Partial band reconstruction of frequency channelized filters

• US 20040042557A1
• Filed: 11/25/2002
• Published: 03/04/2004
• Est. Priority Date: 08/29/2002
• Status: Active Grant

• Current Assignee: Callahan Cellular LLC (Intellectual Ventures LLC)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Vaccaro, Thomas R., Kabel, Allan M.
• Granted Patent: US 6,792,057 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H03H 17/0266 Filter banks
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 1/001 Channel filtering, i.e. selecting a frequency channel within the SDR system multiplexing of multicarrier modulation signals being represented by different frequencies H04L5/06; multiplexing of multicarrier modulation signals H04L5/023
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

A channelized filter design for partial band reconstruction having high dynamic range requirements. The analysis filter and synthesis filter constraints of the present invention permit high performance signal detection with an alias free signal recombination capability for signals that span multiple frequency bins. The filter bank allows the use of a single wideband asset to provide for data channelized for detection processing with the ability to recombine one or more adjacent frequency bins into a wider bandwidth baseband time domain data stream suitable for exploitation processing. The present implementation allows the use of an efficient partial band reconstruction mechanism that allows signal reconstruction using only the frequency subchannels that pertain to the signal of interest that is to be copied. The filter design mechanism separates the specification of the analysis filter to support signal detection in environments of high dynamic range. The signal reconstruction (synthesis) filter uses fewer bins and allows a higher order filter.

Claims

1. A digital channelizer for a wideband signal of K channels, comprising:

an analysis filter coupled to each of said K channels;

a Fast Fourier Transform (FFT) filter bank coupled to said analysis filter for converting each of K channels into a plurality of frequency domain subchannels;

an inverse FFT filter bank coupled to L channels from said FFT filter bank,

wherein L is less than K, and wherein said inverse FFT filter bank converts said L users to a time domain data set; and

a synthesis filter coupled to said inverse FFT filter bank performing partial reconstruction of said time domain data set.

2. The digital channelizer according to claim 1, wherein said analysis filter is a decimation unit and a polyphase filter.

3. The digital channelizer according to claim 1, wherein said synthesis filter is a polyphase filter and an expander unit.

4. The digital channelizer according to claim 1, wherein said synthesis filter uses a mean squared error signal reconstruction.

5. The digital channelizer according to claim 1, wherein said analysis filter is processed according to:

6. The digital channelizer according to claim 1, wherein said analysis filter has a stop band attenuation greater than about 90 dB.

7. The digital channelizer according to claim 6, wherein said analysis filter has a 6 dB crossover point with an adjacent channel.

8. The digital channelizer according to claim 6, wherein said analysis filter is a four fold analysis and said synthesis filter is an eight fold analysis.

9. The digital channelizer according to claim 1, wherein said reconstruction filter has a stop band attenuation greater than about 50 dB.

10. The digital channelizer according to claim 1, wherein said synthesis filter is the solution to the set of linear constraints defined as

11. The digital channelizer according to claim 1, further comprising a residual phase rotation of

12. A multirate filter bank with an analysis and synthesis filter set providing high performance signal detection with alias free recombination for signals spanning multiple frequency bins, comprising:

an analysis filter coupled to each of said K channels;

a Fast Fourier Transform (FFT) filter bank coupled to said analysis filter for converting each of K channels into a plurality of frequency domain subchannels;

an inverse FFT filter bank coupled to L channels from said FFT filter bank,

wherein L is less than K, and wherein said inverse FFT filter bank converts said L users to a time domain data set; and

a synthesis filter coupled to said inverse FFT filter bank performing partial reconstruction of said time domain data set according to a least squared fit criteria.