CMD55产品特点： ·是测量GSM及GSM1800移动电话的紧缩式单元 ·通过RS232，IEC/IEEE远控 ·前面板有多功能连接器 ·话音编码器/解码器可被集成 ·可选择安培表和伏特表 ·高敏感度二级RF输入 ·可改进为GSM、GSM1800及GSM1900测试   CharacteristicsThe CMD52 is a compact unit for testing GSM900 mobiles. The CMD55 is furthermore capable of testing GSM1800 (formerly named PCN orDCS1800)  and GSM1900 (formerly named PCS or DCS1900) mobile phones. Both models  are favourably priced and combine small dimensions with high measurement accuracy and speed.The testers range of capabilities includes all signalling, generator and measurement functions required  for verifying the correct operation of the DUT (Device Under Test). Thanks to its fast go/nogo tests and accurate analysis using optional  extensions, CMD52 and CMD55 are equally well suited for R&D, production and high-end service and production.Based on the wide-range know-how of Rohde & Schwarz in digital radiocommunication testing, which not least was obtained in developing type-approval test systems such as  the GSM900 and GSM1800 system simulators, both CMD models are top- grade testers for present and future measurement applications.Test capabilitiesTo test mobile phones, the CMD simulates a GSM900, 1800  or 1900 base station. One of the two RF synthesizers available for this purpose delivers a continuous BCCH signal while the other one provides all 8 timeslots for TCH signals.The major test functions are :Mobile synchronizationLocation updateIncoming call setupOutgoing call setupMobile power level controlHandover (channel change, timeslot  change)Peak power measurementHigh dynamic range burst analyzer (option CMD-B4 and CMD-B42)Spectrum due to Switching measurement (option CMD-B4 and CMD–B43)Spectrum due to Modulation measurement (option CMD-B4 and CMD–B43Timing Advance measurementSACCH measurement  (eg RxLev, RxQual, power level)Echo testCall clearing by mobile phoneCall clearing by CMDDC current/voltage measurementsPhase and frequency error measurement (option CMD-B4)Measurement of power ramping as a function of time (option CMD-B4)Bit-error rate (BER)  and Fast BER measurement (option CMD-B4)OperationOperation of the CMDis extremely user-friendly and requires no detailed GSM/PCN knowledge. The high-contrast, backlit LCD provided with softkeys on both sides allows convenient callup of test routines under menu control. Various  network-specific parameters are preset and permit direct testing without any operator control. In addition, it is of course possible to modify all parameters individually in the configuration menus.AutotestThe autotest function enables complete measurement routines to be started  at a keystroke without any further intervention by the operator  being required. The test results in tabular form are displayed on the screen.Remote controlThe CMD is remote-controlled via the RS-232  or IEEE/IEC-bus interface using SCPI-compatible commands. In the remote-control mode the CMD is designed for fast speed to yield high  throughputs in production.Echo testThe echo test allows very rapid go/nogo analysis covering all essential parts of the mobile. Words spoken into the microphone of the mobile are sent to the CMD, stored in buffer memory and sent back to the phone. In this way it is possible  to check the whole signal path from the microphone via the RF transmitter  section, RF receiver section, modulator, demodulator, signalling section, speech coder/decoder, analog audio components through to the loudspeaker.Testing handheldsIn addition to the normal RF input /output, the CMD has a high-sensitivity input and a high-level output  which enable tests on modules or on handhelds with built-in antenna by using couplers like the CMD-Z10.Module testingFault localization in mobile telephones requires various measurement functions that can  also be used without signalling so that defective units can be tested down to modular level. The basic model of CMD already provides some of these functions, eg signal generation with or without modulation or power measurements, other functions being available as optional extensions.