Re: [amsat-bb] Digital Satellites Question
On 07/22/2014 08:50 AM, Douglas Phelps wrote: And, in a related question, wouldn't more proccessing demand more power from the batteries/solar panels? I know my PC cetainly draws a lot more power when the CPO is working hard. Not really. The biggest load in a communications satellite, or almost any robotic spacecraft for that matter, is almost always the downlink RF power amplifier(s). Using them more efficiently can justify almost anything. Also, even highly efficient digital modes tend to be easy to generate; many spacecraft do (or did) so purely in hardware. Demodulating and decoding them is more work so uplink and downlink modes are often different, each optimized for its purpose. --Phil ___ Sent via AMSAT-BB@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
Re: [amsat-bb] Inclusion (satcoms?)
On 07/22/2014 11:05 AM, Robert Bruninga wrote: The value of ham radio is providing communications where other systems cannot. And of course, playing with toys just for fun. I'd flip that around. With the Internet, mobile phones and other ubiquitous communications, about the sole reason left for ham radio to exist is **education**. And playing with toys just for fun is often quite educational as well. Ham radio provides a hands-on opportunity to teach and learn radio (and electronics) technology, and you still can't find anything like it anywhere else. Emergency communications is still in there somewhere, but in all honesty I now see it as a distant second. And if one is to teach oneself communications and electronics technology through ham radio, then ham radio really ought to use something like the communications and electronics technologies that the outside world is using today, not just those the world was using 40 years ago. --Phil ___ Sent via AMSAT-BB@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
Re: [amsat-bb] AMSAT where are we going for what it is worth.
On 07/22/2014 11:19 AM, Bryce Salmi wrote: All this requires much much much more power than a 1U satellite is currently capable of producing. At least for always on type operating. We'll get there eventually. Only if you keep the analog modes since they hog nearly all the available power and drive the spacecraft design in many other ways. Let go of them, and many new things suddenly become possible for the first time. ___ Sent via AMSAT-BB@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] Yaesu G-5500 AZ/EL rotor for sale
This rotor is less than a year old. It works perfectly and is in very good condition. Works with any of the ST series interfaces (ST-1 and ST-3). Selling the rotor, control box, Satellite serial port interfaces ST-3 and SAT668. It really is Plug and Play $450 plus shipping Thanks -Original Message- From: Phil Karn Sent: Sunday, July 27, 2014 1:12 AM To: amsat-bb@amsat.org Subject: Re: [amsat-bb] going digital On 07/22/2014 07:27 AM, JoAnne Maenpaa wrote: When thinking of projects to enter into the digital communication world plan on building or buying that digital interface to connect your radio to the soundcard. Soundcard interfaces to existing voice radios were a good start, but it's time to move past them. I've designed several modulation and coding schemes to fit existing radios, and their inherently limited bandwidth is a major pain. For ARISSat-1 I agreed to cram everything through a SSB filter, and I'm not doing that again. Not only does the narrow bandwidth often limit the data rate to much less than what the link budget could actually support, but it enormously aggravates the Doppler problem. It doesn't help that there are no industry-wide standards for SSB phase response or computer tuning, or that every time you retune one (which is often) there is a poorly characterized phase jump. Doppler is much easier to handle at high data rates because it's the ratio of the symbol rate to the Doppler that matters, not the absolute amount of Doppler. Now that we have a variety of pure digital radio front ends to choose from, it's time to set aside the voice radio + soundcard model. Not only do the SDRs support wider bandwidths but they tend to be considerably smaller, lighter and easier to work with in software. Some, like the Funcube dongle, are even considerably cheaper than conventional radios. --Phil ___ Sent via AMSAT-BB@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-BB@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
Re: [amsat-bb] Inclusion (satcoms?)
On Sat, Jul 26, 2014 at 11:31:51PM -0700, Phil Karn wrote: On 07/22/2014 11:05 AM, Robert Bruninga wrote: The value of ham radio is providing communications where other systems cannot. And of course, playing with toys just for fun. I'd flip that around. With the Internet, mobile phones and other ubiquitous communications, about the sole reason left for ham radio to exist is **education**. And playing with toys just for fun is often quite educational as well. Ham radio provides a hands-on opportunity to teach and learn radio (and electronics) technology, and you still can't find anything like it anywhere else. Agreed and this is the primary focus I took when doing up our club brochure. http://www.db.net/~db/oarc_db_brochure.pdf Our future is with the young is education. The idea of sitting in your livingroom talking to people all over the world is something doable with modern technology (even IRC!) not hamradio. This is the wrong approach. Emergency communications is still in there somewhere, but in all honesty I now see it as a distant second. I agree. And if one is to teach oneself communications and electronics technology through ham radio, then ham radio really ought to use something like the communications and electronics technologies that the outside world is using today, not just those the world was using 40 years ago. Yes. SSB is a technology the phone company first used and they have moved on to digital. --Phil ___ Sent via AMSAT-BB@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 -- Diane -- - d...@freebsd.org d...@db.net http://www.db.net/~db ___ Sent via AMSAT-BB@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
Re: [amsat-bb] FM birds
On Sat, Jul 26, 2014 at 10:24:15PM -0700, Phil Karn wrote: On 07/22/2014 07:49 AM, wa4...@comcast.net wrote: SSB/CW birds are the only way to go and if you build it they will come . Think about what it would be like to tune for Doppler while working SSB through a LEO satellite on microwave. Before you say computer control, work out the effect of even a tiny error in your clock or orbital elements on a high elevation pass and remember that SSB has no carrier or pilot tone for closed-loop frequency tracking. Sure, you could have a second receiver track the satellite's beacon. But if you're going to all that trouble, why not just have it track a single high speed data stream from the satellite, one that's much less affected by Doppler in the first place? Exactly. It makes much more sense to go digital. The crucial thing is *not* the complexity of the groundstation it is the lifetime of the satellite. - 73 Diane VA3DB -- - d...@freebsd.org d...@db.net http://www.db.net/~db ___ Sent via AMSAT-BB@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
Re: [amsat-bb] FM birds
Tracking doppler on 2m and 70cm was hard enough at field day. I like 2GHz and up, but do not want to even think about the doppler. In the KITSAT days, I used an IC-751 as the receive IF. It has a true FM detector, with discriminator centered at 0-volts. It steps in 1 or 10 Hz increments, even on FM. I wrote a simple radio-control program which would take data from InstantTrack, calculate frequency from that, and set the radio on the expected frequency at the beginning of the pass. Didn't matter if there was a little error, once AOS happened, the AFC put the receiver dead-on, and I got good data for the entire pass -- hands free. It was a joy to watch. And that was a simple digital mode. The other thing that is exciting about going digital, is the idea of CAT-5 (or fiber) to the box at the antenna, not coax. Digital will enable so much . . . . 73, Jim wb4...@amsat.org On 7/27/2014 1:24 AM, Phil Karn wrote: On 07/22/2014 07:49 AM, wa4...@comcast.net wrote: SSB/CW birds are the only way to go and if you build it they will come . Think about what it would be like to tune for Doppler while working SSB through a LEO satellite on microwave. Before you say computer control, work out the effect of even a tiny error in your clock or orbital elements on a high elevation pass and remember that SSB has no carrier or pilot tone for closed-loop frequency tracking. Sure, you could have a second receiver track the satellite's beacon. But if you're going to all that trouble, why not just have it track a single high speed data stream from the satellite, one that's much less affected by Doppler in the first place? ___ Sent via AMSAT-BB@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 --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ Sent via AMSAT-BB@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
Re: [amsat-bb] FM birds
On 07/27/2014 12:57 PM, Jim Sanford wrote: The other thing that is exciting about going digital, is the idea of CAT-5 (or fiber) to the box at the antenna, not coax. Yep. Rig at the mast-head, fiber (RF noise-immune) to the shack, and a control head at the operators position. Or a software-only control head, (but I like twiddling real knobbies and flipping real switches). Crunch numbers up the pole, at the desk, or both. Will I live long enough? -- Gus 8P6SM The Easternmost Isle ___ Sent via AMSAT-BB@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
Re: [amsat-bb] I want this. I want that. Here comes another FM LEO sat.
I would also vote AO40 was not to complex, it was failed by an accident. Not wishing to bring up bad memories, but two questions: Did anything other than the plug incident happen? (In other words, did any systems fail before the explosion?) Was there a backup bird built of the same design that just might be flyable if we could find a ride? ___ Sent via AMSAT-BB@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
Re: [amsat-bb] I want this. I want that. Here comes another FM LEO sat.
- Original Message - From: Floyd Rodgers kc5...@swbell.net To: bstguitar...@gmail.com; Phil Karn k...@ka9q.net Cc: amsat-bb@amsat.org Sent: Sunday, July 27, 2014 8:17 PM Subject: Re: [amsat-bb] I want this. I want that. Here comes another FM LEO sat. I would also vote AO40 was not to complex, I agree ! Not to complex to be operated. it was failed by an accident. Someone forgot to remove a red cap from a valv fuel and helium system. Not wishing to bring up bad memories, but two questions: Did anything other than the plug incident happen? (In other words, did any systems fail before the explosion?) NO ! Was there a backup bird built of the same design that just might be flyable if we could find a ride? We got for years OSCAR-10 and OSCAR-13 in the Molnyia orbit very similar to that of AO40 but with lover apogee and different orbit inclination, 73 de i8CVS Domenico ___ Sent via AMSAT-BB@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-BB@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
Re: [amsat-bb] I want this. I want that. Here comes another FM LEO sat.
Op 27-07-14 om 20:17 schreef Floyd Rodgers: Was there a backup bird built of the same design that just might be flyable if we could find a ride? Not a backup for phase 3d but a satelite with simular spaceframe and capabiletie to get in the same orbit, phase 3e is capable of being flight test ready in a short time as it was intended to be launched around 2007 if I'm not mistaken. it has a simpler IF system but the signals should be just as strong as ao-40 was. 73 de Andre PE1RDW ___ Sent via AMSAT-BB@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] LituanicaSAT-1 status update
Dear friends, FM transponder is OFF, it's mission is completed, thank you for all the good responses. Based on this there will be more projects in the future making benefit for HAM people of the World. Currently only telemetry packets are to transmit data every 15 seconds. On-board temperature is rising and the altitude is being lost quickly therefore some peculiarities due to changing thermal environment can occur. Would appreciate any of your reports tracking last orbits of LituanicaSAT-1. Thank you for all of your support! Vytenis B. ___ Sent via AMSAT-BB@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] CN88 on CW today
I will be on FO-29, Mode CW on the 0048Z (July 28) and 0234Z passes, mode CW. Looking for some cw contacts. . 73'...Ed WA7ETH ___ Sent via AMSAT-BB@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
