| 摘要 |
FIELD: radio engineering, radio astronomy, medical and biological investigations, physical investigations of materials and mediums. SUBSTANCE: adaptation unit which has frequency-independent circuit, unit for mode switching and controlled phase-shifter is introduced to increase adaptation possibilities of device. Device provides change of modulation frequency in proportional to level of input signal (in other words it is proportional to temperature of object). When modulation frequency is changed, part of power of investigated radiation which exposes detector for modulation period is also changed. This means that change in signal level in signal circuit are kept in narrow limits due to frequency-independent circuit, which voltage gain K1 depends on detector voltage gain K2 as K1(fm) = A/K2(fm), where fm is modulation frequency and A is factor of proportion. In addition controlled phase-shifter compensates phase shift between signal and reference inputs of synchronization detector (said phase shift is caused by reaction of detector on change of modulation frequency) because phase shift angle of phase shifter is also caused by modulation frequency. EFFECT: possibility to measure temperature of low heat radiation, increased dynamic range. 2 dwg |
