[FLWSS] About Locations

[John Logsdon]

Hello from john the elder

I haven't done this myself, but maybe by next June. 

One solution for the pointing problem in azimuth is the good , old-fashioned, feedback loop. The microwave target station puts an audio VCO on their receiver audio output. They then open the mike on a six or two meter liason link. The microwave shooter then transmits and sweeps with the high gain antenna. Hearing the VCO over the link is probably the quickest way to set the dish.

   The assumption is that the fixed station has a lower gain antenna which may be higher up or have some other redeeming feature, like better coax. Trying to point 2 degree antennas in the field with so many degrees of freedom, reflections, absorbtion, altitude, azimuth, North reference, horizontal reference, frequency, stiction in your tripod, for a few. 

  Just a thought. 

john


> From: k4rsv at bellsouth.net
> To: flwss at flwss.net
> Date: Fri, 18 Jan 2008 19:25:02 -0800
> Subject: [FLWSS] About Locations
> 
> Greetings again,
> 
> We noted the recent emails, and Joe and I discussed the issue and now have a
> few other things to throw out. This is relative to dishes with apx +/- 2
> degree beam widths.
> 
> 1) Maidenhead is used for logging, ok. Four places this time, and six places
> for some microwave contest.
> 2) Around here, six place maidenhead grids are about 1 degree latitude by 2
> degrees longitude. 
> 3) From what I understand, grid calculators use the center of these grids.
> 4) Dish pointing errors are terrible the closer grids are to each other,
> even using eight places. Useless in cases of low power contacts.
> 
> ** We've concluded with some simple math, and comparing results using
> longitude/latitude (hddd.mm.ss.s) verses maidenhead grids between our two
> locations, using six places. We don't have anything that will do 8 places.
> We bought them used for $20 and $40 each. That is at a hams budget price. 
> 
> a) Using very similar hand-held GPS units, capable of 12 satellites, WAAS
> enabled, accuracy >3 meters with >5 satellites visiable, the comparison
> results were:
> 
>    1) A distance error of .4 miles, if 1/2 mile out of 15 is ok.
>    2) Bearing differences were 13 degrees for a 15 mile path. In the field,
> this would still be without knowing your true bearing for North by some
> degrees.
> 
> b) At a distances of 60 miles or greater, six place maidenhead grids would
> probably be satisfactory relative to all the other pointing problems we
> encounter.
> 
> NOTE: I must stress, above everything else, being on frequency is priority
> #1. That will kill you before anything else.
> 
> K4rsv/KI4NPV
> 
> 
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