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US 4,727,594 AGranted
Universal land mobile receiver IF system
AssigneeMotorola, Inc.
InventorJohn S. Ruppel
Life of this patent
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Abstract
An IF system that makes satisfactory use of a first IF stage frequency selected from between 108 MHz and 132 MHz to thereby provide an IF system that can be utilized in radios intended for reception in all land mobile frequency bands. The first IF stage (17) includes a high tolerance crystal filter (24) that contributes to the satisfactory reception performance of a radio so equipped.
Claims10
A radio receiver having:
- input means for receiving radio frequency signals comprising a carrier frequency signal and an information signal modulated therewith;
- preselector means for receiving said radio frequency signals from said input means and for providing a frequency selective signal based upon a desired carrier frequency signal, wherein said carrier frequency signal may be any frequency preselected from between 30 MHz to 50 MHz, 66 MHz to 88 MHz, 132 MHz to 174 MHz, 403 MHz to 512 MHz, 851 MHz to 870 MHz, and 935 MHz to 941 MHz;
- and
- first intermediate frequency means for receiving said frequency selective signal and for converting said carrier frequency signal component of said radio frequency transmitted information to a first preselected intermediate frequency;
- wherein said first preselected intermediate frequency has a value between 108 MHz and 132 MHz regardless of the frequency of said carrier frequency signal.
2 more elements
A method of receiving radio frequency signals comprising a carrier frequency signal and an information signal modulated therewith, comprising the steps of:
- (A) preselecting said radio frequency signals and providing a frequency selective signal based upon a desired carrier frequency signal, wherein said carrier frequency signal may be any frequency preselected from between 30 MHz to 50 MHz, 66 MHz to 88 MHz, 132 MHz to 174 MHz, 403 to 512 MHz, 851 MHz to 870 MHz, and 935 MHz to 941 MHz;
- (B) converting said carrier frequency selective signal to a first preselected intermediate frequency, wherein said preselected intermediate frequency has a value between 108 MHz and 132 MHz, regardless of the frequency of said carrier frequency signal;
- (C) further processing said first preselected intermediate frequency to retrieve said information signal.
Dependencies are inferred from the claim text.