[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Date: Fri, 15 Dec 2000 13:55:31 -0500

At 01:27 PM 12/15/2000 -0700, Vince Fiscus, KB7ADL wrote:
>I went to InstantTrack to check headings from newington, ct. to ao-40 and I found that newington Ct isn't listed in the cities database. Hilarious.

InstantTrack's city database is filtered by population. Newington just didn't make the cut. The cutoff in the eastern U.S. is 32,000 people, and Newington has just 28,841, according to the database Franklin used.

An interesting tidbit: if the same cutoff is used for the entire U.S., the map display of cities (hit "C" on the map screen) looks heavily weighted toward the eastern half of the country, with an unnatural-looking dividing line down the middle. InstantTrack's database uses a higher population threshold in the eastern U.S. to even out the coverage.

The main purpose of InstantTrack's city database is to provide understandable descriptions of the satellite's location, like "10.3 km east of Houston, TX" -- much easier for most people to understand than latitude and longitude. Another purpose is to allow the user to type in the name of a city that's reasonably close to another station, to get a rough estimate of the satellite's az/el from the other operator's location. For these purposes, roughly equal geographical spacing is more important than population (or fame within the amateur community, which is what distinguishes Newington).

In this case, you'd probably type in just "CT" and pick one of the Connecticut cities that shows up on the menu. This would provide reasonably good results.

As a further tidbit, you've probably noticed that city coverage outside the U.S. is much sparser than inside the U.S. That's just because Franklin didn't find a machine-readable database of non-U.S. cities, and had to type in a few international cities to build the city list in InstantTrack.

73  -Paul

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org