公开(公告)号：US3689840A

公开(公告)日：1972-09-05

申请号：US3689840D

申请日：1971-04-29

Applicant: BELL TELEPHONE LABOR INC

Inventor： BROWN EARL FRANKLIN ,  KAMINSKI WILLIAM

IPC: H04B1/00

CPC classification number: H03M3/04

Abstract: A differential pulse code modulation system substantially reduces sign redundancy by transmitting sign information only for actual changes in polarity between differential samples. Upon the occurrence of a change in sign when both differential samples of opposite sign do not exceed a predetermined level, one of two polarity words is transmitted in place of the code word that represents the differential sample with the smaller magnitude. One polarity word indicates a positive polarity while the other word indicates a negative polarity. Only the absolute magnitudes of the differential samples are transmitted between sign changes. When both differential samples of opposite sign exceed a predetermined level, the absolute magnitude is transmitted for both differential samples and a run-length code work indicative of the location of the change in sign together with a polarity word are transmitted at a later time.

Abstract translation: 差分脉冲编码调制系统通过仅在差分样本之间的极性的实际变化中发送符号信息来大大减少符号冗余。 当两个相反符号的差分样本都不超过预定电平时发生符号改变，则代替具有较小幅度的差分样本的代码字来发送两个极性字中的一个。 一个极性字表示正极性，而另一个字表示负极性。 只有差异样本的绝对幅度才能在符号变化之间传输。 当相反符号的两个差分样本都超过预定电平时，两个差分采样的绝对幅度都被传输，并且在稍后的时间内传输指示符号变化位置的游程长度代码工作以及极性字。

公开(公告)号：US3657550A

公开(公告)日：1972-04-18

申请号：US3657550D

申请日：1970-04-07

Applicant: BELL TELEPHONE LABOR INC

Inventor： BROWN EARL FRANKLIN ,  KAMINSKI WILLIAM

IPC: G01M11/02 ,  G01R31/22

CPC classification number: G01M11/0292

Abstract: To measure the spatial response characteristics of optical systems, control circuitry is provided to electrically generate a predetermined one-dimensional spatial waveform (e.g., sinusoidal) on the display screen of a cathode ray tube. The optical system to be tested (e.g., a television system) is placed between the spatial waveform display and a suitable detector which comprises a mask having a narrow slit followed by a photomultiplier. The output of the latter is then displayed on an oscilloscope, or measured in some other known fashion. A linear light modulation is achieved for the spatial waveform display by gating a linearly scanned electron beam with constant amplitude, constant duration, variable duty cycle pulses. Appropriate waveforms can be selected to evaluate the spatial frequency response, transient response, linearity, or steady state response of the optical system under test.

Abstract translation: 为了测量光学系统的空间响应特性，提供控制电路以在阴极射线管的显示屏上电生成预定的一维空间波形（例如，正弦曲线）。 要测试的光学系统（例如，电视系统）被放置在空间波形显示器和合适的检测器之间，该检测器包括具有狭窄狭缝的掩模，随后是光电倍增管。 然后将后者的输出显示在示波器上，或以其他一些已知方式测量。 通过门控具有恒定幅度，恒定持续时间，可变占空比脉冲的线性扫描电子束，实现空间波形显示的线性光调制。 可以选择适当的波形来评估被测光学系统的空间频率响应，瞬态响应，线性或稳态响应。