這張條塊測(cè)試卡專(zhuān)門(mén)設(shè)計(jì)為了檢測(cè)電視攝像機(jī)的中級(jí)和深度頻率的傳輸特性。在測(cè)試卡上部4條不同長(zhǎng)度的黑色水平條塊被分布白色背景上。下半部是上面的一個(gè)鏡像，但是是白色條塊分布在黑色背景上。在圖像的中位置有一個(gè)狹小的黑色和白色垂直直條。這些條塊各自產(chǎn)生脈沖信號(hào)大約為2μs,5μs,12μs和32μs。

The bar test chart is designed for checking the transmission characteristics of TV cameras at intermediate and deep frequencies.

In the upper part of the picture 4 black horizontal bars of different length are arranged in a white surrounding. The lower part is a mirror image to be upper one; however white bars are arranged in a black surrounding. A narrow vertical strip of black and white each are located in the center of the picture. These strips resp. bars generate puls signals of approx. 2 μs, 5 μs, 12 μs and 32 μs.

UTILIZATION

Inadequate transmission characteristics at intermediate and deep frequencies generate streaking effects in scanning line direction. Streaking may also be caused by defective clamping circuits. Long streaking (high error-time-constancy) are clearly visible at the monitor. Short streaking (low error-time-constancy) can be better observed in the oscillogram. For this purpose an oscilloscope with a line selector has to be used and the different bars may be observed one after the other. Also the adjustment of streaking (e.g. compensation of afterglow of flying spot scanners) should be effected with the aid of picture monitor and oscilloscope.

The narrow vertical strips in the center of the picture show echo disturbances, as may occur e.g. with defective delay lines in circuits for aperture corrections. The large black and white areas in both parts of the picture are designed to asses shadings, background structure and other errors. For this purpose the test chart may also be used upside down.

STANDARDS

? Pflichtenheft 8/1.1 der ?ffentlichen-rechtlichen Rundfunkanstalten der Bundesrepublik Deutschland “Richtlinien für die Messung der Pflichtenheftsbedingungen an Videoger?ten”

? IEC 611461- 2 Video cameras (PAL/SECAM/NTSC)- Methods of Measurement - Part 2: Two- and three-sensor professional cameras, 1997.