ITU-T O 61-1988 SIMPLE EQUIPMENT TO MEASURE INTERRUPTIONS ON TELEPHONE-TYPE CIRCUITS《简单的设备来衡量中断 电话型电路-规格为测量设备(第4研究组)共3页》.pdf
《ITU-T O 61-1988 SIMPLE EQUIPMENT TO MEASURE INTERRUPTIONS ON TELEPHONE-TYPE CIRCUITS《简单的设备来衡量中断 电话型电路-规格为测量设备(第4研究组)共3页》.pdf》由会员分享,可在线阅读,更多相关《ITU-T O 61-1988 SIMPLE EQUIPMENT TO MEASURE INTERRUPTIONS ON TELEPHONE-TYPE CIRCUITS《简单的设备来衡量中断 电话型电路-规格为测量设备(第4研究组)共3页》.pdf(4页珍藏版)》请在麦多课文档分享上搜索。
1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 / TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU30%#) amended at Geneva, 1980, and at Melbourne, 1988)The requirements for the characteristics of a simple interruption counter equipment capable of detecting shortinterruptions in transmission on audio chann
2、els are described below and must be adhered to in order to ensurecompatibility between equipments standardized by the CCITT and produced by different manufacturers.1 Definitions1.1 interruptionFor the purpose of this specification an interruption shall be regarded as a break in transmission or drop
3、in thelevel of a test tone below a designated threshold.1.2 dead timeThe dead time is defined for the purpose of this specification as the time after which the counter is ready torecord another interruption following the end of the preceding interruption.2 The detector2.1 GeneralAll interruptions ab
4、ove 3.5 ms shall be detected. Interruptions of less than 2 ms shall not be recognized norrestoration of the signal for less than 2 ms. Interruptions separated by more than 4 ms shall be detected separately.2.2 Interruption detection thresholdThe instrument shall be capable of adjustment to threshold
5、 levels of 6 and 10 dB. The accuracy of theinstrument at these threshold levels shall be 1 dB.2.3 Input conditions2.3.1 The detector shall respond to a test signal of 2000 Hz 100 Hz (see also 4).2.3.2 The instrument shall be capable of adjustment for input levels between +10 dBm and 30 dBm.2.4 Input
6、 impedance (frequency range 300 Hz to 4 kHz) balanced, earth free. Input longitudinal interference loss 46 dB2.4.1 Terminating impedance (other impedances optional) 600 ohms Return loss 30 dB2.4.2 High impedance approx. 20 kohms Bridging loss across 300 ohms . 0.15 dB.2.5 Dead time2.5.1 The dead tim
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