How the current localization system works:
When a user enters a zip code into our localization engine, we match it to two databases:
- A database of U.S. zip codes & associated counties provided by the U.S. Postal Service
- A database of county-level station broadcast coverage provided by Nielsen
Currently, the localization database is designed to generate lists of stations based on Nielsen data from the county where the zip code in question is located, as well as data from neighboring counties near that zip code. We believe the inclusion of neighboring county data is the source of certain anomalies in the system that are causing some stations to appear in zip codes that seem illogical (like PBS Guam showing up in Portland, OR).
When the localization update is applied next week, neighboring county data will be excluded from the station list generation process. When a user localizes to a zip code, they will only be able to see the stations that are viewable in the one county where that zip code is located.
In the extensive testing we've done on the updated system, we've found very few examples of the station list changing at all. In a few examples, we've seen the third and fourth stations in the list switching places (for example, in some New Jersey zip codes, NJN jumps from 4th in the list to 3rd in the list, above WLIW, but still below WNET and WHYY), and in a few rare cases stations that seem very out of place (like the Guam example above) fall off the list.
Please continue to let us know if you see anything out of place when you localize on pbs.org. Our goal is to have a data-driven system that makes it easy for users to find the local stations they recognize from what is available on their TV.