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Re: Exercise #14 Multi-Moon LOP's
From: Brad Morris
Date: 2009 May 1, 16:53 -0400
From: Brad Morris
Date: 2009 May 1, 16:53 -0400
Hi Jeremy The newly linked file method just worked. Don't be so hard on yourself regarding the variance in DR. S--- happens. Upon review of the data, it shows that you are indeed subject to the SMG estimation and not to the DR position. That really isn't a surprise. As each LOP is advanced or retarded by a function of velocity, the fix changes as a function of each LOP. The error in SMG contributes almost directly to the error in fix. The same applies to the course made good. The overall method works because of the least squares fit (assuming that is the regression method) at the end. This is nothing more than good old Saint Hilaire. We wouldn't try this on a plotting sheet, simply because all the lines are at a relatively shallow angle. Further, 25 LOPS with 24 advanced LOPS might confuse the living heck out of me, especially when I go for the "cocked hat". However, for a computer, it is an easy day to create the fix. It cannot be confused by the multiplicity of lines, nor will it make a plotting error in advancement or retardation. Yes, a human could perform all of this, albeit at the risk of many minor errors as they go. For similar reasons, the Latitude by Double Altitude methods espoused by Bowditch fell out of favor. Just too easy to make a mistake, and very long in computation. This is very evident in the 4th method (variance of declination permitted). That method is twice as long as any other and certainly longer than a lunar. That makes it easy to make a mistake. I spent a very long time creating a spreadsheet to do this, simply because the directions are obtuse and the cases are many. Now that I have the method programmed, it is easy to fill in the altitudes, declinations and time interval. The latitude pops out. I would never really try this by hand, it is just too cumbersome and error prone. The "rapid fire fix", at least for me, falls into that category. Yes, a computer can perform the calculation. A human, not so much! Best Regards Brad "Confidentiality and Privilege Notice The information transmitted by this electronic mail (and any attachments) is being sent by or on behalf of Tactronics; it is intended for the exclusive use of the addressee named above and may constitute information that is privileged or confidential or otherwise legally exempt from disclosure. If you are not the addressee or an employee or agent responsible for delivering this message to same, you are not authorized to retain, read, copy or disseminate this electronic mail (or any attachments) or any part thereof. If you have received this electronic mail (and any attachments) in error, please call us immediately and send written confirmation that same has been deleted from your system. Thank you." --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---