(25) … LORAN Time Differences …

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An extract from Computing LORAN Time Differences with an HP-25 Hand Calculator, NASA (TM-59), AUG 1978.

I. INTRODUCTION
This technical memorandum presents a program for an HP-25 or HP-25C hand
calculator that will calculate accurate LORAN-C time differences. The program is most useful when checking the accuracy of a LORAN-C receiver at a known latitude and longitude without the aid of an expensive computer. It can thus be used to compute time differences for known landmarks or waypoints to predict in advance the approximate readings during a navigation mission.

11. PROGRAM DESCRIPTION AND ACCURACY
The forty -three step prcgram has a running time of approximately ten seconds and is relatively simple to operate …

III. COMPUTING TIME DIFFERENCES
By following the HP-25 program forms, Appendix A, time differences can be easily calculated. An example problem is shown on page 3 …

IV. FUTURE PROGRAM CONSIDERATIONS
… It is possible that the HP-25 can perform one of these simple methods, but the accuracy and utility has yet to be determined.

V. SUMMARY
Although card reading calculators should give best results, the HP-25 LORAN Time Difference Program has proven itself to be reliable over the coordinates that it has been tested …

Includes program description & listing as well as example.

BEST!
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