On Feb 23, 12:33 pm, Cephalobus_alie...@comcast.net wrote:
> On Feb 23, 12:49 pm, koobee.wub...@gmail.com wrote:
>
>
>
>
>
> > On Feb 20, 4:33 am, "Jon" <jon8...@peoplepc.com> wrote:
>
> > > Supposing three satellites transmit signals with time stamps that are picked
> > > up by a receiver.  If the clocks on the satellites are closely synchronized,
> > > then
>
> > > |AD|=|AB|+t_AB
> > > |BD|=|BC|+t_BC
> > > |CD|=|CA|+t_CA
>
> > > Where
> > > A,B,C=position vectors of three satellites
> > > AB,BC,CA=distances between satellites
> > > t_AB,t_BC,t_CA=time differences between signals at D.
> > > D=position vector of receiver.
>
> > > Once |AD|,|BD|,|CD| are found, the coordinates of D can be derived.
>
> > > Is this how it is done?
>
> > > summarized at
>
> > >http://mypeoplepc.com/members/jon8338/math/id8.html
>
> > You need four satellites where each satellite should know its time and
> > position.  Time can just be a counter with all the satellites
> > synchronized to within a count of each other.  Each satellite then
> > just broadcast its time and position information as almanac signal to
> > whoever wants to receive it.
>
> > Since the distance is traveled by light with a known speed, you can
> > then easily form a set of four equations with four unknowns.  The four
> > unknowns are your time (relative to the counter in each satellite) and
> > position.
>
> > **  c^2 (t1 – t)^2 = (x1 – x)^2 + (y1 – y)^2 + (z1 – z)^2
> > **  c^2 (t2 – t)^2 = (x2 – x)^2 + (y2 – y)^2 + (z2 – z)^2
> > **  c^2 (t3 – t)^2 = (x3 – x)^2 + (y3 – y)^2 + (z3 – z)^2
> > **  c^2 (t4 – t)^2 = (x4 – x)^2 + (y4 – y)^2 + (z4 – z)^2
>
> > Where
>
> > **  (t1, x1, y1, z1) = Time and position of satellite 1
> > **  (t2, x2, y2, z2) = Time and position of satellite 2
> > **  (t3, x3, y3, z3) = Time and position of satellite 3
> > **  (t4, x4, y4, z4) = Time and position of satellite 4
> > **  (t, x, y, z) = Time and position of the receiver
>
> > Notice that relativistic effect is never needed.
>
> Currently, only Block IIR satellites are capable of autonomous
> position monitoring and synchronization independent of the ground
> control segment. This capability allows Block IIR satellites to
> mutually correct their clocks and ephemerides information for a
> period of up to several months should the ground segment be
> knocked out by, say, nuclear war. For optimum performance under
> non-wartime conditions, "ground truth" comparisons are still
> performed on a daily basis to correct the satellites for drift.
>
> GPS satellites before the Block IIR series are incapable of such
> mutual correction, and require monitoring and daily corrections
> by the Ground Segment.
>
> Satellite control requires that the Space Segment and Ground
> Segment clocks be synchronized. The only practical way of
> synchronizing the world-wide network of ground stations is to
> use the network of GPS satellites to disseminate time. The only
> way to use the networks of GPS satellites to disseminate time is
> if the satellite clocks are adjusted via the GR correction so
> that they beat in time with Earth clocks.
>
> Jerry- Hide quoted text -
>
> - Show quoted text -

Jerry

According to Dave's post (see above), the satellites in relative
motion (at about 6.7km/s) so the Kobee-Wublee idiot needs to
understand that, even with Block IIR, the relativistic corrections are
still needed.