1、ELECOMMUNICATION STANDARD LETS 300 380 March 1995 Source: ETSI TC-TE Reference: DI/TE-04025 UDC: 621.39 Key words: UPT, DTMF, Acoustical coupling Universal Personal Telecommunication (UPT); Access devices Dual Tone Multi Frequency (DTMF) sender for acoustical coupling to the microphone of a handset
2、telephone ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: 06921 Sophia Antipolis Cedex - FRANCE Office address: Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE Tel.: +33 92 94 42 O0 - Fax: +33 93 65 47 16 European Telecommunications Standards Institute
3、 1995. All rights reserved. No part may be reproduced except as authorised by written permission. The copyright and the foregoing restriction on reproduction extend to all media in which the information may be embodied. ETSI I-ETS+300 380 95 3400855 0020688 634 ETSI I-ETSU300 380 95 3Y00855 0020689
4、570 Page 2 LETS 300 380: March 1995 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Standards Approval Dept.“ at the address
5、 shown on the title page. ETSI I-ETS*300 380 95 3400855 0020670 292 Page 3 LETS 300 380: March 1995 Contents Foreword . 5 1 Scope . 7 2 Normative references 7 3 Abbreviations . 7 4 Transmission requirements . 8 4.1 Signalling frequencies . 8 4.2 Transmission levels 8 4.3 Duration . 8 4.3.1 Manually
6、controlled sending 8 4.3.2 Automatic controlled sending 8 Unwanted frequency components . 9 4.4 5 Test specification 9 5.1 General . 9 5.2 Frequencies . 9 5.3 Transmission levels 9 5.4 Duration . 9 5.5 Unwanted frequency components . 9 Annex A (normative): Test arrangement 10 A.l IEC 31 8 coupler/fl
7、at plate arrangement 10 Annex B (informative): Comments on acoustic coupling 11 B.l Output level . 11 B.2 Unwanted signals . 11 B.3 Test setup . 11 B.4 Level difference 11 Annex C (informative): Bibliography 12 History 13 ETSI I-ETS*300 380 95 m 3400855 0020693 129 m Page 4 LETS 300 380: March 1995
8、Blank page ETSI I-ETS*300 380 95 3400855 0020b2 Ob5 W Page 5 LETS 300 380: March 1995 Foreword This Interim European Telecommunication Standard (I-ETS) was produced by the Terminal Equipment (TE) Technical Committee of the European Telecommunications Standards Institute (ETSI). An ETSI standard may
9、be given LETS status either because it is regarded as a provisional solution ahead of a more advanced standard, or because it is immature and requires a “trial period“. The life of an LETS is limited to three years after which it can be converted into an ETS, have its life extended for a further two
10、 years, be replaced by a new version, or be withdrawn. Proposed announcement date Date of latest announcement of this LETS (doa): 30 June 1995 i Blank page ETSI I-ETS*3OO 380 75 3400855 0020674 938 Page 7 I-ETS 300 380: March 1995 1 Scope This I-ETS defines the tone generating and acoustical charact
11、eristics of a one-way (sending) Universal Personal Telecommunication (UPT) access device of Dual Tone Multi Frequency (DTMF) type to be acoustically coupled to the mouthpiece of a telephone set. The characteristics specified have been chosen to conform to the transmission requirements as specified i
12、n ETS 300 001 and, therefore, to be generally acceptable for use in the Public Switched Telephone Network (PSTN) and Integrated Services Digital Network (ISDN). The LETS specifies a test arrangement to verify conformance. It is not possible to standardize the physical dimensions for efficient acoust
13、ic coupling because of the wide variety of handset types in use in Europe. When using a device conforming to this I-ETS, the electrical level to the network will depend on the characteristics of the telephone set to which it is acoustically coupled. Annex B to this LETS indicates the variation level
14、 that could be expected. A worst case scenario is that a device conforming to this LETS will not ensure proper functioning. NOTE: The specification of the functional requirements of the device is outside the scope of this I-ETS. Information about functional requirements can be found in prETS 300 391
15、-1. 2 Normative references This I-ETS incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of
16、any of these publications apply to this I-ETS only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. IEC 318: “An IEC artificial ear, of the wideband type, for the calibration of earphones used in audiometry“. 3 Abbrev
17、iations For the purposes of this I-ETS, the following abbreviations apply: DTMF ISDN PSTN SLR SPL U PT Dual Tone Multi Frequency Integrated Services Digital Network Public Switched Telephone Network Sending Loudness Rating Sound Pressure Level Universal Personal Telecommunication ETSI I-ETSx300 380
18、75 3400855 0020695 874 Page 8 I-ETS 300 380: March 1995 4 Transmission requirements 4.1 Signalling frequencies The 16 dual tone frequency combinations assigned to digits or special signalling characters are shown in the matrix given in table 1. Table 1 : Signalling frequency combinations Low group (
19、Hz) High group IHz 1209 I 1336 I 1477 I 1633 697 770 1 2 3 A 4 5 6 B The device shall use either 12 or 16 frequency combinations. In the case of 12 combinations the frequencies assigned to A, B, C and D shall not be used. The accepted tolerance on the frequencies as specified in table 1 shall be 1,5
20、 %. Compliance shall be checked using the test described in subclause 5.2. 4.2 Transmission levels The device shall not produce more than -12 dBPa Sound Pressure Level (SPL) for all the tone combinations that can be generated. NOTE: The operation condition of the DTMF receivers may, as a signal dete
21、ction condition, require that the difference in the levels of the received two signalling frequencies be less than 6 dB (see also annex B, clause B.4). Compliance shall be checked using the tests described in subclause 5.3. 4.3 Duration 4.3.1 Manually controlled sending If the output signal of the s
22、ending device is manually controlled, the duration of any individual tone combination, and of the pause between the tone combinations, shall relate directly to the actuation of the pushbutton. NOTE: If two or more buttons are pressed at the same time, only one tone combination, or no tone combinatio
23、n at all, should be sent to the line. Compliance shall be checked using the test described in subclause 5.4. 4.3.2 Automatic controlled sending If the time characteristics of the sending device are controlled by the device, the duration of any individual tone combination shall be greater than 70 ms,
24、 and the pause between the tone combinations shall also be greater than 70 ms. NOTE 1: If two or more buttons are pressed at the same time, only one tone combination, or no tone combination at all, should be sent to the line. For automatic controlled sending it is desirable that the duration of the
25、signal and the pause length is limited. ETC 300 001, Chapter 5, subclause 5.4.7.2 gives guidelines on suitable values. NOTE 2: 852 94 1 7 8 9 C O # D * ETSI I-ETS*300 380 95 m 3400855 0020bb 700 m Page 9 LETS 300 380: March 1995 Compliance shall be checked using the test described in subclause 5.4.
26、4.4 Unwanted frequency components When transmitting any tone combination, the total power level of all unwanted frequency components over the bandwidth 300 Hz to 3 400 Hz shall be at least 20 dB below the low frequency or the high-frequency component, whichever is the lowest. Compliance shall be che
27、cked using the test described in subclause 5.5. 5 Test specification 5.1 General For all measurements, the device under test shall be placed on an artificial ear according to IEC 318 I fitted with a flat plate mounted on the artificial ear. The test arrangement is defined in annex A. The device is p
28、ressed tightly to the plate with the transmitter opening centered to the artificial ear. The device is then moved to find the position where the largest output signal from the artificial ear is found. The measurements shall be carried out with the device in this position. The measurements shall be c
29、arried out with fresh batteries. 5.2 Frequencies The frequencies shall be measured for each output signal (each character) with a suitable measuring instrument. 5.3 Transmission levels The total signal level shall be measured for each output signal (character) with a suitable measuring instrument. 5
30、.4 Duration The duration of each output signal (character), and the pause between the signals, shall be measured with a suitable measuring instrument. 5.5 Unwanted frequency components The total level of the frequency components, excluding the DTMF tone combinations, shall be measured with a suitabl
31、e measuring equipment. The level of the low-frequency component and the high-frequency component shall be measured separately with a suitable measuring instrument. Additional information about the measurement technique can be found in ETS 300 001, Chapter 5, subclause 5.4. ETSI I-ETSa300 380 95 = 39
32、00855 0020697 647 Page 10 LETS 300 380: March 1995 Annex A (normative): Test arrangement A. 1 IEC 31 8 coupler/flat plate arrangement Coupler + Knife-edge of /:%cai ear Flat platform Cross-section -1 60 Top view Figure A.l ETSI I-ETS*300 380 95 3400855 0020698 583 Page 11 LETS 300 380: March 1995 An
33、nex B (informative): Comments on acoustic coupling B.l Output level Measurements on a number of acoustic DTMF devices connected to a number of different two piece linear telephone sets with conventional types of handsets (according to the principles set out in CCITT Recommendation P.35 (“Handset tel
34、ephones“) show a total spread in output level of about 20 dB, if the telephone sets are normaliced to the same sending sensitivity (Sending Loudness Rating (SLR). The requirement in subclause 4.2 is based on the fact that the most sensitive combination acoustic deviceltelephone set according to thes
35、e measurements gives a signal level to the line of not more than -7 dBm for SLR = -1 dB. The line level of -7 dBm corresponds to the DTMF sending level, option 1, as specified in ETS 300 001. The value SLR = -1 dB corresponds to the nominal value of the most sensitive telephone set that can be found
36、 throughout Europe. As a consequence, the different combinations acoustic device/telephone set gives an output level to the line in the range -7 dBm to -27 dBm. If the spread in SLR between different feeding conditions and different countries also is considered, the expected range will probably be a
37、round -7 dBm to -35 dBm. If the tolerances from the nominal value for individual telephone sets also is considered the spread may even be a little bit wider. If the specification is based on the worst case principle a variation in the output level (taking into account all possible causes of variatio
38、n) from -5 dBm to -40 dBm may be expected. For telephone sets with a peculiar shape, and especially for one piece telephone sets, the output level can be even tower. For many one piece telephone sets the hook function prevents the acoustic device from being fitted in a suitable position. B.2 Unwante
39、d signals There is no requirement on unwanted signals outside the speech band. The reasons are that the acoustic coupler itself probably produces reasonable low signal levels, especially at frequencies above 10 kHz, and that the telephone itself acts as a rather steep filter above approximately 4 kH
40、z. The corresponding requirements for the DTMF function in terminals are to be found in ETS 300 001, Chapter 5, subclause 5.4.5. B.3 Test setup The test setup, including an artificial ear with a defined cavity, is intended to be used for measurements of the receiving characteristics of circumaural e
41、arphones, and is not a perfect tool to measure the electroacoustic characteristics of a device transmitting DTMF tones. However, practical measurements have shown that the proposed test device can give reproducible results. The actual test device is considered to be a temporary solution until a more
42、 suitable device has been designed. B.4 Level difference There is no requirement on the difference between the level of the high and the low frequency component. Devices giving the same difference between the two tones measured with the IEC coupler usually do not give the same difference between the
43、 tones in real use with telephone sets. However, for most couplers, it seems reasonable that the level of the low frequency tone should be 2 dB - 3 dB higher than the level of the high frequency tone (measured with the IEC 318 Il coupler) to give the best performance for most telephone sets. ETSI I-
44、ETSx300 380 95 3400855 0020699 4LT W Page 12 LETS 300 380: March 1995 Annex C (informative): Bibliography The following documents are referenced informatively by this LETS: 1) CCITT Recommendation P.35: “Handset telephones“. 2) prETS 300 391 -1 : “Universal Personal Telecommunication (UPT) - Specifi
45、cation of the security architecture for UPT phase 1 - Part 1: Specification“. ETS 300 O01 : “Attachments to Public Switched Telephone Network (PSTN) - General technical requirements for equipment connected to an analogue subscriber interface in the PSTN (Candidate NET 4)“. 31 ETSI I-ETS*300 380 95 3400855 O020700 TbL Page 13 I-ETS 300 380: March 1995 March 1995 History First Edition Document history ISBN 2-7437-01 02-1 Dpt lgal : Mars 1995
