AM Clear Channel Radio Coverage

AM Clear Channel Radio Coverage A Digital Cartography Project April 6, 2011 Jeffrey K. Herzer
©2011, Jeffrey K. Herzer / www.jeffherzer.com AM Clear Channel Radio Coverage Final Project for 32‐562 Digital Cartography and GeoVisualization Northwest Missouri State University Jeffrey K. Herzer April 6, 2011
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 2 AM Clear Channel Radio Coverage T A B L E O F C O N T E N T S I. Project Background 4 II. About the Map 5 III. Shape File Preparation 6 IV. Data Gathering and Database Preparation 7 V. Proof of Concept Draft; Design Decisions 10 VI. Category (Frequency) Selections 13 VII. Creation and Symbolization of Query Tables 14 VIII. Map Creation and Design Refinements 16 IX. Additional Map Elements 21 X. Required Elements Checklist 24 XI. Conclusions 25 XII. Sources 26
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 3 I. PROJECT BACKGROUND 1, 2 A distinctive and critical feature of AM (medium‐wave) broadcasting is the propagation of radio signals over very long distances at night. During daytime hours, lower layers of the earth’s atmosphere are ionized by the ultraviolet radiation in sunlight; this ionization absorbs radio waves, generally limiting even the strongest radio signals to an effective radius of about 100 miles. After sunset however, ionization disappears in the lower atmosphere and band conditions change drastically. Radio waves in the AM band (530‐1700 kHz) are now reflected off the highest layer (or “F” layer) of the ionosphere roughly 130 to 260 miles high. This is called “skywave” propagation, and AM‐band signals can travel and be reliably heard hundreds or even thousands of miles from their transmission point. The Federal Communications Commission, established in 1934, developed the United States’ AM radio “band plan” around these physical characteristics. A cornerstone of the band plan was the designation of some frequencies as “clear channels”. Here, one dominant station, usually transmitting at a power of 50,000 watts, provided nighttime skywave service to an area within a radius of approximately 750 miles. Other stations on the frequency would be required to reduce power or cease transmitting at night to avoid interfering with the dominant stations, otherwise massive interference would result. Signal coverage maps for station KAAY in Little Rock, Arkansas, which broadcasts a 50,000 watt signal at 1090 kHz. The station transmits in an omnidirectional pattern during the daytime (left) with a primary service area (inner circle) 50 miles in radius. At night (right), KAAY switches to a directional transmission pattern to protect the signal of another clear channel, WBAL radio in Baltimore, MD. The nighttime primary service area (inner circles) is more than 900 miles in radius, stretching from northern Minnesota to the Yucatan peninsula. The secondary service area stretches much further, from northern Canada into South America. (Source: www.1090kaay.com) 3 AM clear channel radio, whose band plan remains largely unchanged, predates television and the Internet and was once a main lifeline of news, information, music, sports and entertainment. Generations listened to St. Louis Cardinals baseball games on KMOX, St. Louis; the Grand Ole Opry on WSM, Nashville; “top‐40” popular music on WLS, Chicago and WABC, New York; and entertainment favorites like “The Jack Benny Program” over CBS network affiliate stations. Clear channel radio remains a critical news and information link today as evidenced by firsthand coverage of Hurricane Katrina in 2005 over clear channel WWL in New Orleans.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 4 II. ABOUT THE MAP The final product is a 1:8,000,000 map of the continental United States, Mexico and southern Canada, displaying locations and transmitter power of AM radio stations on eight selected clear channel frequencies. The map clearly shows the wide separation between 50 kW “dominant” stations on the same frequency, and the wide berth given to the dominant stations by other stations transmitting at reduced power. Frequencies are color‐coded and station symbols are sized according to transmitter power. It is easy to see, for example, how the nearest adjacent nighttime signals (red symbols) to clear channel WSM in Nashville, TN on 650 kHz are local stations in northern Minnesota and southeastern Wyoming. These great physical separations are the main point of the map.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 5 III. SHAPE FILE PREPARATION The basis for the map is four shape files. · · · · “usa50” provides state outlines for the continental United States “canada” provides province outlines for Canada “countries” is used to display boundaries for Mexico and other countries “World Time Zones” shows time zone boundaries. The United States and Canada shapefiles did not include polygon areas for the Great Lakes. As a result, when shapefiles were overlaid, the null spaces were filled in by the World Countries shapefile (left side in graphic below), which did not differentiate between land and water. To properly display the lakes, a 1/0 (yes/no) field called “showfield” was added to the data table of “countries” and values of “1” were added for all country records except the U.S. and Canada. Symbolization for this layer was organized around “showfield” with “0” values having no color and a black outline (right side in graphic below). The outlines, representing international borders, were eventually left out of the final product.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 6 IV. DATA GATHERING AND DATABASE PREPARATION Base information for radio stations was gathered from the Federal Communications Commission web site, 4 www.fcc.gov. The FCC’s AM Radio Database Query page allows access to more than 25,000 radio station listings covering North, Central and South America. The following steps were used to gather this information and process it for importation into ArcMap: 1. The FCC’s AM Radio database was accessed and all available records were downloaded as a pipe‐delimited text file; this option is an output choice on the query page. 2. The .txt file output was imported into MS Access. There were 25,567 records in the raw data dump. 3. Records not necessary for this analysis were deleted from the table, including: a. records that showed a status of CP (construction permit); APP (application pending); PLAN (a planned radio station) or DEL (deleted station) b. records for radio stations outside the United States, Canada and Mexico c. duplicate records d. records for frequencies designated as local/regional (non clear‐channel) in the FCC band plan 4. Unnecessary fields (columns) were deleted. This included unneeded data parameters such as FCC ID number (non‐unique), unneeded descriptive text fields (such as kHz and kW, which existed for every record) plus blank fields that were created by delimiters in the text file. 5. Fields to aid in symbolization and labeling were added, to avoid conflicts like the one shown at right. This included: a. A 1/0 (yes/no) field to more readily identify records for daytime vs. nighttime operation b. 1/0 (yes/no) fields to provide more control over symbol display and labeling of individual records in the event of duplicates or other conflicts. 6. A row designating field names was added at the top of the table. 7. Lat/long information (NAD27) for station transmitter locations had to be concatenated and converted to decimal format. This data was provided in eight separate fields. For example, the lat/long for station WLW in Cincinnati, Ohio is given as: N 39 21 11 W ©2011, Jeffrey K. Herzer / www.jeffherzer.com 84 19 30
Page 7 · The three numeric figures for lat and for long were concatenated into new fields by using the following formula in Excel: =CONCATENATE(N2,”° “,O2,”’ “,P2). This formula added the necessary special characters for degree, minutes and seconds to the output. The formula was propagated through the spread sheet by selecting the first row and dragging the mouse down the column. · Conversion to decimal format was done by creating a module in Excel using VB code from the Microsoft 5
Support web site ©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 8 6 8. According to ESRI’s ArcGIS Resource Center web site , an Excel 2007 Spreadsheet must be saved as an Excel 97‐2003 workbook before it can be converted into a .dbf file. In ArcCatalog, the spreadsheet table is exported to a dBase file, which can be imported into ArcMap. 9. X values (longitude) had to be transposed to negative numbers. Field Calculator was used on the column to multiply all values by ‐1.0 (right). 10. Finally, the dBase file was imported into a Geodatabase (.gdb) created in ArcCatalog.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 9 V. PROOF OF CONCEPT DRAFT; DESIGN DECISIONS From the initial data dump of 25,567 records, the working database consisted of 7,886 records for stations on 78 discrete frequencies between 540 and 1580 kHz. A prototype map was developed to determine how many frequencies could reasonably be accommodated and how they should be symbolized. It was immediately apparent the map was effective in showing how 50 kW clear channel stations were protected or otherwise given a wide berth at night from other stations on the same frequency. A number of design decisions could be made after viewing the proof of concept: · The number of stations to display: it was apparent that five to eight sets of stations grouped by frequency could be shown with sufficient visual separation and without excess clutter. · A physical map size of 36”w x 24” high was chosen to provide sufficient display area and resolution for smaller‐sized symbols and text. Map scale was set at 1:8,000,000. Resolution quality was confirmed by printing physical test documents. · Stations were classified and an initial symbolization scheme and style guide were developed based on transmitter power: (table, next page) .
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 10 Break Values 0.99 Label Icon Size (px) Icon Type > 1 kW 10 Circle – 50% black 9.99 1 – 9 kW 10 Circle 24 10 – 24 kW 25 Diamond – light border 49 25 – 49 kW 35 Diamond – light border 51 50 kW 55 Diamond – heavy border 74 75 kW 38 Cross – light border 99 100 kW 50 Cross – heavy border 149 150 kW 75 Star 199 – 251 250 kW 90 Star‐in Star o Circle shapes were selected for local stations, with the intention of giving them reduced visual significance. o Diamond shapes were selected for 50 kW clear channel stations, the most significant characters on our map, with smaller diamonds selected for regional stations. Diamonds somewhat resemble radio towers, do not imply a signal radius as a circle might, and are not as visually suffocating as larger‐sized circles. o Other shapes were selected for high‐power stations in Mexico. While the maximum power for AM stations in the United States and Canada is 50 kW, stations in Mexico are as powerful as 250 kW. High‐power Mexican stations near the U.S. border are called “border blasters” in the broadcast industry, and their exceptional power has an equally great effect on same‐frequency station assignments in the U.S. and Canada. These stations are certainly special cases and rated symbols than their 50 kW American counterparts. o The number of resulting data classes (nine) was a concern, but it was unlikely all classes would be represented on the final map. Quoting the ColorBrewer 2.0 web 7 site on the number of data classes: “Choosing the number of data classes is an important part of map design. Increasing the number of data classes will result in a more “information rich” map by decreasing the amount of data generalization. However, too many data classes may overwhelm the map reader with information and distract them from seeing general trends in the distribution. In addition, a large numbers of classes may compromise map legibility—more classes require more colors that become increasingly difficult to tell apart.”
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 11 · 7 ColorBrewer 2.0 was used to develop an initial color set. No scheme offered was colorblind safe, so a “print friendly” color set was chosen: Red: 228, 26, 28 Orange: 255, 127, 0 Yellow: 255, 255, 51 · Green: 77, 175, 74 Blue: 55, 126, 184 Purple 152, 78, 163 Brown: 166, 86, 40 Pink: 247, 129, 191 Gray: 153, 153, 153 The trial color set was incorporated into map symbols, but was deemed ineffective because some color differences (e.g. red vs. orange, blue vs. green) were not easily spotted. Use of more vivid colors solved this problem. The trial color set was well‐suited for choropleths or continuous data, but not for stand‐ alone symbols.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 12 VI. CATEGORY (FREQUENCY) SELECTIONS With all elements prepared, map production began with a selection of 11 clear channel radio frequencies to be featured. The eight frequencies that are highlighted were included on the final map. Frequency Featured Station (kHz) Comments (compiled with the assistance of Wikipedia) 650 WSM, Nashville TN Since the 1930s, WSM has been home of the “Grand Ole Opry”, a legendary country music program. 720 WGN, Chicago IL Long time broadcaster of Chicago Cubs baseball; a major source of agriculture news; one‐time Mutual Broadcasting System affiliate. 770 WABC, New York NY From 1960‐1982, WABC brought “top‐40” popular music to the eastern U.S. and beyond. 800 XEROK, Ciudad Juarez, CH A 150 kW “border blaster”. 850 KOA, Denver CO KOA is frequently heard in northern Europe, Australia and Japan, and is one of the most frequently reported stations worldwide. 870 WWL, New Orleans LA 890 WLS, Chicago IL A critical communications asset in the hurricane‐prone Gulf states; for a time, one of the few stations remaining on the air during Hurricane Katrina. “The Big 89” was a nighttime source of “top‐40” popular music, 1960‐ 1985. Earlier generations listened to the “National Barn Dance”, which ran from 1924 to 1952. 900 XEW, Mexico City DF 250 kW news/talk, one of the most powerful AM stations in North America. 990 CBW, Winnipeg MB Broadcasts CBC Radio One, the largest radio network in Canada. 1090 KAAY, Little Rock AR Another legendary rock‐‘n‐roll radio station. At night, “The Mighty Ten Ninety” reached much of the Great Plains, North Central, and mid‐ south regions of the United States. 1120 KMOX, St. Louis MO Broadcaster of St. Louis Cardinals baseball in the 1930s‐1940s and almost continuously since the 1950s.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 13 VII. CREATION AND SYMBOLIZATION OF QUERY TABLES The Geodatabase file containing the “master” edited data table from Section IV was imported into ArcMap. Now, groups of stations selected by frequency had to be pulled from the table. This was done in ArcToolbox by using Data Management Tools > Layers and Tables Views > Make Query Table. · Input Table: AM_Master · Fields: All selected · The expression “freq” = ### AND “day” = 0 was used to select stations by frequency and to select only their nighttime operating profile. · Tables were named for the frequency chosen. Eleven tables were created for the frequencies listed in Section VI. · A unique Key Field was selected to ensure a unique Primary Key existed to identify each record. This would be required in the process for creating buffers around selected features. To display records from the query tables, map layers were created by right‐clicking on the table and selecting the Display XY Data tool (right). · Values for the X (longitude) and Y (latitude) fields were entered. · One of the NAD27 Geographic Coordinate Systems was selected. This is the coordinate system used in the FCC database.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 14 Query Tables were individually symbolized under Quantities > Graduated Symbols based on transmitter power (field: kw) and classified manually using the breaks outlined in Section V (figures below).
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 15 VIII. MAP CREATION & DESIGN REFINEMENTS All map elements were now symbolized and in place with all layers activated. The map could now be viewed in the context of its intended function: to enable users to identify a clear channel station, then look for nearest same‐frequency stations based on same‐color icons. The resulting view (above) showed too much clutter and confusion. Contrast with the graphic below displaying only 850 kHz, that dramatically shows no stations within an 800‐mile radius of KOA in Denver. single‐frequency display, 850 kHz
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 16 7 Once again, the issue of “too many data classes” described by Brewer (Section IV) was considered, and a number of design refinements were made to eliminate distraction and improve clarity: The symbols indicating clear channel stations were given a yellow “halo” to make them more distinctive (right). The symbol indicating the lowest class of transmitter power (< 1 kW) was changed from a half‐color circle (below, right) to a no‐border triangle (below, left) to decrease visual weight and to give these stations a lower visual priority. One by one, station frequency sets were added to the map to see how the points interacted. In some areas, symbolization looked more like confetti, particularly in Mexico (below). As display of Mexico stations was a secondary consideration, this was not deemed to be a problem. In the eastern United States, there were numerous symbols for low‐power stations on 800 and 900 kHz, a condition caused by the massive reach of the high‐power Mexican stations plus a clear‐channel on 900 kHz in Ontario, Canada. The limits to power of U.S. stations on these frequencies was valuable information, a major cause‐and‐effect ‐‐ however, all of the small points served to overpower symbols for stations on other frequencies and reduced the effectiveness of the entire map. As a result, the 900 kHz point layer was removed. The 800 kHz layer showing effects of the “border blaster” station in Juarez, Mexico would be sufficient to illustrate this condition. Two other frequencies, 890 kHz and 990 kHz were also eliminated. Design proceeded with a total of eight frequency groups to display. "confetti" in Mexico
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 17 Attention now turned to labeling. With several event layers turned on, labels indicating station call sign and city were applied to map points. As a result, labeling in this phase was limited to clear channels only, with a power of 50kW or greater. In the Label Properties dialog (below): · · · · “Label features in this layer” was checked “Define classes of features and label each class differently” was selected from the dropdown. A new class called “50” was created, with a SQL Query of "AM_Master.kw" > 49 The text string was set to: [AM_Master.call] +" / " + [AM_Master.city] to produce a label like: WWL / NEW ORLEANS
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 18 Some radio stations were symbolized and labeled twice because of multiple records covering various aspects of nighttime operation. These problems could be solved by deleting records, but to preserve the integrity of the database, changes were made to the yes/no field for “label” or “display” (these added fields previously described in Section IV. ‐ 5b). To make use of these field changes, definition queries were added to Layer Properties: only those records where the label or display field was “1” (yes) would display. It was determined that non‐clear channels could be labeled with their call signs only, rather than the call sign + city labeling used for clear channels. This step increased the amount of information conveyed by the map and added more color and character. The presence of different colors of text made it easier to find stations on the same frequency. The font was light enough in weight to not detract from the overall look. 8 As noted in the class textbook , preferred locations for labels are to the right of their points. Placement properties for each group were set accordingly.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 19 To provide a contextual reference for the service area of a clear channel radio stations, a 750‐mile dashed circle was drawn around KOA/Denver using the buffer tool.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 20 IX. ADDITIONAL MAP ELEMENTS To simplify the process of symbolizing categories for the legend, two special tables were created for frequency and transmitter power values. Fake layers were created from these tables and symbols using Categories > Unique Values. A spectral color scheme was selected for frequencies as we are, indeed, dealing with a frequency spectrum. However, spacing was left between color tiles because we are symbolizing discrete and non‐contiguous frequencies along the spectrum. Use of the tan and gray colors at the upper end is somewhat consistent with color coding used in solid state electronics, except that black and brown are used to represent lower‐end number values. Spectral color coding used to indicate specifications on solid state electronic components. Photo: www.circuitstoday.com
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 21 Interpretive text was developed and added to the map. Interpretive Content ‐ Table 1 of 2
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 22 Interpretive Content ‐ Table 2 of 2
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 23 X. REQUIRED ELEMENTS CHECKLIST The final design step was to add required design elements: Map Title – At top of page. Map Scale – Lower left of map area below the legend. Map Orientation – Graticule with lat/long shown on outside edge of map area. Legend – Lower left corner of map area. Source Citations – Lower left corner of page and inside the “Featured Stations” box below the interpretive text. Neatlines – One around the map area, one surrounding all map elements. Artist Name – Lower right corner of page.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 24 XI. CONCLUSIONS As a former broadcaster, it was very interesting and a bit surprising to see clear channels mapped out. Here’s what I took away from the map: · Clear channel stations truly dominate the nighttime airwaves and the band is otherwise more “sparse” than I had imagined. I was genuinely surprised to see the distance between the 50+ kw dominant stations and the closest stations on the same frequency. · The band plan developed in 1934 and later codified by international treaty is finely coordinated. · I gained a real understanding of the role of low‐power (1 kW or less) stations at night. They provide small and very limited “islands” of local reception in the much larger ocean of clear channel signals. · The “island” effect was especially pronounced on frequencies occupied by Mexican stations broadcasting at 150 kW and 250 kW, 3 to 5 times more powerful than the 50 kW maximum allowed in the United States. The signals of 150 kW “border blaster” XEROK (just south of El Paso, Texas) and 250 kW XEW in Mexico City hold virtually all nighttime AM broadcasting on 800 and 900 kHz in the United States to 1 kW or less east of the Rocky Mountains. This also creates a buffer that allows two Canadian channels, in Hamilton/Toronto and Windsor, ON to operate on these frequencies. West of the Rocky Mountains, an extremely low number of stations operate on 800 & 900 kHz in the US and Canada. · The map does not show daytime‐only stations that leave the air at local sunset to protect clear channel signals. However, only a small number of stations are in this class, and the FCC stopped authorizing new 1 daytime‐only stations in 1987 . · The map does not account for clear channels that operate with a directional (rather than an omnidirectional) signal pattern (see KAAY example on page 3) in order to protect other clear channels. This third parameter could be symbolized, but would add little value to the map. · An electronic version of this map consisting of “layers” would be very effective. Layers could be turned off and on independently to allow users to compare and draw their own conclusions. Groups of frequencies could be turned on with some kind of accompanying text offering analysis. Animated clips with narrated audio would also be very effective. · An electronic or otherwise interactive program could allow users to enter the call sign (e.g. KFEQ) or city/frequency pair (Chicago / 890) of a favorite station so they could see it in relation to other stations on the same frequency.
©2011, Jeffrey K. Herzer / www.jeffherzer.com Page 25 XII. RESEARCH SOURCES 1 ‐ “Why AM Radio Stations Must Reduce Power, Change Operations, or Cease Operations at Night” Author: Federal Communications Commission URL: http://www.fcc.gov/mb/audio/bickel/daytime.html 2 ‐ The ARRL Antenna Book, 14th Edition The American Radio Relay League, 1984 ISBN: 0‐87259‐414‐9 3 ‐ “History”, “Day Coverage”, “Night Coverage” Author: Citadel Broadcasting Company and Media Span (copyright 2011) URL: http://www.1090kaay.com 4 ‐ AMQ AM Radio Database Query Page Author: Federal Communications Commission URL: http://www.fcc.gov/mb/audio/amq.html 5 – “ How to convert degrees/minutes/seconds angles to or from decimal angles in Excel 2000“ URL: http://support.microsoft.com/kb/213449/en‐us 6 – “ Problem: Microsoft Office 2007 Excel does not allow tables to be saved as .dbf format” ArcGIS Resource Center ‐ ESRI URL: http://resources.arcgis.com/content/kbase?fa=articleShow&d=34102 7 ‐ ColorBrewer 2.0 Author: Cynthia Brewer, Mark Harrower and The Pennsylvania State University http://colorbrewer2.org/ 8 – “Thematic Cartography and Geovisualization”, Third Edition Terry A. Slocum, Robert B. McMaster, Fritz C. Kessler and Hugh H. Howard Pearson Prentice Hall, 2009 ISBN 978‐0‐13‐229834‐6 * * * * *
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