Field Report: V-Soft AM-Pro

The Technical Research Department at Salem Communications has been providing research on potential station acquisitions to the company's leadership since 1994. Although there are many software options for evaluating FM stations, there are few software packages to evaluate AM stations. AM-Pro is perhaps the newest package available, and it is proving to be one of the best.

Performance at a glance
Performs all AM studies
Applies M3 or R2 data as needed
Creates atlas-style maps
Plots ground-wave and skywave contours
Performs RSS studies
Analyzes skywave coverage
User-selectable control

Introduced about a year ago, AM-Pro is a broadcast coverage and allocation software tool offered by V-Soft Communications.

Evaluating an AM station's existing coverage and allocation constraints requires an understanding of FCC rules, agreements, treaties, policies and procedural exceptions. With that understanding, engineers need a powerful tool to quickly cut through the mathematics and propagation predictions. AM-Pro is such a tool.

What it does

AM-Pro is a multifunction module that guides the user through AM station coverage and allocation evaluations for any AM station in the United States.

Like all of V-Soft's software, AM-Pro automatically integrates records out of the FCC database (actually the FCC data is crunched into a file AM-Pro uses, which may be downloaded periodically from the V-Soft website). It also obtains data from an M3 conductivity database, the U.S. Census database and the USGS Polygon and Tiger Map databases to create accurate coverage plots and potential audience population data.

An Atlas-style coverage map with labeled contours and pop counts.
How it works

The program begins by providing the user with five options: AM Coverage Study; AM Daytime Allocation Study; Single Station RSS Study; AM Night Allocation Study (skywave/RSS); and AM Night Allocation (groundwave — using daytime rules).

To create an AM station coverage map, select the station record using the software's menus. A detailed, atlas-style map pops up, showing the station's transmitter site. From there select any contour value desired (groundwave or skywave) and have it plotted on the map. A distance to contour file (.DTC file) can also be produced that may be used in other software modules. The user may literally produce a coverage map showing a daytime and a nighttime coverage contour for a particular station in less than a minute.

Unlike FM coverage plots, where you can use the same contours 24 hours a day to show coverage, AM coverage plots vary between the daytime and the nighttime hours, often dramatically. The single biggest handicap many brokers, owners and station engineers face in making a nighttime coverage map is defining nighttime interference free (NIF) contour value. It is a different value for each AM station. The FCC defines this value through a root sum square calculation that can be confusing. With AM-Pro, a Single Station RSS Study can also be done quickly. Simply pull up the nighttime record for the station under study, make sure the study defaults are set up (e.g., FCC 1992 Skywave Rules, 10 percent or 50 percent time, and whether or not you want first-adjacent stations considered), and hit OK. On my computer it takes less than 1 second to get a nice table screen full of data, including the 50 percent IFRSS NIF contour value. Because this value can vary from as little as 2mV/m or 3mV/m to as much as 40mV/m or 50mV/m, knowing the value is important before trying to predict a particular station's night coverage area. Note that accuracy depends on the user's understanding of FCC procedures and of how to properly cull out the potential interfering database records.

The Nighttime module’s pattern evaluation routine allows users to study protected station limits.

AM-Pro lets the user determine how a study will be done. Users can clip contours at the ocean, include every Class A regardless of distance, select the number of points per contour, automatically remove pending applications, and remove U.S. stations with a blank domestic status. The Daytime Allocation study quickly brings up a map showing co- and adjacent-channel protected/interfering stations and a table that provides direct access to the FCC database information for each station. In addition to changing the database information in your study, you can also pull up a pattern editor for any station and change its parameters to immediately see the pattern changes on the screen. The Nighttime Allocation Study modules do all of this in addition to providing skywave evaluation calculations. Once executed, the nighttime modules quickly bring up a table of all pertinent AM station database records for the U.S. and International stations. The user can select, adjust, add or delete any records to the study as desired. Both the daytime and nighttime study modules provide tables with radiation limits.


One of the best features of AM-Pro is its Nighttime Study module's pattern evaluation routine. After doing a nighttime study the user can push a button marked “pattern” and instantly pull up a circular plot with marks showing all of the protected station limits around the pattern. The marks are green if the existing pattern toward the protected station has a radiation value less than the limit, and red if the radiation exceeds the limit (the user can adjust or manipulate things like augmented pattern data and measured conductivity data).

Gluck is the vice president of technical research for Salem Communications, Camarillo, CA.

Editor's note: Field Reports are an exclusive Radio magazine feature for radio broadcasters. Each report is prepared by well-qualified staff at a radio station, production facility or consulting company.

These reports are performed by the industry, for the industry. Manufacturer support is limited to providing loan equipment and to aiding the author if requested.

It is the responsibility of Radio magazine to publish the results of any device tested, positive or negative. No report should be considered an endorsement or disapproval by Radio magazine.

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