定价： 452元

定价： 1819元

定价： 353元

定价： 634元

定价： 1104元

定价： 568元

定价： 65元 / 折扣价： 56 元

The scope of this standard is two-fold. First, to establish and define requirements for methods which can be used to measure the performance of dial-pulse address signaling systems used with voice frequency telecommunications equipment. Second, to establish functional requirements for test equipment needed to make the measurements. Such standard conditions as will be possible with these methods and means are mandatory if consistent and repeatable test results are to be obtained. This standard… read more will be limited to the parameters of dial-pulse signaling systems used in the North-American network that affect addressing performance. These parameters shall be measured at appropriate access points within the telecommunications switching system, on associated local subscriber loops, on trunks interconnecting switching systems, or on station apparatus. Measurements of supervisory signals or of the time relationship between supervisory and dial-pulse address signals, are not included. Signaling systems other than dial pulse (for example, single frequency in-band or out of band) which results in a dial-pulse address may require testing using methods and equipment covered by this standard. read less

定价： 56元 / 折扣价： 48 元

定价： 58元 / 折扣价： 50 元