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1、 TECHNICAL REPORT CISPR 16-3 2003 AMENDMENT 2 2006-11 Amendment 2 Specification for radio disturbance and immunity measuring apparatus and methods Part 3: CISPR technical reports PRICE CODE IEC 2006 Droits de reproduction rservs Copyright - all rights reserved International Electrotechnical Commissi
2、on, 3, rue de Varemb, PO Box 131, CH-1211 Geneva 20, Switzerland Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmailiec.ch Web: www.iec.ch X For price, see current catalogue Commission Electrotechnique Internationale International Electrotechnical Commission INTERNATIONAL SPECIAL CO
3、MMITTEE ON RADIO INTERFERENCE 2 TR CISPR 16-3 Amend. 2 IEC:2006(E) FOREWORD This amendment has been prepared by CISPR subcommittee A: Radio interference measurements and statistical methods. The text of this amendment is based on the following documents: DTR Report on voting CISPR/A/659/DTR CISPR/A/
4、681/RVC CISPR/A/662/DTR CISPR/A/678/RVC Full information on the voting for the approval of this amendment can be found in the report on voting indicated in the above table. The committee has decided that the contents of this amendment and the base publication will remain unchanged until the maintena
5、nce result date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended. _ Page 7 3 Definitions Add, on page 9, after 3.11, the following new d
6、efinitions: 3.12 weighting (e.g. of impulsive disturbance) the pulse-repetition-frequency (PRF) dependent conversion (mostly reduction) of a peak- detected impulse voltage level to an indication which corresponds to the interference effect on radio reception NOTE 1 For the analog receiver, the inter
7、ference effect is the psychophysical annoyance, i.e. a subjective quantity (audible or visual, usually not a certain number of misunderstandings of a spoken text). For the digital receiver, the interference effect may be defined by the critical Bit Error Ratio (BER) (or Bit Error Probability (BEP),
8、for which perfect error correction can still occur, or by another objective and reproducible parameter. 3.13 weighting characteristic the peak voltage level as a function of PRF for a constant effect on a specific radio- communication system, i.e., the disturbance is weighted by the radio communicat
9、ion system itself TR CISPR 16-3 Amend. 2 IEC:2006(E) 3 3.14 weighting function weighting curve the relationship between input peak voltage level and PRF for constant level indication of a measuring receiver with a weighting detector, i.e. the curve of response of a measuring receiver to repeated pul
10、ses 3.15 weighting factor the value in dB of the weighting function relative to a reference PRF or relative to the peak value 3.16 weighting detector detector which provides an agreed weighting function 3.17 weighted disturbance measurement measurement of disturbance using a weighting detector Page
11、10 4 Technical Reports Add, after the existing subclause 4.7 published in Amendment 1, the following new subclauses 4.8 and 4.9: 4.8 Background material on the definition of the r.m.s.-average weighting detector for measuring receivers 4.8.1 Introduction purpose of weighted measurement of disturbanc
12、e Generally, a weighted measurement of impulsive disturbance serves the purpose of minimizing the cost of disturbance suppression, while keeping an agreed level of radio protection. The weighting of a disturbance for its effect on modern digital radiocommunication services is important for the defin
13、ition of emission limits that will protect these services. Amendment 1 of CISPR 16-1-1 defines a detector that is a combination of an r.m.s. and an average detector. The selection of the type of detector and of the transition between these detector functions is based on measurements and theoretical
14、investigations. 4.8.2 General principle of weighting the CISPR quasi-peak detector The effect on radiocommunication services depends on the type of interference (e.g. broadband or narrowband, pulse rate etc.) and on the type of service itself. The effect of the pulse rate was recognized a short time
15、 after the CISPR was founded in 1933. As a result, the quasi-peak weighting receiver for the frequency range of 150 kHz to 1 605 kHz was defined as shown for band B in Figure 4.8.1. However in CISPR 1 1 it was already accepted that “Subsequent experience has shown that the r.m.s. voltmeter might giv
16、e a more accurate assessment” but the quasi-peak type of voltmeter has been retained for certain reasons mainly for continuity. 4 TR CISPR 16-3 Amend. 2 IEC:2006(E) 1 kHz 10 100 1 32 28 24 20 16 12 8 4 0 4 8 12 34 Single pulse 43,5 dB Pulse rate Rel. input level for constant indication dB 0,15 MHz-3
17、0 MHz (band B) 9 kHz-150 kHz (band A) 30 MHz-1000 MHz (band C and D) IEC 2010/06 Figure 4.8.1 Weighting curves of quasi-peak measuring receivers for the different frequency ranges as defined in CISPR 16-1-1. The weighting factor is shown relative to a reference pulse rate (25 Hz or 100 Hz) 4.8.3 Oth
18、er detectors defined in CISPR 16-1-1 Peak detector The peak detector follows the signal at the output of the IF envelope detector and holds the maximum value during the measurement time (also called dwell time) until its discharge is forced. This indication is independent of the pulse repetition fre
19、quency (PRF). Average detector The average detector determines the linear average of the signal at the output of the IF envelope detector. It should be kept in mind that for low PRFs, CISPR 16-1-1 specifies the average detector measurement result as the maximum scale deflection of a meter with a tim
20、e constant specified for the quasi-peak detector. This is necessary to avoid reduced level indication for a pulse modulated disturbance by using long measurement times. The weighting function varies with 20 dB per decade of the PRF (see Figure 4.8.2). RMS detector The r.m.s. detector determines the
21、r.m.s. value of the signal at the output of the IF envelope detector. Despite being mentioned in 1 and being described in CISPR 16-1-1, at the time of writing of this report it has not been put to practical use in CISPR product standards. The weighting function varies with 10 dB per decade of the PR
22、F (see Figure 4.8.2). Up to now, no meter time constant applies for the r.m.s. detector for intermittent, unsteady and drifting narrowband disturbances. TR CISPR 16-3 Amend. 2 IEC:2006(E) 5 Comparison of detector weighting functions (example for bands C and D with 120 kHz bandwidth) 0 10 20 30 40 50
23、 60 70 1 10 1001 00010 000100 000 1 000 000 fp/Hz Weighting factor/dB Average RMS Quasi-Peak Peak IEC 2011/06 Figure 4.8.2 Weighting curves for peak, quasi-peak, r.m.s. and linear average detectors for CISPR bands C and D 4.8.4 Procedures for measuring pulse weighting characteristics of digital radi
24、ocommunications services All modern radio services use digital modulation schemes. This is not only true for mobile radio but also for audio and TV. Procedures for data compression and processing of analog signals (voice and picture) are used together with data redundancy for error correction. Usual
25、ly, up to a certain critical bit-error ratio (BER) the system can correct errors so that perfect reception occurs. Whereas analog radio systems require signal-to-noise ratios of as much as 50 dB for satisfactory operation, in general, digital radio communication systems allow error-free operation do
26、wn to signal-to-noise ratios of approximately 10 dB. However the transition region from error-free operation to malfunction is small. Therefore planning guidelines for digital radio are based on almost 100 % coverage. When a digital radio receiver operates at low input levels, the susceptibility to
27、radio disturbance is important. In mobile radio reception, the susceptibility to radio disturbance is combined with the problem of multi-path propagation. 4.8.4.1 Principles of measurement The significance of the weighting curve for band B in Figure 4.8.1 is as follows: to a listener the degradation
28、 of reception quality, caused by a 100-Hz pulse, is equivalent to the degradation from a 10-Hz pulse, if the pulse level is increased by an amount of 10 dB. In analogy to the above, an interference source with certain characteristics will produce a certain BER, e.g. 103 in a digital radiocommunicati
29、on system, when the interfering signal is received in addition to the radio signal. The BER will depend e.g. on the pulse repetition frequency (PRF) and the level of the interfering signal. In order to keep the BER constant, the level of the interfering signal will have to be readjusted while the PR
30、F is varied. This level variation vs. PRF determines the weighting characteristics. Measurement systems with BER indication are needed to determine the required level of the interfering signal for a constant BER as e.g. shown in Figure 4.8.3. 6 TR CISPR 16-3 Amend. 2 IEC:2006(E) BER Radio signal gen
31、erator Interference source Radio receiver IEC 2012/06 Figure 4.8.3 Test setup for the measurement of the pulse weighting characteristics of a digital radiocommunication system The test setup shown in Figure 4.8.3 consists of a radio signal generator that transmits the wanted radio signal to the rece
32、iver. For the determination of the BER, the radio receiver either has to know the original bit sequence for comparison with the detected bit sequence or the latter must be looped back to the radio signal generator for comparison with the original. Both systems are available and have been used for te
33、sts. Mobile radio testers, e.g., apply the loop-back principle. 4.8.4.2 Generation of the interference signal A signal generator with pulse-modulation capability can be used to generate the interference signal. For correct measurements, the pulse modulator requires a high ON/OFF ratio of more than 6
34、0 dB. Using the appropriate pulse width, the interference spectrum can be broadband or narrowband, where the definition of broadband and narrowband is relative to the communication channel bandwidth. Figure 4.8.4 gives an example of an interference spectrum used for the determination of weighting ch
35、aracteristics. Att. 0 dB* B 1 PK* CLRWR *RBW 9 kHz Ref. 90 dBV Center 128 MHz Span 50 MHz 5 MHz PRN 1 Marker 1 T1 61,89 dBV 128 000 000 000 MHz VBW 30 kHz SWT 3,1 s 90 80 70 60 50 40 30 20 10 0 10 IEC 2013/06 Figure 4.8.4 Example of an interference spectrum: pulse modulated carrier with a pulse dura
36、tion of 0,2 s and a PRF Zref = 204 h = 65 mm Zref = 248 h = 90 mm Zref = 270 Any two-port network may be represented using various sets of parameters; each of these gives a complete characterisation of the two-port device. Examples of two-port parameter sets are: S11, S21, S12 and S22 S-parameters:
37、four complex numbers, related to a reference impedance Zref ; A, B, C, D (ABCD matrix: 4 complex numbers); other types of two-port parameter representations are described in the literature, but do not offer any advantages in the present context. Reference planes close to the mechanical end of the CM
38、AD under test Ground plane CMAD under test Metal rod of 4 mm in diameter as test conductor 2-port device Port 2 Port 1 Reference plane Reference plane IEC 2045/06 -,-,- TR CISPR 16-3 Amend. 2 IEC:2006(E) 35 4.9.2.2 Parameters of a CMAD represented as a two-port device The performance of a CMAD can b
39、asically be defined by the four complex S-parameters when measured as a two-port device in a test jig. The test conductor in the test jig has a diameter of 4 mm. The height above the ground plane, h, is defined by the dimensions of the CMAD. These two parameters define the reference impedance, Zref,
40、 for the S-parameter measurements. If the CMAD is symmetrical, S11 and S22 have the same value. If the device is not symmetrical, the test report must describe which port was used for the S11 test (the end closed to the EUT to be used for radiated emissions measurements), or the results must be repo
41、rted for both ports of the CMAD. 4.9.2.3 Conversion between S-parameters and ABCD-parameters for a two-port network element The conversion from S-parameters to ABCD-matrix representation is given by the following equations (Zref is the reference impedance to which the S-parameters are referred): ()(
42、) 21 21122211 2 11 S SSSS A + = (4.9.1) ()() ref 21 21122211 2 11 Z S SSSS B + = (4.9.2) ()() ref 21 21122211 2 11 Z S SSSS C = (4.9.3) ()() 21 21122211 2 11 S SSSS D + = (4.9.4) The inverse equations are: DCBA S + = 2 21 (4.9.5) DCBA DCBA S + + = 11 (4.9.6) () DCBA CBDA S + = 2 12 (4.9.7) DCBA DCBA
43、 S + + = 22 (4.9.8) where ref ZBB = (4.9.9) ref ZCC= (4.9.10) NOTE All operations in preceding equations are for complex numbers. All parameters are functions of frequency. The equations are valid at each frequency point. 36 TR CISPR 16-3 Amend. 2 IEC:2006(E) 4.9.2.4 Range of variations for S11 due
44、to undefined impedance at the far end of a CMAD The apparent impedance of a two-port network element characterized by its ABCD- parameters is given by: DZC BZA Z + + = end end apparent From this equation the S11 parameter can be calculated using: ()() ()() 0end0 0end0 0apparent 0apparent apparent11
45、ZDBZZCA ZDBZZCA ZZ ZZ S + + = + = Zapparent and S11apparent are the values seen at port 1 if port 2 is connected to an impedance of Zend. Both quantities Zapparent and S11apparent are a conformal mapping of Zend, expressed as: () dZc bZa Zf + + = end end end The general form of the equation for this
46、 type of conformal mapping is: ( ) dzc bza zf + + = This type of function has the property that it transforms straight lines and circles in the z- plane into either straight lines or circles in the f-plane. In particular, if the values of z are restricted to positive real values, the transformation
47、of this half plane results in a circle in the f-plane, as shown in Figure 4.9.3. f0 f z-plane f-plane IEC 2046/06 Figure 4.9.3 Conformal mapping between z-plane and f-plane The centre of this circle is at: ()c a cdc dacb f+ = /Re2 2 0 (complex value) The radius of this circle is: TR CISPR 16-3 Amend
48、. 2 IEC:2006(E) 37 ()cdc dacb f /Re2 2 = (scalar value) The maximum value of f is then: fff+= 0 max (scalar value) The minimum value of f is then: fff= 0 min if ff 0 else 0 min =f Using these relations for Zapparent gives the following parameters: Position of the centre of the circle: () C A CDC DACB Z+ = /Re2 2 enterapparent/c (complex value) Radius of the circle: ()CDC DACB Z /Re2 2 apparent = (scalar value) Maximum value of Zapparent: apparententerapparent/c max apparent ZZZ+= Minimum value of Zapparent: apparententerapparent/c min apparent ZZZ= if apparententerapparen