[Federal Register Volume 84, Number 17 (Friday, January 25, 2019)]
[Notices]
[Page 368]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-00111]


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 Notices
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  Federal Register / Vol. 84, No. 17 / Friday, January 25, 2019 / 
Notices  

[[Page 368]]



DEPARTMENT OF DEFENSE

Department of the Air Force


2017 Public Interface Control Working Group and Forum for the 
NAVSTAR GPS Public Documents

    AGENCY: Global Positioning System Directorate (GPSD), Department of 
the Air Force, Department of Defense.
    ACTION: The Global Positioning System Testing notice.
SUMMARY: This notice informs the public that the Space and Missiles 
Center Global Positioning Systems (GPS) Directorate Engineering (SMC/
GPE) Systems Integration Demonstration (SI Demo) team plans to execute 
a test in February 2019 to investigate legacy receiver week roll-over 
behavior and analyze any off-nominal behavior exhibited. Additonal 
details about the test and how interested civil vendors may participate 
is detailed below.

DATES: Questionaire due by February 4, 2019.

ADDRESSES: SMC/GPE, 483 North Aviation Boulevard, El Segundo, CA 90245-
2808.

SUPPLEMENTARY INFORMATION: The Global Positioning System (GPS) week 
number rollover occurs in the GPS legacy navigation (LNAV) message 
every 1024 weeks due to the GPS week number being represented by only 
10 bits within the LNAV message. The next GPS week number roll over 
will occur 18 seconds prior to the 0000Z boundary (Coordinated 
Universal Time) between April 6/7 2019. In most cases, any negative 
response from a GPS receiver caused by a problem accounting for the 10-
bit week number week roll over would likely affect the calendar 
conversion from GPS time to UTC date/time and could result in the GPS 
receiver thinking it had jumped backward in time by 1024 weeks to 21/22 
August 1999. Many receiver-specific design documents contain 
requirements that ensure proper handling of a rollover event. However, 
SMC/GPE does not control, maintain, or even have an awareness of the 
software and requirements baseline of every GPS receiver in operation. 
Many performance conditions, especially those in older GPS receivers, 
may differ from expectations laid out in modernized receiver-specific 
design documents. It should be noted that the modernized civil 
navigation (CNAV) signals all utilize a 13-bit week number 
representation and the use of those CNAV signals can delay potential 
week number roll-over problems to 5/6 January 2137. Below are a few 
questions whose answers would help SMC/GPE understand your receiver's 
expected behavior during the upcoming GPS 10-bit week number roll-over:
    1. Does your strategy involve user input?
    2. Do the users understand and know the procedure?
    3. Is the procedure detailed in a manual or other document?
    4. Is the procedure, manual, or documentation posted on your 
website?
    5. Are there concerns for any automated systems your receiver is 
integrated into?
    6. Do you plan on posting product advisories for each receiver 
type? If so, where?
    7. Has testing been planned/completed to confirm receiver 
performance expectations?
    8. Would you be interested in participating in the test by either: 
1) Supplying receivers & technical support to test with the government 
team? 2) Testing using your own test setup and configuration?
    9. How many receiver types would you be able to supply/test for 
this effort? (Note, not all receiver types may be applicable to this 
test event.)
    If you wish to participate in this test, please submit the answers 
to the questions above to SMC/GPE mailbox at 
[email protected] by February 4, 2019. After the submition of 
the questinaire, the SI Demo team will schedule individual meetings 
with interested civil vendors to further discuss their participation in 
the test in more detail.

FOR FURTHER INFORMATION CONTACT: 2Lt Marcy Gouri 
([email protected]) or Capt Aaron Knoblauch 
([email protected])

Henry Williams,
Acting Air Force Federal Register Liaison Officer.
[FR Doc. 2019-00111 Filed 1-24-19; 8:45 am]
 BILLING CODE 5001-10-P