Applying for FM Digital Power Operation
   Digital Maximum ERP Calculator for Superpowered FM Stations
   Procedure for Filing STA Requests for Increased FM Digital Power

Applying for FM Digital Power Operation

The January 29, 2010 Order, in MM Docket 99-325PDF | Word ], authorized a general power increase for FM digital operations.  In sum, most FM broadcast stations can obtain authority to operate with a digital effective radiated power (ERP) up to 10% of the authorized analog ERP.  Details of how to calculate the maximum permissible digital ERP are found in the Order.

FM stations operating with ERP and antenna height above average terrain (HAAT) combinations that fall within the station's class may operate with up to 4% of the authorized analog ERP without prior authority from the Commission.  However, the station MUST electronically file a digital notification in the Commission's CDBS filing system within 10 days of commencing such operation.  Operation with digital ERP between 4% and 10% of the authorized analog ERP may only commence after the Commission has granted authority for such operation.  Requests for increased digital ERP may be filed electronically in the CDBS system.

Digital ERP Calculator for Superpowered FM Stations

Stations operating with facilities in excess of the station's class ("super-powered stations") have different permissible digital ERP limits and different filing requirements for increased digital ERP.  For these stations, digital ERP is limited to 10% of the ERP which, for the station's antenna height, would produce a 60 dBu (1 mV/m) contour distance equivalent to the reference facilities for the station's class (see Section 73.211(b) of the Commission's rules).  In addition, for a few stations operating with very high ERP values, the digital ERP may be further limited to 1% of the station's analog ERP.  We have provided the calculator below to compute the maximum permissible digital ERP for these stations.  Super-powered stations must request authority from the Commission for any increase in digital ERP above 1% of the currently authorized analog ERP, via Special Temporary Authority (STA), or by informal request in CDBS.

You must enter both the Call Sign and the corresponding Facility ID number before submitting this form.
Call Sign: (-FM or -LP not required)
Facility ID Number: (must be exact)

        Results appear in the box below


* No list is available of stations operating with facilities in excess of station class.
Calculations are made based on current station data.

Procedure for Filing STA Requests for Increased FM Digital Power

For your convenience, print these instructions and collect the necessary data before you file the STA request.  Questions may be directed to Arthur, 202-418-2754.

STA requests for increased FM digital power, pursuant to the Media Bureau’s January 29, 2010, Order in MM Docket 99-325, should be filed electronically via the Media Bureau's CDBS system  Please have the station's account information before you begin.

  1. On the main e-filing forms page, scroll to the bottom and select the link to Additional Non-form Filings and select Engineering STA.
  2. Item 3, select Engineering STA.
  3. Item 4, Service, enter “FM”.
  4. Complete Items 5 and 6 as appropriate.
  5. Item 7.0, select Licensed Antenna System with Other Variance.
  6. Do Not complete Items 7.1 through 7.10.
  7. Complete Item 7.11 as appropriate.
  8. Item 8 should reference the attached narrative exhibit (See below).
  9. Complete Item 9 and the certifications as appropriate.
  10. Attach a narrative exhibit with the following information:
    • The amount of digital power requested, expressed as a percentage of analog effective radiated power (“ERP”), or in decibels relative to analog carrier ERP (“dBc”).  Most requests will be for 4 percent of analog ERP, or 14 dB below analog ERP; i.e., -14 dBc.  If requesting greater power (up to a maximum of 10 percent of analog ERP (-10 dBc), a showing of eligibility must be made.  See Paragraph 20 of the Order.  Also, super-powered FM stations have additional eligibility requirements.  See Paragraph 15 of the Order.
    • Technical contact information; i.e., the name and telephone number of the person responsible for the station’s technical operation, for use in the event of an interference problem.
    • The type of digital operation proposed; for example, low-level combined, high-level combined, dual antenna, dual feed.  If dual antenna operation is proposed, the license file number, geographic coordinates and elevation data for the licensed auxiliary antenna to be used for the digital signal.  Also, if interleaved antenna bays are employed, a certification that sufficient filtering equipment has been installed to reduce spurious emissions below the level required by Section 73.317.
    • The analog, digital and, if appropriate, combined transmitter power outputs for the proposed operation, taking into account all system losses and antenna gains.
    • A certification that, with the exception of the digital power level requested, the proposed digital operation will comply with the technical specifications set forth in Appendix B of the First Report and Order in MM Docket No. 99-325.

Additional information about FM broadcast radio stations is available at the Audio Division on the FCC's website, and at Broadcast Radio Links.

FCC > Media Bureau > Audio Division, (202) 418-2706.


Wednesday, June 30, 2021