April 2017 - AMSAT-BB - mailman.amsat.org

Dupe contacts on SO-50
by Tucker McGuire 17 Apr '17

17 Apr '17

Hello space bird enthusiasts, I have noticed that certain stations on busy SO-50 passes work the same stations that they have worked on many previous passes when they are in the same grid. Dupe contacts. This can prevent and has prevented other stations from trying to work new grids that happen to be on or perhaps prevented them from working a new guy that hasn't been on the satellites before. On quiet passes I see no issues with working the same station you've worked hundreds of times before but on busy SO-50 passes it is just disruptive. Maybe I'm just a curmudgeon but that's my two cents. Cheers & 73, Tucker W4FS

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SDR transmitter asa Doppler dig-gen
by Robert Bruninga 17 Apr '17

17 Apr '17

Some students built an HF inverting SSB transponder simulator. (4 diodes, and a siggen at 58 MHz) so they can then use two FT-817’s on the 21.4 MHz uplink and 29.4 MHz downlink) for our next satellite: http://aprs.org/hfsat.html ) Now we want to use an USRP 2922 SDR as the programmabel oscillator around 58 MHz so we can simulate Doppler. Can anyone whip out some code to make the oscillator follow a Doppler Ramp in freuqncy from say 58.100 to 58.900 MHz over a ten minute pass. That should be easy enough for one-observer. Can just be linear for now (simulating a low pass). But then once that is done, we need the driver to then FLIP the Doppler shift instantly in the opposite direction to simulate the shift seen by another observer at the other end of the pass. This is another layer of complexity, but we will simply have a push button input to shift between the two states when one station or the other is transmitting. But for now, the students just need some handholding to get the basic SDR acting as a signal gen at 58 MHz and how to input the freqncy ramp to it. Thanks Bob, WB4APR

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EM85 semi-rare?
by Philip Jenkins 17 Apr '17

17 Apr '17

HI After having a long - but awesome - lunch with John KG4AKV after the Raleigh Hamfest on Saturday, the urge to become more active on satellites has increased :-) I live towards the eastern edge of EM85, and I am curious how many might need this grid-square. There is one fairly large city - Knoxville TN - and another medium sized - Asheville NC - inside EM 85, so I'd be a bit surprised if it is that rare. (I don't know any other sat ops in western NC, but east TN may be a different story.) I have equipment for both FM and analog sats, but taking a Kenwood TS 2000 portable can be a bit of a problem, so I would appreciate advice on set-ups/radios (or SDR receiver?) for operating analog portable. (It's been 24 years since I have been on an analog sat - AO-13 - but that's perhaps a short article for the AMSAT Journal.) I don't live far from EM95, so that's a possibility, although I think N4UFO keeps that one fairly active., Other nearby grids are a possibility too, but only FM at first till I decide on what I want to do, rig-wise, for operating SSB/CW portable. (Already have a great antenna, an M^2, for that, and all the coax.) Philip N4HF

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Re: [amsat-bb] Dupe contacts on SO-50
by Ken Alexander 17 Apr '17

17 Apr '17

I see a new category of LID on the horizon: the operator who likes to say hello to his friends. When this is over, will there be any satellite operators left who AREN'T LIDs for one reason or another? -------------------------------------------- On Sun, 4/16/17, Tucker McGuire <tucker(a)mcguireland.com> wrote: Subject: [amsat-bb] Dupe contacts on SO-50 To: amsat-bb(a)amsat.org Received: Sunday, April 16, 2017, 9:58 PM Hello space bird enthusiasts, I have noticed that certain stations on busy SO-50 passes work the same stations that they have worked on many previous passes when they are in the same grid. Dupe contacts. This can prevent and has prevented other stations from trying to work new grids that happen to be on or perhaps prevented them from working a new guy that hasn't been on the satellites before. On quiet passes I see no issues with working the same station you've worked hundreds of times before but on busy SO-50 passes it is just disruptive. Maybe I'm just a curmudgeon but that's my two cents. Cheers & 73, Tucker W4FS _______________________________________________ Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb

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Traveling through EM grids
by Matthew Stevens 17 Apr '17

17 Apr '17

I will be leaving next Sunday afternoon (Apr. 23) for a trip to EM22 in Texas. Driving, I will likely be traveling through EL89, EM80/70/60/50/51/52/42/32/22. I'll have linear and FM capabilities along the way. This is a family trip with a deadline for our arrival in TX...so not a lot of time for stops. However, if you need any of these grids send me an email off list. I've gotten a few requests for EM52/42, and EM60. No promises on anything, but if I know what people need I'll try and accommodate as much as possible! 73 - Matthew kk4fem Sent from my iPhone

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Nayif Data Warehouse
by David Johnson 16 Apr '17

16 Apr '17

Hi We are experiencing difficulties with the server after the restart yesterday, please bear with us while we investigate, 73 Dave, G4DPZ Sent from my iPad

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Re: [amsat-bb] Dupe contacts on SO-50
by John KI4RO 16 Apr '17

16 Apr '17

Absolutely, Tucker. The lack of situational awareness is one of the worst problems on SO 50, if not the worst. 73 John KI4RO

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Re: [amsat-bb] Thoughts on ISS packet switch back to 145.825 MHz (long)
by Kevin M 16 Apr '17

16 Apr '17

Well, if that's what you believe and a logical argument based on similar experience isn't convincing enough, I suppose only 'proof' will do. But I don't have any 'proof' in hand and my experiences are merely similar, so a trip to a tower transmitter site won't be effective in this case. I wonder if it's possible to get the astronauts to make a recording of the receiver audio and send it to the ground by other means. X^D <this is sarcasm and humor for anyone not getting it...> Good luck! From: Stefan Wagener <wageners(a)gmail.com> To: Kevin M <n4ufo(a)yahoo.com> Cc: "amsat-bb(a)amsat.org" <amsat-bb(a)amsat.org> Sent: Sunday, April 16, 2017 7:25 PM Subject: Re: [amsat-bb] Thoughts on ISS packet switch back to 145.825 MHz (long) Thanks Kevin, I appreciate your insight and experience. Thanks for your work as a statewide packet coordinator. That is great! I just worked the last ISS pass 20 min ago and the ISS radio was silent for 20 sec+ in between most packets. NO, I do not believe that the cause is colliding packets, since I can fire off rapid packets and they get repeated quickly, if I choose to and NO, no one has ever told me that I create QRM :-) Traffic was low on the last pass. Made three contacts easily. Hope that helps, Stefan On Sun, Apr 16, 2017 at 6:00 PM, Kevin M via AMSAT-BB <amsat-bb(a)amsat.org> wrote: > No, you are not creating QRM if the ISS does not repeat your packet. Listen to the path of the ISS and > you will hear that 50% of the time the radio is silent. It does not TX since there are no valid packets. > Where is the QRM? I don't have a dog in this fight since I don't work packet any more... but at one time I was a statewide packet coordinator and personally took care of numerous dual band packet nodes. I've listened to the audio while at those sites. There may be one thing to consider than a regular 'ground op' doesn't think of... At high altitude, the receiver can hear a LOT and there are a lot of packets that do not get decoded because two, three, even four or more stations will all transmit at once and cover some part of another stations packet, thereby negating each other. (FM capture effect does not really apply for packet unless it's near 100% with clear audio, which is rare.) Because those stations are not hearing each other, they will key up and transmit at will, whether another station is transmitting at the time or not. From the 'digipeaters' point of view, it hears only partial packets, with lots of overlapping signals, so it decodes none. Whether or not the activity is appropriate, I'm not commenting on that... but I'm addressing your question so that you can better decide for yourself that question. My answer to 'where is the QRM?' is... 'The radio is silent 50% of the time, because it cannot decode enough valid packets... true. But the reason it can't decode enough valid packets may well be (and most likely IS) that all the transmitting stations continually overlap each other. (QRM each other)' The error in the logic here is assuming that it doesn't retransmit because it doesn't 'hear'... On the contrary, it HEARS TOO MUCH and can't make sense of the mess to decode it. In other words, it manages to hear a packet in the clear, about 50% of the time. In simple terms, it's most likely silent BECAUSE of the QRM... as opposed to the silence being an indicator of a LACK of QRM as you have suggested. Which would be no different than SO-50 staying silent because 3-4 stations are all keying up at once and SO-50 can't make sense enough to decode someone's PL tone. In both cases... too many stations, bird can't hear... bird does not retransmit. 73 and good luck to all in finding a workable solution. Kevin N4UFO ______________________________ _________________ Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/ listinfo/amsat-bb

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Re: [amsat-bb] Thoughts on ISS packet switch back to 145.825 MHz (long)
by Kevin M 16 Apr '17

16 Apr '17

> No, you are not creating QRM if the ISS does not repeat your packet. Listen to the path of the ISS and > you will hear that 50% of the time the radio is silent. It does not TX since there are no valid packets. > Where is the QRM? I don't have a dog in this fight since I don't work packet any more... but at one time I was a statewide packet coordinator and personally took care of numerous dual band packet nodes. I've listened to the audio while at those sites. There may be one thing to consider than a regular 'ground op' doesn't think of... At high altitude, the receiver can hear a LOT and there are a lot of packets that do not get decoded because two, three, even four or more stations will all transmit at once and cover some part of another stations packet, thereby negating each other. (FM capture effect does not really apply for packet unless it's near 100% with clear audio, which is rare.) Because those stations are not hearing each other, they will key up and transmit at will, whether another station is transmitting at the time or not. From the 'digipeaters' point of view, it hears only partial packets, with lots of overlapping signals, so it decodes none. Whether or not the activity is appropriate, I'm not commenting on that... but I'm addressing your question so that you can better decide for yourself that question. My answer to 'where is the QRM?' is... 'The radio is silent 50% of the time, because it cannot decode enough valid packets... true. But the reason it can't decode enough valid packets may well be (and most likely IS) that all the transmitting stations continually overlap each other. (QRM each other)' The error in the logic here is assuming that it doesn't retransmit because it doesn't 'hear'... On the contrary, it HEARS TOO MUCH and can't make sense of the mess to decode it. In other words, it manages to hear a packet in the clear, about 50% of the time. In simple terms, it's most likely silent BECAUSE of the QRM... as opposed to the silence being an indicator of a LACK of QRM as you have suggested. Which would be no different than SO-50 staying silent because 3-4 stations are all keying up at once and SO-50 can't make sense enough to decode someone's PL tone. In both cases... too many stations, bird can't hear... bird does not retransmit. 73 and good luck to all in finding a workable solution. Kevin N4UFO

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Fwd: Thoughts on ISS packet switch back to 145.825 MHz (long)
by Gabriel Zeifman 16 Apr '17

16 Apr '17

Stefan, Did you listen to that last pass? There may have been only 10 stations, the problem is then 8 of them are sending beacons every 30 seconds and have no intention of making a QSO! This is a longstanding problem on the ISS 2m digi. I don't agree about your claims on the reliability of the ISS digi; I have routinely worked it and decoded my digipeated packets to the horizon with an Arrow and HT, even on 70cm. With little doubt I would consider the ISS digi one of out most reliable space based transponders, only not functioning when shut off for more prudent matters aboard the station. The ISS has a particularly sensitive receive, it will digipeat plenty, as with most satellites. As is a common disease among sat ops, people focus more on their transmit than receive. Take a listen to an FO-29 pass on the weekend, odds are you'll hear half a dozen stations calling CQ at the exact same spot in the middle with excessive power, and none of them will make a QSO. Maybe you'll hear a station crank the power up on AO-7 "because they can't hear themselves" and knock it into mode A, ruining the pass for most. It IS QRM. If you are preventing QSOs of people that can hear with blind transmissions, that is QRM. Knock yourself transmitting beacons in Western Australia, but over North America you will hear stations, and in any case you will hear RS0ISS (on the condition that you CAN HEAR. You may assume you are not creating QRM, but you often are. The ISS is not so different than SO-50 actually, people blindly transmitting not being able to hear and sharing a single channel, precluding other QSOs. I seem to recall hearing you on a pass a few days ago and giving you a call (which I heard myself clearly) and you didn't hear it. Maybe just a coincidence. 73, Gabe NJ7H On Sun, Apr 16, 2017 at 5:18 PM, Stefan Wagener <wageners(a)gmail.com> wrote: > Thanks Mike, > > Again, you don't seem to get the point. Based on your setup, TNC, software > etc you will NOT be able to decode every single packet and based on your > setup and the ISS position the ISS digipeater will not re-transmit. It's > the nature of the beast. No, you are not creating QRM if the ISS does not > repeat your packet. Listen to the path of the ISS and you will hear that > 50% of the time the radio is silent. It does not TX since there are no > valid packets. Where is the QRM? There is none other than in you local > environment where nobody cares. Don't discourage those that are trying to > make it work. If you want a case, point out the stations and callsigns that > create QRM and are not listenting/responding! > > Just check out the last pass over the US. You will find 10 stations, > that's a station a minute with room to spare. This is NOT SO-50! > > 73, Stefan, VE4NSA > > > > On Sun, Apr 16, 2017 at 5:05 PM, Mike Diehl <diehl.mike.a(a)gmail.com> > wrote: > >> Stefan, >> >> I think you're taking Gabe's comment too literal. The point he's trying >> to make is that many stations just keep on transmitting when they can't >> hear anything. >> >> We can use that amateur radio on ISS as an experiment as an excuse but >> that doesn't really fly. APRS is beyond an experiment as it is a well >> established form of using APRS via satellite, nothing new here. >> >> Furthermore, what is the point of trying repeatedly to transmit if you >> can't decode? It is the golden rule for a reason and it applies everywhere, >> satellite or terrestrial. If you can't hear it you can't work it, bottom >> line. Until you can decode packets you're just creating QRM. >> >> 73, >> >> Mike Diehl >> AI6GS >> >> > On Apr 16, 2017, at 2:46 PM, Stefan Wagener <wageners(a)gmail.com> wrote: >> > >> > Hi Gabe, >> > >> > With all respect I very much disagree. The amateur radio equipment on >> the >> > ISS is an experiment! Sometimes it works and sometimes it doesn't. >> Based on >> > your location, equipment and ISS position you will* NOT* decode every >> > packet, and yes that includes your own packets. So folks will be trying >> > again and that's okay. *They don't become a source of QRM* on the ISS >> since >> > the ISS will only re-transmit if its a good packet. They are exercising >> > their license privileges to work through the ISS and for many having >> that >> > first digipeat after many tries is their success story and we welcome >> that. >> > >> > 73, Stefan, VE4NSA >> > >> > >> > >> > On Sun, Apr 16, 2017 at 1:43 PM, Gabriel Zeifman < >> gabrielzeifman(a)gmail.com> >> > wrote: >> > >> >> I think the golden rule of working all sats applies to ISS as well: if >> you >> >> can't hear (or decode), don't transmit! It's easy to become a source >> of QRM >> >> if you keep transmitting in the blind when you can't hear. >> >> >> >> 73, >> >> Gabe >> >> NJ7H >> >> >> >>> On Apr 16, 2017, at 1:28 PM, Robert Bruninga <bruninga(a)usna.edu> >> wrote: >> >>> >> >>> I agree completely. ISS digipeting should be for LIVE operators. Or >> for >> >>> LIVE things.... (a student experimental ocean going buoy for >> example)... >> >>> >> >>> NOT for non-moving-fixed egos... >> >>> >> >>> Bob, WB4APR >> >>> >> >>> -----Original Message----- >> >>> From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of >> Patrick >> >>> STODDARD (WD9EWK/VA7EWK) >> >>> Sent: Saturday, April 15, 2017 7:51 PM >> >>> To: amsat-bb(a)amsat.org >> >>> Subject: [amsat-bb] Thoughts on ISS packet switch back to 145.825 MHz >> >>> (long) >> >>> >> >>> Hi! >> >>> >> >>> Earlier today, I tweeted a quick comment about what I saw on the ISS >> >>> 145.825 MHz digipeater just after 1900 UTC this afternoon. Since >> tweets >> >>> are limited in length, I'm posting a longer message here... >> >>> >> >>> In the past few weeks, once word got out that a replacement for the >> >> failed >> >>> Ericsson VHF HT on the ISS was being sent up to the station, many were >> >>> anxiously looking forward to seeing the ISS digipeater move from >> 437.550 >> >>> MHz back to 145.825 MHz, where it had been until the old radio's >> failure >> >>> in mid-October 2016. I understood that many would welcome this change, >> >> but >> >>> I was not jumping up and down with excitement. Unfortunately, after >> >> seeing >> >>> the activity on the ISS digipeater in the past day or so since the >> >>> replacement VHF radio was put on 145.825 MHz, my worries have been >> >>> confirmed. >> >>> >> >>> For many, the move to 437.550 MHz meant many stations that could >> easily >> >>> work 145.825 MHz would have to change. Whether it was a different >> antenna >> >>> for the 70cm band or dealing with Doppler with the 437.550 MHz >> frequency, >> >>> almost all of the unattended stations that had been present on the >> >> 145.825 >> >>> MHz frequency were gone. If you wanted to use the ISS digipeater to >> work >> >>> other stations, this was a great opportunity. Many stations using >> >>> APRS-ready HTs and mobile transceivers were showing up, using a group >> of >> >>> memory channels to compensate for Doppler, and were making contacts. >> Some >> >>> fixed stations, including those already capable of satellite >> operating, >> >>> were also showing up. Even on the busier passes, the >> >>> 437.550 MHz always seemed to be clear of the clutter from the >> unattended >> >>> stations that previously inhabited 145.825 MHz. >> >>> >> >>> Fast forward to yesterday (Friday, 14 April). The ISS digipeater >> switched >> >>> to 145.825 MHz in time for afternoon/evening passes over Europe >> (around >> >>> 1330-1400 UTC). Lots of stations showed up, based on looking at the >> >>> ariss.net web site. The same thing started to happen here in North >> >>> America, later in the day. The passes I worked last night were not >> bad, >> >>> but there were more stations on one pass that went over much of the >> >>> continental USA than I'd typically see on 437.550 MHz. >> >>> >> >>> By midday today (1900 UTC), it seemed like many more stations were on >> the >> >>> frequency. I saw 11 other call signs on a pass just after that time >> this >> >>> afternoon. At best, there may have been 4 or 5 other operators at >> their >> >>> keyboards or keypads, looking to make contacts. >> >>> The others were just squawking away, not answering APRS messages sent >> to >> >>> them. By the time the ISS footprint was reaching the east coast, the >> >>> frequency was congested. Lots of position beacons were coming through, >> >> but >> >>> not much of anything else. This is not new; Clayton W5PFG wrote about >> >> this >> >>> about a year ago, here on the AMSAT-BB list: >> >>> >> >>> http://amsat.org/pipermail/amsat-bb/2016-April/058200.html >> >>> >> >>> For the two passes I worked this afternoon, around 1900 and 2035 UTC, >> I >> >>> made two QSOs on the earlier pass, and one on the later pass. A shame, >> >>> considering there were so many other call signs on the earlier pass, >> and >> >>> even some rare spots - stations in DM44 in northern Arizona and CM86 >> in >> >>> Santa Cruz CA were seen. >> >>> >> >>> It is interesting that hams want to have their stations squawk on >> >>> 145.825 MHz when nobody is at the keyboard. It could be doing it >> 24/7, no >> >>> matter if the ISS is in view or not. Would anyone think of setting up >> >>> their satellite station to automatically transmit their call sign and >> >>> location every 15/30/60 seconds to SO-50, unattended? I think not! >> That >> >>> could be a violation of the regulations, and would definitely be poor >> >> form >> >>> by that operator. >> >>> >> >>> Bob Bruninga WB4APR has a couple of documents with recommendations for >> >>> beacon intervals when working the ISS digipeater. One mentioned a >> >> 5-minute >> >>> interval for unattended stations: >> >>> >> >>> http://www.aprs.org/iss-aprs/iss-tx.txt >> >>> >> >>> Another document recommends that unattended stations should be in >> >> "receive >> >>> ONLY mode." (emphasis is Bob's): >> >>> >> >>> http://www.aprs.org/iss-aprs/utiquet.txt >> >>> >> >>> I agree with the latter. If your station is unattended, why have it >> >>> transmit at all?! It may be different for less-populated parts of the >> >>> world, where gateway stations may transmit and then receive their >> beacons >> >>> from the ISS, which will show up on ariss.net and other sites. For >> >> Europe, >> >>> and definitely North America, the gateways really don't need to >> transmit >> >>> if they are unattended. There should be activity on most passes, maybe >> >>> even late into the night, to know 145.825 MHz on the ISS is up and >> >>> running. >> >>> >> >>> Please don't misunderstand me... I think it is great for hams to set >> up >> >>> gateway stations listening on 145.825 MHz for the space-borne APRS >> >>> activity (ISS, NO-84, even NO-44 when it gets enough power to transmit >> >>> complete packets). But these stations, like other stations that aren't >> >>> operating as gateways yet transmit automatically, shouldn't >> contribute to >> >>> the congestion on the frequency. >> >>> >> >>> I know I am in the minority on the ISS digipeater moving back to >> >>> 145.825 MHz. Between the unattended stations clogging up the frequency >> >> and >> >>> some local interference I hear on 145.825 MHz around my house, having >> the >> >>> ISS on 437.550 MHz was fun! I worked it from home, and on some of my >> road >> >>> trips in the past 5+ months. Even for some of my last NPOTA >> activations >> >> at >> >>> the end of 2016. I'll continue to work the ISS digipeater, almost >> >>> exclusively with my APRS-ready HTs (TH-D72A, or TH-D74A), looking to >> make >> >>> QSOs by exchanging APRS messages with other stations. If you can work >> >>> packet from your station, and we are in the same footprints, I hope to >> >>> hear you (and see you on my screen) soon. Like W5PFG mentioned a year >> >> ago, >> >>> let's get more stations on 145.825 MHz making QSOs... >> >>> >> >>> 73! >> >>> >> >>> >> >>> >> >>> >> >>> >> >>> Patrick WD9EWK/VA7EWK >> >>> http://www.wd9ewk.net/ >> >>> Twitter: @WD9EWK >> >>> _______________________________________________ >> >>> Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum >> available to >> >>> all interested persons worldwide without requiring membership. >> Opinions >> >>> expressed are solely those of the author, and do not reflect the >> official >> >>> views of AMSAT-NA. >> >>> Not an AMSAT-NA member? Join now to support the amateur satellite >> >> program! >> >>> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb >> >>> _______________________________________________ >> >>> Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available >> >>> to all interested persons worldwide without requiring membership. >> >> Opinions expressed >> >>> are solely those of the author, and do not reflect the official views >> of >> >> AMSAT-NA. >> >>> Not an AMSAT-NA member? Join now to support the amateur satellite >> >> program! >> >>> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb >> >> _______________________________________________ >> >> Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available >> >> to all interested persons worldwide without requiring membership. >> Opinions >> >> expressed >> >> are solely those of the author, and do not reflect the official views >> of >> >> AMSAT-NA. >> >> Not an AMSAT-NA member? Join now to support the amateur satellite >> program! >> >> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb >> >> >> > _______________________________________________ >> > Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available >> > to all interested persons worldwide without requiring membership. >> Opinions expressed >> > are solely those of the author, and do not reflect the official views >> of AMSAT-NA. >> > Not an AMSAT-NA member? Join now to support the amateur satellite >> program! >> > Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb >> > >

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