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cyoung / stratux

Aviation weather and traffic receiver based on RTL-SDR.
BSD 3-Clause "New" or "Revised" License
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Altitude error above 32768ft #402

Closed AMNegron closed 8 years ago

AMNegron commented 8 years ago
  1. Stratux version: 0.8r2

  2. Stratux config: SDR [ x ] single - type: ​NooElec Nano 2

    GPS [ x ] yes - type: U-blox7

    AHRS [ x ] no

    power source: Innergie PocketCell - 3,000 mAh 2.1A usb cable: USB2.0 / 28AWG

  3. EFB app and version: FltPlan Go 4.2.4 EFB platform: iOS 9.3.1 EFB hardware: iPad Mini 1
  4. Description of your issue:

Altitudes above 32768 ft are not being passed properly in the data stream. Above that altitude, on FPG, the altitude value gains a "few extra bits", but on FF the altitude turns negative. GPS altitude value compared to internal iPad GPS.

Test 1: Level flight FL360. Stratux GPS GUI showed 36521 ft. FltPlan Go (iPad mini/Stratux) was showing 4294958387.0 m ForeFlight (iPad 2/Stratux) was showing -28985 ft (http://imgur.com/DoCmMzY)

During descent passing FL330, FPG jumped down to 9999 m and values remained fairly accurate through the remainder of the descent. On FF, the altitude descended until reaching approximately -33000 ft, then the negative sign disappeared and again, the value remained fairly accurate (and continued a proper descent) for the remainder of the descent.

Test 2 (iPad mini) Level flight FL330. Stratux GPS GUI showed 34015 ft (http://imgur.com/s283swH) FltPlan Go (Stratux ublox) was showing 4294957692.0 m (http://imgur.com/Rxz7fnN) FltPlan Go (iPad GPS) was showing 10385.31 m (http://imgur.com/gdq64rE)

I think the trigger point is 32768 ft (9989 m) [0x8000]

Attached logs should be from Test 2. Stratux_Altitude_Error.zip

If possible, enable "Replay Logs", reproduce the problem, and provide a copy of the logs in http://192.168.10.1/logs/stratux/ and http://192.168.10.1/logs/stratux.log.

skypuppy commented 8 years ago

Cool. FltPlan Go with ublox was showing you at 21,664 miles, or about where the geostationary satellites are in orbit! What an airplane!!! May I borrow it sometime?

ghost commented 8 years ago

It's an int16 overflow during creation of the ownship altitude message. Noted as issue #373, addressed as #375, and will be included in the next release.

cyoung commented 8 years ago

Thanks for the report @AMNegron. This has been fixed, watch for v0.8r3 soon.