Path: csiph.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Sylvia Else Newsgroups: sci.physics.relativity,sci.physics Subject: Re: GPS Again. Date: Fri, 9 Jun 2017 11:37:14 +1000 Lines: 38 Message-ID: References: <0smdnRoX7NsQULXEnZ2dnUU7_8zNnZ2d@giganews.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net Ie8zJv35LZgE4zUr4COoVQbsG6QZELVLvLYUjsPoNENeS26rGU Cancel-Lock: sha1:S37Zd0oi0GgSlNJ03ODRyvWAY8s= User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 In-Reply-To: Xref: csiph.com sci.physics.relativity:422008 sci.physics:635861 On 31/05/2017 5:15 AM, Ernest Rivers wrote: > Tom Roberts wrote: > >>> The receivers are working only, >>> and only, on the DATA received from the satellites. NOT on the speeds >>> of the signals carrying IT. >> >> The algorithm does depend on the speed of the signals relative to the >> ECI. > > No, it doesn't. Lol, the algorithm is burned into the chip, SoC (system on > chip, a MCU). It reveals you lack Embedded Systems, and never programmed > such one for real in the field, with maps and so on. The GPS time in the transmitted data from a GPS satellite allows the construction of an equation that essentially asserts that the distance between the receiver (at the time of reception) and the satellite (at the time of transmission) equals the time taken for the data to arrive multiplied by the speed of light. Since space is three dimensional, the equation contains four unknowns - the three spacial coordinates of the receiver, and the (unknown) GPS time at the receiver. The receiver solves four such equations simultaneously to determine the values of the four unknowns[*]. But, significantly, since the equations contain the speed of light, the algorithm is certainly dependent on it. The fact that the algorithm is burned into a chip (in those cases where it is), has no bearing on whether it is dependent on the speed of light. Sylvia. [*] With suitable allowance for the fact that the transmissions were not received simultaneously, and using data from more than four satellites where they are available.