GPS week rollover bug hits Nextel

Discussion in 'Global Navigation Satellite Systems' started by Paul Hirose, Jul 23, 2004.

  1. Paul Hirose

    Paul Hirose Guest

    Several models of Nextel phones have been malfunctioning in the past
    few days. The phones crash and reboot when the user attempts to use
    the GPS part of the phone. This includes the E911 feature that
    provides GPS location during an emergency call.

    It seems to be a GPS week rollover problem. Last Sunday was the
    beginning of GPS week 1280, which is a multiple of 256.

    Nextel and Motorola have issued a press release acknowledging the
    problem. "Nextel has temporarily disabled the transmission of the
    A-GPS enabled location information for E911 Phase II location services
    until a permanent solution to the software issue is available.",,4465_3799_23,00.html
    Paul Hirose, Jul 23, 2004
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  2. Paul Hirose

    Burnie M Guest

    I do not think you can consider this to be a GPS week rollover problem
    (as occurred in August 1999 with the 1024 week rollover).

    More like just bad firmware coding.
    Burnie M, Jul 24, 2004
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  3. Paul Hirose

    Tom Guest

    Does anyone out there know if 2SOPS could do a leap second update but
    keep the number of leap seconds constant so that the week since last
    update counter doesn't rollover?

    Tom, Jul 24, 2004
  4. Paul Hirose

    Sam Wormley Guest

    Tom--Can you clarify this question for me. Thanks.
    Sam Wormley, Jul 24, 2004
  5. Paul Hirose

    Paul Hirose Guest

    A Nextel press release says:

    "...Motorola has advised us that they have identified the root cause
    of this issue and are currently testing a remedy... Once this testing
    is complete, Nextel will roll out a program to deploy the new software
    for the phones..."

    Motorola and SiRF issued a joint statement:

    "...Motorola and SiRF Technology Holdings, Inc. today announced that
    the SiRFstarIIe/LP chipset, SiRFstarII/IP core and SiRFLoc Multimode
    A-GPS software module, incorporated in these Motorola phones, has been
    operating as designed. The software issue affecting A-GPS location
    services for the Motorola phones is in the interface between the SiRF
    software module and the Motorola handsets. Motorola and SiRF have
    identified a solution they are currently testing for deployment
    through their operator customers...",,4469_3802_23,00.html

    The last 8 bits of the GPS week rolled over at the beginning of
    Sunday, July 18, 2004, and before that on August 22, 1999 (the
    infamous rollover that began GPS week 1024).

    I don't know if an 8-bit rollover caused the Nextel bug. The trouble
    began around that time. However, one Web site said "users are
    reporting inability to access GPS position-location services since
    Friday". To me that says the problems *began* on Friday. In any time
    zone, Friday is before the GPS week change at 0 hours Greenwich time
    on Sunday.

    Someone on an iDEN developer mailing list said, "On Friday the GPS
    almanac week rolled over to week zero due to the use of an 8-bit field
    for weeks since 22 August 1999 (256 weeks)... Anyone have any ideas
    for a fix or are we just stuck with no GPS in our phone..."

    Although his understanding of the GPS calendar may be defective, the
    message does give a strong impression his Nextel GPS began to fail on
    Paul Hirose, Jul 24, 2004
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