Title: Radio communication transmitter

Abstract: A multi-channel radio communication system comprising a number of stations for the transmission of speech between the stations, each station transmitting not only the speech signal but also a special so-called busy signal located in a frequency band beyond the speech frequency band, which busy signal informs the remaining stations in the group of which are not occupied by a call to another station that the actual carrier frequency or channel is occupied and cannot be selected for a new connection. According to the invention the busy signal is automatically controlled in amplitude as a function of the instantaneous value of the speech signal and this in such a manner that the envelope of the combination of the speech signal and the busy signal is maintained substantially constant so that as a result of the normal interruptions in a conversation the busy signal will be automatically and repeatedly adjusted to full amplitude.

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Inventors: Lunden, Peter L:Son (Jarfalla, SW)

Application Number: 443974
Filing Date: 1974-02-20
Publication_date: 1976-02-10
Assignee: U.S. Philips Corporation (New York, NY)
Primary Class(es): 455/528 332/119, 370/480, 370/527, 455/70
Other Classes:
US Patent Ref:

3376509	Apr, 1968	Willcox et al.	325/57.
3452156	Jun, 1969	Engelbrecht	179/15.
3477042	Nov, 1969	Wachs	332/16.
3617892	Nov, 1971	Hawley et al.	325/145.

Other Refs:
Primary Examiner: Safourek, Benedict V.
Assistant Examiner: Bookbinder, Marc E.
Attorney: Trifari; Frank R., Steckler; Henry I.