The 2015 US and Canadian mediumwave broadcast pattern reference is now available for download. You'll find the links at the upper right of this page.
I've spent much of the last year working on mediumwave pattern mapping, when time permitted.
Included is a complete set (daytime and nighttime) of GoogleMap-based, HTML-driven maps which show the most current pattern plots of all licensed US and Canadian mediumwave broadcast stations from 530 - 1700 KHz. The set includes all frequencies for the indicated services: Unlimited, Daytime, Nighttime, and Critical Hours. Individual maps are grouped by channel frequency: 540, 550, 560 KHz, etc. Data for the plots in this offering is based on the current FCC and Industry Canada databases available at the time of its creation (January 22, 2015).
1. Groundwave pattern maps have been streamlined and made more accurate.
2. This current set of maps uses an enhanced version of the FCC's M3 Ground Conductivity data base. Many errors in the original database were found, things like segments not joining properly, missing data, odd values for the Canadian land mass, problems with Alaska and Hawaii. I have corrected all these, plus added the conductivity data for the five Great Lakes bodies of water which were missing from the original database. Even little Lake St. Clair near Detroit has been incorporated.
3. I have written from scratch nighttime skywave mapping code using the standard FCC formulas, and now nighttime skywave pattern maps are newly available in this download. Nighttime signal patterns represent the standard SS+6 (sunset plus 6 hours, or approximately midnight), 50% signal probability at 0.25 millivolts per meter (48 dBµV/m, a.k.a. dBu). Note that nighttime reception of signals out beyond the depicted pattern is very possible, and in fact likely for the DXer. The maps represent a signal strength between distant and fringe, a level generally easily received at night on most portable radios. I have chosen this signal level to give a good representation of what should be fairly easily received by most DXers on an average evening. The nighttime signal probability of 50% means that the signal will be received at this level approximately 50% of the time at that location for the sunset+6 hour time. Also included in the nighttime map series is a web-based HTML table listing all nighttime stations in the US and Canada. It has clickable links which will take you directly to the FCC pages for that station (US stations only).
4. The daytime map series shows expected groundwave coverage patterns for Unlimited, Daytime, and Critical Hours operations. Daytime signal patterns represent groundwave coverage out to the 0.15 millivolts per meter contour (43.5 dBµV/m, a.k.a. dBu). Note that daytime reception of signals out beyond the depicted pattern is very possible, and in fact likely for the DXer. The contour line represents a signal strength at the station's fringe distance, a level usually received on a sensitive portable radio with a low ambient local-noise level. I have chosen this signal level to give a good representation of what should be fairly easily received by most DXers during sunlight hours. Also included in the daytime map series is a web-based HTML table listing all daytime stations in the US and Canada. It has clickable links which will take you directly to the FCC pages for that station (US stations only).
5. The Industry Canada Canadian database has now also been included in the daytime and nighttime pattern maps, showing each Canadian mediumwave station and its broadcast pattern. A lot of time was also spent incorporating the Canadian engineering data and coding up software to process it. Unfortunately, no Mexican patterns are available. I have elected to exclude them from the maps as the Mexican government does not provide technical engineering data via the internet. FCC Mexican data is redundant and inaccurate at best, though I may at some point offer some pattern maps of what is available.
Downloads are at upper right as always. Remember the download link changes each time I publish these files, so always come back here to get the latest files. Files at upper right are current as of the January 22, 2015 FCC and Industry Canada databases.
Be sure to read the readme.txt file contained in the .zips for tips on how to use the maps.
Click the image for a full-sized map representation.
|760 KHz at night. 0.25 mV/m, 50% reception level.|