NIM-ECL/TTL-ECL level adapter;

Taking the non-symmetrical square wave as a physical model,the essay has,as a result of the full investigation of SCVRTNSI,confirmed that the high voltage level of the square wave on the secondary-coil of the transformer is directly proportional to the low voltage level time within the period,and the lower voltage level to the high voltage level time.

it illustrates that the scheme of real-time monitoring of the level of communication channels is realized by beans of increasing level measurement device and the modification soft wares on the basis of remote control system, so as to improve the stability and reliability of the system.

This instrument can meter the electric level, frequency spectrum, carry to noise ratio , A/V , cobbly ratio , voltages of the AC trunk line and the battery.

Harmonics analysis and simulation research of multi-cell-cascade multi-level inverter;

This paper reviews the main techniques of DC-DC converters,which are soft switching technique,synchronous rec- tification,shift-phase PWM and multi-level technique.

One asymmetrical multi-level inverter is proposed based on the topology of cell cascade,every cell in this in-verter is composed of one two-levels inverter in series with several three-levels H bridges,the controlling system is con-structed by DSP and FPGA.