Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: GPS Reliability -- Warnings surely must be a HOAX
    From: John Brenneise
    Date: 2004 Jun 19, 19:31 -0700
    These warnings are undoubtedly a HOAX!!!
    Read the Bowditch chapter(s) on Electronic Navigation. 
    All GPS (Global Positioning System) satellites  transmit on the same two frequencies,  modulating a unique, per-satellite C/A (Course Acquisition) code onto their SPS (Standard Positioning Service) frequency signal.  Civilian GPS receivers, which use the SPS have internal knowledge of the C/A code for each satellite from which they are capable of receiving a signal. SPS receivers employ the C/A code to amplify the signal by constructive interference, thereby picking out a given satellite's signal from the "soup".
    As you can see, the satellites interfere with each other BY DESIGN. 
    The other frequency is used by the PPS (Precise Positioning Service) which is essentially the domain of military receivers, but is, nonetheless, also described in Bowditch.
    Additional information is available on a variety of web sites that describe the system.
    John Brenneise
    ----- Original Message -----
    Sent: Saturday, June 19, 2004 2:00 PM
    Subject: Re: GPS Reliability

    In the United Kingdom the Royal Institute of Navigation are issuing warnings on the vulnerability of GPS to loss of signal and interference.   The received GPS signal is so weak that any interference could stop the GPS receiver completely.
    With the GPS acting as a back up to normal navigational methods this is not so important.   However where navigation is 100% dependent on GPS this could be catastrophic!   Fortunately the GPS does not produce an error signal so when it is not working it should be relatively obvious.
    Philip Ouvry
    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site