01-31-2020, 10:51 PM

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.

source: Radio & Electronics World, Distance and Bearing Programs, SEP 1884, pgs. 45-46

BEST!

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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:

1 LBL 'DIST

2 FIX 0

3 51.3

4 STO 01

5 -0.1

6 STO 02

7 'LAT N?

8 PROMPT

9 STO 03

10 'LONG E?

11 PROMPT

12 STO 04

13 RCL 02

14 RCL 04

15 -

16 COS

17 RCL 03

18 COS

19 *

20 RCL 01

21 COS

22 *

23 RCL 01

24 SIN

25 RCL 03

26 SIN

27 *

28 +

29 ACOS

30 STO 05

31 69.0468

32 *

33 CLA

34 'τD=

35 ARCL X

36 'τIMLS

37 AVIEW

38 PSE

39 RCL 01

40 SIN

41 RCL 05

42 COS

43 *

44 CHS

45 ENTER↑

46 RCL 03

47 SIN

48 +

49 ENTER↑

50 RCL 01

51 COS

52 RCL 05

53 SIN

54 *

55 /

56 ACOS

57 STO 06

58 RCL 04

59 X<0?

60 XEQ 'NEG

61 XEQ 'TRU

62 LBL 'TRU

63 CLA

64 RCL 06

65 'τBEAM

66 ARCL X

67 'τDEG

68 AVIEW

69 STOP

70 LBL 'NEG

71 360

72 ENTER↑

73 RCL 06

74 -

75 CLA

76 'τBEAM

77 ARCL X

78 'τDEG

79 AVIEW

80 STOP

BEST!

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