damon@lsrhs.UUCP (Damon Micheals) (02/06/86)
Loran-C in aviation seems to be a hot topic these days, for good reason. Marine Navigators have relied on its great accuracy for over 10 years. Despite these many years of Loran-C experience, design of receivers is still an art, not a science. It's not like a calculator which always gives the same answers, given the same inputs. There are many, many pitfalls for the unknowledgeable user or buyer. My companys only product is Loran-C receivers, so I know whereof I speak. We make the absolute top-end Marine Loran. (I do all the assembly language programs that live inside of our recievers.) We have just introduced our first aviation Loran, the NorthStar M1, we expect it to dominate the market shortly. Though programs are pretty nearly in final shape, there is always room for extra bells and whistles if they would be valuable to the navigation community. I am hereby soliciting comments about desireable features for aviation Loran-C. I would also like to hear of users experiences, good or bad, with the Loran system. Finally, if you have any questions about Loran-C in general, or the Northstar M1 in particular, I would be happy to discuss them with you. Shel Michaels.
falk@sun.uucp (Ed Falk) (02/17/86)
Just a couple quick notes about what would be desirable in a LORAN. My father's plane has an Apollo with what they call "flybrary". This is a ROM directory of major airports, nav-aids and waypoints. You can also add to the library by hand. My father loves this feature, all you need to do is get the plane in the air, punch in the three-letter code of your destination, couple the autopilot, and enjoy the scenery until you're there. Autopilot coupling is a must for IFR. Get an IFR rating for the M1. A loran with IFR capability is a tool. A loran for VFR only is a toy. Push-buttons suck. If you're trying to use an electronic nav-aid in IFR conditions, you're probably also encountering turbulance. Push buttons are hard to press quickly and accurately if the cabin is moving about because your hand waves around as you reach for the button. The worse the weather is (and the more desperately you need the nav-aid), the harder it is to push buttons. Knobs such as the kind used in most modern radios (the digital kind that have click stops and probably use opto-interrupters) are *much* easier to use in flight. Use knobs instead of buttons whenever feasible -- especially for data entry such as frequencies and headings. Even menu selection should be done via a dial (have entries scroll up and down as you turn the dial). Personally, I prefer LCD to LED, you can read it during the day. DONT assume that the users will be computer jocks. This means dont design a user interface syntax that makes sense to computer programmers but not pilots. For instance, having a pilot enter a frequency on a keypad, hit "enter freq.", enter lattitude and longitude on the keypad, hit "enter LAT/LON", etc. is a pretty bad way to do it. Far better, to have the pilot hit "enter freq.", turn a dial, hit "enter LAT/LON", turn a dial, etc. is better. I.e. have the pilot enter functions before data (prefix notation) and have annunciators to remind them what they're doing. The best human interface I ever saw was on a Kliegel theater lighting board -- not only were there sufficient annunciators, but there were led's under each button which indicated what the available options were at any given moment. Don't forget to have a "clear" key. During data entry, this should clear the system to an unambiguous, easily recognized state.