telecom@ucbvax.UUCP (12/26/85)
I am investigating the electrical characteristics of current
telephone handsets and speakers. (It used to be easy, but these
days you can't count on having a carbon button mike and a ring-armature
earphone!) I would like to know the following.
1. Which transducers are the major suppliers of telephones for
commercial applications (such as AT&T, ITT, GTE, TIE, etc) using in their
handsets and speaker phones? Also, who are the manufacturers of
these transducer units?
2. What are the advantages and disadvantages of these newer transducers over
the standard units (carbon button and ring armature)?
3. What analog signal processing occurs in electronic telephones?
4. Where can I get technical details (such as magnitude and phase response,
harmonic distortion, and directivity) about these transducers?
On a different topic, how do PBXs, local loop circuits, and
long distance circuits affect analog voice channels. I am particularly
interested in identifying the types of circuit or switching that do
the following: (1) distort the passband frequency response, (2) distort the
envelope delay, and (3) add transient phenomena, such as impulse noise
or dropouts.
I would appreciate specific information, references, pointers, etc.
Thanks for you help.
David Burton
Entropic Processing Inc.
USENET: ...!{seismo | decvax}!epiwrl!burton
ARPANET: epiwrl!burton@seismo.ARPAtelecom@ucbvax.UUCP (01/04/86)
I hate to type, and the subject you ask about is quite complex, but if you care to call, I will try to help. You can reach me at Digitech Communications, Inc. (we manufacture telephone central office equipment). (205) 533-5941 office, (205) 882-0503 home. Call any time. Roger Atkinson