These references contain additional information relating to transmission and speech quality measurements. It is assumed that the reader is conversant with the ETSI TETRA specifications.
ETSI permit you to download a limited number of specifications for free at http://www.etsi.org/. ITU are a bit behind the times and insist you pay lots of money to look at anything. You can find them at http://www.itu.int/. Another extremely useful site is the IETF http://www.ietf.org/. They are the source of all the Internet Standards and assigned numbers (follow the links to IANA).
"Transmission and Multiplexing (TM); DECT Transmission aspects 3,1 kHz telephony Interworking with other networks"
This describes the DECT transmission plan and discusses interoperation with the various European national telecommunications systems. See also EN300176-2 part 2: speech.
"Planning of loudness rating and echo values for private networks digitally connected to the public network"
This specifies echo loss (TETRA needs echo cancellation), minimum stability margin and loudness ratings for connection to the public network.
"Digital cellular telecommunications system (Phase 2+); Transmission planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) system"
This describes the transmission plan for the GSM system and specifies what levels the system performance shall meet. It has several informative and normative annexes which describe how the requirements shall be tested. See also GSM 11.10-1 (EN300607-1) chapter 30.
"Assumptions for the calculation of noise on hypothetical reference circuits for telephony"
Defines noise weighting and levels used for telephone measurements.
"Pulse Code Modulation (PCM) of voice frequencies"
This describes the encoding and decoding of A-Law and M-Law CODECs.
"Transmission performance charactistics of pulse code modulation channels"
This describes the physical charactistics of the PCM system. The section on adjustment of relative levels is relevant.
"International telephone connections and circuits - General charactistics of the 4-wire chain formed by the international circuits and national extension circuits - Control of talker echo"
This describes the effects of echo on the user and presents a set of figures for the maximum echo which can be tolerated by the talker for different round trip delays. It also covers the use of echo suppressors and echo cancellers.
"Echo Cancellers"
Defines the requirements for echo cancellers as used on the PSTN network.
"Locally Generated Information Tones"
This defines the set of standardised tones which may be generated by the PSTN.
"Effect of transmission impairments"
Describes (at great length) the effects of the transmission channel effects, it presents a matrix covering all the major impairments.
"Withdrawn - see P.340"
"Artificial Mouth"
Describes the reference sound source used for acoustic measurements.
"Artificial Ears"
Describes the requirements for the artificial ear as used for making acoustic measurements.
"Determination of sensitivity/frequency charactistics of local telephone systems"
This describes how the acoustic sensitivity of a telephone handset is measured. It defines the reference points when making measurements. See also P51 - Artificial mouth and P.57 Artificial Ear.
"Calculation of Loudness Ratings for telephone sets"
This specifies the method of calculation for loudness ratings.
"Transmission charactistics of hands-free telephones"
Contains a set of recommendations relating to the operation of hands-free telephones.
"Harmonization of the laws of member states relating to electrical equipment designed for use within certain voltage limits"
Although this specification relates to electrical hazards it is sufficiently broad in its scope as to include acoustic shock and other hazards.
Copyright ©2002 Andy Fletcher andy@x31.com