Comprehensive 4-wire DDS Local Loop test set. Monitor and test 56k, Switched-56k and 64k Primary and Secondary DDS services. Quick 56k Frame-Relay turn-up. Real-time Invalid BPV Receive Monitor. Received Signal Level measurement with +/-1dBm accuracy. Standard TERM mode and unique THRU mode provides real-time non-Intrusive monitor of NW or CPE. CSU/DSU emulation provides response and activation of incoming CSU or DSU loopbacks. Transmit CCITT V.64 latching loopback for end-to-end testing. 2047, 511, Alt, All-1's and All-0's BERT testing with complete error analysis including Bit count, BER, EFS, %EFS, SES and %SES with Error insertion. Built-in Help and Tips guide