SignalDigitalizingbyUndersampling,anApproachfortheDataAcquisitionoftheInterferometertobeUsedAboardtheLISASatellite资源-CSDN文库

3 浏览量 2020-01-19 16:37:14 上传评论收藏 451KB PDF 举报

资源推荐

资源详情

资源评论

Signal digitalizing by undersampling, an approach for the

data acquisition of the interferometer to be used aboard the

LISA satellite

Wei Zhou, Claus Braxmaier

Hochschule f

¨

ur Technik, Wirtschaft & Gestaltung,

Brauneggerstr. 55, 78462 Konstanz, Germany

Abstract:

We present a method for digitalizing narrowband signal by undersampling to

reduce the hardware for the data acquisition and processing of an interferometer.

Keywords: Data acquisition, undersampling, interferometer

1. Introduction

A compact laser interferometer for translation and tilt metrology has been presented in [1]. It

is going to serve as a demonstrator for an optical readout of the free-ﬂoating proof mass position

and tilt aboard the LISA (Laser Interferometer Space Antenna, a ESA/NASA collaborative space

mission) satellites.

The measurement signal i

m

and the reference signal i

r

are proportional to cos(∆ωt − φ(t)) and

cos(∆ωt) respectively. ∆f =

∆ω

2π

is the heterodyne frequency of the interferometer. φ(t) is given

by φ(t) =

4π

λ

∆l(t). In order to obtain the phase of the measurement signal φ(t), in-quadrature

measurement has been used to get the two signals S

1

=

1

2

AB ·cos(φ(t)) and S

2

=

1

2

AB ·sin(φ(t)) at

ﬁrst. Then φ(t) can be calculated by φ(t) = tan

−1

(

S

2

S

1

). Fig. 1 shows the schematic of this technique.

Here, the measurement has bee n carried out by hardware. The computer merely computes the value

of tan

−1

(

S

1

S

2

). Of course the digitalizing of both signals i

m

and i

r

can be done directly at the output

of the interferometer, i.g. directly behind the diodes, so that the in-quadrature measurement can

be carried out by software on the computer. Even though quicker data acquisition units can be

used, the speed of computer gives the limit of real-time processing, because the quicker the data

acquisition is, the more data have to be processed in computer. Usually it is desirable to have a

higher heterodyne frequency to minimize the inﬂuence of noise. Consequently, a very hight speed

of the com puter would be necessary.

In this paper, data acquisition by deliberate undersampling is discussed. For phase signal φ(t),

which doesn’t change very fast, i.g. it has only a very narrow bandwidth, we will see that a high

sampling rate is not necessary, especially for static measurement, where φ(t) is a constant. In that

1

http://www.paper.edu.cn

本内容试读结束，登录后可阅读更多

下载后可阅读完整内容，剩余4页未读，立即下载

内容反馈

weixin_38747592

粉丝: 7
资源: 937

最新资源

资源上传下载、课程学习等过程中有任何疑问或建议，欢迎提出宝贵意见哦~我们会及时处理！点击此处反馈

feedback-tip