Sec. 68.308 Signal power limitations.
(a) General. Limitation on signal power shall be met at the
interface for all 2-wire network ports, tip and ring conductors to PSDS
Types II and III, and, where applicable to services, both transmit and
receive pairs of all 4-wire network ports. Signal power measurements
will be made using terminations as specified in each of the following
limitations. The transmit and receive pairs of 4-wire network ports
shall be measured with the pair not under test connected to a
termination equivalent to that specified for the pair under test.
Through-gain limitations apply only in the direction of transmission to
the network.
(b) Voice band metallic signal power--(1) Limitations at the
interface on internal signal sources not intended for network control
signaling.
(i) For registered terminal equipment or registered protective
circuitry, connected to interfaces associated with services contained in
Sec. 68.2(a) (1), (2), and (7), other than data equipment or data
protective circuitry which is registered in accordance with
Sec. 68.308(b)(4), the maximum power of other than live voice signals
delivered to a loop simulator circuit shall not exceed-9dB with respect
to one milliwatt, when averaged over any 3-second interval. No
manufacturing tolerance is allowed which would permit this power to be
exceeded by any unit of equipment.
(ii) For tie trunk type interfaces, the maximum power of other than
live voice signals delivered to a 600 ohm termination shall not exceed
the following:
Maximum Power With Respect to One Milliwatt When Averaged Over Any 3-
Second Interval
------------------------------------------------------------------------
2-wire 4-wire Lossless 4-wire CTS (b)
------------------------------------------------------------------------
-15 dB(a)....................... -15 dB(a)......... -19 dB, nom.
------------------------------------------------------------------------
Notes: (a) The maximum signal power may be exceeded by as much as 1.0 dB
by a single unit of equipment or circuitry, provided that the power
averaged over all units of production, complies with the specified
limitations.
(b) The 4-Wire CTS shall meet the requirements for Tie Trunk
Transmission Interfaces as defined in Sec. 68.3.
(iii) For OPS lines, the maximum power of other than live voice
signals delivered to an OPS line simulator circuit shall not exceed -13
dB with respect to one milliwatt, when averaged over any 3-second
interval.
(iv) For AIOD channels, the maximum signal power delivered to an
AIOD data channel simulator circuit in each of the following operating
states shall not exceed -4 dB with respect to one milliwatt averaged
over any 3-second time interval:
------------------------------------------------------------------------
AIOD tip
Simulator circuit \1\ and ring
\2\
------------------------------------------------------------------------
1........................................................... -42.5-56.5
2........................................................... 0
3........................................................... 0
------------------------------------------------------------------------
\1\ Operating state of simulator circuit.
\2\ Remote terminal equipment open circuit DC volts to ground on AIOD
tip and ring.
The maximum signal power may exceed -4 dB with respect to one milliwatt
by as much as 1.0 dB provided that the power averaged over all units
of the equipment complies with the specified maximum.
Note: The maximum signal power may be exceeded by as much as 1.0 dB by a
single unit of equipment or circuitry, provided that the power,
averaged overall units of production, complies with the specified
limitations.
(v) For registered test equipment or registered test circuitry the
maximum signal power delivered to a loop simulator circuit shall not
exceed 0 dBm when averaged over any 3-second interval. No manufacturing
tolerance is allowed which would permit this power to be exceeded by any
unit of equipment.
(vi) For voiceband private lines using ringdown or inband signaling
the maximum power of other than live voice signals delivered to a 600
ohm termination shall not exceed -13dBm when averaged over any 3-second
interval.
(vii) For voiceband private lines using inband signaling in the band
2600&177;150 Hz, the maximum power delivered to a 600-ohm
termination shall not exceed -8 dBm during the signaling mode. The
maximum power delivered to a 600 Ohm termination in the on-hook steady
state supervisory condition shall not exceed -20 dBm. The maximum power
of other than live voice signals delivered to a 600-ohm termination
during the non-signaling mode and for other inband systems shall not
exceed -13dBm when averaged over any 3-second interval. The maximum
signal power may be exceeded by as much as 1.0 dB by a single unit of
equipment or circuitry, provided that the power averaged over all
[[Page 283]]
units of production complies with the specified limitation.
(viii) For PSDS (Types I, II and III) terminal equipment when in the
digital mode of transmission, the maximum equivalent power of any
encoded analog signal (other than live voice) shall not exceed -12dBm
when averaged over any 3-second interval. The equivalent analog power
shall be derived by a zero-level decoder at the network interface to
PSDS (Type II or III) facilities.
(2) Limitations on internal signal sources primarily intended for
network control signaling, contained in voice and data equipment.
(i) For all operating conditions of registered terminal equipment
and registered protective circuitry, the maximum power delivered to a
loop simulator circuit shall not exceed one milliwatt when averaged over
any 3-second interval.
(ii) For tie trunk applications, the maximum power delivered to a
600 ohm termination for registered terminal equipment and registered
protective circuitry under all operating conditions shall not exceed the
following:
Maximum Power With Respect to One Milliwatt, When Averaged Over Any 3-
Second Interval
------------------------------------------------------------------------
2-wire 4-wire Lossless 4-wire CTS
------------------------------------------------------------------------
-4 dB........................... -4 dB............. -8 dB, nom.
------------------------------------------------------------------------
(iii) For PSDS (Types I, II and III) terminal equipment, when in the
digital mode of transmission, the maximum equivalent power of any
encoded analog signal shall not exceed -3dBm when averaged over any 3-
second time interval. The equivalent analog signal shall be derived by a
zero-level decoder located at the network interface to PSDS (Type II or
III) facilities.
(3) Registered one port and multiport terminal equipment and
protective circuitry with provision for through transmission from other
terminal equipment, excluding data equipment and data protective
circuitry which are registered in accordance with Sec. 68.308(b)(4).
(i) Where through-transmission equipment provides a dc electrical
signal to equipment connected therewith (e.g., for powering of electro-
acoustic transducers), dc conditions shall be provided which fall within
the range of conditions provided by a loop simulator circuit unless the
combination of the through-transmission equipment and equipment
connected therewith is registered as a combination which conforms to
Sec. 68.308(b) (1) and (2).
(ii) Through-transmission equipment to which remotely connected data
terminal equipment may be connected shall not be equipped with or
connected to either a Universal or Programmed Data Jack used in data
configurations. (See Secs. 68.308(b)(4) and 68.502(e)).
(4) Limitations on registered data terminal equipment and registered
one-port protective circuitry with provision for through-transmission
from data equipment. When such equipment or circuitry is used for the
transmission of data signals to the telephone network, it shall assure
in all operating conditions, other than network control signaling (see
Sec. 68.308(b)(2) of this section), that one of the following
limitations is met, depending upon the means of connection of the
equipment or circuitry to the telephone network. The transmitted signal
power, averaged over any 3-second time interval, delivered to a loop
simulator circuit, shall not exceed:
(i) A maximum level adjustable to no greater than -4 dB with respect
to one milliwatt, for connection to a Universal Data Jack used in the
``fixed loss loop'' configurations of Sec. 68.502(e).
(ii) A maximum level determined by means of connections in the
Programmed Data Jack or Universal Data Jack, used in the ``programmed''
configurations of Sec. 68.502(e), which level can be programmed in 1 dB
steps from -12 dB to 0 dB with respect to one milliwatt by means of
programming connections made within the jack.
(iii) A nonadjustable level no greater than -9 dB with respect to
one miliwatt for connection by means other than those which implement
the limitations in paragraphs (b)(4)(i) and (ii) of this section.
Equipment or circuitry designed in accordance with this -9 dBm
limitation shall be treated as non-live voice equipment within these
rules.
The maximum signal power specified in (paragraphs (b)(4) (i) and (ii) of
this
[[Page 284]]
section may be exceeded by as much as 1.0 dB by a single unit of
equipment or circuitry, provided that the power averaged over all units
of production, complies with the specified limitations. The maximum
signal power specified in paragraphs (b)(4)(iii) of this section may not
be exceeded by any units of production.
(5) Registered one port and multiport terminal equipment and
protective circuitry with provision for through-transmission from ports
to other equipment which is separately registered for the public
switched network, or ports to other network interfaces.
(i) Registered terminal equipment and registered protectives
circuitry shall have no adjustments that will allow net amplification to
occur in either direction of transmission in the through-transmission
path within the freguency range of 200 to 4000 Hertz that will exceed
the following:
[[Page 285]]
[GRAPHIC] [TIFF OMITTED] TC02JN91.015
[[Page 286]]
(A) The source impedance for all measurements shall be 600 ohms. All
ports shall be terminated in appropriate loop or private line channel
simulator circuits or 600 ohm terminations. The numerical ``avg.'' and
``max.'' requirements mean that the net gain for each type of connection
through such equipment or circuitry shall be designed not to exceed the
average gain for such paths in all units; however, the gain for any path
of any single unit may exceed the average by as much as the maximum
provided that the net gain, averaged over such paths in all units of
production, is no greater than the average. The term ``nom.'' allows for
variations encountered in conventional terminating set losses as defined
in Sec. 68.3.
(B) These ports are for 2-wire on-premises station ports to
separately registered terminal equipment.
(C) The 4-Wire CTS shall meet the requirements for Tie Trunk
Transmission Interfaces as defined in Sec. 68.3.
(D) These through gain limitations are applicable to multiport
systems where channels are not derived by time or frequency compression
methods. Terminal equipment employing such compression techniques shall
assure that equivalent compensation for through gain parameters is
demonstrated in the registration application.
(E) Registered terminal equipment and registered protective
circuitry may have net amplification exceeding the limitations of this
subsection provided that, for each network interface type to be
connected, the absolute signal power levels specified on this section
are not exceeded.
(F) The indicated gain is in the direction which results when moving
from the horizontal entry toward the vertical entry.
(G) Registered terminal equipment or protective circuitry with the
capability for through-transmission from voiceband private line channels
or voiceband metallic channels to other telephone network interfaces
shall assure that the absolute signal power levels specified in this
section, for each telephone network interface type to be connected, are
not exceeded.
(H) Registered terminal equipment or protective circuitry with the
capability for through transmission from voiceband private line channels
or voiceband metallic private line channels to other telephone network
interfaces shall assure, for each telephone network interface type to be
connected, that signals with energy in the 2450 to 2750 Hertz band are
not through transmitted unless there is at least an equal amount of
energy in the 800 to 2450 Hertz band within 20 milliseconds of
application of signal.
(ii) The insertion loss in through connection paths for any
frequency in the 800 to 2450 Hertz band shall not exceed the loss at any
frequency in the 2450 to 2750 Hertz band by more than 1 dB (maximum loss
in the 800 to 2450 Hertz band minus minimum loss in the 2450 to 2750
Hertz band plus 1 dB.
(6) For tie trunk type interfaces--Limitation on idle circuit
stability parameters. For idle state operating conditions of registered
terminal equipment and registered protective circuitry, the following
limitations shall be met:
(i) For the two-wire interface
[GRAPHIC] [TIFF OMITTED] TC02JN91.016
[[Page 287]]
[GRAPHIC] [TIFF OMITTED] TC02JN91.017
[[Page 288]]
(7) Registered terminal equipment and registered protective
circuitry shall provide the following range of dc conditions to off-
premises station (OPS) lines. (i) DC voltages applied to the OPS
interface for supervisory purposes and during network control signaling
shall meet the limits specified in Sec. 68.306(a)(6)(i).
(ii) DC voltages applied to the OPS interface during the talking
state shall meet the following requirements:
(A) The maximum open circuit voltage across the tip (T(OPS)) and
ring (R(OPS)) leads for Classes A, B, and C shall not exceed 56.5 volts,
and
(B) Except for class A OPS interfaces, the maximum dc current into a
short circuit across the tip (T(OPS)) and ring (R(OPS)) leads shall not
exceed 140 mA, and
(C) Except for class A OPS interfaces, the dc current into the OPS
line simulator circuit must be at least 20 mA for the following
conditions (see Fig. 68.3(f)):
R2 + RL
------------------------------------------------------------------------
Condition Class B Class C
------------------------------------------------------------------------
1..................................................... 600 1300
2..................................................... 1800 2500
------------------------------------------------------------------------
(8) For Message Registration the requirements of Sec. 68.308(b) do
not apply.
(9) For connections to 1.544 Mbps digital services, the permissible
code words for unequipped Mu-255 encoded subrate channels are limited to
those corresponding to signals of either polarity, of magnitude equal to
or less than X48, where code word, XN is derived by:
XN=(255-N) base 2
-XN=(127-N) base 2
(c) Signal power in the 3995-4005 Hz frequency band--(1) Power
resulting from internal signal sources contained in registered
protective circuitry and registered terminal equipment (voice and data),
not intended for network control signaling. For all operating conditions
of registered terminal equipment and registered protective circuitry
which incorporate signal sources other than sources intended for network
control signaling, the maximum power delivered by such sources in the
3995-4005 Hertz band to an appropriate simulator circuit, shall be 18 dB
below maximum permitted power specified in paragraph (b) of this
section, for the 200-4000 Hertz band.
(2) Terminal equipment with provision for through-transmission from
other equipments. The loss in any through transmission path of
registered terminal equipment and registered protective circuitry at any
frequency in the 600 to 4000 Hertz band shall not exceed, by more than 3
dB, the loss at any frequency in the 3995 to 4005 Hertz band, when
measured into an appropriate simulator circuit from a source which
appears as 600 ohms across tip and ring.
(3) For Message Registration the requirements of Sec. 68.308(c) do
not apply.
(d) Longitudinal voltage at frequencies below 4 kHz. The weighted
root-mean-squared voltage* averaged over 100 milliseconds that is the
resultant of all of the component longitudinal voltages in the 100 Hz to
4 kHz band after weighting according to the curve of Figure 68.308(a),
shall not exceed the maximum indicated under the conditions stated in
paragraph (g). The weighting curve in Figure 68.308(a) has an absolute
gain of unity at 4 kHz.
---------------------------------------------------------------------------
* Note: Average magnitudes may be used for signals that have peak-
to-RMS ratios of 20 dB and less. RMS limitations must be used instead of
average values if the peak-to-RMS ratio of the interfering signal
exceeds this value.
------------------------------------------------------------------------
Maximum RMS
Frequency range voltage Impedance
------------------------------------------------------------------------
100 Hz to 4 kHz................... -30 dBV 500 ohms
------------------------------------------------------------------------
(e) Voltage in the 4 kHz to 6 MHz frequency range--general case--2-
wire and 4-wire lossless interface--4-wire CTS interface (except LADC).
Except as noted, the root-mean-squared (RMS) voltage as averaged over
100 milliseconds at the telephone connections of registered terminal
equipment and registered protective circuitry in all of the possible 8
kHz bands within the indicated frequency range and under the conditions
specified in paragraph (g) shall not exceed the maximum indicated below.
For (1)(i) and (2)(i) below, ``f'' is the center frequency in kHz of
each of the possible 8 kHz bands beginning at 8 kHz.
[[Page 289]]
(1) Metallic voltage--(i) 4 kHz to 270 kHz.
------------------------------------------------------------------------
Metallic
Center frequency (f) of 8 kHz Max voltage in all 8 kHz terminating
band bands impedance
------------------------------------------------------------------------
8 kHz to 12 kHz.............. -(6.4+12.6 logf) dBV 300 ohms
12 kHz to 90 kHz............. (23-40 logf) dBV 135 ohms
90 kHz to 266 kHz............ -55 dBV 135 ohms
------------------------------------------------------------------------
(ii) 270 kHz to 6 MHz. The RMS value of the metallic voltage
components in the frequency range of 270 kHz to 6 MHz shall, averaged
over 2 microseconds, not exceed -15 dBV. This limitation applies with a
metallic termination having an impedance of 135 ohms.
(2) Longitudinal voltage--(i) 4 kHz to 270 kHz.
------------------------------------------------------------------------
Longitudinal
Center frequency (f) of 8 kHz Max voltage in all 8 kHz terminating
band bands impedance
------------------------------------------------------------------------
8 kHz to 12 kHz.............. -(18.4+20 logf) dBV 500 ohms
12 kHz to 42 kHz............. (3-40 logf) dBV 90 ohms
42 kHz to 266 kHz............ -62 dBV 90 ohms
------------------------------------------------------------------------
(ii) 270 kHz to 6 MHz. The RMS value of the longitudinal voltage
components in the frequency range of 270 kHz to 6 MHz shall, not exceed
-30 dBV. This limitation applies with a longitudinal termination having
an impedance of 90 ohms.
(f) LADC interface. The metallic voltage shall comply with the
general requirements in (1) below as well as the additional requirements
specified in (2) and (3) as stated. The requirements apply under the
conditions specified in paragraph (g). Terminal equipment for which the
magnitude of the source and/or terminating impedance exceeds 300 ohms,
at any frequency in the range of 100 kHz to 6 MHz, at which the signal
(transmitted and/or received) has significant power, shall be deemed not
to comply with these requirements. A signal is considered to have
``significant power'' at a given frequency if that frequency is
contained in a designated set of frequency bands which collectively have
the property that the RMS voltage of the signal components in those
bands is at least 90% of the RMS voltage of the total signal. The
designated set of frequency bands must be used in testing all
frequencies.
(1) Metallic voltages--frequencies below 4 kHz--(i) Weighted RMS
Voltage in the 10 Hz to 4 kHz Frequency Band. The weighted root-mean-
square (rms) metallic voltage averaged over 100 milliseconds, frequency
components weighted according to the curve in Figure 68.308(a), shall
not exceed the maximum indicated below. The weighting curve in Figure
68.308(a) has an absolute gain of unity at 4 kHz.
------------------------------------------------------------------------
Frequency range Maximum voltage
------------------------------------------------------------------------
10 Hz to 4 kHz.............................. +3 dBV
------------------------------------------------------------------------
(ii) RMS voltage in 100 Hz bands in the frequency range 0.7 kHz to 4
kHz. The root-mean-squared (rms) metallic voltage averaged over 100
milliseconds in the 100-Hz bands having center frequencies between 750
Hz and 3950 Hz shall not exceed the maximum indicated below.
------------------------------------------------------------------------
Center frequency (f) of 100-Hz bands Maximum voltage
------------------------------------------------------------------------
750 to 3950 Hz.............................. -6 dBV
------------------------------------------------------------------------
(2) Metallic voltages--frequencies above 4 kHz--LADC interface--(i)
100 Hz Bands over frequency range of 4 kHz to 270 kHz. The root-mean-
square (rms) voltage as averaged over 100 milliseconds in all possible
100 Hz bands between 4 kHz and 270 kHz for the indicated range of center
frequencies and under the conditions specified in paragraph (g) shall
not exceed the maximum indicated below:
------------------------------------------------------------------------
Maximum voltage in all 100 Hz
Center frequency (f) of 100 Hz bands bands
------------------------------------------------------------------------
4.05 kHz to 4.60 kHz.................. 0.5 dBV
4.60 kHz to 5.45 kHz.................. (59.2-90 log f)dBV
5.45 kHz to 59.12 kHz................. (7.6-20 log f)dBV
59.12 kHz to 266.00 kHz............... (43.1-40 log f)dBV
------------------------------------------------------------------------
Where f=center frequency in kHz of each of the possible 100 Hz
bands.
(ii) 8 kHz bands over frequency range of 4 kHz to 270 kHz. The root-
mean-square (rms) voltage as average over 100-milliseconds in all of the
possible 8 kHz bands between 4 kHz and 270 kHz for
[[Page 290]]
the indicated range of center frequencies and under the conditions
specified in paragraph (g) shall not exceed the maximum indicated below:
------------------------------------------------------------------------
Maximum voltage in all 8 kHz
Center frequency of (f) 8 kHz bands bands
------------------------------------------------------------------------
8 kHz to 120 kHz...................... (17.6-20 log f)dBV
120 kHz to 266 kHz.................... (59.2-40 log f)dBV
------------------------------------------------------------------------
Where f=center frequency in kHz of each of the possible 8 kHz bands.
(iii) RMS voltage at frequencies above 270 kHz. The root-mean-square
(rms) value of the metallic voltage components in the frequency range of
270 kHz to 6 mHz shall, averaged over 2 microseconds, not exceed -15
dBV. This limitation applies with a metallic termination having an
impedance of 135 ohms.
(iv) Peak voltage. The total peak voltage for all frequency
components in the 4 kHz to 6 MHz shall not exceed 4.0 volts.
(3) Longitudinal voltage--(i) Frequencies below 4 kHz. With the
frequency components weighted in accordance with the curve in Figure
68.308(a), the weighted root-mean-square voltage of all frequency
components, in the frequency band from 10 Hz to 4 kHz, averaged over 100
milliseconds, shall not exceed the maximum indicated below under the
conditions stated in paragraph (g). The weighting curve in Figure
68.308(a) has an absolute gain of unity at 4 kHz.
------------------------------------------------------------------------
Frequency range Max RMS voltage
------------------------------------------------------------------------
10 Hz-4kHz................................. -37 dBV
------------------------------------------------------------------------
(ii) 4 kHz to 270 kHz
------------------------------------------------------------------------
Longitudinal
Center frequency (f) of 8 kHz Max voltage in all 8 kHz terminating
band bands impedance
------------------------------------------------------------------------
8 kHz to 12 kHz.............. -(18.4+20logf) dBV 500 ohms
12 kHz to 42 kHz............. (3-40logf) dBV 90 ohms
42 kHz to 266 kHz............ -62 dBV 90 ohms
------------------------------------------------------------------------
Where f= center frequency in kHz of each of the possible 8 kHz
bands.
(iii) 270 kHz to 6 MHz. The root-mean-square (RMS) value of the
longitudinal voltage components in the frequency range of 270 kHz to 6
MHz shall, averaged over 2 microseconds, not exceed -30 dBV. This
limitation applies with a longitudinal termination having an impedance
of 90 ohms.
(g) Requirements in paragraphs (d), (e) and (f) apply under the
following conditions:
(1) All registered terminal equipment, except equipment to be used
on LADC, and all registered protective circuitry must comply with the
limitations when connected to a termination equivalent to the circuit
depicted in Figure 68.308(b) and when placed in all operating states of
the equipment except during network control signaling. For message
registration in the ground return mode, a termination equivalent to
Figure 68.308(c) is required, and metallic voltage limitations do not
apply. LADC registered terminal equipment must comply with the metallic
voltage limitations when connected to the circuits of Figure 68.3(k) and
must comply with the longitudinal limitations when connected to the
circuits of Figure 68.308(b), as indicated.
(2) All registered terminal equipment and registered protective
circuitry must comply with the limitations in the offhook state over the
range of loop current that would flow with the equipment connected to an
appropriate loop simulator circuit.
(3) Registered terminal equipment and registered protective
circuitry with provision for through-transmission from other equipments
shall comply with the limitations with a 1000 Hz tone applied from a
600-ohm source (or, if appropriate, a source which reflects a 600-ohm
impedance across tip and ring) at the maximum level that would be
applied during normal operation. Registered protective circuitry for
data shall also comply with the tone level 10 dB higher than that
expected during normal operation.
(4) Voice terminal equipment containing electroacoustic transducers
for live voice input, including recording devices, shall comply with the
limitations with a 1000 Hz acoustic signal applied to the
electroacoustic transducers that results in a power delivered into a 600
ohm load impedance of -13 dB with respect to one milliwatt for the 2-
wire and 4-wire lossless interfaces
[[Page 291]]
and -19 dB with respect to one milliwatt for the 4-wire CTS interface.
(5) Except during the transmission of ringing (Sec. 68.306(d)) and
Dual Tone Multifrequency (DTMF) signals, LADC registered terminal
equipment shall comply with all requirements in all operating states and
with loop current which may be drawn for such purposes as loop back
signaling. The requirements in Sec. 68.308(f)(1) except in paragraphs
(i) and (ii) also apply during the application of ringing. The
requirement in Sec. 68.308(d)(2) and the requirements in
Sec. 68.308(f)(1) (i) and (ii) apply during ringing for frequencies
above 300 Hz and with the maximum voltage limits raised by 10 dB. DTMF
signals which are used for the transmission of alphanumeric information
and which comply with the requirements in Sec. 68.308(f)(1)((i) and in
Sec. 68.308(f)(2) or (3) as applicable, shall be deemed to comply with
the requirements in Sec. 68.308(f)(1)(ii) provided that, for
automatically originated DTMF signals, the duty cycle is less than 50
percent.
(6) LADC registered terminal equipment shall comply with all
applicable requirements, except those specified in Sec. 68.308(f)(1) (i)
and (ii), during the transmission of each possible data signal sequence
of any length. For compliance with Sec. 68.308(f)(3)(i), the limitation
applies to the rms voltage averaged as follows:
(i) For digital signals, baseband or modulated on a carrier, for
which there are defined signal element intervals, the rms voltage is
averaged over each such interval. Where multiple carriers are involved,
the voltage is the power sum of the rms voltages for the signal element
intervals for each carrier.
(ii) For baseband analog signals, the rms voltage is averaged over
each period (cycle) of the highest frequency of the signal (3 dB point
on the spectrum). For analog signals which are modulated on a carrier
(whether or not the carrier is suppressed), it is averaged over each
period (cycle) of the carrier. Where multiple carriers are involved, the
voltage is the power sum of the rms voltage of each carrier.
(iii) For signals other than the types defined in paragraphs (g)(6)
(i) and (ii) of this section, the peak amplitude of the signal must not
exceed +1 dBV.
(7) Equipment shall comply with the requirements in
Sec. 68.308(f)(1) (i) and (ii) during any data sequence which may be
transmitted during normal use with a probability greater than 0.001. If
the sequences transmitted by an equipment are application dependent, the
user instruction material shall include a statement of any limitations
assumed in demonstrating compliance of the equipment.
(8) In addition to the conditions specified in paragraph (g)(5) of
this section, LADC registered terminal equipment which operates in one
or more modes as a receiver shall comply with requirements in
Sec. 68.308(f)(3) with a tone at all frequencies in the range of
potential received signals and at the maximum power which may be
received.
(h) Interference limitations for transmission of bipolar signals
over digital services--(1) Limitations on Terminal Equipment Connecting
to Subrate Digital Services--(i) Pulse repetition rate. The pulse
repetition rate shall be synchronous with 2.4, 4.8, 9.6 or 56.0 kilobits
per second.
(ii) Template for maximum output pulse. When applied to a 135 ohm
resistor, the instantaneous amplitude of the largest isolated output
pulse obtainable from the registered terminal equipment shall not exceed
by more than 10% the instantaneous voltage defined by a template
obtained as follows: The limiting pulse template shall be determined by
passing an ideal 50% duty cycle rectangular pulse with the amplitude/
pulse rate characteristics defined in table I through a single real pole
low pass filter having a cutoff frequency in Hertz equal to 1.3 times
the bit rate. For bit rates of 2.4, 4.8 and 9.6 kbps, the filtered
pulses shall also be passed through a filter providing the additional
attenuation in table II.
Table I--Driving Pulse Amplitude
------------------------------------------------------------------------
Amplitude
Pulse rate (R) (kbps) (A) (volts)
------------------------------------------------------------------------
2.4........................................................ 1.66
4.8........................................................ 1.66
9.6........................................................ 0.83
56.0....................................................... 1.66
[[Page 292]]
------------------------------------------------------------------------
Table II--Minimum Additional Attenuation
------------------------------------------------------------------------
Frequency Frequency
Pulse rate (R) (kbps) band 24 to band 72 to
32 kHz (dB) 80 kHz (dB)
------------------------------------------------------------------------
2.4........................................... 5 1
4.8........................................... 13 9
9.6........................................... 17 8
------------------------------------------------------------------------
The attenuation indicated may be reduced at any frequency within the
band by the weighting curve of Figure 68.308(d). Minimum rejection is
never less than 0 dB; i.e., the weight does not justify gain over the
system without added attenuation.
(iii) Average power. The average output power when a random signal
sequence, (0) or (1) equiprobable in each pulse interval, is being
produced as measured across a 135 ohm resistance shall not exceed 0 dBm
for 9.6 kbps or +6 dBm for 2.4 kbps, 4.8 kbps and 56 kbps.
(iv) Encoded analog content. If registered terminal equipment
connecting to subrate services contains an analog-to-digital converter,
or generates signals directly in digital form which are intended for
eventual conversion into voiceband analog signals, the encoded analog
content of the digital signal must be limited. The maximum equivalent
power of encoded analog signals for other than live voice as derived by
a zero level decoder test configuration shall not exceed -12 dBm when
averaged over any 3-second time interval. The maximum equivalent power
of encoded analog signals as derived by a zero level decoder test
configuration for signals intended for network control signaling shall
not exceed -3 dBm when averaged over any 3-second interval.
(2) Limitations on Terminal Equipment Connecting to 1.544 Mbps
Digital Services and ISDN PRA Services--
(i) Pulse repetition rate. The pulse repetition rate shall be within
plus-minus 75 pulses per second of 1.544 x 106
pulses per second.
(ii) Output pulse templates. The registered terminal equipment shall
be capable of optionally delivering three sizes of output pulses. The
output pulse option shall be selectable at the time of installation.
Table III
------------------------------------------------------------------------
------------------------------------------------------------------------
Pulse Height (volts)...................... 2.4 to 3.6.
Pulse Width (half amplitude) (nsec)....... 324 +/-45.
Maximum rise or fall time; from 10% to 90% 100.
points (nsec).
------------------------------------------------------------------------
(A) Option A output pulse. When applied to a 100 ohm resistor, the
instantaneous amplitude of the largest output pulse obtainable from the
registered terminal equipment shall fall within the pulse template
defined in table III.
(B) Option B output pulse. When applied to a 100 ohm resistor, the
instantaneous amplitude of the output from the registered terminal
equipment obtained when Option B is implemented shall fall within the
pulse template obtained by passing the bounding pulses permitted by
table III through the following transfer function.
[GRAPHIC] [TIFF OMITTED] TC13NO91.006
where:
n0=1.6049 x 106
n1=7.9861 x 10-1
n2=9.2404 x 10-8
d0=2.1612 x 106
d1=1.7223
d2=4.575 x 10-7
d3=3.8307 x 10 -14
S=j2 f
f=frequency (Hertz)
(C) Option C output pulse. When applied to a 100 ohm resistor, the
instantaneous amplitude of the output from the registered terminal
equipment obtained when Option C is implemented shall fall within the
pulse template obtained by passing the pulses obtained in Option B
through the transfer function in Option B a second time.
(iii) Adjustment of signal voltage. The signal voltage at the
network interface must be limited so that the range of pulse amplitudes
received at the first Telephone Company repeater is controlled to
&177;4dB. This limitation is achieved by implementing the
appropriate output pulse option as a function of Telephone Company cable
loss as specified at time of installation.
------------------------------------------------------------------------
Terminal equipment
----------------------------------
Cable loss at 772 kHz (dB) Loss at 772
Output pulse kHz
------------------------------------------------------------------------
15 to 22............................. Option A........... 0
[[Page 293]]
7.5 to 15............................ Option B........... 7.5
0 to 7.5............................. Option C........... 15.0
------------------------------------------------------------------------
(iv) Output power. The output power in a 3 kHz band about 772 kHz
when an all ones signal sequence is being produced as measured across a
100 Ohm terminating resistance shall be within the following limits:
------------------------------------------------------------------------
Power in 3 kHz
Output pulse option band about 772
kHz (dBm)
------------------------------------------------------------------------
A..................................................... 12 to 19
B..................................................... 4.5 to 11.5
C..................................................... -3 to + 4
------------------------------------------------------------------------
The power in a 3 kHz band about 1.544 Mhz shall be at least 25dB below
that in a 3 kHz band about 772 kHz.
(v) Encoded analog content. If registered terminal equipment
connected to 1.544 Mbps digital service or to ISDN PRA service contains
an analog-to-digital converter, or generates signals in digital form
which are intended for eventual conversion to voiceband analog signals,
the encoded analog content of the subrate channels of the ISDN
information bearing channels within the 1.544 Mbps signal must be
limited. The maximum equivalent power of encoded analog signals for
other than live voice that are not intended for network control
signaling as derived by a zero level decoder test configuration shall
not exceed -12 dBm when averaged over any 3-second time interval. The
maximum equivalent power of encoded analog signals as derived by a zero
level decoder test configuration for signals intended for network
control signaling shall not exceed -3 dBm when averaged over any 3-
second interval.
(3) PSDS Types II and III Maximum Output Pulse Templates. For PSDS
(Type II) the pulse repetition rate shall be a maximum of 144,000 pulses
per second +/-5 pulses per second; for PSDS (Type III) the pulse
repetition rate shall be a maximum of 160,000 pulses per +/-5 pulses per
second.
(i) Template for maximum output pulse. When applied to a 135 ohm
resistor the instantaneous amplitude of the largest isolated output
pulse obtainable from the registered terminal equipment shall fall
within the template of table IV(A) for PSDS Type II or table IV(B) for
PSDS Type III. The limiting pulse template shall be defined by passing
an ideal 50% duty cycle rectangular pulse within he amplitude/pulse rate
characteristics of table IV(A) or table IV(B) through a 1-pole low-pass
filter with a 3dB frequency of 260 kHz.
(ii) Below is the template for maximum output pulse:
------------------------------------------------------------------------------------------------
----------------
Pulse characteristics Table IV(A) T
able IV(B)
------------------------------------------------------------------------------------------------
----------------
Pulse Height +/-5%...................... 2.6 volts +/-5%............................. 2.4. vol
ts
Pulse Width--100ns...................... 3472.2 +/-150ns............................. 3125 +/-
.
Max Rise or Fall Time--microsecond...... 100ns...................................... 1.2.
(From 10% to 90% points) microsecond ............................................ +/- 0.2.
------------------------------------------------------------------------------------------------
----------------
[[Page 294]]
[GRAPHIC] [TIFF OMITTED] TC02JN91.018
[[Page 295]]
[GRAPHIC] [TIFF OMITTED] TC02JN91.019
[[Page 296]]
[GRAPHIC] [TIFF OMITTED] TC02JN91.020
[[Page 297]]
[GRAPHIC] [TIFF OMITTED] TC02JN91.021
(4) Limitations on Terminal Equipment Connected to ISDN BRA. If
registered terminal equipment connecting to ISDN BRA services contains a
digital-to-analog converter, or generates signals directly in digital
form, which are intended for eventual conversion into voiceband analog
signals, the encoded
[[Page 298]]
analog content of the digital signal must be limited. The maximum
equivalent power of the encoded analog signals, other than live voice as
derived from a zero-level-decoder test configuration, shall not exceed -
12 dBm when averaged over a three second interval. The maximum
equivalent power of encoded analog signals, as derived by a zero-level
decoder test configuration, for network control signaling, shall not
exceed -3 dBm when averaged over any three-second interval.
[ 45 FR 20853 , Mar. 31, 1980, as amended at 46 FR 40192 , Aug. 7, 1981; 47 FR 10219 , Mar. 10, 1982; 47 FR 39687 , Sept. 9, 1982; 49 FR 48721 , Dec.
14, 1984; 50 FR 48210 , Nov. 22, 1985; 51 FR 945 , Jan. 9, 1986; 51 FR 16689 , May 6, 1986; 61 FR 42392 , Aug. 15, 1996; 62 FR 9989 , Mar. 5,
1997]
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