Intermediate frequency FM receiver using analog oversampling to increase signal bandwidth

A radio receiver for receiving a selected FM signal in which a message signal A(t) modulates the frequency of a carrier signal, said radio receiver comprising:

• a local oscillator for producing a local oscillator signal;
• a heterodyning stage for heterodyning said selected FM signal with said local oscillator signal so as to reduce the frequency which is modulated by said message signal to an intermediate frequency;
• and,
• a demodulator stage for accepting an output signal from said heterodyning stage and extracting said message signal therefrom;
• wherein said heterodyning stage comprises:
• signal producing means for producing n signals a.sub.1 . . . a.sub.n wherein each of said n signals consists of said message signal A(t) modulated at said intermediate frequency, and said n signals a.sub.1 . . . a.sub.n are related by the expression
• a.sub.i =cos {.omega..sub.IF t+k.sub.f .intg..sup.t A(t)*dt+.OMEGA.+.pi.*(.sup.i /n)}
• where .omega..sub.IF, k.sub.f and .OMEGA. are constants, n is a positive integer greater than or equal to 2 and i takes the values of all positive integers up to and including n, and
• multiplier means for multiplying said n signals together and thus producing said heterodyning stage output signal wherein said message signal A(t) is modulated at a frequency of n times said intermediate frequency.