Location Based Scanning Tips and Tricks
From The RadioReference Wiki
Tips / Tricks for more effective location-based scanning
Not every city is the shape of a circle or is of moderate size. You may need to consider custom shapes and large listening areas when programming your scanner. You can create a duplicate site with a different radius to make an oblong entity. Essentially, the scanner narrows and expands the coverage area by scanning the same site twice (but it doesn’t slow the scan rotation enough to be noticeable to the end user since it only scans twice in overlap areas.) Your scanner also needs to be able to handle large geographical areas for statewide and nationwide channels in a scan rotation.
- A custom shaped listening area can be as simple as an oblong shape or it can accommodate the rare instance you may monitor a system that operates in two simulcast locations separated by a long distance. As a complex example, imagine a large military simulcast system with more than one base or campus. Your main listening area is base A & B & C (or however many campus locations.) Instead of drawing a large radius around the 3 campus locations you could create multiple sites for each location and have a radius for each that only covers the specific campus. If the military police travel one or two miles down certain roads to get from point A to point B, you can create more sites with smaller radius that follow the roads, essentially giving you location-based scanning coverage of just the areas in which the military police operate, the 3 main campuses and the roads in between.
- Statewide systems, depending on your state, may need to have custom shapes defined. GPS data for states in the radio reference database are all based on a perfect circle surrounding an entire state. In rare cases for statewide agencies listed in the database the agency may inherit the statewide coordinates if there are no agency, county, or subcategory coordinates entered in the database. However, you must be aware that the XT model scanners are only capable of storing a radius of up to 125 miles and the other models are only capable of up to 50 miles radius. If you live in an average or larger size state, you will likely encounter these limits. (Similarly, note that the third party software programs may round up or down and any radius under 1.0 may get rounded to 0 depending on the program you are using.) Hence, the data stored in the RadioReference database may not be useable in your scanner and may not be processed correctly by your third party software. In this case you can duplicate entries with different radius information to cover a large area – similar to the tip / trick above for odd shape sites.
- Nationwide frequencies listed in the RR are now able to be downloaded into many third party software programs. All of the Nationwide frequencies have a center point in the middle of the US and a range of 1800 miles. While the scanners have limitations on the range of a frequency, site or system, it would be memory prohibitive to draw many circles and enter duplicate entries for any Nationwide channels. You can always tell the software not to scan a particular entry using GPS. You will want to set all Nationwide frequencies to scan all the time, and you can manually lock them out if you need to. They will be active wherever you go (which is how scanning used to work anyhow, remember?)
How do I decipher coordinates that look like 445812.79N?
Geographical coordinates -- latitude and longitude -- can be represented in a few different ways. Both the following examples refer to the same location:
- 38.89767, -77.03655
- 38° 53′ 51.61″ N, 77° 2′ 11.58″ W
Note that they use different notation for the number of degrees. The first example is in decimal degree ("Deg") notation while the second is in DMS, or degree-minute-second. Decimal degrees simply use the degrees expressed as a decimal number. 38° 53' 51.61" equates to 38.89767°. Mathematically, you can change DMS to Deg using the formula DDD + MM/60 + SS.ss/3600. You would perform the reverse calculation to convert Deg to DMS. To more easily convert Decimal Degrees to the DDDMMSS.sss format or vice versa, see the FCC's handy converter.