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Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 12:45 pm
by nukkxx5058
Hello,
I don't see the meaning of having such a contact jumping all the time all over the map. What does it mean ? Once detected it is supposed to remain stable within its uncertainty region. No ?
The larger the uncertainty region, the greater the uncertainty. Instead, it's jumping everywhere. This brings absolutely no added value in terms of information.
I have the impression (but I might be wrong) that this behavior is quite recent. I have 1147.38
What do you think ?
https://www.youtube.com/watch?v=YCrQDGasozE
Any explanation ?
It's PBEM but can provide the save + password by PM if necessary.
Thanks
RE: Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 2:19 pm
by thewood1
I know one of the factors is the platforms detecting it. If you have a lot of platforms detecting and undetecting it, that will cause the focal point of the contact to shift in real-time. As far back as I remember, that's how it worked in many complex scenarios.
RE: Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 2:28 pm
by thewood1
btw, in larger and more complex scenarios, and some smaller ones, I use the mark contact feature a lot to help zero in on contacts over time. This is especially useful for subs with intermittent contact.
RE: Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 6:26 pm
by nukkxx5058
I was suspecting it's maybe because the detectors are satellite like this #48 - Mercury [Advanced Vortex] (United States - 1994) ?
But why are the other contacts stable ?
RE: Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 7:11 pm
by Kushan04
Video is private so can't see what may be happening. As the FAQ says, you should always upload a save for something like this.
RE: Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 7:38 pm
by thewood1
As I and others always say, without a save, its all guess work.
RE: Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 8:08 pm
by nukkxx5058
Ok I changed the video. It's now available.
Regarding the save, pls read my comment in my original post.
I'm reposting the link in case it changed when I made the video public
https://youtu.be/YCrQDGasozE
RE: Why is this contact jumping all over the place ?
Posted: Mon Jan 03, 2022 8:56 pm
by BeirutDude
It's jumping around because you only have a satellite fix on it at the periphery of the Satellite's imaging area. Remember with the curvature of the Earth you're looking at it obliquely and there are huge parallax errors.
RE: Why is this contact jumping all over the place ?
Posted: Tue Jan 04, 2022 5:14 am
by nukkxx5058
I was suspecting something linked with the satellites.
Now, there's something more than odd about this particular satellite (the one detecting the jumping contact) and a few others. It's its altitude: 35.000 km !!! Which is far from earth orbit, in deep space. It should be 350 km IMO.
About half the satellites are located at such crazy altitude while other sats are located at more normal altitude (350-800 km distance)
And some contacts (including the jumping one) are detected by satellites navigating very far from the action (like above Africa in my case) which can be explained just by the wrong altitude, because of the earth curvature, as you said. If a satellite is flying at 350km altitude above Africa, I think (without doing the math) it can't detect action near Vietnam. But if it's flying at 35.000km, which is the case, then it's another story. No ?
See altitude in the picture below
RE: Why is this contact jumping all over the place ?
Posted: Tue Jan 04, 2022 5:24 am
by Kushan04
ORIGINAL: nukkxx5058
Now, there's something more than odd about this particular satellite (the one detecting the jumping contact) and a few others. It's its altitude: 35.000 km !!! Which is far from earth orbit, in deep space. It should be 350 km IMO.
And you would be in correct. Looking at
USA 105 and
USA 118 you will notice they are at around 35,000 km.
RE: Why is this contact jumping all over the place ?
Posted: Tue Jan 04, 2022 5:55 am
by AKar
ORIGINAL: nukkxx5058
It's its altitude: 35.000 km !!! Which is far from earth orbit, in deep space. It should be 350 km IMO.
35'786 km or thereabouts - also known as geostationary orbit. [:)]
RE: Why is this contact jumping all over the place ?
Posted: Tue Jan 04, 2022 6:04 am
by nukkxx5058
OK. I just learned something. I didn't realize that geostationary satellites were flying that high.
So does it explain the jumping contact issue ?
Altitude classifications for geocentric orbits
Low Earth orbit (LEO): geocentric orbits with altitudes below 2,000 km (1,200 mi).[3]
Medium Earth orbit (MEO): geocentric orbits ranging in altitude from 2,000 km (1,200 mi) to just below geosynchronous orbit at 35,786 kilometers (22,236 mi). Also known as an intermediate circular orbit. These are used for Global Navigation Satellite System spacecraft, such as GPS, GLONASS, Galileo, BeiDou. GPS satellites orbits at the height of 20,200 kilometers (12,600 mi) with an orbital period of almost 12 hours.[4]
Geosynchronous orbit (GSO) and geostationary orbit (GEO) are orbits around Earth matching Earth's sidereal rotation period. Although terms are often used interchangeably, technically a geosynchronous orbit matches the Earth's rotational period, but the definition does not require it to have zero orbital inclination to the equator, and thus is not stationary above a given point on the equator, but may oscillate north and south during the course of a day. Thus, a geostationary orbit is defined as a geosynchronous orbit at zero inclination. Geosynchronous (and geostationary) orbits have a semi-major axis of 42,164 km (26,199 mi).[5] This works out to an altitude of 35,786 km (22,236 mi). Both complete one full orbit of Earth per sidereal day (relative to the stars, not the Sun).
RE: Why is this contact jumping all over the place ?
Posted: Wed Jan 05, 2022 5:23 am
by nukkxx5058
In fact it would be good to be able to disable the info from the satellite about the jumping contact. Because it brings no added value at all and spams the signal received from other sensors.