[amsat-bb] Re: Malaysian airliner puzzle
On 3/26/2014 3:28 PM, Howie DeFelice wrote: This was a very clever use of available data for an unintended purpose. I am a little surprised that they retained enough data to do the doppler analysis. For example, once I successfully download a telemetry frame from AO-73, the demodulated and decoded data is sent off to the Funcube warehouse. I sure don't save all the audio to disk! -Joe KM1P ___ 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] Re: Malaysian airliner puzzle
I idid some checking on www.satellite-calculations.com and was surprised at what I found. SAT LOCATION INCLINATION 3-F1 64E 1.67 deg 3-F2 15W 0.21 deg 3-F3 178E 1.07 deg 3-F4 54W 3.6 deg 3-F5 24E 0.39 deg 4-F1 143E 2.67 deg 4-F2 24E 2.34 deg 4-F3 98W 3.01 deg 2-F2 142W 9.33 deg I didn't expect some of the older 3rd generation satellites to have lower inclinations than the newer 4th generations sats considering that the newer sats use scanning spot beam technology. It might have something to do with customer lease requirements since INMARSAT will lease excess capacity users, but that's only a guess. As to the question about retaining the data, you can think of it as meta data similar to what the cellphone carriers collect about cellphone calls. They don't record and save you conversations but they do record information about origination, destination,time, duration and type of call. This information is collected and logged automatically in most cases. - Howie ___ 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] Re: Malaysian airliner puzzle
As to the question about retaining the data, you can think of it as meta data similar to what the cellphone carriers collect about cellphone calls. They don't record and save you conversations but they do record information about origination, destination,time, duration and type of call. This information is collected and logged automatically in most cases. - Howie I would not be too sure about They don't record and save you conversations maybe not the carrier itself but someone else might be. Kevin WA6FWF ___ 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] Re: Malaysian airliner puzzle
As to the question about retaining the data, you can think of it as meta data similar to what the cellphone carriers collect about cellphone calls. They don't record and save you conversations but they do record information about origination, destination,time, duration and type of call. They sure do that, as it has value for network utilization, billing etc. I bet (a small bet anyway) my cell phone carrier doesn't save receive frequency data accurate enough to determine what direction I am driving though. Maybe they do though. We are considering similar functionality for the Fox telemetry software, but of course we have a vested interest in knowing where our spacecraft is. -Joe KM1P ___ 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] Re: Malaysian airliner puzzle
All Inmarsat satellites though the F-3 series have been in inclined orbits since beginning of life. This gives them extended on orbit lifetime. The beamwidth of the Inmarsat L band ground terminals is large enough that tracking isn't required. The gateway stations operate at C band with large antennas that require continuous step tracking. I don't know for sure if the F-4 satellites are inclined or not. This was a very clever use of available data for an unintended purpose. ___ 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] Re: Malaysian airliner puzzle
On 03/26/2014 12:28 PM, Howie DeFelice wrote: All Inmarsat satellites though the F-3 series have been in inclined orbits since beginning of life. Ah so, I was wondering if that might be the case because the user antennas are mobile and have broad patterns to begin with. What is their nominal inclination? ___ 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] Re: Malaysian airliner puzzle
Finally, (some) technical details, though still not as many as I'd like. https://www.facebook.com/permalink.php?story_fbid=740971779281171id=17856654999stream_ref=10 The original analysis was based either on a round trip time measurement or a reported transmitter power, which depends on satellite elevation. Either way, it could only yield a locus of positions that fell on a circle of constant distance (or elevation angle) to the satellite. Erasing the part of the circle that could not be reached with the available fuel left the arcs. I don't understand why there would have been a gap between the two around the equator. The big problem was to solve the ambiguity -- northern hemisphere or southern? I believe the answer relies on the fact that Inmarsat 3 F1 is an old satellite launched in 1996. Its inclination has risen to 1.67 degrees, probably because its stationkeeping fuel has run out. The total measured Doppler would be the sum of the Doppler caused by the plane's motion with respect to the satellite and that due to the satellite's non-zero motion with respect to the earth. Judging from the diagrams on heavens-above.com, I'd say the satellite was moving southward during the flight, which took place between roughly midnight and dawn local time. Since the plane was in the southern hemisphere, the satellite was moving toward it, resulting in a higher net frequency shift than if the plane had been in the northern hemisphere. Note the shapes of the curves in the plot titled MH370: Burst Frequency Offset. The southerly track has the Doppler increasing with time, while the northerly track would have it decreasing with time. The analysis does have to assume a certain fixed speed for the aircraft but it seems to produce consistent results. It should be possible to replicate Inmarsat's graphs using the three line elements for the satellite and their presumed ground tracks for the aircraft. 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
[amsat-bb] Re: Malaysian airliner puzzle
The distance calculated between the satellite and the plane won't be credible if the time on both are not synchronized, even if the transmission from the plane is time tagged. As a matter of fact, it's quite difficult to keep such an synchronization. Michael Chen, BD5RV/4 AMSAT-China: http://www.camsat.cn --- Twitter: http://twitter.com/bd5rv Email: michael.bd...@gmail.com MSN:bd...@jsdxc.org Skype: michael-bd5rv On Mon, Mar 17, 2014 at 4:27 AM, James Duffey jamesduf...@comcast.net wrote: I think that the transmissions from the airplane are time tagged, even without the data packets being transmitted. By comparing the ping time to the time on the satellite, one can tell how far away the ping is. You can draw a circle with that radius, taking into account fuel available on the airplane and last heading to sort of kind of bound where the airplane is. That is where the red circles in the NY Times article come from. A second satellite is needed to pinpoint a more exact location, but even that will have a relatively position error on the ground. I don't think it is within range of another INMARSAT. Whether or not other assets exist that could receive the signal is a matter of speculation. - KK6MC On Mar 16, 2014, at 2:01 PM, Rick Walter wb3...@gmail.com wrote: Tony, since the satellite cannot tell direction of the Ping, only distance, the arcs have the same distance from the plane making up a half circle. You would need to sats to hear the plane, see where the two arcs cross to determine a location. This is the same way seismic stations locate earthquakes. Rick - WB3CSY Sent from Rick's iPhone 5 Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein On Mar 16, 2014, at 12:24 PM, Anthony Japha aja...@earthlink.net wrote: Those so-called arcs that are said to be possible routes for the plane look much like the outer edge of one of the Inmarsat footprints. Is there logic behind the arcs or is it oversimplified nonsense? They are said to be the result of the signals Inmarsat received. But then why wouldn't it be possible for the plane to be anywhere in the footprint? I'm sure many in our group have good ideas. I'm not trying to start a discussion of the entire mystery, only this one narrow, but possibly misleading, aspect related to our hobby. 73, Tony, N2UN LM 183 --- 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 ___ 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 ___ 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] Re: Malaysian airliner puzzle
The news has been reporting that they are using the angle of the last known ping from the ACARS system to the satellite. This is where the 40-degree arc around the satellite comes from. What I don't understand is how INMARSAT knows what that angle is. CNN says that the satellite steers its antenna to the location where it expects the next ping, but that doesn't make sense. I have been looking for the algorithm, but I can't find it. Signal strength? Some sort of electronic steering? Trade secret? I don't know. Tom WB8WOR On Sun, Mar 16, 2014 at 10:57 PM, R.T.Liddy k...@ameritech.net wrote: Tony, They would use the time differential between receipt to measure the distance versus the location of the satellites. The more satellites, then the more accurate the triangulation. 73, Bob K8BL From: Anthony Japha tjja...@earthlink.net To: amsat-bb amsat-bb@amsat.org Sent: Sunday, March 16, 2014 4:49 PM Subject: [amsat-bb] Malaysian airliner puzzle Thanks Rick, How do those sats determine distance to the source? Tony, N2UN --- 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 ___ 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
[amsat-bb] Re: Malaysian airliner puzzle
Looks like I'm wrong. The Steering info wasn't from CNN. It's from this Huffington Post article: http://www.huffingtonpost.com/2014/03/16/malaysia-airlines-takeover_n_4972889.html. I still would like to know how the satellite knows. It also says that these pings occur every hour, so I suppose it could have kept flying for an hour after the last contact. Tom WB8WOR On Mon, Mar 17, 2014 at 11:28 AM, Tom Busch t...@bloomington.com wrote: The news has been reporting that they are using the angle of the last known ping from the ACARS system to the satellite. This is where the 40-degree arc around the satellite comes from. What I don't understand is how INMARSAT knows what that angle is. CNN says that the satellite steers its antenna to the location where it expects the next ping, but that doesn't make sense. I have been looking for the algorithm, but I can't find it. Signal strength? Some sort of electronic steering? Trade secret? I don't know. Tom WB8WOR On Sun, Mar 16, 2014 at 10:57 PM, R.T.Liddy k...@ameritech.net wrote: Tony, They would use the time differential between receipt to measure the distance versus the location of the satellites. The more satellites, then the more accurate the triangulation. 73, Bob K8BL From: Anthony Japha tjja...@earthlink.net To: amsat-bb amsat-bb@amsat.org Sent: Sunday, March 16, 2014 4:49 PM Subject: [amsat-bb] Malaysian airliner puzzle Thanks Rick, How do those sats determine distance to the source? Tony, N2UN --- 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 ___ 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
[amsat-bb] Re: Malaysian airliner puzzle
This is really a mystery, wonder what is the ELT frequencies used on modern aircraft , is it 121.5 Mhz or the new 406 Mhz. 73 Nitin [VU3TYG] From: Michael Chen michael.bd...@gmail.com To: amsat-bb amsat-bb@amsat.org Sent: Monday, 17 March 2014 8:35 PM Subject: [amsat-bb] Re: Malaysian airliner puzzle The distance calculated between the satellite and the plane won't be credible if the time on both are not synchronized, even if the transmission from the plane is time tagged. As a matter of fact, it's quite difficult to keep such an synchronization. Michael Chen, BD5RV/4 AMSAT-China: http://www.camsat.cn --- Twitter: http://twitter.com/bd5rv Email: michael.bd...@gmail.com MSN: bd...@jsdxc.org Skype: michael-bd5rv On Mon, Mar 17, 2014 at 4:27 AM, James Duffey jamesduf...@comcast.net wrote: I think that the transmissions from the airplane are time tagged, even without the data packets being transmitted. By comparing the ping time to the time on the satellite, one can tell how far away the ping is. You can draw a circle with that radius, taking into account fuel available on the airplane and last heading to sort of kind of bound where the airplane is. That is where the red circles in the NY Times article come from. A second satellite is needed to pinpoint a more exact location, but even that will have a relatively position error on the ground. I don't think it is within range of another INMARSAT. Whether or not other assets exist that could receive the signal is a matter of speculation. - KK6MC On Mar 16, 2014, at 2:01 PM, Rick Walter wb3...@gmail.com wrote: Tony, since the satellite cannot tell direction of the Ping, only distance, the arcs have the same distance from the plane making up a half circle. You would need to sats to hear the plane, see where the two arcs cross to determine a location. This is the same way seismic stations locate earthquakes. Rick - WB3CSY Sent from Rick's iPhone 5 Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein On Mar 16, 2014, at 12:24 PM, Anthony Japha aja...@earthlink.net wrote: Those so-called arcs that are said to be possible routes for the plane look much like the outer edge of one of the Inmarsat footprints. Is there logic behind the arcs or is it oversimplified nonsense? They are said to be the result of the signals Inmarsat received. But then why wouldn't it be possible for the plane to be anywhere in the footprint? I'm sure many in our group have good ideas. I'm not trying to start a discussion of the entire mystery, only this one narrow, but possibly misleading, aspect related to our hobby. 73, Tony, N2UN LM 183 --- 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 ___ 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 ___ 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
[amsat-bb] Re: Malaysian airliner puzzle
I read that the handshakes were still occurring when they lost contact with the aircraft. In an article posted here from the Inmarsat web site Inmarsat mentioned that they and their partner Sita are working with officials to use handshakes to triangulate the position. On the topic of Steering, the satellites have the capability to steer spot beams to address capacity needs, but to steer for one subscriber would make things worse for the others. Here is a link on the Sita service OnAir. I don't know how accurate it is, but here it is for anyone that may want to learn more. http://en.m.wikipedia.org/wiki/OnAir_(telecommunications) Sent from my iPhone On Mar 17, 2014, at 11:11 AM, Tom Busch t...@bloomington.com wrote: Looks like I'm wrong. The Steering info wasn't from CNN. It's from this Huffington Post article: http://www.huffingtonpost.com/2014/03/16/malaysia-airlines-takeover_n_4972889.html. I still would like to know how the satellite knows. It also says that these pings occur every hour, so I suppose it could have kept flying for an hour after the last contact. Tom WB8WOR On Mon, Mar 17, 2014 at 11:28 AM, Tom Busch t...@bloomington.com wrote: The news has been reporting that they are using the angle of the last known ping from the ACARS system to the satellite. This is where the 40-degree arc around the satellite comes from. What I don't understand is how INMARSAT knows what that angle is. CNN says that the satellite steers its antenna to the location where it expects the next ping, but that doesn't make sense. I have been looking for the algorithm, but I can't find it. Signal strength? Some sort of electronic steering? Trade secret? I don't know. Tom WB8WOR On Sun, Mar 16, 2014 at 10:57 PM, R.T.Liddy k...@ameritech.net wrote: Tony, They would use the time differential between receipt to measure the distance versus the location of the satellites. The more satellites, then the more accurate the triangulation. 73, Bob K8BL From: Anthony Japha tjja...@earthlink.net To: amsat-bb amsat-bb@amsat.org Sent: Sunday, March 16, 2014 4:49 PM Subject: [amsat-bb] Malaysian airliner puzzle Thanks Rick, How do those sats determine distance to the source? Tony, N2UN --- 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 ___ 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 ___ 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] Re: Malaysian airliner puzzle
What I do not understand is why the Transponder is capable of being shut off at all? That thing as soon as the plane is powered up should start transmitting, and continue to do so till the plane is shut down. And have no way anyone can shut it off in any way. Why does something like this seem sooo simple? Then The the Black Box There is also no reason what so ever that it has to be the only recording of the planes parameters. Sure record it, no problem, BUT... there is no reason why this can not be transmitted live or compressed and transmitted in packets to ground stations to save. This way if a plane goes down you do not need to Recover the Black Box every bit of data is already on the ground saved. Again Like DUH? Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com On 3/17/2014 12:22 PM, Nitin Muttin wrote: This is really a mystery, wonder what is the ELT frequencies used on modern aircraft , is it 121.5 Mhz or the new 406 Mhz. 73 Nitin [VU3TYG] From: Michael Chen michael.bd...@gmail.com To: amsat-bb amsat-bb@amsat.org Sent: Monday, 17 March 2014 8:35 PM Subject: [amsat-bb] Re: Malaysian airliner puzzle The distance calculated between the satellite and the plane won't be credible if the time on both are not synchronized, even if the transmission from the plane is time tagged. As a matter of fact, it's quite difficult to keep such an synchronization. Michael Chen, BD5RV/4 AMSAT-China: http://www.camsat.cn --- Twitter: http://twitter.com/bd5rv Email: michael.bd...@gmail.com MSN:bd...@jsdxc.org Skype: michael-bd5rv On Mon, Mar 17, 2014 at 4:27 AM, James Duffey jamesduf...@comcast.net wrote: I think that the transmissions from the airplane are time tagged, even without the data packets being transmitted. By comparing the ping time to the time on the satellite, one can tell how far away the ping is. You can draw a circle with that radius, taking into account fuel available on the airplane and last heading to sort of kind of bound where the airplane is. That is where the red circles in the NY Times article come from. A second satellite is needed to pinpoint a more exact location, but even that will have a relatively position error on the ground. I don't think it is within range of another INMARSAT. Whether or not other assets exist that could receive the signal is a matter of speculation. - KK6MC On Mar 16, 2014, at 2:01 PM, Rick Walter wb3...@gmail.com wrote: Tony, since the satellite cannot tell direction of the Ping, only distance, the arcs have the same distance from the plane making up a half circle. You would need to sats to hear the plane, see where the two arcs cross to determine a location. This is the same way seismic stations locate earthquakes. Rick - WB3CSY Sent from Rick's iPhone 5 Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein On Mar 16, 2014, at 12:24 PM, Anthony Japha aja...@earthlink.net wrote: Those so-called arcs that are said to be possible routes for the plane look much like the outer edge of one of the Inmarsat footprints. Is there logic behind the arcs or is it oversimplified nonsense? They are said to be the result of the signals Inmarsat received. But then why wouldn't it be possible for the plane to be anywhere in the footprint? I'm sure many in our group have good ideas. I'm not trying to start a discussion of the entire mystery, only this one narrow, but possibly misleading, aspect related to our hobby. 73, Tony, N2UN LM 183 --- 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 ___ 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 ___ 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
[amsat-bb] Re: Malaysian airliner puzzle
Sorry if off topic. Looks like it is all three 121.5 / 243/ 406 http://www.acrartex.com/products/catalog/elts-commercialmilitary/b406-4/ If the aircraft did crash in Bay of Bengal / Indian ocean and ELT operational the signals would have been picked up by satellites .http://inmcc.istrac.org/brochurehtml/index.htm 73 Nitin [VU3TYG] From: Nitin Muttin vu3...@yahoo.co.in To: amsat-bb amsat-bb@amsat.org Sent: Monday, 17 March 2014 10:52 PM Subject: Re: [amsat-bb] Re: Malaysian airliner puzzle This is really a mystery, wonder what is the ELT frequencies used on modern aircraft , is it 121.5 Mhz or the new 406 Mhz. 73 Nitin [VU3TYG] From: Michael Chen michael.bd...@gmail.com To: amsat-bb amsat-bb@amsat.org Sent: Monday, 17 March 2014 8:35 PM Subject: [amsat-bb] Re: Malaysian airliner puzzle The distance calculated between the satellite and the plane won't be credible if the time on both are not synchronized, even if the transmission from the plane is time tagged. As a matter of fact, it's quite difficult to keep such an synchronization. Michael Chen, BD5RV/4 AMSAT-China: http://www.camsat.cn --- Twitter: http://twitter.com/bd5rv Email: michael.bd...@gmail.com MSN: bd...@jsdxc.org Skype: michael-bd5rv On Mon, Mar 17, 2014 at 4:27 AM, James Duffey jamesduf...@comcast.net wrote: I think that the transmissions from the airplane are time tagged, even without the data packets being transmitted. By comparing the ping time to the time on the satellite, one can tell how far away the ping is. You can draw a circle with that radius, taking into account fuel available on the airplane and last heading to sort of kind of bound where the airplane is. That is where the red circles in the NY Times article come from. A second satellite is needed to pinpoint a more exact location, but even that will have a relatively position error on the ground. I don't think it is within range of another INMARSAT. Whether or not other assets exist that could receive the signal is a matter of speculation. - KK6MC On Mar 16, 2014, at 2:01 PM, Rick Walter wb3...@gmail.com wrote: Tony, since the satellite cannot tell direction of the Ping, only distance, the arcs have the same distance from the plane making up a half circle. You would need to sats to hear the plane, see where the two arcs cross to determine a location. This is the same way seismic stations locate earthquakes. Rick - WB3CSY Sent from Rick's iPhone 5 Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein On Mar 16, 2014, at 12:24 PM, Anthony Japha aja...@earthlink.net wrote: Those so-called arcs that are said to be possible routes for the plane look much like the outer edge of one of the Inmarsat footprints. Is there logic behind the arcs or is it oversimplified nonsense? They are said to be the result of the signals Inmarsat received. But then why wouldn't it be possible for the plane to be anywhere in the footprint? I'm sure many in our group have good ideas. I'm not trying to start a discussion of the entire mystery, only this one narrow, but possibly misleading, aspect related to our hobby. 73, Tony, N2UN LM 183 --- 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 ___ 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 ___ 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
[amsat-bb] Re: Malaysian airliner puzzle
Now I get it... The satellite pings the plane, which responds with I am here. By measuring the round trip time between the transmit and receive signals, the satellite can determine the aircraft's distance, and thus the angle to it. Article here: http://theaviationist.com/2014/03/16/satcom-acars-explained/ Tom WB8WOR On Mon, Mar 17, 2014 at 1:28 PM, Chandler Heath conve...@gmail.com wrote: I read that the handshakes were still occurring when they lost contact with the aircraft. In an article posted here from the Inmarsat web site Inmarsat mentioned that they and their partner Sita are working with officials to use handshakes to triangulate the position. On the topic of Steering, the satellites have the capability to steer spot beams to address capacity needs, but to steer for one subscriber would make things worse for the others. Here is a link on the Sita service OnAir. I don't know how accurate it is, but here it is for anyone that may want to learn more. http://en.m.wikipedia.org/wiki/OnAir_(telecommunications) Sent from my iPhone On Mar 17, 2014, at 11:11 AM, Tom Busch t...@bloomington.com wrote: Looks like I'm wrong. The Steering info wasn't from CNN. It's from this Huffington Post article: http://www.huffingtonpost.com/2014/03/16/malaysia-airlines-takeover_n_4972889.html . I still would like to know how the satellite knows. It also says that these pings occur every hour, so I suppose it could have kept flying for an hour after the last contact. Tom WB8WOR On Mon, Mar 17, 2014 at 11:28 AM, Tom Busch t...@bloomington.com wrote: The news has been reporting that they are using the angle of the last known ping from the ACARS system to the satellite. This is where the 40-degree arc around the satellite comes from. What I don't understand is how INMARSAT knows what that angle is. CNN says that the satellite steers its antenna to the location where it expects the next ping, but that doesn't make sense. I have been looking for the algorithm, but I can't find it. Signal strength? Some sort of electronic steering? Trade secret? I don't know. Tom WB8WOR On Sun, Mar 16, 2014 at 10:57 PM, R.T.Liddy k...@ameritech.net wrote: Tony, They would use the time differential between receipt to measure the distance versus the location of the satellites. The more satellites, then the more accurate the triangulation. 73, Bob K8BL From: Anthony Japha tjja...@earthlink.net To: amsat-bb amsat-bb@amsat.org Sent: Sunday, March 16, 2014 4:49 PM Subject: [amsat-bb] Malaysian airliner puzzle Thanks Rick, How do those sats determine distance to the source? Tony, N2UN --- 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 ___ 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 ___ 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] Re: Malaysian airliner puzzle
interesting thing is that i am sure that the u.s. as well as other countries have spy satellites that have been taking pictures 24/7 with resolution that can see a person on the ground. that being said, i would further venture to say that none of them will want to show pictures of the jet as it would give away their secret ability. possibly they are fixed on a particular country or city and not the ocean. 73...bruce -- Bruce Paige, KK5DO AMSAT Director Contests and Awards ARRL Awards Manager (WAS, 5BWAS, VUCC), VE Houston AMSAT Net - Wed 0100z on Echolink - Conference *AMSAT* Also live streaming MP3 at http://www.amsatnet.com Podcast at http://www.amsatnet.com/podcast.xml or iTunes Latest satellite news on the ARRL Audio News http://www.arrl.org AMSAT on Twitter http://www.twitter.com/amsat ___ 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] Re: Malaysian airliner puzzle
On Mon, Mar 17, 2014 at 12:40:05PM -0500, Joe wrote: What I do not understand is why the Transponder is capable of being shut off at all? That thing as soon as the plane is powered up should start transmitting, and continue to do so till the plane is shut down. And have no way anyone can shut it off in any way. Because it takes a ludicrous amount of power to run. It would be one of the first things you'd turn off if you were load-shedding for some reason. -- Gordonjcp MM0YEQ ___ 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] Re: Malaysian airliner puzzle
At 12:40 PM 3/17/2014, Bruce wrote: i am sure that the u.s. as well as other countries have spy satellites that have been taking pictures 24/7 with resolution that can see a person on the ground. that being said, i would further venture to say that none of them will want to show pictures of the jet as it would give away their secret ability. Hey, good to see a post that's on topic. Satellites! Actually, the capability is not very secret. Its pretty much out in the open. Although every nation keeps the details secret, but you don't need details to understand what kind of a picture is possible. Physics will tell you that. You can calculate the resolution of a spy satellite. Its just physics. You know the diameter of the aperture (lens or mirror). You know that because dimensions for many classified objects have been published. Also you know the diameter of the space shuttle's payload bay. You know the wavelength of light. Simple formula gives you the resolving power as an angle. To turn that into the size of an object you need to know a distance. You can look up the orbits of many classified satellites, so know how far away they are. But because you get more resolution by being closer, you know the best pictures will come from low orbit, and here the limit is the Earth's atmosphere. No need to know classified orbit data. Just presume there are some spy satellites in low but stable orbits, perhaps 300 to 500 km. So, yes, they should be able to see something smaller than a person, but here's the kicker... They can't do that everywhere at once. Because they are in orbit close to the earth, they can only see stuff that's under them. This is a tiny fraction of the earth. Also, within that area, you have to tell them where to point. A simple number-of-pixels thing. Looking at the whole footprint at max resolution would be an enormous # of pixels. We would have to guess the limit, but its not hard to guess that the maximum image is way smaller than the footprint. This is great for taking pictures of your opponent's military installations, and maybe even seeing what assets there come and go over time, but it is unlikely to be of help in tracking an airplane that unexpectedly flies some unknown path to some unknown location. Also, the plane flew at night, in the dark. I'm sure the big boys are thinking about new capabilities as we speak, and writing them into next year's budget! ___ 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] Re: Malaysian airliner puzzle
nice, thanks antonio. i still think that we have enough of our spy satellites watching that part of the world that they saw it and night should not matter. if we can think outside the box, i am sure we have created it. br/br/73...brucea href=https://overview.mail.yahoo.com?.src=iOS;br/br/Sent from Yahoo Mail for iPhone/a ___ 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] Re: Malaysian airliner puzzle
Tony, since the satellite cannot tell direction of the Ping, only distance, the arcs have the same distance from the plane making up a half circle. You would need to sats to hear the plane, see where the two arcs cross to determine a location. This is the same way seismic stations locate earthquakes. Rick - WB3CSY Sent from Rick's iPhone 5 Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein On Mar 16, 2014, at 12:24 PM, Anthony Japha aja...@earthlink.net wrote: Those so-called arcs that are said to be possible routes for the plane look much like the outer edge of one of the Inmarsat footprints. Is there logic behind the arcs or is it oversimplified nonsense? They are said to be the result of the signals Inmarsat received. But then why wouldn’t it be possible for the plane to be anywhere in the footprint? I’m sure many in our group have good ideas. I’m not trying to start a discussion of the entire mystery, only this one narrow, but possibly misleading, aspect related to our hobby. 73, Tony, N2UN LM 183 --- 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 ___ 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] Re: Malaysian airliner puzzle
I think that the transmissions from the airplane are time tagged, even without the data packets being transmitted. By comparing the ping time to the time on the satellite, one can tell how far away the ping is. You can draw a circle with that radius, taking into account fuel available on the airplane and last heading to sort of kind of bound where the airplane is. That is where the red circles in the NY Times article come from. A second satellite is needed to pinpoint a more exact location, but even that will have a relatively position error on the ground. I don’t think it is within range of another INMARSAT. Whether or not other assets exist that could receive the signal is a matter of speculation. - KK6MC On Mar 16, 2014, at 2:01 PM, Rick Walter wb3...@gmail.com wrote: Tony, since the satellite cannot tell direction of the Ping, only distance, the arcs have the same distance from the plane making up a half circle. You would need to sats to hear the plane, see where the two arcs cross to determine a location. This is the same way seismic stations locate earthquakes. Rick - WB3CSY Sent from Rick's iPhone 5 Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein On Mar 16, 2014, at 12:24 PM, Anthony Japha aja...@earthlink.net wrote: Those so-called arcs that are said to be possible routes for the plane look much like the outer edge of one of the Inmarsat footprints. Is there logic behind the arcs or is it oversimplified nonsense? They are said to be the result of the signals Inmarsat received. But then why wouldn’t it be possible for the plane to be anywhere in the footprint? I’m sure many in our group have good ideas. I’m not trying to start a discussion of the entire mystery, only this one narrow, but possibly misleading, aspect related to our hobby. 73, Tony, N2UN LM 183 --- 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 ___ 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
[amsat-bb] Re: Malaysian airliner puzzle
I think it is like GPS, the signal from the plane has encoded in it the time it was sent and the satellite knows when it arrived at the sat. Using a formula to compensate for our atmosphere and using the speed of light it knows the distance travelled. Rick Sent from Rick's iPhone 5 Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein On Mar 16, 2014, at 4:49 PM, Anthony Japha tjja...@earthlink.net wrote: Thanks Rick, How do those sats determine distance to the source? Tony, N2UN --- 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 ___ 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] Re: Malaysian airliner puzzle
Hi Tony, I'm not up to speed on the current Inmarsat Aero service, but they are most likely using thee 4th generation satellite constellation which has numerous small overlapping spotbeams. They also have larger area beams as well as a global beam. There are several different aero services provided by Inmarsat for different classes of planes. I haven't seen the report you mention so I can't make any guesses how this relates to the footprints. - Howie AB2S ___ 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] Re: Malaysian airliner puzzle
There a couple of news items on the Inmarsat web-site: http://www.inmarsat.com/news/inmarsat-appointed-technical-adviser-flight-mh3 70/ http://www.inmarsat.com/news/inmarsat-statement-malaysia-airlines-flight-mh3 70/ hv -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Howie DeFelice Sent: Sunday, March 16, 2014 8:59 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: Malaysian airliner puzzle Hi Tony, I'm not up to speed on the current Inmarsat Aero service, but they are most likely using thee 4th generation satellite constellation which has numerous small overlapping spotbeams. They also have larger area beams as well as a global beam. There are several different aero services provided by Inmarsat for different classes of planes. I haven't seen the report you mention so I can't make any guesses how this relates to the footprints. - Howie AB2S ___ 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
[amsat-bb] Re: Malaysian airliner puzzle
Tony, They would use the time differential between receipt to measure the distance versus the location of the satellites. The more satellites, then the more accurate the triangulation. 73, Bob K8BL From: Anthony Japha tjja...@earthlink.net To: amsat-bb amsat-bb@amsat.org Sent: Sunday, March 16, 2014 4:49 PM Subject: [amsat-bb] Malaysian airliner puzzle Thanks Rick, How do those sats determine distance to the source? Tony, N2UN --- 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 ___ 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
