US MEDIUMWAVE PATTERN REFERENCES by RADIO-TIMETRAVELLER © 2014 http://radio-timetraveller.blogspot.com ================================================= US Mediumwave Pattern References are produced by the Radio Data MW program. 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). 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 dBuV/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). The nighttime map series shows expected skywave coverage patterns for Unlimited and Nighttime operations. 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 dBu). Note also 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). Unfortunately, no Mexican patterns are available due to lack of official Mexican engineering information. HOW THEY ARE PRODUCED ---------------------------------------- Using the actual FCC database files Radio Data MW will auto-generate an interactive HTML pattern map, showing the pattern plots for all stations included at the discretion of the user. A complete set of mediumwave pattern maps can be generated within minutes. Radio Data MW generates a real pattern plot based on ground conductivity, ground dielectric constant, and can display actual (but approximate of course) signal level boundaries for Local, Distant, Fringe, Extreme mV/m levels, or any custom mV/m level chosen by the user. The online Google Maps API is used to generate and plot each station on a map of the US. An accurate flag pin is placed at each transmitter location, and in satellite view may be zoomed in to see the actual transmitter site. Map flags are color-coded to indicate Unlimited (light red), Daytime (yellow), Nighttime (black), and Critical Hours (grey) services. Each flag has a tooltip-type note, and when hovered over with the mouse will display a note on the station. A pattern plot for each station is generated and displayed. Each pattern is calculated using standard formulas used by the FCC to compute the base values at one kilometer, and field strength formulas at distance based on the works of many people over the years. See Field Strength Calculations: A History and Field Strength Calculator One, previously posted on RADIO-TIMETRAVELLER. Finally, an accurate ray path can be drawn from all transmitters to a user-specified receiving location by inputting latitude-longitude coordinates on the heading bar at the top of the map. Super-imposed on the pattern plots, the ray paths show the listener where he or she falls on each station's pattern, a handy guide to knowing where you stand. INSTALLING ---------------------------------------- The maps are HTML-based, so no regular install is necessary. Simply unzip the downloaded file and click on the individual file to run. The map will open up in your web browser. You must have an internet connection. USING THE MAPS ---------------------------------------- Note again that these maps are web-based. As stated, they use Google Maps and thus require access to Google. In order to view them you need a connection to the internet. They have been tested in the Internet Explorer, Firefox, Chrome, Opera, and Safari desktop browsers. If using Internet Explorer, best results are had with the latest version, IE 10 or greater. You will also find that the maps will generally work on most tablet or phone browsers, but no guarantee is given. Android and IOS browsers are in a constant flux of change, and in testing the most recent varieties I have had good success. The Google Chrome browser will work the best. Note also that the maps, being script-driven and with many lines of code are very CPU-intensive, and may cause many tablets or phones to choke. These are the latest US pattern references available, and coverage is based on actual ground conductivities. >>> Lat-Lon boxes (Latitude and Longitude) Your home location. Modify as you wish. Be sure to use negative values for the western and southern hemispheres. Click ReDraw to redraw the map. >>> Show Paths Check the box and click ReDraw and great-circle paths will be drawn from each station to your home location, as indicated in the latitude (lat) and longitude (lon) boxes. These paths will help you determine where you fall in each stations broadcast pattern. >>> ReDraw Redraws the map according to settings. >>> Map/Satellite Click one or the other to display the map in either map form or satellite form. Subsequently, "Map" form may be displayed as a road map or terrain map. "Satellite" form may be displayed with or without labels (hybrid = labels). >>> mV/m and Conductivity Levels These maps are produced by Radio Data MW for a specific mV/m (millivolt per meter) level and ground conductivity. The map itself in HTML form, once produced, cannot be altered to change these levels. >>>Station Flags Station flags are colored according to service. Unlimited: red Daytime: yellow Nighttime: black Critical Hours: grey UPDATES ---------------------------------------- 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. 4. The Industry Canada Canadian database has now also been included in the daytime and nighttime pattern maps, showing each Canadian mediumwave station. 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. 5. Note that some daytime stations may have a Critical Hours pattern map super-imposed on the same location. It will be the smaller of the two patterns. September 26, 2013: 1. The latest maps show actual calculated received signal strength based on FCC ground conductivity data from the M3 map database. 2. The pinch-to-zoom bug and map scroll bug has been found which caused maps to lose these features when viewed on some mobile browsers. NOTES ---------------------------------------- The flag pin for each station is accurate, geographically. Zoom in at maximum level in satellite view and you should see the station's transmitter site. If you are lucky enough that Google has taken a street view photo, you can also see that too.