If two positions of a spacecraft at different times are known with good precision from for example a GPS fix the complete orbit can be derived with this algorithm, i . e . an interpolation and an extrapolation of these two position fixes is obtained.
42.
Confusion over the location of the " Princess Victoria " had contributed to the rescue vessels'difficulty in locating her and it was not until the crew had sighted the coast of Northern Ireland at 1335hrs and transmitted a new position fix that the rescue attempt was able to home in.
43.
To be precise, A-GPS features depend mostly on an internet network or connection to an L1 front-end radio receiver and no GPS acquisition, tracking, and positioning engine only works when it has an internet connection to an ISP / CNP where the position fix is calculated offboard the device itself.
44.
By contrast, a printed chart on a Yeoman Navigator provides a 35-inch " display " at extremely high resolution, that one can draw on, make notes upon, and use for traditional operations with dividers and rulers, combined with instant ( permanent ! ) position fixes and range-and-bearing information from the Yeoman mouse.
45.
The time needed to acquire the ephemeris is becoming a significant element of the delay to first position fix, because as the receiver hardware becomes more capable, the time to lock onto the satellite signals shrinks; however, the ephemeris data requires 18 to 36 seconds before it is received, due to the low data transmission rate.
