Title: Radio communication transmitter

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Claims: What is claimed is:

1. A radio transmitter comprising:

means for providing a speech signal in a selected band,

means for generating a busy signal outside of said selected band,

means for adding said speech and busy signals to provide a sum signal,

envelope signal producing means responsive to at least said speech signal to provide an envelope signal which varies with the instantaneous speech amplitude,

means for varying the amplitude of said busy signal in accordance with said envelope signal to provide said sum signal at constant amplitude,

means for transmitting said constant amplitude sum signal in a single selected channel.

2. A transmitter as claimed in claim 1, wherein said envelope producing means is coupled to an output of said adding means and to said varying means.

3. A transmitter as claimed in claim 1 further comprising means for generating a switching signal located in another frequency band other than the frequency band available for the speech information signal and the busy signal, and a second means for adding said switching signal to the sum signal.
Other info:

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.