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EIBASS Petition Regarding use of Codecs in the BAS Service

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Released: February 20, 2013
Federal Communications Commission
Washington, D.C. 20554
February 20, 2013
DA 13-235
Engineers for the Integrity of
Broadcast Auxiliary Services Spectrum (EIBASS)
18755 Park Tree Lane
Sonoma, CA 95476
Attention:
Dane E. Ericksen P.E., CSRTE, 8-VSB, CBNT
Richard A. Rudman, CPBE
Dear Mr. Ericksen and Mr. Rudman:
On March 11, 2012, Engineers for the Integrity of Broadcast Auxiliary Services
Spectrum (EIBASS) filed a request for declaratory ruling pursuant to Section 1.2 of the
Commission’s rules, regarding the use of certain equipment by television Broadcast Auxiliary
Service (BAS) operators.1 In its Request, EIBASS asks Commission staff to confirm that it is
permissible for a TV BAS station licensed with an analog emission designator to install an
encoder-decoder (codec) that allows a microwave radio to pass an asynchronous serial interface
(ASI) digital signal without having to modify the license to change the emission designator. By
this letter, we clarify that installation and use of a codec in this manner is permissible without a
license modification.
Section 2.201 of the Commission’s Rules specifies the elements that define an emission
designator.2 The first symbol of the emission designator indicates the type of modulation of the
main carrier, the second symbol indicates the nature of the signal modulating the main carrier,
and the third symbol indicates the type of information to be transmitted.3 The second symbol can
consist of a variety of different configurations (e.g., single channel containing analog information,
a single channel containing quantized or digital information, etc.). Analog emissions are
characterized by either a 3 or 8 in the second character of the emission.4 Digital emissions are
characterized by a 1, 2, 7, or 9 in the second character of the emission.5 Section 1.915 and 1.929
describe when an application to modify a station must be filed, and what constitutes a major or
minor modification.6

1 See Request for Declaratory Ruling, EIBASS (filed March 11, 2012) (EIBASS Request).
2 See 47 CFR§ 2.201.
3 See 47 CFR § 2.201(b).
4 See 47 CFR § 2.201(d).
5 See Id.
6See 47 CFR § 1.915 and 1.929.

EIBASS states that there are many TV stations that have existing TV studio-to-
transmitter (STL) or Inter City Relay (ICR) microwave links licensed for 25M0F8W FM analog
video emission.7 For these analog stations, a cost effective way to carry a digital signal across an
existing analog link is to use a codec pair. However, EIBASS indicates that there is regulatory
uncertainty within the broadcast industry as to whether the use of codecs would require a BAS
licensee to file a modification application to change emission designators to reflect the
transmission of ASI data.8
EIBASS states that using codecs with analog radios simply applies the digital bit stream
to the baseband input of the FM (analog) microwave transmitter, so that the transmitted signal
still employs frequency modulation of the microwave carrier. In support of its position, EIBASS
submitted figures comparing the spectra of a conventional FM video signal with the signal from
an FM video transmitter using codecs to demonstrate that they both have the signature
“triangular” spectral shape associated with an analog transmission as opposed to the “rectangular”
spectral shape seen when using QAM or COFDM.9
After careful review of the issues and the information submitted, we find that when a
transmitted emission continues to be frequency modulated and is contained within the bandwidth
limits specified for frequency modulation, and when there are no modifications to transmitter
circuitry, a change in the emission designator is not necessary. Therefore, we agree with EIBASS
that it is not necessary for a licensee to modify its license to reflect a change in the emission
designator in the circumstances described above.
Accordingly, EIBASS’s request for declaratory ruling IS GRANTED to the extent
indicated herein.
This action is taken under delegated authority pursuant to Sections 0.131 and 0.331 of the
Commission’s rules, 47 C.F.R. §§ 0.131, 0.331, and 1.2.
FEDERAL COMMUNICATIONS COMMISSION
Stephen Buenzow
Deputy Chief
Broadband Division
Wireless Telecommunications Bureau

7 See EIBASS Request at 1
8 See EIBASS Request at 2
9 See Id.

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