Opened 14 years ago
Closed 13 years ago
#8459 closed defect (fixed)
[PATCH] Calculate correct Azimuth positioning for Diseqc Rotor
| Reported by: | Owned by: | robertm | |
|---|---|---|---|
| Priority: | minor | Milestone: | 0.25 |
| Component: | MythTV - DVB | Version: | 0.23rc2 |
| Severity: | medium | Keywords: | diseqc rotor azimuth |
| Cc: | Ticket locked: | no |
Description
I'm not 100% sure this is a mythtv bug or my misunderstanding.
When positioning a rotor using GotoXX-diseqc (Diseqc1.3) commands, Myth calculates the Azimuth-angle for the current latitude/longitude.
This Azimuth is visible when running "mythbackend -v important,channel"
When I compare the Azimuth with other software, like kaffeine, SMWLink (www.smw.se/FreeSoftware.htm), xdipo (http://panteltje.com/panteltje/satellite/) or sites like http://www.dishpointer.com http://www.satsig.net/ssazelm.htm myth seems a few degrees wrong... Example: For my location the Astra19.2E satellite should point to 15.3E, but myth calculates 13.5E
I have attached a patch that calculates the same value as the calculators above.
The current code also calculates the elevation, I removed those lines in the patch.
Attachments (1)
Change History (5)
Changed 14 years ago by
| Attachment: | calc_correct_azimuth.diff added |
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comment:1 Changed 14 years ago by
Your azimuth calculation is only correct on a flat earth. That said the difference looks too large. I'll try to validate our formula.
comment:2 Changed 14 years ago by
| Status: | new → assigned |
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comment:3 Changed 13 years ago by
| Owner: | changed from Janne Grunau to robertm |
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I'll take this. Although I have neither a satellite dish or a rotor, I've checked into satellite azimuth calculations a bit and found that the above patch is indeed the "textbook" calculation for azimuth (and it doesn't seem to be going anywhere otherwise).
http://engr.nmsu.edu/~etti/3_2/3_2e.html http://www.angelfire.com/trek/ismail/theory.html
comment:4 Changed 13 years ago by
| Milestone: | unknown → 0.25 |
|---|---|
| Resolution: | → fixed |
| Status: | assigned → closed |
DiSEqC: Calculate Azimuth for Rotors in line with online references.
It appears that we lifted a bit too much from another available Azimuth calculation, which threw off our rotor positioning.
I've checked numerous online sources which indicate that this should be the correct calculation for Azimuth.
Fixes #8459, "meat" of the patch by Pieter Hoekstra. Thanks.
Branch: master Changeset: 5a01fdade9683ddea23f60d2438fd526db788523
Patch to fix issue