Agilent Technologies Switch/Measure Bedienungsanleitung Seite 1

Agilent Technologies Wireless/GSM SolutionsApplication Note 1312Understanding GSM Transmitter and Receiver Measurements for Base Transceiver Stations

10Mean transmitted RF carrier powerPurpose of measurement—what it provesOutput power is a fundamental transmitter characteristic and is linked directl

11Graphical view of limits/specificationsThe ETSI and ANSI specifications define power limits both in terms of absoluteaccuracy and relative accuracy

12Practical measurementsIn practice, many types of test equipment can be used to make power measurements in GSM systems. Accuracy, linearity and repea

13Transmitted RF carrier power versus timePurpose of measurement—what it provesThis measurement assesses the envelope of carrier power in the time dom

14Graphical view of limits and specificationsAs shown in Figure 10, the limit lines for BTS are dependent on a number offactors, the most fundamental

15Spectrum due to modulation and wideband noisePurpose of measurement—what it provesThis measurement and the next “spectrum due to switching,” are oft

16Graphical view of limits and specificationsAs with other measurements, the actual limits depend on many factors, namely,class, type, system and powe

17Last, at wide offsets it is possible to pre-attenuate, or notch out the central part ofthe GSM signal (in the frequency domain). This gives a signif

18Spectrum due to switchingPurpose of measurement—what it provesGSM transmitters ramp RF power rapidly. The “transmitted RF carrier power versus time”

19Graphical view of limits and specificationsAs with other measurements the actual limits depend on many factors, namely,class, type, system and power

2Table of ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Why measure

20SpuriousPurpose of measurements—what they proveSpurious measurements are necessary in all radio communications systems, andin GSM they are extensive

21Tx and Rx band spuriousTheory in picturesTx band spurious is a measurement set that checks that the transmitter does not put undesirable energy into

22Practical measurementsTo date, no analyzer has sufficient dynamic range to measure Rx band spuriousto the ETSI and ANSI specifications directly. Usu

23Cross-band spurious (for example, GSM900 into DCS1800)In some countries GSM900 and DCS1800 systems exist together and in somecases base stations for

24Out-of-band spuriousThe out-of-band spurious is a series of spectrum analyzer measurements over a large frequency range from 100 kHz through to 12.7

25Choosing transmitter measurements for an applicationThe following table is given for guidance only and the actual measurement setused in any one app

26Receiver measurements in GSM basestationsIntroductionWhile transmitter power is limited by the GSM standards, there is no limit onthe ability of a r

27GSM speech codingTo transmit actual voice data would require more bandwidth than a system canpractically afford. Most digital communication systems

28MeasurementsTest setups Abis versus loopbackIn normal operation, the GSM basestation receives signals from the mobile over the air interface, demodu

29Static reference sensitivity levelPurpose of measurements—what it provesSensitivity is the most significant in-channel receiver test. The sensitivit

3Choosing transmitter measurements for an application . . . . . . . . . . . . . . . .25Receiver measurements in GSM basestations . . . . . . . . . .

30Practical measurementsIn practice, there are really two values of sensitivity, compliance sensitivity andabsolute sensitivity. To verify compliance

31Reference interference levelPurpose of measurements—what it provesReference interference level tests the receiver’s ability to demodulate and decode

32Practical measurementsWhen to use the measurementInterference measurements are also performed in every phase of the BTS lifecycle. During full type

33Additional ETSI 11.21 receiver testsIn addition to the Sensitivity and Reference Interference Level tests, the ETSI11.21 standard includes two funct

34SummaryThis application note explains and describes the key transmitter and receivermeasurements required for testing GSM. The ETSI and ANSI test sp

35References1. GSM 05.05/ETS 300-577. GSM and DCS1800 Radio transmission and reception. 2. GSM 11.10/ETS 300-607. GSM and DCS1800 Mobile Station (M

36For more information about AgilentTechnologies test and measurement products,applications, services, and for a current salesoffice listing, visit ou

4IntroductionThis application note presents the fundamental RF parametric measurements necessary to characterize GSM900, DCS1800 and PCS1900 base tran

5Origins of measurementsGSM transmitter and receiver measurements originate from the following ETSIand ANSI standards:GSM 05.05/ETS 300-577. GSM and

6Choosing measurementsAs mentioned, ETSI and ANSI specifications are devised for type approval purposes. It is not practical to perform the complete s

7Base station transmitter measurements in GSMPhase error and mean frequency errorNote: For each measurement, process and limits vary between device ty

8Graphical view of limits and specificationsThe ETSI and ANSI specifications define test limits for both base transceiver stations and mobiles. Phase

9Practical measurementsAs mentioned, modern test equipment performs the necessary signal processingautomatically, making these measurements straightfo