§ 68.310 - Transverse balance limitations.

(a) Technical description and application. The Transverse Balancem−1, coefficient is expressed as

ER19NO97.026

(1) Where eL is the longitudinal voltage produced across a longitudinal termination Z1 and eM is the metallic voltage across the tip-ring or tip 1 and ring 1 interface of the input port when a voltage (at any frequency between f1 and f2, see Table 68.310(a) is applied from a balanced source with a metallic impedance Z0 (see Table 68.310(a). The source voltage should be set such that eM = E volts (see Table 68.310(a) when a termination of Z0 is substituted for the terminal equipment.

(2) The minimum transverse balance coefficient specified in this section (as appropriate) shall be equalled or exceeded for all 2-wire network ports, OPS line ports and the transmit pair (tip and ring) and receive pair (tip 1 and ring 1) of all 4-wire network ports at all values of dc loop current that the port under test is capable of drawing when attached to the appropriate loop simulator circuit (See § 68.3). An illustrative test circuit that satisfies the above conditions is shown in Figure 68.310-1(a) for analog and 68.310-1(b) for digital and subrate; other means may be used to determine the transverse balance coefficient specified herein, provided that adequate documentation of the appropriateness, precision, and accuracy of the alternative means is provided by the applicant.

(3) The minimum transverse balance requirements specified below shall be equalled or exceeded under all reasonable conditions of the application of earth ground to the equipment or protective circuitry under test.

Table68.310(a)Analog voicebandSubrate digital1.544 Mbps digitalLongitudinal Termination—Zl500 ohms See Table 310(b) 90 ohms.Metallic Source Impedance—Z0600 ohms 135 ohms 100 ohms.Lower Frequency—f1200 Hz 200 Hz 10 kHz.Upper Frequency—f24 kHz (1) 1.544 MHz.Metallic Voltage for Test—E 0.775 V 0.367 V 0.316 V.1 The upper frequency equals the digital line rate for the subrate service under test (See Table 68.310(b)).

(b) Analog voiceband equipment. All registered analog voiceband equipment shall be tested in the off-hook state. The minimum transverse balance requirement in the off-hook state shall be 40 dB, throughout the range of frequencies specified in Table 68.310(a). For some categories of equipment, additional requirements also apply to the on-hook state. When both off-hook and on-hook requirements apply, they are:

StateFrequency (f)BalanceOff-hook 200 Hz≦f≦4000 Hz ≥40 dB.On-hook 200 Hz≦f≦1000 Hz ≥60 dB.On-hook 1000 Hz≦f≦4000 Hz ≥40 dB.

(1) For analog one-port 2-wire terminal equipment with loop-start, ringdown, or inband signaling or for voiceband metallic channel applications, both off-hook and on-hook requirements apply.

(2) For analog one port equipment with ground-start and reverse-battery signaling only off-hook requirements apply.

(3) For analog registered protective circuitry for 2-wire applications with loop-start, ringdown, or inband signaling; or for voiceband metallic channel applications, both off-hook and on-hook requirements apply. Criteria shall be met with either terminal of the interface to other equipment connected to earth ground. The interface to other equipment shall be terminated in an impedance that will be reflected to the telephone connection as 600 Ohms in the off-hook state of the registered protective circuit, and the interface should not be terminated in the on-hook state. Figure 68.310(f) shows the interface of the protective circuitry being tested and the required arrangement at the interface to other equipment.

(4) For analog registered protective circuitry with ground-start and reverse-battery signaling only off-hook requirements apply. Criteria shall be met with either terminal of the interface to other equipment connected to earth ground. The interface to other equipment shall be terminated in an impedance that will be reflected to the telephone connection as 600 ohms in the off-hook state of the registered protective circuit. Figure 68.310(f) shows the interface of the protective circuitry under test and the required arrangement at the interface to the other equipment.

(5) For analog multi-port equipment with loop-start signaling both off-hook and on-hook requirements apply. Criteria shall be satisfied for all ports when all the ports not under test are terminated in their appropriate networks, as will be identified below, and when interface connections other than the ports are terminated in circuits appropriate to that interface. The minimum transverse balance coefficients shall also be satisfied for all values of dc loop current that the registered equipment is capable of drawing through each of its ports when these ports are attached to the loop simulator circuit specified in these rules. The termination for all ports other than the particular one whose transverse balance coefficient is being measured shall have a metallic impedance of 600 ohms and a longitudinal impedance of 500 ohms. Figure 68.310(c) shows this termination.

(6) For analog multi-port equipment with ground-start and reverse-battery signaling, only off-hook requirements apply. Criteria shall be satisfied for all ports when all ports not under test are terminated in their appropriate networks as will be identified below, and when interface connections other than the ports are terminated in circuits appropriate to that interface. The minimum transverse balance coefficients shall be satisfied for all values of dc loop current that the registered equipment is capable of drawing through each of its ports when these ports are attached to the loop simulator circuit specified in these rules. The terminations for all ports other than the particular one whose transverse balance coefficient is being measured shall have a metallic impedance of 600 ohms and a longitudinal impedance of 500 ohms. Figure 68.310(c) shows this termination and a longitudinal impedance of 500 ohms. Figure 68.310(c) shows this termination.

(7) For analog registered terminal equipment and protective circuitry for 4-wire network ports, both the off-hook and on-hook requirements apply. The pair not under test shall be terminated in a metallic impedance of 600 ohms. Other conditions are as follows:

(i) For analog registered protective circuitry with loop-start, ground-start, reverse battery, ringdown, or inband signaling; or for voiceband metallic channel applications. Criteria shall be met with either terminal of the interface to other equipment connected to earth ground. The interface to other equipment shall be terminated in an impedance that will result in 600 ohms at each of the transmit and receive pairs of the 4-wire telephone connection in the off-hook state of the registered protective circuit, and the interface should not be terminated in the on-hook state. Figure 68.310(d) shows the interface of the protective circuitry being tested and the required arrangement at the interface to other equipment.

(ii) For analog multiport equipment with loop start, ground start, and reverse battery, ringdown, or inband signaling; or for voiceband metallic channel applications. Criteria shall be satisfied for all network ports when all the ports not under test are terminated as defined below, and when interface connections other than the network ports are terminated in circuits appropriate to the interface. The criteria shall also be satisfied for all values of dc loop current that when the port is connected to the appropriate 4-wire loop simulator circuit. The terminations for both pairs of all network ports not under test shall have a metallic impedance of 600 ohms and a longitudinal impedance of 500 ohms. Figure 68.310(c) shows this termination.

(8) For analog PBX equipment (or similar systems) with class B or class C off-premises interfaces, only off-hook requirements apply. Criteria shall be satisfied for all off-premises station interface ports when these ports are terminated in their appropriate networks for their off-hook state, and when all other interface connections are terminated in circuits appropriate to that interface. The minimum transverse balance coefficients shall also be satisfied for all values of dc loop current that the registered PBX is capable of providing through off-premises station ports when these ports are attached to the off-premises line simulator circuit specified in these rules.

(9) For Type Z equipment with loop-start signaling, both off-hook and on-hook requirements apply. Equipment that has on-hook impedance characteristics which that do not conform to the requirements of § 68.312 (e.g., Type Z), shall comply with minimum transverse balance requirements of 40 dB in the voiceband. See § 68.312(h) for conditions upon registration of “Type Z” equipment.

(c) Digital equipment. The minimum transverse balance requirements for registered terminal equipment connected to digital services shall be equalled or exceeded for the range of frequencies applicable for the equipment under test and under all reasonable conditions of the application of earth ground to the equipment. All such terminal equipment shall have a transverse balance in the acceptable region of Figure 68.310(e) for the range of frequencies shown in Table 68.310(b) for the specified digital service in question. The metallic impedance used for the transverse balance measurements for all subrate services shall be 135 ohms and for 1.544 Mbps shall be 100 ohms. The longitudinal termination for 1.544 Mbps and subrate services shall be as defined in Table 68.310(b).

Table68.310(b)—Frequency Ranges of Transverse Balance Requirements for Digital ServicesDigital serviceFrequency rangeLongitudinal termination (ohms)Metallic termination (ohms)2.4 200 to 2.4 kHz 500 1353.2 200 to 3.2 kHz 500 1354.8 200 to 4.8 kHz 500 1356.4 200 to 6.4 kHz 500 1359.6 200 to 9.6 kHz 500 13512.81200 to 12.8 kHz 500/90 13519.21200 to 19.2 kHz 500/90 13525.61200 to 25.6 kHz 500/90 13538.41200 to 38.4 kHz 500/90 135561200 to 56 kHz 500/90 135721200 to 72 kHz 500/90 1351.544 10 kHz to 1.544 MHz 90 1001 For 200 to 12 kHz the longitudinal termination shall be 500 ohms and above 12 kHz the longitudinal termination shall be 90 ohms. ER19NO97.013 ER19NO97.014 ER19NO97.015 ER19NO97.016 ER19NO97.017 ER07MY98.006