LORAN-C equipment alignment

• US 4,150,380 A
• Filed: 02/27/1978
• Issued: 04/17/1979
• Est. Priority Date: 11/12/1976
• Status: Expired due to Term

• Current Assignee: Sanders Associates, INC. (BAE Systems Plc)
• Original Assignee: Sanders Associates, INC. (BAE Systems Plc)
• Inventors: Brodeur, Lester R.
• Primary Examiner(s): Tubbesing, T. H.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/881,485
• Time in Patent Office: 414 Days
• Field of Search: 343/103, 343/105 R
• US Class Current: 342/389
• CPC Class Codes: G01S 1/245 Details of receivers cooperating therewith, e.g. determining positive zero crossing of third cycle in LORAN-C
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308

Abstract

LORAN-C navigation equipment is disclosed wherein digital circuitry is used to automatically distinguish a master LORAN-C transmitting station from a secondary station. The equipment operator manually enters approximate time difference of signal arrival information for a particular secondary station into the equipment after consulting a LORAN-C chart. The operator then manually determines the exact time difference of arrival using thumbwheel switches and a LED lamp display. This procedure is repeated to determine exact time difference of arrival information for the master and each selected secondary station, and the information is plotted in a well-known manner on the LORAN-C chart to locate the position of the craft upon which the equipment is located. Manual acquisition of secondary stations simplifies the equipment and eliminates interference problems caused by skywaves and other transmissions. The set oscillator is easily and quickly caibrated by the operator who manually enters the LORAN-C chain group repetition interval information found on the LORAN-C chart on the thumbwheel switches of the receiver and then adjusts the oscillator for an match as indicated on the LED display.

Claims

1. A method of calibrating a navigation receiver-indicator that provides navigation information by receiving and measuring differences in the time of arrival of signals periodically transmitted by each of a plurality of pairs of transmitters and the difference measurements are plotted on a navigation chart to determine position and comprising the steps of:

entering the periodic rate of transmission of the signals from said transmitters into said receiver-indicator to make time difference of signal arrival measurements based thereupon,

comparing said last-mentioned time difference of signal arrival measurement with said signal transmission rate entered into said receiver-indicator to determine if they are equal to each other, said receiver-indicator being in calibration only when said measurement and said transmission rate are equal, and

adjusting said receiver-indicator so that said time difference of signal arrival measurement and said signal transmission rate are equal as required to calibrate said receiver-indicator.

2. A method of calibrating a LORAN-C navigation receiver-indicator that provides navigation information by receiving and measuring the difference in time of arrival of coded signals periodically transmitted by a master station and ones of a plurality of secondary stations, the time difference of arrival measurements between said master station and at least two of said secondary stations being plotted on a LORAN-C navigation chart to determine the position of said receiver-indicator and said chart having thereon the time perod of signal transmission of each of said master and secondary stations comprising the steps of:

entering the time period of transmission of said coded signals from said stations into said receiver-indicator which, in response to said time period, measures the difference in time of arrival of sequentially transmitted coded signals from said master station,

comparing said last-mentioned time difference of signal arrival measurement with said time period entered into said receiver-indicator to determine if they are equal to each other, said receiver-indicator being in calibration only when said last-mentioned measurement and said time period are equal, and

adjusting said receiver-indicator so that said last-mentioned measurement and said time period are equal as required to calibrate said receiver-indicator.