It is in a very large range that communication field is involved, except traditional exchange, various transmission nets such as optic fibre, microwave satellite communication system, still involve various wide narrowband communication, computer conferencing, Internet's business, broadcasting the television network, moving and fixing radio communication service, business of the access network and various apparatus manufacturing industries,etc.. New developing appearance of communicating device at present with the development of various communication new technologies, used for the means of testing tested in communication and various specialized, multipurpose test equipment getting application in a large amount. Odd pieces of developing direction tested to communicate make a argumentation on the whole just as follows.
First, mobile communication test engineering
China a with the fastest developing speed one the digital mobile communication at present. The digital honeycomb mobile communication rule is mainly as follows, G S M 900 ; D C S 1800 European rule; C D M A code division multiple access American rule; P D C Japan rule. The digital mobile communication general purpose tester calbiration system of G S M rule that the institute develops can be used for normalizing H P China's measuring 8 9 6 0 , H P 6392 E , W a v e t e k 4 4 0 0 , I F R 2 9 3 5 , W a v e t e k 4 2 0 1 , R e c a l 6113,etc. communication test instrument.
C D M A technological system have potential application prospect because of the intersection of capacity and old, the intersection of antijamming capability and strong, the intersection of confidentiality and advantage such as being fine. It is based on technology of code division multiple access, uses P N (the pseudo-random code) Allow to adjoin in the Residential Area and share all frequency allocation that the business provider offers with these two kinds of methods of power control, a user's communication signal is expanded with an only orthogonal code, in 2 G, C D M A signal is by 1. 2288 M b i t / s expands, third generation C D M A 2000 will use S R 3 code rate, can be in 3. 75 M H z expand in the carrier ' Multi-carrier way) . In order to improve the signal channel, the station end of group uses the fertile assorted yard of orthogonality. According to these techincal characteristics, the traditional R F generator must have digital modulation capability of broadband, with the intersection of simulation and one the intersection of C D M A and transmitting set of broadband, for measuring receiver and the intersection of C D M A and the intersection of mobile equipment and signal channel and the intersection of signal channel and exterior the intersection of R F and the intersection of part and characteristic. Because of the complexity of C D M A signal, should guarantee to test the precision and meet the machine format test of the high speed, must improve the intellectual intensity of the instrument, in order to find various useful parameters of C D M A from the basic data, the software of the test instrument wants the convenient staging in order to this kind of temporary standard of supporting emerging C D M A standard and L D G E. Suitable for the mobile communication technical test of smooth transitive third generation and use the signal source, transmit analysis meter, tester of the signalling and spectrum analyzer and vector analysis meter to introduce to the market one after another. The instrument with V X I total collinear communication instrument module tests the frequency domain is great, directed primarily to the using of test of mobile communication.
Second, fiber optics telecommunication test engineering
The optic fibre optical cable is the transmissive medium of the optical signal, it is a foundation of optical communication. In this domain International Telecommunications Union (I T U) Having made a series of standard, they have G. 650, G. 651, G. 652, G. 653, G. 655 grades. Except that G. 650 is beyond relevant test methods, other standards are all according to the systematic product standard of optic fibre kind. The intersection of norm and the optic fibre and by concrete performance index to make up optical cable it in standard these. The characteristic parameters of the optic fibre divides geometirc characteristic parameters, optical characteristic parameters, transmission characteristic. In addition as to high speed, multi channel, the intersection of long distance and optical communication system, optic fibre that does not provide whether optical communication need important index that consider too in the norm. The test instruments of optic fibre and optical cable are mostly set up in optics and electronics principle, so the system is complicated, the apparatus is expensive.
Optical communication has actually provided a high-capacity conveyance platform for various signal services, can set up the basic network of communication extending in all direction on this platform with technology such as D W D M, S D H, router at the same time, and it is the mere communicating device to form each network element in this network. Because of diversity and complexity of the network equipment, its standard is a large amount of. Mere communicating device test is divided into three kinds as follows: The mere interface parameter tests, electric the interface parameter to test and the apparatus realizes the test of the function.
The instrument that the fiber optic net tests is the products that every communication test instrument supplier especially valued, especially to dense wave division mutlipurpose (D W D M) Test equipment. The Er early mere test instrument adds all switching device to form in front of the electric test instrument mostly, such as the digital sampling oscilloscope T D of T e k t r o n i x Company 6 8 0 0 0 , The intersection of itself and the intersection of electricity and equivalent bandwidth to have 50 G H z, add the optical bandwidth turns into 30 G H z behind the photoelectric attachment, research and development used for optical element and optical integrated circuit; Can form the optical time domain reflectometer, the completeness test of optical signal used for optical fibre link after adding the time domain reflection attachment; Allocate some proprietary software, light source, light splitter,etc., form the test system of optical communication ' The type is C S A 8 0 0 0 ) ,Test used for D W D M. Utilize similar method, spectrum analyzer of electricity can construct standard design also, every communication instrument company of the world, factory all produce according to the standard of I T U. Is it here that the diversity of the products of every instrument company mainly behave? Serial completeness, the intersection of instrument and intellectual the intersection of software and procedure, difference between specialized chip design, special craft of instrument,etc. that instrument adopt of editor that instrument produce. So, company's technological competition focus per instrument in the world is the soft project and competition of special purpose chip.
----" communication industry's newspaper "
