Sec.  21.908   Transmitting equipment.

   

   (a) Except as otherwise provided in this section, the requirements of
   paragraphs (a), (b), (c), (d), and (e) of Sec. 73.687 of this chapter
   shall apply to stations in this service transmitting standard
   television signals.

   Editorial Note:   At  63 FR 65104 , Nov. 25, 1999, paragraph (b) was
   redesignated as paragraph (a) and newly designated paragraph (a) was
   revised. However, paragraph (a) already exists. The text of the newly
   redesignated paragraph (a) follows:

   (a) The maximum out-of-band power of an MDS station transmitter or
   booster transmitting on a single 6 MHz channel with an EIRP in excess
   of -9 dBW employing analog modulation shall be attenuated at the
   channel edges by at least 38 dB relative to the peak visual carrier,
   then linearly sloping from that level to at least 60 dB of attenuation
   at 1 MHz below the lower band edge and 0.5 MHz above the upper band
   edge, and attenuated at least 60 dB at all other frequencies. The
   maximum out-of-band power of an MDS station transmitter or booster
   transmitting on a single 6 MHz channel or a portion thereof with an
   EIRP in excess of -9 dBW (or, when subchannels are used, the
   appropriately adjusted value based upon the ratio of the
   channel-to-subchannel bandwidths) employing digital modulation shall
   be attenuated at the 6 MHz channel edges at least 25 dB relative to
   the licensed average 6 MHz channel power level, then attenuated along
   a linear slope to at least 40 dB at 250 kHz beyond the nearest channel
   edge, then attenuated along a linear slope from that level to at least
   60 dB at 3 MHz above the upper and below the lower licensed channel
   edges, and attenuated at least 60 dB at all other frequencies.
   Notwithstanding the foregoing, in situations where an MDS station or
   booster station transmits, or where adjacent channel licensees jointly
   transmit, a single signal over more than one contiguous 6 MHz channel
   utilizing digital modulation with an EIRP in excess of -9 dBW (or,
   when subchannels or superchannels are used, the appropriately adjusted
   value based upon the ratio of 6 MHz to the subchannel or superchannel
   bandwidth), the maximum out-of-band power shall be attenuated at the
   channel edges of those combined channels at least 25 dB relative to
   the power level of each channel, then attenuated along a linear slope
   from that level to at least 40 dB at 250 kHz above or below the
   channel edges of those combined channels, then attenuated along a
   linear slope from that level to at least 60 dB at 3 MHz above the
   upper and below the lower edges of those combined channels, and
   attenuated at least 60 dB at all other frequencies. However, should
   harmful interference occur as a result of emissions outside the
   assigned channel, additional attenuation may be required. A
   transmitter licensed prior to November 1, 1991, that remains at the
   station site initially licensed, and does not comply with this
   paragraph, may continue to be used for its life if it does not cause
   harmful interference to the operation of any other licensee. Any
   non-conforming transmitter replaced after November 1, 1991, must be
   replaced by a transmitter meeting the requirements of this paragraph.

   (b) A booster transmitting on multiple contiguous or non-contiguous
   channels carrying separate signals (a "broadband" booster) with an
   EIRP in excess of -9 dBW per 6 MHz channel and employing analog,
   digital or a combination of these modulations shall have the following
   characteristics:

   (1) For broadband boosters operating in the frequency range of
   2.150-2.160/2 GHz, the maximum out-of-band power shall be attenuated
   at the upper and lower channel edges forming the band edges by at
   least 25 dB relative to the licensed analog peak visual carrier or
   digital average power level (or, when subchannels are used, the
   appropriately adjusted value based on upon the ratio of the
   channel-to-subchannel bandwidths), then linearly sloping from that
   level to at least 40 dB of attenuation at 0.25 MHz above and below the
   band edges, then linearly sloping from that level to at least 60 dB of
   attenuation at 3.0 MHz above and below the band edges, and attenuated
   at least 60 dB at all other frequencies.

   (2) For broadband boosters operating in the frequency range of
   2.500-2.690 GHz, the maximum out-of-band power shall be attenuated at
   the upper and lower channel edges forming the band edges by at least
   25 dB relative to the licensed analog peak visual carrier or digital
   average power level (or, when subchannels are used, the appropriately
   adjusted value based on upon the ratio of the channel-to-subchannel
   bandwidths), then linearly sloping from that level to at least 40 dB
   of attenuation at 0.25 MHz above and below the band edges, then
   linearly sloping from that level to at least 50 dB of attenuation at
   3.0 MHz above and below the band edges, then linearly sloping from
   that level to at least 60 dB of attenuation at 20 MHz above and below
   the band edges, and attenuated at least 60 dB at all other
   frequencies.

   (3) Within unoccupied channels in the frequency range of 2.500-2.690
   GHz, the maximum out-of-band power shall be attenuated at the upper
   and lower channel edges of an unoccupied channel by at least 25 dB
   relative to the licensed analog peak visual carrier power level or
   digital average power level of the occupied channels (or, when
   subchannels or 125 kHz channels are used, the appropriately adjusted
   value based upon the ratio of the channel-to-subchannel bandwidths),
   then linearly sloping from that level to at least 40 dB of attenuation
   at 0.25 MHz above and below the occupied channel edges, then linearly
   sloping from that level to at least 50 dB of attenuation at 3.0 MHz
   above and below the occupied channel edges, and attenuated at least 50
   dB at all other unoccupied frequencies.

   (c) Boosters operating with an EIRP less than -9 dBW per 6 MHz channel
   shall have no particular out-of-band power attenuation requirement,
   except that if they cause harmful interference, their operation shall
   be terminated within 2 hours of notification by the Commission until
   the interference can be cured.

   (d) The maximum out-of-band power of an MDS response station using all
   or part of a 6 MHz channel, employing digital modulation and
   transmitting with an EIRP greater than -6 dBW per 6 MHz channel shall
   be attenuated (as measured in accordance with paragraph (e) of this
   section) at the 6 MHz channel edges at least 25 dB relative to the
   average 6 MHz channel power level, then attenuated along a linear
   slope to at least 40 dB at 250 kHz beyond the nearest channel edge,
   then attenuated along a linear slope from that level to at least 60 dB
   at 3 MHz above the upper and below the lower licensed channel edges,
   and attenuated at least 60 dB at all other frequencies. The maximum
   out-of-band power of an MDS response station using all or part of a 6
   MHz channel, employing digital modulation and transmitting with an
   EIRP no greater than -6 dBW per 6 MHz channel shall be attenuated (as
   measured in accordance with paragraph (e) of this section) at the
   channel edges at least 25 dB relative to the average 6 MHz channel
   transmitter output power level (P), then attenuated along a linear
   slope to at least 40 dB or 33+10log(P) dB, whichever is the lesser
   attenuation, at 250 kHz beyond the nearest channel edge, then
   attenuated along a linear slope from that level to at least 60 dB or
   43+10log(P) dB, whichever is the lesser attenuation, at 3 MHz above
   the upper and below the lower licensed channel edges, and attenuated
   at least 60 dB or 43+10log(P) dB, whichever is the lesser attenuation,
   at all other frequencies. Where MDS response stations with digital
   modulation utilize all or part of more than one contiguous 6 MHz
   channel to form a larger channel (e.g., a channel of width 12 MHz),
   the above-specified attenuations shall be applied only at the upper
   and lower edges of the overall combined channel. Notwithstanding these
   provisions, should harmful interference occur as a result of emissions
   outside the assigned channel(s), additional attenuation may be
   required by the Commission.

   (e) In measuring compliance with the out-of-band emissions
   limitations, the licensee shall employ one of two methods in each
   instance: (1) absolute power measurement of the average signal power
   with one instrument, with measurement of the spectral attenuation on a
   separate instrument; or (2) relative measurement of both the average
   power and the spectral attenuation on a single instrument. The formula
   for absolute power measurements is to be used when the average signal
   power is found using a separate instrument, such as a power meter; the
   formula gives the amount by which the measured power value is to be
   attenuated to find the absolute power value to be used on the spectrum
   analyzer or equivalent instrument at the spectral point of concern.
   The formula for relative power measurements is to be used when the
   average signal power is found using the same instrument as used to
   measure the attenuation at the specified spectral points, and allows
   different resolution bandwidths to be applied to the two parts of the
   measurement; the formula gives the required amplitude separation (in
   dB) between the flat top of the (digital) signal and the point of
   concern.

   For absolute power measurements:

   Attenuation in dB (below channel power) = A + 10[log] (C[BW] / R[Bw])

   For relative power measurements:

   Attenuation in dB (below flat top) = A + 10[log] (R[BW1] / R[BW2])

   Where:

   A = Attenuation specified for spectral point (e.g., 25, 35, 40, 60 dB)

   C[BW] = Channel bandwidth (for absolute power measurements)

   R[BW] = Resolution bandwidth (for absolute power measurements)

   R[BW1] = Resolution bandwidth for flat top measurement (relative)

   R[BW2] = Resolution bandwidth for spectral point measurement
   (relative)

   [ 55 FR 46011 , Oct. 31, 1990, as amended at  56 FR 57818 , Nov. 14, 1991;
    63 FR 65105 , Nov. 25, 1998;  65 FR 46617 , July 31, 2000]