Ship performance analyzer

In a system for enabling the performance of a ship on a test run to be analyzed and including a means for determining the speed of the ship propellor shaft, a means for determining the rotational torque on the ship propeller shaft, and means for receiving successive readings in time of Loran navigational signals, the improvement comprising means responsive to the successive readings in time of the received Loran navigational signals for determining the ship speed regardless of whether or not the ship is traveling substantially perpendicular to Loran lines of hyperbolae, said means for determining the ship speed including:

• a. means for calculating the ship speed by determining the rate at which Loran lines of hyperbolae of two Loran station pairs are crossed;
• b. means, utilizing said rates of crossing, for calculating the speed at which the ship crosses line of latitude and longitude;
• c. means, responsive to said last named means, for correcting for a difference in scale between the lines of latitude and lines of longitude;
• and
• d. means, responsive to said correcting means, for utilizing the Pythagorean Theorem to calculate the ship speed.

A system responsive to the successive readings in time received by a Loran receiver from first and second sets of Loran navigational stations, for determining the speed of the receiver which received the successive readings in time regardless of whether or not the receiver is traveling substantially perpendicular to Loran lines of hyperbolae and including:

• a. means for storing expected values of a given physical parameter which is dependent upon Loran time difference readings at an assumed geographical location;
• b. means, responsive to the successive readings in time, for calculating measured values of said given physical parameter;
• c. means for comparing the expected values of said given physical parameter with the measured values of said given physical parameter to determine if they are within given error tolerances;
• and
• d. means responsive to a determination that said values are not within said given error tolerances for iteratively correcting the assumed location and then determining new expected values of said given physical parameter for the next assumed location and repeating the comparison and iteration until the given error tolerances are met.

A system, responsive to the successive readings in time received by a Loran receiver from first and second sets of Loran navigational stations, for determining the speed of the receiver which received the successive readings in time regardless of whether or not the receiver is traveling perpendicular to Loran lines of hyperbolae and including:

• a. means, responsive to the successive readings in time, for calculating the speed by determining the rate at which Loran lines of hyperbolae of two Loran station pairs are crossed;
• b. means, utilizing said rates of crossing, for calculating the speed of crossing of lines of latitude and longitude;
• c. means, responsive to said last named means, for correcting for a difference in scale between the lines of latitude and the lines of longitude;
• and
• d. means, responsive to said correcting means, for utilizing the Pythagorean Theorem to calculate the speed.

In apparatus for determining the speed of a ship during a run, a method comprising the following steps:

• a. taking a plurality of Loran time difference signals from two different sets of Loran master/slave stations over a period of time during the run;
• b. operating on the plurality of signals according to statistical techniques to minimize random errors in the plurality of readings;
• c. generating signals corresponding to expected values of a given physical parameter for an assumed geographical location of the run midpoint which is dependent upon Loran time difference readings expected at the assumed geographical location;
• d. utilizing the statistically treated Loran time difference signals to generate further signals corresponding to measured values of said given physical parameter for the midpoint of the run;
• e. comparing the signals corresponding to expected values of said given physical parameter with the signals corresponding to measured values of said given physical parameter to determine if they are within given error tolerances;
• and
• f. iteratively correcting the generated signals corresponding to expected values of the given physical parameter for an assumed geographical location until the error tolerances are met.