GB1175740A - Method and device for Measuring the Reference Equivalent or Articulation of Telephone Sets - Google Patents

Abstract

1,175,740. Testing telephone transducers. TESLA NARODNI PODNIK. 5 May, 1967 [18 May, 1966], No. 20992/67. Heading H4J. Characteristics of the transducers of telephone sets are measured by apparatus comprising a signal generator 1 energizing at least two parallel connected filters 2, 3. Where two filters are used, one. may pass frequencies below 1000 c/s. and the other above 1000 c/s. Two band pass filters having frequency ranges of 200 to 1000 c/s. and 1000 to 4000 c/s. may alternatively be used. Alternatively there may be four parallel filters having bands of 200 to 450 c/s., 450 to 850 c/s., 850 to 1900 c/s. and 1900 to 4000 c/s. or bands of 200 to 850 c/s. 850 to 1600 c/s., 1600 to 2300 c/s. and 2300 to 4000 c/s. A switch 4 cyclically connects all the filters to a switch 5 in a period of one second. Contact a connects the signal to an amplifier 6 from where it is converted to sound in an artificial mouth 7. The microphone 8 of a telephone set 9 converts this sound to an electrical signal and, through contact c of a switch 14, its characteristics are shown on a meter 15. Contact of switch 5 connects the filter signal to a telephone set 10 having a receiver 11. Sound from the receiver 11 is picked up by an artificial ear 12, the electrical output of which is amplified in an amplifier 13 and, through contact d, is applied to the meter 15. The switches 5, 14 may be mechanical or electronic.