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:
Jan. 29, 1991
Filed:
Apr. 24, 1990
Hideho Tomita, Tokyo, JP;
NEC Corporation, , JP;
Abstract
In a demodulator for demodulating into a demodulated signal a quadrature phase modulated signal having a large varying amplitude caused by various radio transmission link conditions, a preprocessing circuit (21) logarithmically processes the envelope to produce a first preprocessed signal having a logarithmically compressed and digitized amplitude and limits the amplitude to multiple values to produce a second preprocessed signal. A phase detecting circuit (22) detects a phase difference between a reference signal having a reference frequency and the second preprocessed signal and produces a phase difference signal representative of the phase difference. A processing circuit (23) processes the first preprocessed signal and the phase difference signal to produce first and second processed signals collectively as the demodulated signal. Preferably, the processing circuit comprises an exponential processor for exponentially processing the first preprocessed signal to produce an exponentially processed signal as the first processed signal.