April 2011 - AMSAT-BB - mailman.amsat.org

ARISSSAT-1 due for April 12th, not 11th!
by Achim Vollhardt 12 Apr '11

12 Apr '11

ISS On-Orbit Report April 11th: http://www.nasa.gov/directorates/somd/reports/iss_reports/index.html "Dmitri performed hardware setup and test activation of the TEKh-43 Radioskaf-B “Kedr” microsatellite in the MRM2 Poisk module, connecting it to an 825M3 Orlan battery and checking out its 430 MHz transmitter from the satellite control panel. [The small satellite was named Kedr in honor of the call sign of Yuri Gagarin. It will be activated onboard the station tomorrow, April 12, i.e., Cosmonautics Day, when the world celebrates the anniversaries of the first human flight into space and the first Space Shuttle flight.(...)]" Looks completely normal to me, that nobody heard anything.. activation is now planned for April 12th (today). 73s Achim, DH2VA

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Still Nothing From ARISSat-1 In DO33
by B J 12 Apr '11

12 Apr '11

I had a good view of the ISS during the pass, though. 73s Bernhard VA6BMJ @ DO33FL

4 3

ARISSat-1
by Louis McFadin 12 Apr '11

12 Apr '11

Nothing heard on the 7 AM EDT 65 degree pass over Orlando. On Apr 12, 2011, at 2:51 AM, amsat-bb-request(a)amsat.org wrote: > Send AMSAT-BB mailing list submissions to > amsat-bb(a)amsat.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://amsat.org/mailman/listinfo/amsat-bb > or, via email, send a message with subject or body 'help' to > amsat-bb-request(a)amsat.org > > You can reach the person managing the list at > amsat-bb-owner(a)amsat.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of AMSAT-BB digest..." > > > Today's Topics: > > 1. Re: The Need for Phonetics (Jim Shorney) > 2. ARISsat-1 not heard (John Heath) > 3. ARISSat-1 update (Gould Smith) > 4. Re: ARRISSat Reception 14.45 UTC (Joe Fitzgerald) > 5. Arissat still silent (P. Pakr) > 6. Nothing Heard in VK of ARISSat-1 (Colin Hurst) > 7. Nice view of ISS ... (Viktor Kudielka) > 8. Re: ARRISSat Reception 14.45 UTC (Phil Karn) > 9. Re: ARRISSat Reception 14.45 UTC (KF1BUZ) > 10. Nothing Heard 2M ARISSat-1 9:32PM PDT (Clint Bradford) > 11. Just an hour from now ... (Clint Bradford) > 12. R50KEDR Heard on 14.190 (John Heath) > 13. ARISSat-1 No Signal (John Spasojevich) > 14. Re: ARISSat-1 No Signal (KF1BUZ) > 15. Nothing here either: 0606z pass over California (Greg D.) > 16. Nothing Heard From ARISSat-1 In DO33 (B J) > 17. Not Heard 1106 PM PDT (Clint Bradford) > 18. satellite average elevation (Bob- W7LRD) > 19. Nothing heard over Nashville 0610 (Alan P. Biddle) > 20. Re: ARRISSat Reception 14.45 UTC (Phil Karn) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 11 Apr 2011 19:03:22 -0500 > From: "Jim Shorney" <jshorney(a)inebraska.com> > Subject: [amsat-bb] Re: The Need for Phonetics > To: "amsat-bb" <amsat-bb(a)amsat.org> > Message-ID: <20110412000315.B8E5816E398(a)mail03.inebraska.com> > Content-Type: text/plain; charset="iso-8859-1" > > On Mon, 11 Apr 2011 14:17:49 -0700, Jeff Moore wrote: > >> <== Could it be that they understand the quicksand you're standing on? > > > No. We know from long experience (35+ years in my case) that Glen is right. > > 73 > > -Jim > > > -- > Ham Radio NU0C > Lincoln, Nebraska, U.S.S.A. > TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! > > "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." > > HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ > http://incolor.inetnebr.com/jshorney > http://www.nebraskaghosts.org > > > > > ------------------------------ > > Message: 2 > Date: Tue, 12 Apr 2011 01:22:39 +0100 (BST) > From: John Heath <g7hia(a)btinternet.com> > Subject: [amsat-bb] ARISsat-1 not heard > To: Amsat <amsat-bb(a)amsat.org> > Message-ID: <330370.94421.qm(a)web86606.mail.ird.yahoo.com> > Content-Type: text/plain; charset=iso-8859-1 > > 0107? AOS pass in range UK - nothing heard on 145.950 > > 73 john g7hia > > ------------------------------ > > Message: 3 > Date: Mon, 11 Apr 2011 20:35:42 -0400 > From: "Gould Smith" <gouldsmi(a)bellsouth.net> > Subject: [amsat-bb] ARISSat-1 update > To: <amsat-bb(a)amsat.org> > Message-ID: <0EE1E8CB77EF40158B1BCB10C560994B@GouldMainPC> > Content-Type: text/plain; charset="iso-8859-1" > > As Armando, N8IGJ noted in his earlier email, NASA as published an update of today's activities ( it can be found at :http://www.nasa.gov/directorates/somd/reports/iss_reports/index.html) .Contained this document is a section about ARISSat > > Dmitri performed hardware setup and test activation of the TEKh-43 Radioskaf-B "Kedr" microsatellite in the MRM2 Poisk module, connecting it to an 825M3 Orlan battery and checking out its 430 MHz transmitter from the satellite control panel. [The small satellite was named Kedr in honor of the call sign of Yuri Gagarin. It will be activated onboard the station tomorrow, April 12, i.e., Cosmonautics Day, when the world celebrates the anniversaries of the first human flight into space and the first Space Shuttle flight. Development, manufacturing and launch of Kedr is the first phase in Russia's integrated program approved by UNESCO, with the goal to create and operate mini-satellites with a mass less than 100 kg by combined efforts of students across the world. Once Kedr is activated, it will transmit 25 greetings in 15 languages, pictures of Earth, and telemetry data from science hardware and support systems, as well as historical audio recordings. 50 years after Gagarin's fl! > ight all ham radio operators across the world thus will have a unique opportunity to hear the famous "Poyekhali" (Let's Go!) from Earth orbit.] > > Some clarifications: > ARISSat-1, RadioSkaf-V, RadioSkaf-B, Kedr are all names for the same satellite. > It is doubtful that the satellite will transmit pictures of earth as it is inside the ISS. > ARISSat-1 only transmits on 2M. The ARISS team has arranged for the TM-D700 transceiver aboard the ISS to also transmit the ARISSat signals on 437.55 MHz. > There are 24 different messages that will transmit in a sequence, one of which is the Gagarin-ground station conversation. > The crew operates on UTC time and sleeps from 2130Z - 0600Z usually so probably no activity until after 0600Z > The 12 April schedule found at http://www.nasa.gov/pdf/534825main_041211_tl.pdf doesn't specifically list an activity to turn on ARISsat-1 > Keep listening, we'll let you know more as we know more. > > 73, > Gould, WA4SXM > > ------------------------------ > > Message: 4 > Date: Mon, 11 Apr 2011 20:47:28 -0400 > From: Joe Fitzgerald <jfitzgerald(a)alum.wpi.edu> > Subject: [amsat-bb] Re: ARRISSat Reception 14.45 UTC > To: amsat-bb(a)amsat.org > Message-ID: <4DA3A120.9040701(a)alum.wpi.edu> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 4/11/2011 1:44 PM, Phil Karn wrote: >> Since it's already connected to the station antenna, it sure would be nice >> if they could just plug it directly into the ISS power supply, switch it on >> full duty cycle, and just *leave* it for a couple of, oh, years. > > Phil, > > I am curious to see how your BPSK1000 fares on a rapidly tumbling > platform. Let's hope ISS doesn't start tumbling more than once per orbit! > > If you do convince them to leave the ISS powered up on board ISS, we > could evaluate rapit deep fades in the channel by putting middle school > students in charge of holding an arrow antenna. > > -Joe KM1P > > > ------------------------------ > > Message: 5 > Date: Tue, 12 Apr 2011 01:02:59 +0200 > From: "P. Pakr" <p.pakr(a)seznam.cz> > Subject: [amsat-bb] Arissat still silent > To: amsat-bb(a)amsat.org > Message-ID: <20110411220258.6CDE08A8006(a)sg1.krivonet.info> > Content-Type: text/plain ; charset="UTF-8" > > Next pass over Czech, nothing heard here :-( > 73! Petr > > > ------------------------------ > > Message: 6 > Date: Tue, 12 Apr 2011 10:52:47 +0930 > From: "Colin Hurst" <cjhurst(a)bigpond.net.au> > Subject: [amsat-bb] Nothing Heard in VK of ARISSat-1 > To: "amsat-bb" <amsat-bb(a)amsat.org> > Message-ID: <C8B6CE92B219472DBF5394B1577A6723@Athlon> > Content-Type: text/plain; charset="us-ascii" > > Had a nice pass at 0045utc 12/4/2011, 67 degrees elevation. > No signals heard. > 73 > Colin VK5HI > > > > ------------------------------ > > Message: 7 > Date: Tue, 12 Apr 2011 03:39:11 +0000 > From: Viktor Kudielka <viktor.kudielka(a)ieee.org> > Subject: [amsat-bb] Nice view of ISS ... > To: amsat-bb(a)amsat.org > Message-ID: <20110412033911.GD26119(a)SATURN.lan> > Content-Type: text/plain; charset=us-ascii > > ... over Vienna at 03:25UTC with 47 degrees elevation. > Automatic antenna tracking seems to be nearly perfect, > but no signal ? > The CW decoder of ARISSatTLM produced a random string of > characters including ...HIHI... > 73, Viktor OE1VKW > > > > ------------------------------ > > Message: 8 > Date: Mon, 11 Apr 2011 20:58:54 -0700 > From: Phil Karn <karn(a)philkarn.net> > Subject: [amsat-bb] Re: ARRISSat Reception 14.45 UTC > To: Joe Fitzgerald <jfitzgerald(a)alum.wpi.edu> > Cc: amsat-bb(a)amsat.org > Message-ID: <BANLkTi=gMJKZbivTEVeoP+zV2+Wj_mA1xw(a)mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > On Mon, Apr 11, 2011 at 5:47 PM, Joe Fitzgerald <jfitzgerald(a)alum.wpi.edu>wrote: > >> >> I am curious to see how your BPSK1000 fares on a rapidly tumbling >> platform. Let's hope ISS doesn't start tumbling more than once per orbit! >> > > It's a pretty sensitive mode, but it still won't work with a zero-watt > transmitter. > > >> >> If you do convince them to leave the ISS powered up on board ISS, we >> could evaluate rapit deep fades in the channel by putting middle school >> students in charge of holding an arrow antenna. >> >> > My concern is that the on/off cycling won't play well with my convolutional > interleaver. It takes 16.384 seconds to fill the interleaver at AOS. You > might get decoded data up to 8 seconds earlier than that if what you do get > is very clean, but there's little margin for additional error correction. > > And when the transmitter switches off, the interleaver will drain over > 16.384 seconds as it fills with noise. If the signal in the last 16.384 > seconds before switch-off is unusually strong, you may be able to decode > data up to 8 seconds before LOS. But anywhere from 8 to 16 seconds will be > chopped off *each end* of each already very short 40-60 second > transmission. > > I designed this signal to deal well with occasional deep fades lasting up to > 1-1.5 seconds -- not for total "fades" lasting 2 minutes at a time. Had I > known that this "emergency low power mode" was actually going to be used, I > would have designed the whole mode completely differently, with block > interleaving aligned to the transmit on/off times. > > The golden rule of the modem designer: "know your channel". Optimizing for > one impairment usually pessimizes it for something else. > > > ------------------------------ > > Message: 9 > Date: Mon, 11 Apr 2011 21:22:28 -0700 > From: KF1BUZ <kf1buz(a)gmail.com> > Subject: [amsat-bb] Re: ARRISSat Reception 14.45 UTC > To: <karn(a)ka9q.net>, "'Joe Fitzgerald'" <jfitzgerald(a)alum.wpi.edu> > Cc: amsat-bb(a)amsat.org > Message-ID: <00f101cbf8c9$3ceed0b0$b6cc7210$@com> > Content-Type: text/plain; charset="us-ascii" > > Well its 421 am they will be awake around 0600 am utc.. 2 hours from now, > then we will see if they flippa da switcha > > Kf1buz > > -----Original Message----- > From: amsat-bb-bounces(a)amsat.org [mailto:[email protected]] On > Behalf Of Phil Karn > Sent: Monday, April 11, 2011 8:59 PM > To: Joe Fitzgerald > Cc: amsat-bb(a)amsat.org > Subject: [amsat-bb] Re: ARRISSat Reception 14.45 UTC > > On Mon, Apr 11, 2011 at 5:47 PM, Joe Fitzgerald > <jfitzgerald(a)alum.wpi.edu>wrote: > >> >> I am curious to see how your BPSK1000 fares on a rapidly tumbling >> platform. Let's hope ISS doesn't start tumbling more than once per orbit! >> > > It's a pretty sensitive mode, but it still won't work with a zero-watt > transmitter. > > >> >> If you do convince them to leave the ISS powered up on board ISS, we >> could evaluate rapit deep fades in the channel by putting middle >> school students in charge of holding an arrow antenna. >> >> > My concern is that the on/off cycling won't play well with my convolutional > interleaver. It takes 16.384 seconds to fill the interleaver at AOS. You > might get decoded data up to 8 seconds earlier than that if what you do get > is very clean, but there's little margin for additional error correction. > > And when the transmitter switches off, the interleaver will drain over > 16.384 seconds as it fills with noise. If the signal in the last 16.384 > seconds before switch-off is unusually strong, you may be able to decode > data up to 8 seconds before LOS. But anywhere from 8 to 16 seconds will be > chopped off *each end* of each already very short 40-60 second > transmission. > > I designed this signal to deal well with occasional deep fades lasting up to > 1-1.5 seconds -- not for total "fades" lasting 2 minutes at a time. Had I > known that this "emergency low power mode" was actually going to be used, I > would have designed the whole mode completely differently, with block > interleaving aligned to the transmit on/off times. > > The golden rule of the modem designer: "know your channel". Optimizing for > one impairment usually pessimizes it for something else. > _______________________________________________ > Sent via AMSAT-BB(a)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 > > > > ------------------------------ > > Message: 10 > Date: Mon, 11 Apr 2011 21:47:09 -0700 > From: Clint Bradford <clintbradford(a)mac.com> > Subject: [amsat-bb] Nothing Heard 2M ARISSat-1 9:32PM PDT > To: AMSAT BB <amsat-bb(a)amsat.org> > Message-ID: <4FF01222-2099-4C54-8C94-D658CFE02E7C(a)mac.com> > Content-Type: text/plain; CHARSET=US-ASCII > > Another poor pass for me ... nothing heard. > > BUT AT 11:06PM PDT - a whopper of a pass. Followed by a pass in the morning that should be VISIBLE! > > ("Honey, brew another pot o' coffee, will you please?") > > Clint, K6LCS > 909-241-7666 - cell > > > ------------------------------ > > Message: 11 > Date: Mon, 11 Apr 2011 22:09:42 -0700 > From: Clint Bradford <clintbradford(a)mac.com> > Subject: [amsat-bb] Just an hour from now ... > To: AMSAT BB <amsat-bb(a)amsat.org> > Message-ID: <D8875A02-4FA0-4E30-A5FF-1EBE90BADE92(a)mac.com> > Content-Type: text/plain; CHARSET=US-ASCII > > Added a photo of me working (unsuccessfully) a pass of the ISS this evening (9:32PM PDT, Riverside, CA DM13). > > In the background, FirstOrbit.org's incredible film that will be released to the world tomorrow - a re-creation of Yuri's 108-minute flight, taken by modern cameras aboard the ISS. > > http://gallery.me.com/clintbradford#100077 > > Clint, K6LCS > Skype - clintbradford > > > ------------------------------ > > Message: 12 > Date: Tue, 12 Apr 2011 06:20:53 +0100 (BST) > From: John Heath <g7hia(a)btinternet.com> > Subject: [amsat-bb] R50KEDR Heard on 14.190 > To: Amsat <amsat-bb(a)amsat.org> > Message-ID: <951449.92923.qm(a)web86601.mail.ird.yahoo.com> > Content-Type: text/plain; charset=utf-8 > > 0520 UTC > > The gagarin station R50KEDR on 14.190 working split listening 5 up. > > Weak signal at my QTH in southern England > > 73 john g7hia > > ------------------------------ > > Message: 13 > Date: Tue, 12 Apr 2011 00:08:25 -0500 > From: John Spasojevich <johnag9d(a)gmail.com> > Subject: [amsat-bb] ARISSat-1 No Signal > To: amsat-bb(a)amsat.org > Message-ID: <BANLkTinhnB5fFMb7TbOPUUOacrF3pie2pw(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Nothing heard on the 0437 UTC pass in Montgomery, IL 76 degrees elevation, > nice night though. > > John - AG9D > > > ------------------------------ > > Message: 14 > Date: Mon, 11 Apr 2011 23:16:30 -0700 > From: KF1BUZ <kf1buz(a)gmail.com> > Subject: [amsat-bb] Re: ARISSat-1 No Signal > To: "'John Spasojevich'" <johnag9d(a)gmail.com>, <amsat-bb(a)amsat.org> > Message-ID: <00f201cbf8d9$2accaf00$80660d00$@com> > Content-Type: text/plain; charset="us-ascii" > > Nothing heard over reno, no packet or anything.. > > Slacking space doods!! > Kf1buz > > -----Original Message----- > From: amsat-bb-bounces(a)amsat.org [mailto:[email protected]] On > Behalf Of John Spasojevich > Sent: Monday, April 11, 2011 10:08 PM > To: amsat-bb(a)amsat.org > Subject: [amsat-bb] ARISSat-1 No Signal > > Nothing heard on the 0437 UTC pass in Montgomery, IL 76 degrees elevation, > nice night though. > > John - AG9D > _______________________________________________ > Sent via AMSAT-BB(a)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 > > > > ------------------------------ > > Message: 15 > Date: Mon, 11 Apr 2011 23:23:27 -0700 > From: "Greg D." <ko6th_greg(a)hotmail.com> > Subject: [amsat-bb] Nothing here either: 0606z pass over California > To: <amsat-bb(a)amsat.org> > Message-ID: <BLU133-W298B2A1BBC173A8237AC00A9AB0(a)phx.gbl> > Content-Type: text/plain; charset="iso-8859-1" > > > No signal on 145.950 here in Cal. With my luck they probably started the 15 min timer just before LOS... > > By the way, confirming the earlier post about inconsistent KEPs. Gpredict updates from Celestrak, and was slightly behind Predict which I had loaded from Amsat.org website. (I use Gpredict for pass prediction and eye candy during a pass; predict drives my rotor and Doppler shift radio client.) > > Greg KO6TH > > > > ------------------------------ > > Message: 16 > Date: Mon, 11 Apr 2011 23:25:29 -0700 (PDT) > From: B J <top_gun_canada(a)yahoo.com> > Subject: [amsat-bb] Nothing Heard From ARISSat-1 In DO33 > To: amsat-bb(a)amsat.org > Message-ID: <794603.7473.qm(a)web30906.mail.mud.yahoo.com> > Content-Type: text/plain; charset=us-ascii > > I listened until 0620 UTC but it was a low-elevation pass. The next 3 will be over 30 degrees. > > 73s > > Bernhard VA6BMJ @ DO33FL > > > > ------------------------------ > > Message: 17 > Date: Mon, 11 Apr 2011 23:35:36 -0700 > From: Clint Bradford <clintbradford(a)mac.com> > Subject: [amsat-bb] Not Heard 1106 PM PDT > To: AMSAT BB <amsat-bb(a)amsat.org> > Message-ID: <0816DB2F-0E77-455C-ABC2-E58B55990C4C(a)mac.com> > Content-Type: text/plain; CHARSET=US-ASCII > > Darn .... Nada heard on an excellent pass of the ISS at 1106PM PDT. > > But I think the astronauts were just awakened at the top o' the hour. > > OK - 5:30-ish AM PDT next pass over Southern CA DM13-land! > > Clint > Skype - clintbradford > > > ------------------------------ > > Message: 18 > Date: Tue, 12 Apr 2011 06:35:48 +0000 (UTC) > From: Bob- W7LRD <w7lrd(a)comcast.net> > Subject: [amsat-bb] satellite average elevation > To: amsat-bb(a)amsat.org > Message-ID: > <1639302076.3920933.1302590148277.JavaMail.root(a)sz0126a.emeryville.ca.mail.comcast.net> > > Content-Type: text/plain; charset=utf-8 > > > > I saw on this bb a site or note that shows the overall?average elevatation.? As I remember it elevation is surprisingly low for most passes.? Where can I find it? > > 73 Bob W7LRD > > > ------------------------------ > > Message: 19 > Date: Tue, 12 Apr 2011 01:41:15 -0500 > From: "Alan P. Biddle" <APBIDDLE(a)UNITED.NET> > Subject: [amsat-bb] Nothing heard over Nashville 0610 > To: "AMSAT-BB" <amsat-bb(a)amsat.org> > Message-ID: <0D3F14EBAC99494FA86A73A7FD1D8543@WA4SCA> > Content-Type: text/plain; charset="us-ascii" > > All, > > Silence over Nashville on the 0610 UTC pass. All but 2 of the passes during > the scheduled period of activation will be "in the weeds" from an elevation > standpoint at my QTH. > > Did get a nice I/Q recording of the passband, though. > > > Alan > WA4SCA > > ----------------------------------- > > The prospect of domination of the > nation's scholars by Federal employment, > project allocations, and the power of money > is ever present - and is gravely to be > regarded. > > President Dwight D. Eisenhower > > > > > ------------------------------ > > Message: 20 > Date: Mon, 11 Apr 2011 23:50:44 -0700 > From: Phil Karn <karn(a)philkarn.net> > Subject: [amsat-bb] Re: ARRISSat Reception 14.45 UTC > To: Joe Fitzgerald <jfitzgerald(a)alum.wpi.edu> > Cc: amsat-bb(a)amsat.org > Message-ID: <BANLkTimUmhaTC0BhCvuQaid90A4DmFWdrQ(a)mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > To elaborate: > > BPSK-1000 uses "convolutional interleaving" with a depth of 16,384 symbols. > The symbol rate is 1 kHz (1,000 symbols/sec) so it takes 16.384 seconds for > a data symbol to pass through both the transmit and receive interleave > buffers. The transmitter delay changes a lot from one symbol to the next, > but every symbol experiences the same *total* (transmitter + receiver) > delay: 16,384 symbol times or 16.384 seconds. The idea of any interleaver is > to chop up (short) fades and spread them out in time so that they can be > easily corrected by the Viterbi error correction algorithm (which deals well > with random thermal noise but not with burst errors). > > The usual rule of thumb is that an interleaver can easily handle a complete > fade lasting up to 10% of its length, as long as you give it time to recover > between fades. That would be 1.6 seconds, which seemed plenty long for a > continuously transmitting LEO spacecraft on 2 meters. > > Of course, you pay a price in delay -- there's no way around it. I have > Sirius Satellite Radio in my car, and it always cuts out 4 seconds *after* I > drive into the parking garage at work. It doesn't come back until (at least) > 4 seconds *after* I drive out and it sees the satellite(s) again. The reason > is exactly the same -- an interleaver that takes care of brief fades but not > the really long ones caused by driving into a parking garage. > > I chose convolutional interleaving for BPSK-1000 because it has half the > delay of block interleaving for the same fade performance. > > Convolutional interleavers also operate continuously, a good match to > ARISSat-1's continuous transmitter. At AOS, your deinterleaver is still full > of noise received earlier; it takes 16.384 seconds to flush it all out and > feed "solid" data to the decoder. During that time, it ramps from pure noise > to pure signal, and at some point it starts correcting what it sees. > Depending on how strong the signal is, that may happen before the flushing > is complete. I.e., it might reconstruct some of the missing symbols sent > before your AOS. > > Similarly there is a slow ramp from solid signal down to pure noise over > 16.384 seconds at LOS. > > See how this helps handle fading? Even an abrupt, complete fade starts the > same, slow 16-second ramp down from signal to noise. If the fade ends only a > second or two later, the rampdown won't have progressed very far and the > decoder will still see mostly signal when the trend reverses and ramps back > up to pure signal. That takes a few extra seconds, but the error correction > can easily handle it all -- as long as the fade isn't *too* long. > Interleaving takes a signal that may be solid one moment and gone the next > and smooths it out so that the signal-to-noise ratio changes only slowly. It > literally averages the signal-to-noise ratio. > > Since even a short LEO pass is usually several minutes long, these 16 second > fill/drain intervals didn't seem like a big deal. Besides, we've already had > a similar problem since the old days of the uncoded Phase III block > telemetry format. You might have AOS in the middle of a frame and have to > wait for the next one to start before you can decode anything. Interleaving > isn't really any worse. > > The problem is that I didn't count on having the transmitter turned on for > only 40-60 seconds at a time. So....if the transmissions are only 40 sec, > and if you have to wait 16.384 seconds for the interleaver to fill, and you > can't rely on the last 16.384 seconds as the interleaver drains, that leaves > 40 - 2*16.384 = 7.232 seconds of solid, noise-free "middle" to work with. > > As I recall, ARISSat-1 data frames can be up to 512 bytes long. Ignoring > HDLC flags, bit stuffing, CRC, etc, that's 4K bits. At a data rate of 500 > bps (the FEC is rate 1/2), 512 bytes will take 4096/500 = 8.192 seconds to > transmit. > > 8.192 seconds is longer than 7.232 seconds. > > Ooops. > > But wait, there's more. If the satellite sends a series of back-to-back 512 > byte frames, and the transmitter comes on too late after one has already > started, you'll have to wait for it to end before you can begin decoding the > next one. Meanwhile, the clock is quickly ticking down until the transmitter > goes OFF again... > > Double oops. > > Now this probably overstates the problem a bit. Being the engineer that I > am, this is a very conservative analysis -- I made the most pessimistic > assumption at each step. After all, I was stunned when somebody streamed > BPSK-1000 over the net with a lossy MP3 encoder and it *decoded*; I never > thought that would work. > > Error correction can fill in for a remarkable variety of ills. In reality, > the satellite won't send a continuous stream of 512 byte frames. In reality, > the key-down intervals may be more than 40 seconds. So I actually won't be > too terribly surprised if the thing actually works. But it won't perform > anything like it will when the satellite is eventually operated in its > intended 100% duty cycle mode. > > > ------------------------------ > > _______________________________________________ > Sent via amsat-bb(a)amsat.org. Opinions expressed are those of the author. > Not an AMSAT member? Join now to support the amateur satellite program! > http://amsat.org/mailman/listinfo/amsat-bb > > > End of AMSAT-BB Digest, Vol 6, Issue 207 > **************************************** Lou McFadin W5DID ARISS US Hardware manager

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Re: Still Nothing From ARISSat-1 In DO33
by B J 12 Apr '11

12 Apr '11

<snip> > I had a good view of the ISS during > the pass, though. I forgot to mention that the pass was just before 1100 UTC. <snip> 73s Bernhard VA6BMJ @ DO33FL

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ARISSat-1 09:27 UTC Nothing Heard
by Peter Portanova 12 Apr '11

12 Apr '11

Hello, Happy Yuri Day to all, still waiting for the parade to begin. 73, Pete WB2OQQ

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ARISSat-1 No Signal
by John Spasojevich 12 Apr '11

12 Apr '11

Nothing heard on the 0437 UTC pass in Montgomery, IL 76 degrees elevation, nice night though. John - AG9D

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ARISSat-1 tlm decoder.
by G0MRF＠aol.com 12 Apr '11

12 Apr '11

Hi all. I have a minor (probably operator error) with the TLM software. Is there a way to get the audio to feed through to the PC speakers? I've tried Spectran and Spectraview without problem, but the ARISSat software does not appear to send audio out on my system. I cant hear the radio as I have a jack in the headphone socket which mutes the radio's speaker. The software is working. I can decode the CW callsign and locator of a 2m beacon and the level is controlled nicely with the windows 'microphone' record level. It's not muted It's got the correct input selected and the gain turned up. But.....no audio out...so I'm just setting the frequency by visually putting the signal in the right place. 73 David

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BBC - PLT Interference at VHF
by Trevor . 12 Apr '11

12 Apr '11

This report is worth a read: http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP195.pdf 73 Trevor M5AKA

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Nothing heard over Nashville 0610
by Alan P. Biddle 12 Apr '11

12 Apr '11

All, Silence over Nashville on the 0610 UTC pass. All but 2 of the passes during the scheduled period of activation will be "in the weeds" from an elevation standpoint at my QTH. Did get a nice I/Q recording of the passband, though. Alan WA4SCA ----------------------------------- The prospect of domination of the nation's scholars by Federal employment, project allocations, and the power of money is ever present - and is gravely to be regarded. President Dwight D. Eisenhower

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Not Heard 1106 PM PDT
by Clint Bradford 12 Apr '11

12 Apr '11

Darn .... Nada heard on an excellent pass of the ISS at 1106PM PDT. But I think the astronauts were just awakened at the top o' the hour. OK - 5:30-ish AM PDT next pass over Southern CA DM13-land! Clint Skype - clintbradford

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