telemetry updates in over a week. http://www.amsat.dk/oz7sat/tlm/ Thanks, -- Mark L. Hammond [N8MH] ___ Sent via amsat...@amsat.org. 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
[amsat-bb] UHF/VHF Polarization Switch
Hello, I've been asked by a club member if anyone has any experience using an M2 VHF/UHF Polarization Switch, and what their opinion of it may be. I can't seem to find any reviews on field performance, thank you. 73's Pete WB2OQQ www.massapequanyweather.com ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
At 02:20 AM 4/22/2010, Stephen Melachrinos wrote: Ah, but this focuses on my question: Why is ERP referenced to a dipole? Why did someone assume that Arecibo's stated gain of 60 dB was dBd and not dBi? I've never seen the gain of a dish antenna used in satellite work quoted in dBd. All of the references for calculating gain are based on the isotropic reference. And all of the usages I have seen (in professional satellite work) use ERP and EiRP interchangeably, and the i in EiRP is used to explicitly state referenced to isotropic. In fact, the amateur community is the only place where there is a fascination with the dipole reference. The dBd specs are useless for any real calculation purposes. Satcom engineering is much simpler if everyone quotes isotropic, and all commercial/government/military satellite link budgets are based on isotropic references. Steve Melachrinos W3HF (Professional) Satcom Engineer since 1979 ERP is about 243 MW and that comes from the conversion from dBi to dBd. ___ Sent via amsat...@amsat.org. 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 In fact the first gain number published over a month ago was 58 dBi. Then I suppose a bunch of hams complained that they didn't understand isotropic gain so the Arecibo folks kindly converted the number to 60 dBd. (i.e. unity isotropic gain, dBi=0, is what a true omni-directional antenna produces in free space) Does anyone on this reflector know the formula for calculating gain of a parabolic dish (Yes, I know-I'm asking if you know)? Did you know that Arecibo dish is spherical and not parabolic? So we can only use the gain number they provide (BTW the UHF line-feed corrects for spherical aberration of the dish surface at Arecibo). Arecibo can track a small amount of angle because the dish is spherical. It is my understanding (might be wrong on this) the line-feed can adjust for the amount of surface irradiated (which will change the gain). The formula normally used in radio astronomy and mw engineering is in terms of dBi. Most (not all) eme hams use dBi vs dBd. I am really amazed at this thread on amsat-bb. I thought the satellite community was more globally oriented (International). The different convention in expressing decimal numbers (aka using comma or period) is pretty well known (I thought). US/UK use period and most EU use comma. Most antenna analysis sw express gain in dBi 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 dubus...@hotmail.com == ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
At 07:46 AM 4/22/2010, Edward Cole wrote: At 02:20 AM 4/22/2010, Stephen Melachrinos wrote: Ah, but this focuses on my question: Why is ERP referenced to a dipole? Why did someone assume that Arecibo's stated gain of 60 dB was dBd and not dBi? I've never seen the gain of a dish antenna used in satellite work quoted in dBd. All of the references for calculating gain are based on the isotropic reference. And all of the usages I have seen (in professional satellite work) use ERP and EiRP interchangeably, and the i in EiRP is used to explicitly state referenced to isotropic. In fact, the amateur community is the only place where there is a fascination with the dipole reference. The dBd specs are useless for any real calculation purposes. Satcom engineering is much simpler if everyone quotes isotropic, and all commercial/government/military satellite link budgets are based on isotropic references. Steve Melachrinos W3HF (Professional) Satcom Engineer since 1979 ERP is about 243 MW and that comes from the conversion from dBi to dBd. ___ Sent via amsat...@amsat.org. 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 In fact the first gain number published over a month ago was 58 dBi. Then I suppose a bunch of hams complained that they didn't understand isotropic gain so the Arecibo folks kindly converted the number to 60 dBd. (i.e. unity isotropic gain, dBi=0, is what a true omni-directional antenna produces in free space) Does anyone on this reflector know the formula for calculating gain of a parabolic dish (Yes, I know-I'm asking if you know)? Did you know that Arecibo dish is spherical and not parabolic? So we can only use the gain number they provide (BTW the UHF line-feed corrects for spherical aberration of the dish surface at Arecibo). Arecibo can track a small amount of angle because the dish is spherical. It is my understanding (might be wrong on this) the line-feed can adjust for the amount of surface irradiated (which will change the gain). The formula normally used in radio astronomy and mw engineering is in terms of dBi. Most (not all) eme hams use dBi vs dBd. I am really amazed at this thread on amsat-bb. I thought the satellite community was more globally oriented (International). The different convention in expressing decimal numbers (aka using comma or period) is pretty well known (I thought). US/UK use period and most EU use comma. Most antenna analysis sw express gain in dBi hmm dBi = dBd +2.15. Gain of dipole = 1.64 10Log(1.64) = 2.15 dB so what gives here? is it 58 dBd and 60 dBi? Sorry if I wrote that backwards. Or we just playing around with significant numbers and gain is approx 58 to 60 dB (somethings). Pat, Joe? can you please clear up this mess and state for everyone what the gain is for Arecibo on 432-MHz? 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 dubus...@hotmail.com == ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: OZ7SAT? Off the air?
Thank you Bent and OZ7SAT. I find it very useful and have come to depend on it ;) 73, Mark N8MH On Thu, Apr 22, 2010 at 10:41 AM, Bent OZ6BL oz...@fern.dk wrote: On 2010-04-22 16:05, Mark L. Hammond wrote: Does anybody (Ib ;) ) know if OZ7SAT is off the air? I haven't seen any telemetry updates in over a week. http://www.amsat.dk/oz7sat/tlm/ It has been off the air for some days (I blew a software update ;-() It should be up again now. 73 de Bent/OZ6BL AMSAT-OZ hostmaster ___ Sent via amsat...@amsat.org. 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 -- Mark L. Hammond [N8MH] ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Wow that's all messed up? I'm 52 and this is the very first time i have ever seen anything like this and i have been dealing with science worldwide all my life. wow. Joe The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com On 4/22/2010 1:14 PM, Sil - ZL2CIA wrote: Idle-Tyme wrote: On 4/21/2010 8:25 PM, i8cvs wrote: Comma or no comma, shouldn't matter 1000 mega watts or 1,000 Mega watts is still one thousand million watts! NOT one thousands watts. true? The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com Hi Idle-Tyme I don't agree with your statement: 1000 mega watt are one thousand million watt 1,000 mega watt or 1.000 mega watt is only one million watt because zero after the comma means nothing like 1,0 is still one million watt or 1 MW NO! it's a comma, not a decimal point! it's one thousand, one thousand written 1000 or 1,000 is still one thousand they are exactly the same. That's only true in the English speaking world, and this is the cause of the confusion in this debate. In the Netherlands (and most of Europe), you would write one thousand million watts as 1.000 megawatts. The decimal indicator in Europe is a comma. For example, 1,5 means one and a half 1.000.000 means one million. Sil (ex PA3HIL) ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Congrats to K7CWQ
Loren, K7CWQ, just received his VUCC award - using a FT-60R and Arrow Sat Antenna as his station. CONGRATULATIONS, Loren! Clint, K6LCS http://www.work-sat.com ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
- Original Message - From: Sil - ZL2CIA zl2...@amsat.org To: Idle-Tyme n...@mwt.net Cc: i8cvs domenico.i8...@tin.it; AMSAT-BB amsat-bb@amsat.org Sent: Thursday, April 22, 2010 8:14 PM Subject: Re: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations) In the Netherlands (and most of Europe), you would write one thousand million watts as 1.000 megawatts. The decimal indicator in Europe is a comma. For example, 1,5 means one and a half 1.000.000 means one million. Sil (ex PA3HIL) Hi Sil, ZL2CIA In Italy you would write one thousand million watt as 1000 megawatt or alternatively 1000 MW In addition the units in Italy are written without plural and to write megawatts is wrong in Italy but the plural is used in England and USA In any calculator 1.5 means one and half because the calculators are not using comma. In any calculator 100. means one million I thing that the best for everybody should be to write numbars as any calculator shows. 73 de i8CVS Domenico ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Congrats to K7CWQ
Great Job Loren!! Dave, kn4ok Loren, K7CWQ, just received his VUCC award - using a FT-60R and Arrow Sat ntenna as his station. CONGRATULATIONS, Loren! Clint, K6LCS ttp://www.work-sat.com __ ent via amsat...@amsat.org. Opinions expressed are those of the author. ot an AMSAT-NA member? Join now to support the amateur satellite program! ubscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
I think we should all use hexidecimal. Or binary :) Mark N8MH Sent via BlackBerry from T-Mobile -Original Message- From: i8cvs domenico.i8...@tin.it Date: Thu, 22 Apr 2010 23:12:16 To: Sil - ZL2CIAzl2...@amsat.org; Idle-Tymen...@mwt.net Cc: AMSAT-BBamsat-bb@amsat.org Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations) - Original Message - From: Sil - ZL2CIA zl2...@amsat.org To: Idle-Tyme n...@mwt.net Cc: i8cvs domenico.i8...@tin.it; AMSAT-BB amsat-bb@amsat.org Sent: Thursday, April 22, 2010 8:14 PM Subject: Re: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations) In the Netherlands (and most of Europe), you would write one thousand million watts as 1.000 megawatts. The decimal indicator in Europe is a comma. For example, 1,5 means one and a half 1.000.000 means one million. Sil (ex PA3HIL) Hi Sil, ZL2CIA In Italy you would write one thousand million watt as 1000 megawatt or alternatively 1000 MW In addition the units in Italy are written without plural and to write megawatts is wrong in Italy but the plural is used in England and USA In any calculator 1.5 means one and half because the calculators are not using comma. In any calculator 100. means one million I thing that the best for everybody should be to write numbars as any calculator shows. 73 de i8CVS Domenico ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
There is also the group of Virtucons who use gagillion, fafillion, shabolubalu million illion yillion, when describing lasers. I believe this was first described in a movie with Mr. Myers. 73 de W4AS On Apr 22, 2010, at 5:31 PM, Mark Hammond N8MH wrote: I think we should all use hexidecimal. Or binary :) Mark N8MH Sent via BlackBerry from T-Mobile -Original Message- From: i8cvs domenico.i8...@tin.it Date: Thu, 22 Apr 2010 23:12:16 To: Sil - ZL2CIAzl2...@amsat.org; Idle-Tymen...@mwt.net Cc: AMSAT-BBamsat-bb@amsat.org Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations) - Original Message - From: Sil - ZL2CIA zl2...@amsat.org To: Idle-Tyme n...@mwt.net Cc: i8cvs domenico.i8...@tin.it; AMSAT-BB amsat-bb@amsat.org Sent: Thursday, April 22, 2010 8:14 PM Subject: Re: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations) In the Netherlands (and most of Europe), you would write one thousand million watts as 1.000 megawatts. The decimal indicator in Europe is a comma. For example, 1,5 means one and a half 1.000.000 means one million. ___ Sent via amsat...@amsat.org. 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
[amsat-bb] : For sale, Yaesu VX-3R HT, ARR RF switched pre amp ( pre-amp sold)
The pre-amp is sold. The VX-3R is still available. Thanks to everyone for their interest, Michael Original Message Subject:For sale, Yaesu VX-3R HT, ARR RF switched pre amp Date: Tue, 20 Apr 2010 17:19:26 -0400 From: Michael Tondee mat...@netcommander.com To: amsat-bb@amsat.org I have for sale a Yaesu VX-3R dual band HT. While it is not full duplex, it works well as the RX side of a mode J handheld station. I've had it less than six months if even that long. It has never even been outside the house and is in like new condition. Of course box, manual, charger and stock rubber duck are all included. I'll also throw in a 3ft. long adapter cable that goes from the SMA jack on the radio to an SO-239 where an external antenna can be used. Price is $110.00 shipped priority mail in the lower 48. The pre amp is an Advanced Receiver Research SP432VDG with N connectors. The RF switching circuit is rated at 25 watts, I actually only ever used it on a receive only setup with the VX-3R. The pre amp has been mast mounted in a weatherproof enclosure. ARR says these units will withstand heat and cold extremes with no problem, they just have to be mounted in a waterproof enclosure if put outside. As with the HT the unit has seen very little use and is like new. Price is $85.00 shipped priority mail in the lower48. I will accept Paypal or a United States Postal Service money order as payment. Sorry, no international shipping. If you are interested, please contact me off list. Thanks for the bandwidth everyone, Michael, W4HIJ ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Tickets from Space
PIPS Technology has developed a license plate recognition system that uses two cameras on the ground and one mounted on a satellite to catch speeders. Blog entry at ... http://tinyurl.com/39c9hlp Clint, K6LCS ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
--- On Thu, 4/22/10, Mark Hammond N8MH marklhamm...@gmail.com wrote: I think we should all use hexidecimal. Or binary :) I tell my electronics students that we can express gain or loss in dB by taking the log of power ratios and multiplying by 10, or by taking the log of the voltage or current ratios and multiplying by 20. If we multiply the log by 16 instead, then the result is expressed in hexadecibels. :-) (Hexabels sounds too much like a made-up word.) 73, de John, KD2BD -- Visit John on the Web at: http://kd2bd.ham.org/ ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: UHF/VHF Polarization Switch
Pete - I have had one for about 1 1/2 years - on the 70cm antenna. When the GO-32 9K6 BBS board was up it made the difference between reliably receiving and not. (I am working on getting on the AO-51 BBS) I know S meter readings are all relative -- I usually see at least +20 when the polarization is correct. I have roof mounted antennas so I was able to do the modification without taking the antenna down. I did shift the antenna mounting position on the boom to account for the extra length/weight. During installation checkout - I did have an issue with the protection diode that was installed across the relay -- I had to replace it. Other than that -- it has worked fine. 73, Bruce WA3SWJ At 10:48 AM 4/22/2010, you wrote: Hello, I've been asked by a club member if anyone has any experience using an M2 VHF/UHF Polarization Switch, and what their opinion of it may be. I can't seem to find any reviews on field performance, thank you. 73's Pete WB2OQQ www.massapequanyweather.com ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Tickets from Space
Unless California changes Vehicle Code section 40802 (speed traps prohibited), this wonderfully techno-geeky system will not be lawful for any excess speed prosecution in California. My 911 was happy to hear that. hihi Craig N6RSX -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org]on Behalf Of Clint Bradford Sent: Thursday, April 22, 2010 5:40 PM To: AMSAT BB Subject: [amsat-bb] Tickets from Space PIPS Technology has developed a license plate recognition system that uses two cameras on the ground and one mounted on a satellite to catch speeders. Blog entry at ... http://tinyurl.com/39c9hlp Clint, K6LCS ___ Sent via amsat...@amsat.org. 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 NOTICE: This communication may contain privileged or other confidential information. If you are not the intended recipient of this communication, or an employee or agent responsible for delivering this communication to the intended recipient, please advise the sender by reply email and immediately delete the message and any attachments without copying or disclosing the contents. Thank you. ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
Nigel - There are lots of lots of reasons ... 1. All link budgets use a path loss calculation that's also referenced to an isotropic radiator. If you use antenna gain referenced to a dipole, you'll have to add back the gain of the dipole (referenced to the isotropic radiator). 2. It's the standard way of calculating gain for virtually all professionals in the satellite, radar, deep space, avionics, microwave and many other fields. 3. Arguably, dBi is less ambiguous that dBd. By definition, an isotropic reference has the same gain (0 dB) in all directions. A dipole has a directional pattern, so dBd only makes sense if you also define the direction. I believe the assumption is gain broadside to the antenna, but that is still an assumption. 4. If you don't want to actually do link budgets, so you say reason #1 above is irrelevant, then your only real purpose is to compare two different antennas. And then the difference is always going to be dB, whether the two antennas are specified in dBi or dBd. So I still say to use the universal, unambiguous standard. 5. Finally, and most significantly, your statement Why would I believe, or want to use, something I can neither have, use or measure? An isotropic antenna doesn't exist. is just as applicable to the ideal dipole that is your reference for dBd as it is to an isotropic radiator. You can't build a dipole that has zero resistance along its physical length, you can't build a dipole that has zero interaction with its feedline, and you certainly can't achieve any placement that perfectly represents the dipole in free space assumption upon which the dBd reference is based. In summary, there are plenty of reasons whay virtually anyone who builds or uses antennas for a living, does it in dBi Steve W3HF Apr 22, 2010 09:15:04 AM, ni...@ngunn.net wrote: I guess because it's impossible to build an isotropic radiator and therefore just as impossible to measure it. Why would I believe, or want to use, something I can neither have, use or measure? An isotropic antenna doesn't exist. In fact, the amateur community is the only place where there is a fascination with the dipole reference. ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Satellite VUCC # 194
It came in the mail today. It took from November 2009 through February 2010. About 600 QSOs. FT-60R and an Arrow. 36 states confirmed. Thank you all that returned cards. Yeah, I'm jazzed. 73 Loren k7cwq CN94 ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Deployable Solar Panels on a 1U CubeSat
Interesting presentation by Abhishek Bajpayee on deployable Solar Panels at http://www.ustream.tv/channel/CubeSatWorkshop/v3 A number of other presentations from the first two days are also available at this URL 73 Trevor M5AKA Daily Amateur Radio Email/RSS News: http://www.southgatearc.org/ Email Your News To: editor at southgatearc.org Or Upload Using Form At: http://www.southgatearc.org/news/your_news_1.htm ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Satellite VUCC # 194
That'll teach you to stand out in a blizzard on the driveway, hi Congrat's Loren. Myself I have 118 grids confirmed now, but havent had them checked, and I got 47 states confirmed. Still need Maine, Nebraska and Rhode Island on my end for W.A.S. John W6ZKH From: LOREN RASMUSSEN lorenrasmus...@msn.com To: amsat-bb@amsat.org Sent: Thu, April 22, 2010 1:48:49 PM Subject: [amsat-bb] Satellite VUCC # 194 It came in the mail today. It took from November 2009 through February 2010. About 600 QSOs. FT-60R and an Arrow. 36 states confirmed. Thank you all that returned cards. Yeah, I'm jazzed. 73 Loren k7cwq CN94 ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
dBi is used in range calculations because a isotropic antenna has an even radiating field leaving only distance as a variable when calculating path loss. After determining the path loss for a given distance, the antenna gain, transmit power, receiver sensitivity, receiver noise, cable loss, and connector losses are factored into the equation to give a link budget. With the excess allocated to fade margin. ERP calculations are used by regulatory agency's to determine possible interference. Art, KC6UQH -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Edward Cole Sent: Thursday, April 22, 2010 8:47 AM To: w...@arrl.net; amsat-bb@amsat.org Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations) At 02:20 AM 4/22/2010, Stephen Melachrinos wrote: Ah, but this focuses on my question: Why is ERP referenced to a dipole? Why did someone assume that Arecibo's stated gain of 60 dB was dBd and not dBi? I've never seen the gain of a dish antenna used in satellite work quoted in dBd. All of the references for calculating gain are based on the isotropic reference. And all of the usages I have seen (in professional satellite work) use ERP and EiRP interchangeably, and the i in EiRP is used to explicitly state referenced to isotropic. In fact, the amateur community is the only place where there is a fascination with the dipole reference. The dBd specs are useless for any real calculation purposes. Satcom engineering is much simpler if everyone quotes isotropic, and all commercial/government/military satellite link budgets are based on isotropic references. Steve Melachrinos W3HF (Professional) Satcom Engineer since 1979 ERP is about 243 MW and that comes from the conversion from dBi to dBd. ___ Sent via amsat...@amsat.org. 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 In fact the first gain number published over a month ago was 58 dBi. Then I suppose a bunch of hams complained that they didn't understand isotropic gain so the Arecibo folks kindly converted the number to 60 dBd. (i.e. unity isotropic gain, dBi=0, is what a true omni-directional antenna produces in free space) Does anyone on this reflector know the formula for calculating gain of a parabolic dish (Yes, I know-I'm asking if you know)? Did you know that Arecibo dish is spherical and not parabolic? So we can only use the gain number they provide (BTW the UHF line-feed corrects for spherical aberration of the dish surface at Arecibo). Arecibo can track a small amount of angle because the dish is spherical. It is my understanding (might be wrong on this) the line-feed can adjust for the amount of surface irradiated (which will change the gain). The formula normally used in radio astronomy and mw engineering is in terms of dBi. Most (not all) eme hams use dBi vs dBd. I am really amazed at this thread on amsat-bb. I thought the satellite community was more globally oriented (International). The different convention in expressing decimal numbers (aka using comma or period) is pretty well known (I thought). US/UK use period and most EU use comma. Most antenna analysis sw express gain in dBi 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 dubus...@hotmail.com == ___ Sent via amsat...@amsat.org. 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 __ Information from ESET NOD32 Antivirus, version of virus signature database 5051 (20100422) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __ Information from ESET NOD32 Antivirus, version of virus signature database 5051 (20100422) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
The mathematical model is well proven. The difference between a isotropic and a dipole antenna is 2.1 dB. The practical accuracy of field strength measurements on a antenna range is +/- 3dB, making this whole discussion theoretical. (Just In The Interest Of Science) or JITIOS! Art, KC6UQH -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Nigel Gunn G8IFF/W8IFF Sent: Thursday, April 22, 2010 6:15 AM To: w...@arrl.net Cc: amsat-bb@amsat.org; Stephen Melachrinos Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations) I guess because it's impossible to build an isotropic radiator and therefore just as impossible to measure it. Why would I believe, or want to use, something I can neither have, use or measure? An isotropic antenna doesn't exist. On 22-Apr-10 10:20, Stephen Melachrinos wrote: In fact, the amateur community is the only place where there is a fascination with the dipole reference. -- 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 ni...@ngunn.net 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...@amsat.org. 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 __ Information from ESET NOD32 Antivirus, version of virus signature database 5051 (20100422) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __ Information from ESET NOD32 Antivirus, version of virus signature database 5051 (20100422) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ___ Sent via amsat...@amsat.org. 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
[amsat-bb] Double da Donation!
A reminder - You can make contributions online in the AMSAT Store - and the Dayton Amateur Radio Association (DARA) will match one-for-one any donations made to AMSAT between now and June 30, 2010 up to a maximum of $5,000. No, only your half is tax-deductible for you ... (grin) What a great way to show your support of amateur satellites! Please tell your ham friends and club members! Clint Bradford, K6LCS 909-241-7666 ___ Sent via amsat...@amsat.org. 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
