Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Publication of NL76813CpublicationCriticalpatent/NL76813C/xx
H03G3/00—Gain control in amplifiers or frequency changers
H03G3/20—Automatic control
H03G3/22—Automatic control in amplifiers having discharge tubes
H03G3/24—Control dependent upon ambient noise level or sound level
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04M—TELEPHONIC COMMUNICATION
H04M9/00—Arrangements for interconnection not involving centralised switching
H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
