Need for measurement of weak signals exists in many fields of science and technology. An example of such area is the optical spectroscopy of substances with low concentration of the centers of coloring. Use of devices of synchronous detecting allows to solve this problem. The need for the reliable, inexpensive and convenient device in use defines interest in development of the new schemes meeting these requirements. In this work the new scheme of the programmable synchronous detector with use of sequence filters and the digital phase shifter is offered. Advantages of the offered scheme is the high sensitivity and low cost in comparison with commercial versions of synchronous detectors.

Keywords: lock in amplifier ,sequence filter, detecting, phase shifter

The modern schemes of phase shifters used in radio receivers, antenna systems, synchronous detectors are limited in a wide frequency range to dependence of phase shift at the release of the scheme from the frequency of an entrance signal. In this work the new scheme of the programmable phase shifter which allows to use the phase shifter in the wide frequenciest range irrespective of the frequency of an entrance signal and also to carry out a phase displacement with a high precision is offered.

Keywords: phase shifter, synchronous detector, lag line