Radio receiving apparatus for receiving communication signals of different bandwidths

• US 6,307,897 B1
• Filed: 12/08/1999
• Issued: 10/23/2001
• Est. Priority Date: 03/27/1996
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Inogai, Kazunori, Sudo, Hiroaki, Ohta, Gen-ichiro, Sasaki, Fujio
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US09/456,469
• Time in Patent Office: 685 Days
• Field of Search: 375/316, 375/324, 375/329, 375/344, 375/345, 375/348, 375/350, 370/488, 370/497, 708/300, 708/313
• US Class Current: 375/316
• CPC Class Codes: H03D 3/006 by sampling the oscillations and further processing the samples, e.g. by computing techniques H03D3/007 takes precedence
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H03D 3/009 Compensating quadrature phase or amplitude imbalances
• CPC Class Codes: H04B 1/0014 using DSP [Digital Signal Processor] quadrature modulation and demodulation
• CPC Class Codes: H04B 1/0039 using DSP [Digital Signal Processor] quadrature modulation and demodulation
• CPC Class Codes: H04B 1/26 for superheterodyne receivers multiple frequency-changing H03D7/16
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Claims

1. A radio receiving apparatus for receiving multi-band signals, comprising a plurality of channel filters connected in cascade, each of the channel filters comprising a lattice-type complex coefficient filter, a sampling frequency of each of the channel filters being decimated properly when necessary to enable reception of multi-band signals having a bandwidth ratio M, the channel filters being provided in a number obtained by rounding up a decimal portion of a number N that satisfies M=4^N.

2. The radio receiving apparatus according to claim 1, wherein the channel filters further comprise an equalizer that is commonly used by at least part of the channel filters.

3. The radio receiving apparatus according to claim 2, further comprising a root Nyquist filter provided downstream of the channel filters, for compensating for a deterioration component that is added to a Nyquist characteristic by a receiving characteristic for a desired channel.

4. The radio receiving apparatus according to claim 1, further comprising a root Nyquist filter provided downstream of the channel filters, for compensating for a deterioration component that is added to a Nyquist characteristic by a receiving characteristic for a desired channel.

5. The radio receiving apparatus according to claim 1, further comprising a first frequency offset circuit for changing the offset frequency and a second frequency offset circuit for eliminating the offset frequency.