On the basis of throughly analysing all the factors that influence the radiance contrast of the object to background on the target area of the detector

a method of using spectral filtering to increase the effect range of TV tracking system is put up.For the sake of studying how to use spectral filtering to effectually raise the effect range

the author measured the objects spectral radiant intensity and studied the spectral radiance of the low sky background theorically according to the optical properties of the atmosphere and the atmospherical optical principle. Based on these reault of the measurement and theorical computation

the author uses computer simulating the effect of various filter

the result showed

the spectral filtering can effectually and steadily raised the radiance contrast of th object to background that on the target area of the detector

under the studied circumstance

the contrast has been raised above 4 - 7 times

the maximum effect range has been raised from 40km to 50~53km. The experiment result shows

under the experimental circumstance

the original contrast has been raised 1. 25~3. 59 times.Some improvemental proposal on the properties of the detector and the spectral properties of cooperate object are put up in this paper.