The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 25, 1989
Filed:
Oct. 31, 1986
Bruce C Eastmond, Downers Grove, IL (US);
Sharon E Phillips, Lake In The Hills, IL (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A radio communications system is described in which analog voice signals are transmitted and received via single sideband amplitude modulation, and digital data signals are transmitted and received via narrowband frequency modulation in a single trunked radio system having dedicated channel bandwidths. The base station continuously transmits the FM signalling information on a dedicated control channel. The remote station transceiver initially acquires lock to the data channel FM carrier, which is then demodulated to determine the frequency of an assigned voice channel. The remote station then acquires lock to the single sideband pilot carrier on the appropriate voice channel. The controller incorporates a memory state for holding AFC for the mobile transmit frequency. In the preferred embodiment, the data channel incorporates 2400 bps FSK-FM data in a 6.25 KHz channel bandwidth, while the voice channel includes a reduced pilot carrier located below the voice band for AFC and AGC reference, and an audio subcarrier located above the voice band for low speed FM data within the same 6.25 KHz channel bandwidth.