Malaysian airliner puzzle
Thanks Rick, How do those sats determine distance to the source? Tony, N2UN
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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" [email protected] wrote:
Thanks Rick, How do those sats determine distance to the source? Tony, N2UN
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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 [email protected] To: amsat-bb [email protected] 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 [email protected]. 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
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 [email protected] 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 [email protected] To: amsat-bb [email protected] 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 [email protected]. 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 [email protected]. 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
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_497288.... 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 [email protected] 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 [email protected] 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 [email protected] To: amsat-bb [email protected] 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 [email protected]. 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 [email protected]. 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
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 [email protected] 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_497288.... 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 [email protected] 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 [email protected] 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 [email protected] To: amsat-bb [email protected] 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 [email protected]. 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 [email protected]. 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 [email protected]. 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
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 [email protected] 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 [email protected] 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_497288... .
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 [email protected]
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 [email protected]
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 [email protected] To: amsat-bb [email protected] 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 [email protected]. 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 [email protected]. 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 [email protected]. 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
participants (5)
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Anthony Japha -
Chandler Heath -
R.T.Liddy -
Rick Walter -
Tom Busch