Applied with Artek's unique technology for analog / mixed signal and advanced electro-magnetics, the CLE1200 & CLE1000 are designed as a variable Inter-Symbol-Interference (ISI) channel for high speed serial interface stress tests. It controls the insertion loss continuously at 0.1% step (1,000 steps) in its dynamic range for fine adjustment. The differential transmission lines are totally passive and DC coupled. The adjusted insertion loss amount is reliably repeatable and stable for secure test results. The control is done by the volume dial on the front panel and/or PC remote via USB (and Ethernet) for automated calibration. Four (4) models of different loss range are prepared to cover various data rates. 4ch versions are also available. The CLE1200 & CLE1000 are convenient ISI channel, applicable for various standard stress tests and compliance tests.