Differentiate video bandwidth

The video bandwidth of alleged projector, point to video channel namely actually volume of total frequency band width, size of this numerical value is in umbriferous input the amplitude of signal drops 0.707 times when, correspondence outputs the upper limit frequency of umbriferous signal. The bandwidth increment as a result of 0.707 times correspondence is - 3db, so video bandwidth is called again normally - 3db bandwidth. Differentiate to what video takes wide property, can your projector is in test and verify the ability of umbriferous detail respect. When differentiating this function, you are OK the signal generator of major of have the aid of, perhaps use the computer directly, of the biggest resolution that considers method to issue projector to be able to be obtained in good position, the image signal that setting is white, in inputting projector, discern carefully next the image picture that come is shown on screen act, see the smallest character on the picture show whether the result is clear. If is below the high resolution condition that is close to projector ideal, the smallest character still returns clear and can visible word, the video bandwidth performance that means this projector is good; Contrary, when signal of image of umbriferous high resolution, the character on screen looks to send empty a bit, or horizontal line sense is realer, if perpendicular line is unsharpness, the video bandwidth performance that shows this projector is not too good.

Little hint: Video bandwidth is the index of a main function of projector, it also is an evaluation level that measures of low quality of projector function actor, the scanning frequency size on the umbriferous resolution volume that the discretion of this function and projector average direction, upend direction to go up in water, perpendicular direction is concerned, want to raise the indication resolution of umbriferous picture normally, the video that must raise projector takes bounty small.

Differentiate focusing function

The smallest indication unit of umbriferous picture is to resemble element normally, if resemble element be worth less word, the indication resolution that shows umbriferous picture is higher. And in CRT projector, the size that resembles element is decided by the focusing function place of projector commonly. Because of function of this pair of focusing differentiate, can help you examine projector shows the result whether very clear, if focusing performance is good, show this projector is adjusted very easily, and easier also umbriferous the picture effect that gives harmonious, clarity, if focusing performance is bad, umbriferous the character to screen and image very won't clear. When differentiating this function, you are OK the signal builder of major of have the aid of, perhaps use the computer, input signal of a pane to projector, undertake discerning according to the indication effect of pane next. Of course, when using this method to differentiate focusing function, you need to export information of a paragraph of aleatoric text to projector with the computer above all, adjust the focal length of projector stage by stage next, till the character that finds umbriferous picture to go up with naked eye till you is very clear; Hold bulk of this focal length next changeless, be linked together the RGB port of professional signal generator and projector directly again, input pane signal to projector then, observe pane signal is in appoint umbriferous focal length to fall, whether can show very clearly, if cannot very clear if showing, show performance of this projector focusing is not too good; Right now, you might as well adjust umbriferous indication contrast stage by stage again, had better make its numeric from low to tall change, observe case of one lower part is in the process that contrast changes stage by stage next, whether does its level, perpendicular foul line have medicinal powder anxious " suspicion " , if comes loose if anxious phenomenon is more apparent, can conclude performance of this projector focusing is not very good.
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