1、 ETSI ES 201 235-3 V1.3.1 (2006-03)ETSI Standard Access and Terminals (AT);Specification of Dual-Tone Multi-Frequency (DTMF) Transmitters and Receivers;Part 3: ReceiversETSI ETSI ES 201 235-3 V1.3.1 (2006-03) 2 Reference RES/AT-010127 Keywords DTMF, PSTN, signalling ETSI 650 Route des Lucioles F-069
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6、oing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2006. All rights reserved. DECTTM, PLUGTESTSTM and UMTSTM are Trade Marks of ETSI registered for the benefit of its Members. TIPHONTMand the TIPHON logo are Trade Marks currently being registered by
7、 ETSI for the benefit of its Members. 3GPPTM is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. ETSI ETSI ES 201 235-3 V1.3.1 (2006-03) 3 Contents Intellectual Property Rights4 Foreword.4 1 Scope 5 2 References 5 3 Definitions, symbols and abbr
8、eviations .5 3.1 Definitions5 3.2 Symbols6 3.3 Abbreviations .6 4 DTMF receiver.6 4.1 Area of application .6 4.2 Operate and non-operate requirements.7 4.2.1 Signal condition requirements 7 4.2.1.1 Valid signal for an analogue receiver7 4.2.1.2 Invalid signal for an analogue receiver .8 4.2.1.3 Vali
9、d signal for a digital receiver8 4.2.1.4 Invalid signal for a digital receiver .9 4.2.2 Digit Recognition Condition (DRC) requirements .9 4.3 Speech immunity performance.10 4.4 Electrical characteristics.10 Annex A (normative): Speech immunity test signal11 Annex B (informative): Example test signal
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12、ursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present
13、document. Foreword This ETSI Standard (ES) has been produced by ETSI Technical Committee Access and Terminals (AT). The present document is part 3 of a multi-part deliverable covering the Specification of Dual-tone Multi-Frequency (DTMF) Transmitters and Receivers, as identified below: Part 1: “Gene
14、ral“; Part 2: “Transmitters“; Part 3: “Receivers“; Part 4: “Transmitters and Receivers for use in Terminal Equipment for end-to-end signalling“. ETSI ETSI ES 201 235-3 V1.3.1 (2006-03) 5 1 Scope The present document specifies the Dual-tone Multi-Frequency (DTMF) signalling system. The various parts
15、of ES 201 235 1 provide a complete set of requirements for applications intending to use DTMF signalling. The present document is intended to provide the level of detail that will enable manufacturers of telecommunications equipment incorporating DTMF signalling, to design the equipment such that it
16、 facilitates highly reliable signalling. This should not be taken to imply that any DTMF signalling system that fails to meet all the criteria described in the present document will not provide reliable signalling. The present document is not intended to be used for the definition of regulated inter
17、faces. The present document covers the requirements for the DTMF receiver for the case of DTMF signalling over the local loop. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. References are either specific
18、(identified by date of publication and/or edition number or version number) or non-specific. For a specific reference, subsequent revisions do not apply. For a non-specific reference, the latest version applies. Referenced documents which are not found to be publicly available in the expected locati
19、on might be found at http:/docbox.etsi.org/Reference. 1 ETSI ES 201 235 (all parts): “Access and Terminals (AT); Specification of Dual-tone Multi-Frequency (DTMF) Transmitters and Receivers“. 3 Definitions, symbols and abbreviations 3.1 Definitions For the purposes of the present document, the follo
20、wing terms and definitions apply: Digit Recognition Condition (DRC): output state of the receiver in response to a valid input signal when the relevant signal condition and time requirements are satisfied high group: signalling frequencies, which have nominal values of 1 209 Hz, 1 336 Hz, 1 477 Hz a
21、nd 1 633 Hz low group: signalling frequencies, which have nominal values of 697 Hz, 770 Hz, 852 Hz and 941 Hz Valid Signal Condition (VSC): state of the line at the input of the receiver when: 1) one of the frequency combinations specified in ES 201 235-1 is present and; 2) the frequencies are withi
22、n the tolerances specified in clauses 4.2.1.1 and 4.2.1.3, item a); and 3) the signalling levels are within the range of acceptable levels specified in clauses 4.2.1.1 and 4.2.1.3, items b) and c); and ETSI ETSI ES 201 235-3 V1.3.1 (2006-03) 6 4) any unwanted frequencies are within the limits as spe
23、cified in clause 4.2.1.1 and 4.2.1.3, items i) to iii) of ES 201 235-3. 3.2 Symbols For the purposes of the present document, the following symbols apply: The Star on the standard 3x4 keypad array, also known as the asterisk # The Square on the standard 3x4 keypad array, also known as the hash, shar
24、p, or number sign (“pound“ in the USA) dBm0 Power level expressed in decibels relative to 1 mW in a 0 dBr level reference point dBV Absolute voltage level expressed in decibels relative to 1 volt 3.3 Abbreviations For the purposes of the present document, the following abbreviations apply: CLI Calli
25、ng Line Identification DRC Digit Recognition ConditionDTMF Dual-tone Multi-Frequency HPF High Pass Filter LPF Low Pass Filter PBX Private Branch eXchange R Rectifiers SPF Single Pole Filter STF Single Tone Filter TC Threshold Comparator TE Terminal Equipment VSC Valid Signal Condition 4 DTMF receive
26、r 4.1 Area of application The present document describes the properties of the DTMF receiver function for terminal and for network equipment. The receiver shall respond to signals received over a line from a distant transmitter conforming to parts 1 and 2 of this multi-part deliverable. The receiver
27、 shall be equipped to recognize the sixteen signals designated 0 to 9, *, #, A, B, C and D. The system may be utilized with only, ten discrete signals, in which case the signals designated 0 to 9 should be used; or with twelve discrete signals, in which case the signals 0 to 9, *, # should be used.
28、In the interests of system security, the receiver may be conditioned to recognize only specific digits from the complete set of sixteen digits. NOTE: The principal uses of the receiver as dealt with in the present document are expected to be: a) in a local exchange for receiving DTMF signals from a
29、TE (e.g. for dialling); b) in a local exchange for receiving DTMF signals from a PBX (e.g. for dialling); c) in a PBX for receiving DTMF signals from a TE (e.g. for dialling); d) in a PBX for receiving DTMF signals from a local exchange (e.g. for Direct Dialling -In or CLI); e) in a TE for receiving
30、 DTMF signals from a local exchange (e.g. for CLI); f) in a TE for receiving DTMF signals from a PBX (e.g. for CLI); g) in a PBX for receiving DTMF signals from another PBX (e.g. for dialling or CLI). ETSI ETSI ES 201 235-3 V1.3.1 (2006-03) 7 A DTMF receiver or receiver function can be either analog
31、ue, i.e. intended for connection to an analogue point in the network, or digital, i.e. intended for connection to a digital point in the network. Figure 1 shows typical usage in a local exchange or a PBX. RdD/AA/DDRaLocal exchange or PBXAARdRaDA: Analogue transmission path A/D: Analogue to Digital c
32、onverter D: Digital transmission path D/A: Digital to Analogue converter Ra: Analogue DTMF receiver Rd: Digital DTMF receiver Figure 1: Reference configuration 4.2 Operate and non-operate requirements 4.2.1 Signal condition requirements The following clauses define the conditions under which the DTM
33、F function shall decide to indicate or not indicate to the host equipment the digit that is represented by a received signal. There will be some conditions that fall into neither of these two states and the designer of the DTMF function can make their own decision whether such signals are best consi
34、dered valid or not valid. 4.2.1.1 Valid signal for an analogue receiver The received DTMF signal shall be detected as valid when only two of the signalling frequencies are present at the receiver input, one from the high group and one from the low group which meet the conditions described in items a
35、) to c): a) each of these signalling frequencies is within (1,5 % + 2 Hz) of the nominal value; b) the level of each of these two signalling frequencies is within the range -28 dBV to -3 dBV; and c) the difference in level of these two signalling frequencies is not more than 6 dB. The received DTMF
36、signal shall also be detected as valid even if accompanied by other frequency components not exceeding: i) in the frequency range 15 Hz to 500 Hz; an individual signal level of +21 dBV at 15 Hz to 33 Hz with the limit then falling at 20 dB per octave until 300 Hz and from 300 to 500 Hz a level of 5
37、dBV. The last requirement is aimed to protect the DTMF receiver against dial tone; ii) in the frequency range 500 Hz to 3 400 Hz; a total voltage level of 20 dB below the level of the low group signalling frequency; iii) at frequencies over 3 400 Hz; an individual signal level of -36 dBV at 3 400 Hz
38、 rising at 6 dB per octave to a level of +10 dBV. NOTE 1: Old equipment operating under previous regimes in certain countries was permitted a frequency tolerance of 1,8 %. Where network operators need to continue support for such TE, the frequency tolerance for the receiver will need to be extended
39、to (1,8 % + 2 Hz). NOTE 2: In item b), a dynamic range of 25 dB is specified to take into account tolerances in the send levels of the DTMF transmitter and also variations in attenuation found in the local lines of the various networks. ETSI ETSI ES 201 235-3 V1.3.1 (2006-03) 8 NOTE 3: It is pointed
40、 out that some networks may require protection to cover interference from specified sources, e.g. meter pulses. This may be in addition to that specified in item iii). NOTE 4: Equipment receiving DTMF signals in a high impedance state, as in the case of CLI, the level of each one of the two tones ca
41、n be as high as 0 dBV. 4.2.1.2 Invalid signal for an analogue receiver The received DTMF signal shall be considered as invalid if any of the conditions given in items a) to c) are satisfied at the receiver input: a) the signal levels are correct for valid signals but more than two of the signalling
42、frequencies are present; or b) the level of the signalling frequency in the low group is less than -36 dBV; or c) the level of the signalling frequency in the high group is less than -36 dBV. As an aid to the understanding of clauses 4.2.1.1 and 4.2.1.2, table 1 is given. Table 1: Signal condition r
43、equirements Signal condition Frequency deviation (Hz) Signal level x (dBV) Signal level difference y (dB) Unwanted frequencies z (dBV) Valid (1,5 % + 2) -28 x -3 y (1,5 % + 2) -36 x -3 y 6 z Not valid x (1,5 % + 2) -36 x -4 y 6 z Not valid x 40 ms Shall cease Not VSC 40 ms May exist 20 ms VSC 40 ms
44、May cease 20 ms Not VSC 40 ms Shall not exist VSC 20 ms Shall not cease Not VSC 20 ms * or optionally a different digit recognition condition Legend: VSC The continuous existence of a valid signal condition. Not VSC The continuous non-existence of valid signal condition. DRC The existence of digit r
45、ecognition condition. Not DRC The non-existence of digit recognition condition. 4.3 Speech immunity performance The receiver should not perform more than 46 false operations per 100 speech hours at a long term active speech level of -13 dBV at analogue receivers and -13 dBm0 at digital receivers. A
46、speech hour is defined as a total duration of one hour when speech (in both directions) may, be present, that is when the circuit is seized and the call established (conversation condition). NOTE 1: In addition to the simulation of signals by speech entering via the microphone, misoperation may also
47、 be caused by disturbances preventing detection of valid signals and/or splitting them into double digits. The design of a receiver with very high rejection efficiency against signal imitation might lead to an intolerable increase in the number of blockings. The general design aim should be to limit
48、 both types of misoperation (imitation and blocking) to a total level not exceeding one per 10 000 digits dialled. NOTE 2: The duration of 100 hours has been given as the recommended test duration but sufficient accuracy can be achieved by using 10 speech hours, which can be further reduced by apply
49、ing the time compression procedure described in annex A. For test of the speech immunity performance or for comparison between different receivers the test specified in annex A can be used. 4.4 Electrical characteristics NOTE: The electrical characteristics of the interface will be determined by the apparatus into which the function of the DTMF Receiver has been incorporated. ETSI ETSI ES 201 235-3 V1.3.1 (2006-03) 11Annex A (normative): Speech immunity test signal The speech immunity performance of the receiver is tested by mea
