(41C) Distance-Bearing from LAT-LON
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01-31-2020, 10:51 PM
Post: #1
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(41C) Distance-Bearing from LAT-LON
A recent survey showed that within amateur radio … home micros dominate the scene … Presented here are … programs for … (… the Hewlett Packard HP41C/CV) to find the exact distance and bearing of any station, anywhere in the world.
The only information required is the latitude & longitude of the distant station which is easily read from any World map found in the majority of amateur 'shacks', and these figures need only be approximate. In this way, no matter where the station you wish to contact is, you can have your beam pointing accurately at him in seconds. These programs are a considerable improvement on previous distance/bearing programs and are very accurate, simple to type in, user-friendly, and … are guaranteed to work! If required, the reader could use such programs as a basis to automatically rotate the beam using a digital to analogue converter. The amateur simply glances at his map, plugs in the rough coordinates and the micro does the rest! In use, the only listing changes needed are for your own QTH latitude & longitude; Lines 3 & 5 for the HP41C/CV Simply change the values shown (based on London) for your own. No other changes are needed. When prompted for lat/long of the DX station, values are entered as degrees NORTH and EAST. For example, Tokyo would be entered as 35,140, ie 35N & 140E. Locations West of Greenwich and South of the Equator are entered as negative values; eg Sydney is entered as -34,152. The -34 indicates 'minus 34 degrees North' ie 34 deg South. Similarly, New York is 42,-74; -74 meaning 'minus 74 degrees East' ie 74 deg West. Accordingly, Port Stanley would be entered as -51.5, -57.6 and so on. Program Checks Once you have entered your program it is advisable to test run it with the following data which cover all four 'quadrants' of the globe. ┌───────────────────────────────────────┐ │Location Lat Long Distance Bearing │ │ (miles/Km) (deg) │ │Tokyo 35.40N 139.45E 5960/9591 32 │ │Sydney 33.55S 151.10E 10641/17123 63 │ │Honolulu 21.19N 157.50W 7420/11649 338 │ │Stanley 51.45S 57.56W 7846/12626 21 │ └───────────────────────────────────────┘ If your results agree, or nearly agree to those given, then all is well. If not, then you have made a typing error or errors entering the program. Check especially the lines with trigonometry … as these are the most likely sources of error. As a final word, these programs are simple but effective. Code:
BEST! SlideRule |
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02-01-2020, 08:47 PM
(This post was last modified: 02-01-2020 08:50 PM by StephenG1CMZ.)
Post: #2
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RE: (41C) Distance-Bearing from LAT-LON
"The only info needed is the lat and long of the distant station"...
I suspect the lat and long of both stations would be useful in calculating the distance "SEP 1884" I know the HP41 calculator is old, but really, that belongs in Valentino's time travel story. Stephen Lewkowicz (G1CMZ) https://my.numworks.com/python/steveg1cmz |
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02-01-2020, 11:46 PM
Post: #3
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RE: (41C) Distance-Bearing from LAT-LON
(02-01-2020 08:47 PM)StephenG1CMZ Wrote: "The only info needed is the lat and long of the distant station"... Lines 3 & 5 for the HP41C/CV Simply change the values shown (based on London) for your own. This is the Museum of HP Calculators, no? BEST! SlideRule |
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02-03-2020, 06:25 AM
Post: #4
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RE: (41C) Distance-Bearing from LAT-LON
Thanks for the info.
Here’s a working link to the non-1884-but-less-time-travel-1984 Article (pdf) p.45; Radio & Electronics World september 1984 There’s also 2 Basic versions (ZX81 & BBC-B). The focal program doesn’t seam to use degrees but degrees minutes seconds and express results in English miles. I don’t get the point of the 61 line !? Travel space and time safely... |
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02-03-2020, 01:42 PM
Post: #5
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RE: (41C) Distance-Bearing from LAT-LON
(02-03-2020 06:25 AM)dayd Wrote: I don’t get the point of the 61 line !? The author of that article simply didn't understand FOCAL programming very well. Since he puts a STOP to end the program inside a subroutine, it never returns to the calling line, where the program should have been ended properly. It looks like it will run properly (as seen by the user) but it is structured poorly. --Bob Prosperi |
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