Digital Lightwave Inc. A14 PDH 1020 PDH/T-Carrier module with JITTER 1.5M/2M/34M/45M/139M - DS1/E1/E3/DS3/E4 Includes: " Intrinsic Jitter Measurement, Jitter Tolerance and Jitter Transfer testing " Fractional E1 and 56K/64K Fractional DS1 testing " Meets requirements of ANSI T