October 28, 2020, the Commission released a Report and Order (“R&O”) authorizing AM radio stations to transition to an all-digital signal on a voluntary basis. This item was adopted during the October Open Meeting (MB Docket No. 19-311; MB Docket No. 13-249).
Specifically, the R&O adopts rules to allow AM radio stations – at their discretion – to broadcast an all-digital signal using the HD Radio in-band on-channel (“IBOC”) mode named MA3, and rejects proposals to mandate that some or all AM stations continue broadcasting in analog. The R&O recognizes benefits of digital broadcasting, including improved audio quality and coverage, as well as energy and spectrum efficiencies, but also references that broadcasters should take into account the cost of conversion (which it anticipates will be minimal) and access to digital receivers, when determining whether to convert to all-digital. Accordingly, the Commission anticipates that “while some broadcasters may be prepared for immediate conversion, many broadcasters may choose to postpone all-digital conversion based on their own circumstances and the readiness of their market.” (¶ 17).
Operating and Technical Rules
Nominal Power Limits. The Commission adopts Nautel’s proposal to use the average power of the all-digital signal, including the unmodulated analog carrier power and all of the digital sidebands, to determine whether the station is complying with the nominal power limits in section 73.21 of the Commission’s rules. The Commission finds that this approach is technically feasible will enable more stations to use existing transmitters for all-digital operations, and will result in a lower operating power for all digital stations, thereby decreasing interference risks.
Digital Spectral Emissions Limits. The Commission applies the emissions mask set forth in section 73.44 for all-digital operations, which limits special emissions outside a bandwidth of 20 kHz to the point where they do not cause significant adjacent channel interference.
Power Measurements. The R&O affords all-digital licensees the flexibility to choose any reliable and reasonably accurate method to measure their compliance with the Commission’s operating power and power spectral density rules.
Free Audio Stream Requirement. Each all-digital station is obligated to provide at least one free over-the-air digital programming stream that is comparable to or better in audio quality than a standard analog broadcast. Beyond this requirement, an all-digital licensee can use its additional digital bitrate capacity for either broadcast or non-broadcast services consistent with the Commission’s technical rules. Each AM broadcaster can select either core-only or enhanced mode transmission as their particular situation requires.
Carrier Frequency Tolerance Standard & NRSC-5-D Standard. The R&O adopts the same carrier frequency tolerance applicable to analog and hybrid stations (±20 Hz) for all-digital AM stations. The R&O declines to incorporate the NRSC-5-D standard into the Commission’s rules, as proposed in the NPRM.
Prohibited Interference & Remediation. All-digital operations must not cause prohibited interference to other broadcast stations. The R&O adopts a streamlined remediation procedure in the event that prohibited interference does occur. The Commission expects that AM all-digital operators and complaining stations will work together to identify whether interference exists and to resolve interference complaints together.
Operation Timing & EAS Obligations. The Commission determines that all-digital operation should be permitted at both day and night. The R&O also confirms that all-digital AM licensees are obligated to participate in the national Emergency Alert System (“EAS”) and should provide emergency alerts.
Notification of All-Digital Operations.
- The R&O adopts a modified version of the current digital notification procedure for all-digital stations by adding a 30-day waiting period for certain operational changes. Licensees should electronically file a digital notifications to notify the Commission of: (1) the commencement of new all-digital operation; (2) an increase in nominal power of an all-digital AM station; or (3) a transition from core-only to enhanced operating mode. The notifications will be placed on a Commission public notice and new operation may begin no sooner than 30 calendar days from the date of the public notice.
- Digital notification must be submitted within ten days of implementing all other changes including: (1) any reduction in nominal power of an all-digital AM station; (2) a transition from enhanced to core-only operating mode; or (3) a reversion from all-digital to hybrid or analog operation.
- The AM station must also give its listeners reasonable notice before it converts to all-digital operations and will no longer be available on analog receivers. The Commission provides broadcasters flexibility to use reasonable methods intended to reach their audience, including on-air and website announcements, but also explains that it would consider it presumptively sufficient if the broadcaster provided at least the same amount of notice that is set out in the local public notice rule in section 73.3580.