§ 15.115   TV interface devices, including cable system terminal devices.

   (a) Measurements of the radiated emissions of a TV interface device shall be
   conducted  with  the  output terminal(s) of the device terminated by a
   resistance equal to the rated output impedance. The emanations of a TV
   interface device incorporating an intentional radiator shall not exceed the
   limits in § 15.109 or subpart C of this part, whichever is higher for each
   frequency. Where it is possible to determine which portion of the device is
   contributing a particular radio frequency emission, the emissions from the
   TV  interface  device portion shall comply with the emission limits in
   § 15.109, and the emissions from the intentional radiator shall comply with
   subpart C of this part.

   (b) Output signal limits:

   (1)  At  any  RF output terminal, the maximum measured RMS voltage, in
   microvolts, corresponding to the peak envelope power of the modulated signal
   during maximum amplitude peaks across a resistance (R in ohms) matching the
   rated output impedance of the TV interface device, shall not exceed the
   following:

   (i) For a cable system terminal device or a TV interface device used with a
   master antenna, 692.8 times the square root of (R) for the video signal and
   155 times the square root of (R) for the audio signal.

   (ii) For all other TV interface devices, 346.4 times the square root of (R)
   for the video signal and 77.5 times the square root of (R) for the audio
   signal.

   (2)  At  any  RF output terminal, the maximum measured RMS voltage, in
   microvolts, corresponding to the peak envelope power of the modulated signal
   during maximum amplitude peaks across a resistance (R in ohms) matching the
   rated output impedance of the TV interface device, of any emission appearing
   on frequencies removed by more than 4.6 MHz below or 7.4 MHz above the video
   carrier frequency on which the TV interface device is operated shall not
   exceed the following:

   (i) For a cable system terminal device or a TV interface device used with a
   master antenna, 692.8 times the square root of (R).

   (ii) For all other TV interface devices, 10.95 times the square root of (R).

   (3) The term master antenna used in this section refers to TV interface
   devices employed for central distribution of television or other video
   signals within a building. Such TV interface devices must be designed to:

   (i) Distribute multiple television signals at the same time;

   (ii) Distribute such signals by cable to outlets or TV receivers in multiple
   rooms in the building in which the TV interface devices are installed; and,

   (iii) Distribute all over-the-air or cable signals.

   Note: Cable-ready video cassette recorders continue to be subject to the
   provisions for general TV interface devices.

   (c) A TV interface device shall be equipped with a transfer switch for
   connecting the antenna terminals of a receiver selectively either to the
   receiving antenna or to the radio frequency output of the TV interface
   device, subject to the following:

   (1) When measured in any of its set positions, transfer switches shall
   comply with the following requirements:

   (i) For a cable system terminal device or a TV interface device equipped for
   use with a cable system or a master antenna, as defined in paragraph (b)(3)
   of this section, the isolation between the antenna and cable input terminals
   shall be at least 80 dB from 54 MHz to 216 MHz, at least 60 dB from 216 MHz
   to 550 MHz and at least 55 dB from 550 MHz to 806 MHz. The 80 dB standard
   applies at 216 MHz and the 60 dB standard applies at 550 MHz. In the case of
   a transfer switch requiring a power source, the required isolation shall be
   maintained in the event the device is not connected to a power source or
   power is interrupted.

   (ii) For all other TV interface devices, the maximum voltage, corresponding
   to the peak envelope power of the modulated video signal during maximum
   amplitude peaks, in microvolts, appearing at the receiving antenna input
   terminals when terminated with a resistance (R in ohms) matching the rated
   impedance of the antenna input of the switch, shall not exceed 0.346 times
   the square root of (R).

   (iii) Measurement to determine compliance with the transfer switch limits
   shall be made using a connecting cable, where required, between the TV
   interface device and the transfer switch of the type and length:

   (A) Provided with the TV interface device,

   (B) Recommended in the instruction manual, or

   (C) Normally employed by the consumer.

   (2) A TV interface device shall be designed and constructed, to the extent
   practicable,  so  as to preclude the possibility that the consumer may
   inadvertently attach the output of the device to the receiving antenna, if
   any, without first going through the transfer switch.

   (3) A transfer switch is not required for a TV interface device that, when
   connected, results in the user no longer having any need to receive standard
   over-the-air broadcast signals via a separate antenna. A transfer switch is
   not required to be marketed with a cable system terminal device unless that
   device provides for the connection of an external antenna. A transfer switch
   is not required for a device that is intended to be used as an accessory to
   an authorized TV interface device.

   (4) An actual transfer switch is not required for a TV interface device,
   including  a  cable  system terminal device, that has an antenna input
   terminal(s); provided, the circuitry following the antenna input terminal(s)
   has sufficient bandwidth to allow the reception of all TV broadcast channels
   authorized under part 73 of this chapter and: For a cable system terminal
   device that can alternate between the reception of cable television service
   and an antenna, compliance with the isolation requirement specified in
   paragraph (c)(1)(i) of this section can be demonstrated; and, for all other
   TV  interface  devices,  the  maximum voltage appearing at the antenna
   terminal(s)  does not exceed the limit in paragraph (c)(1)(ii) of this
   section.

   (5) If a transfer switch is not required, the following label shall be used
   in addition to the label shown in § 15.19(a):

   This device is intended to be attached to a receiver that is not used to
   receive over-the-air broadcast signals. Connection of this device in any
   other fashion may cause harmful interference to radio communications and is
   in violation of the FCC Rules, part 15.

   (d) A TV interface device, including a cable system terminal device, shall
   incorporate circuitry to automatically prevent emanations from the device
   from exceeding the technical specifications in this part. These circuits
   shall be adequate to accomplish their functions when the TV interface device
   is presented, if applicable, with video input signal levels in the range of
   one to five volts; this requirement is not applicable to a TV interface
   device that uses a built-in signal source and has no provisions for the
   connection of an external signal source. For devices that contain provisions
   for an external signal source but do not contain provisions for the input of
   an external baseband signal, e.g., some cable system terminal devices,
   compliance with the provisions of this paragraph shall be demonstrated with
   a radio frequency input signal of 0 to 25 dBmV.

   (e) For cable system terminal devices and TV interface devices used with a
   master antenna, as defined in paragraph (b)(3) of this section, the holder
   of the grant of authorization shall specify in the instruction manual or
   pamphlet, if a manual is not provided, the types of wires or coaxial cables
   necessary to ensure that the unit complies with the requirements of this
   part.  The  holder  of the grant of authorization must comply with the
   provisions of § 15.27. For all other TV interface devices, the wires or
   coaxial cables used to couple the output signals to the TV receiver shall be
   provided by the responsible party.

   (f)  A  TV  interface device which is submitted to the Commission as a
   composite device in a single enclosure containing a RF modulator, video
   source  and  other  component  devices  shall be submitted on a single
   application (FCC Form 731) and shall be authorized as a single device.

   (g) An external device or accessory that is intended to be attached to a TV
   interface  device  shall  comply with the technical and administrative
   requirements set out in the rules under which it operates. For example, a
   personal  computer  must  be  certificated to show compliance with the
   regulations for digital devices.

   (h) Stand-alone switches used to alternate between cable service and an
   antenna  shall  provide  isolation between the antenna and cable input
   terminals that is at least 80 dB from 54 MHz to 216 MHz, at least 60 dB from
   216 MHz to 550 MHz and at least 55 dB from 550 MHz to 806 MHz. The 80 dB
   standard applies at 216 MHz and the 60 dB standard applies at 550 MHz. In
   the case of stand-alone switches requiring a power source, the required
   isolation shall be maintained in the event the device is not connected to a
   power source or power is interrupted.

   (i) Switches and other devices intended to be used to by-pass the processing
   circuitry of a cable system terminal device, whether internal to such a
   terminal device or a stand-alone unit, shall not attenuate the input signal
   more than 6 dB from 54 MHz to 550 MHz, or more than 8 dB from 550 MHz to 804
   MHz. The 6 dB standard applies at 550 MHz.

   [ 54 FR 17714 , Apr. 25, 1989, as amended at  57 FR 33448 , July 29, 1992;  59 FR 25341 , May 16, 1994;  61 FR 18509 , Apr. 26, 1996;  77 FR 4913 , Feb. 1, 2012]

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