Rohde & schwartzn155_cts55 电路图.pdf

33News from Rohde & Schwarz Number 155 (1997/III) Digital Radio Tester CTS55 is a compact unit for testing GSM, DCS1800 and PCS1900 mobile phones in qualified service 1. Rohde & Schwarz has now enhanced measurement and control functions, making this successful tester suitable for new fields of applications. The BER search routine offers an inter- esting application. Here CTS55 per- forms successive bit-error-rate measure- ments in the course of which the signal level is continuously reduced relative to a selectable start value until the BER limit, which can also be adjusted, is reached. With this function the sensi- tivity of a mobile phone can be deter- mined in an extremely easy way and with high accuracy. Another function of modern mobile phones the short message service can also be tested conveniently with CTS55. Without explicit call setup, either a text message is sent from the tester to the mobile phone or a message received from the mobile phone. If an error occurs in transmission, eg if the text memory of the mobile is full, the tester will output a corresponding error message. The module test mode (option CTS-B7) allows measurements and adjustments of individual modules of mobile phones or operation in the service mode. For this purpose CTS55 contains an RF synthesizer that, in addition to GSM, DCS1800 and PCS1900 bands, also covers the 900 to 995 MHz and 1800 to 1990 MHz bands. The level can be adjusted at two outputs in the range 10 to 110 dBm with or without burst shaping. Available modulation modes are “dummy burst modulation” with se- lectable midamble (training sequence) and “unmodulated”. After entry of the expected frequency, ie channel number, and power, the RF signal generator can synchronize to GSM sig- nals (FIG 1). Measurement is triggered by pulsed signals on the received burst and by CW signals on a midamble. CTS55 then measures peak power, average power, power ramp versus time as well as frequency and phase error. The I/Q spectrum measurement func- tion allows simple checking or adjust- ment of an I/Q modulator module. Graphical display of the spectrum close to the carrier provides a quick overview of carrier and sideband suppression, while the delta marker functions allow qualitative assessment (FIG 2). The remote-control function of CTS55 (option CTS-K6) opens up further possibilities. The tester can be fully controlled via an RS-232-C interface for setting parameters, conducting measure- ments and reading out results. With few exceptions, the remote-control com- mands are identical to those for the GSM testers of the CMD series 2. So automatic test routines, as used for CMD testers on repair lines in production for instance, can also be implemented with CTS55. This means an interesting variety of applications for the customer, such as automatic product-specific test routines, test-result documentation, cen- tral evaluation or statistical analyses. Gottfried Holzmann REFERENCES 1 Vohrer, M.: Digital Radio Tester CTS55 All-in-one service tester for GSM, PCN and PCS mobile telephones. News from Rohde & Schwarz (1996) No. 152, pp 46 2 Mittermaier, W.: Module test with Digital Radiocommunication Tester CMD52/55. News from Rohde & Schwarz (1995) No. 149, pp 3637 Reader service card 155/14 Panorama New measurement functions in Digital Radio Tester CTS55 FIG 1Result of signal analysis in module testFIG 2I/Q spectrum analysis with Digital Radio Tester CTS55 RadioFans.CN 收音机爱 好者资料库