1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2.!4)/.!,G0G0!.!,/5%G0G0#!22)%2G0G03934%-3%.%2!,G0G0#(!2!#4%2)34)#3G0#/-/.G0G04/G0G0!,!.!,/5%G0G0#!22)%2G0G13G042!.3-)33)/.G0G03934%-3-%!352).G0G0-%4(/$3G0G02.3.2 bandstop filters (see Table 3/G.230).Note -
2、 Measuring frequencies of Table 1/G.230 and filter characteristics of Tables 2/G.230 and 3/G.230 (withthe exception of the 70-kHz filter) are the same as in CCIR Recommendations 399 1 and 482 2 and CCITTRecommendation G.228 used for line system arrangements. Annex B to Recommendation G.228 deals wit
3、h the subjectof corrections, if any, to be applied to measurements to allow for filter effects.TABLE 2/G.230Bandpass filtersCapacityLimit of bandoccupiedEffective cut-offfrequencies ofbandpass filters (kHz)Frequency bands (kHz) insideof which the discriminationshould exceed 75 dB(channels) by teleph
4、onechannels(Khz)Highpass LowpassBelow thepassbandAbove thepassbandBasic Group B 12 60- 108 61 2 107 2 6- 52 116- 1 200Basic supergroup 60 312- 552 320 8 546 10 6- 288 577- 8 500Basic mastergroup 300 812- 2 044 840 16 2 004 30 6- 412 2 318- 26 000Basic 15supergroupassembly 900 312- 4 028 320 8 4 070
5、60 6- 288 4 544- 30 000Basicsupermastergroup(15 supergroupsassembly No. 3)9009008 516- 12 3888 620- 12 3368 560 200 12 250 180 6- 7 686 13 085-135 000Above and below these bands,the discrimination may decreasewith a slope of 6 dB/octave.Fascicle III.2 - Rec. G.230 3TABLE 3/G.230Bandstop filtersa) CC
6、IR Recommendation 482 2.b) CCIR Recommendation 399 1.2.4 Measuring proceduresThe measuring procedures should comply with Recommendation G.228. Measurements must be carried outwith the regulators, if any, not included and with the levels at the nominal value.Note - Some Administrations have chosen fo
7、r groups and supergroups not being tested in conformance withTable 1/G.230 higher values of the load, but only for testing equipments with some margin to take account of theapplication where higher than nominal activity is to be expected.As a consequence, in such cases, higher noise limits have to b
8、e admitted than those indicated inRecommendation G.222, 4).3 Through-connection filters3.1 Allocation of loadingFor the measurement of noise produced by through-connection filters the values for the allocation of theconventional load according to Table 2/G.223 to the different filters are given in T
9、able 4/G.230.Centrefrequence fc(kHz)Bandwith (kHz)in relation to fcoverwhich the discriminationshould be at leastBandwith (kHz),in relation to fc outside ofwhich the discriminationshould not exceedNotes70 dB 55 dB 30dB 3dB 0.5dB70983315341 0021 2481 7303 8863 8869 07311 700 1.5 1.5 1.5 1.5 1.5 1.5 1
10、.5 1.5 1.5 1.5 1.7 1.8 2.7 3.5 4.0 4.0 4.2 1.8 15.0 2.7 3.0 2.0 2.1 4.0 7.0 9.0 11.0 14.0 3.5 30.0 5.8 7.0 5 4 17 15 27 35 48 12 110 18 20 10 9 30 48 90 110 155 100 350 250 300a)b)a)b)a)b)b)4 Fascicle III.2 - Rec. G.230TABLE 4/G.230Note 1 - Group and supergroup through-connection filters require two
11、 measurements. One with“broadband loading“ with components outside the pass-band, and an additional one with loading in thepassband only. Since in these cases the number of transmitted channels is smaller than 240 (the rangewhere the power level of the conventional load is not proportional to 10 log
12、10 n, see 2.1 ofRecommendation G.223) the proportional part of the broadband loading transmitted in the passband givesa loading which is lower than the conventional load for 12 or 60 channels respectively.Note 2 - The choice of the correct load figure for the measurement of the noise produced by the
13、 through-supermastergroup filter requires careful consideration bearing in mind that band limiting filters for abandwidth complying with actual load conditions are not available.3.2 Measuring frequenciesSee 2.2.3.3 Filter characteristicsHighpass and lowpass filters complying with Table 2/G.228 and 3
14、 can be used to limit the frequency of thenoise spectrum. For bandstop filters, see Table 3/G.230.3.4 Measuring proceduresThe measuring procedure should comply with Recommendation G.228. For through-group and through-supergroup filters, two measurements have to be carried out in the appropriate meas
15、uring slots in the passband.References1 CCIR Recommendation Measurement of noise using a continuous uniform spectrum signal on frequency-division multiplex telephony radio-relay systems, Vol. IX, Rec. 399, Dubrovnik, 1986.2 CCIR Recommendation Measurement of performance by means of a signal of a uni
16、form spectrum for systemsusing frequency-division multiplex telephony in the fixed satellite service, Vol. IV, Rec. 482, Dubrovnik, 1986.3 CCIR Recommendation Measurement of performance by means of a signal of a uniform spectrum for systemsusing frequency-division multiplex telephony in the fixed sa
17、tellite service, Vol. IV, Rec. 482, Table I,Dubrovnik, 1986.Filter for the basic Band of the noisespectrum (kHz)level of the noise power(dBm0)Group12 to 25260 to 108+ 6.1 ( =60 channels)+ 3.3 (=12 channels)Supergroup 60 to 1 296316 to 552+ 9.8 (=300 channels)+ 6.1 (=60 channels)Mastergroup316 to 2 600+ 12.3 (=530 channels)Supermastergroup 4 370 to 17 300+ 17.6 (=1800 channels)15 supergroupassembly 316 to 8 160+ 17.6 (=1800 channels)
