Since 21st century

the test service for digital TV terrestrial broadcasting has been successively carried out in some Chinese big cities

and bus commuters can watch TV programmes while traveling in the signal covered regions.In the trial

it has been found that the environment noise comprising two dominant and distinct components:white Gaussian noise and impulsive noise affects the reception of mobile TV on the vehicle continuously

and that when the equipped vehicle traces along the traffic courses

in a limited time and space

the TV antenna is not able to avoid the noise source from the environment.In order to plan high-effective DTTV signal coverage

it is necessary for engineers to foreknow the noise level of a DTTV channel in the real electromagnetic environment.This paper introduces the results of average noise power of a digital TV channel in UHF band on public transportation lines in Shanghai.Not only the noise fact models but also the noise factor K times variance deviation of its upper decile under three typical communication environments has been obtained through the analysis of nonlinear regression of cumulative distribution functions on the test results.