Demodulation method and apparatus incorporating charge coupled devices

• US 5,126,682 A
• Filed: 03/18/1991
• Issued: 06/30/1992
• Est. Priority Date: 10/16/1990
• Status: Expired due to Term

• Current Assignee: Exelis Incorporated (L3Harris Technologies, Inc.)
• Original Assignee: Stanford Telecommunications, Inc. (Nokia Corporation)
• Inventors: Urban, Daniel, Weinberg, Aaron, Cunningham, Kenneth
• Primary Examiner(s): MIS, DAVID C
• Application Number:
  US07/670,810
• Time in Patent Office: 470 Days
• Field of Search: 329/304, 329/306, 329/310, 375/52, 375/53, 375/54, 375/55, 375/56, 375/57, 375/80, 375/83, 375/84, 375/85, 375/86, 375/87
• US Class Current: 329/304
• CPC Class Codes: H03D 2200/0062 Computation of input samples, e.g. successive samples
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H03D 3/22 by means of active elements with more than two electrodes to which two signals are applied derived from the signal to be demodulated and having a phase difference related to the frequency deviation, e.g. phase detector
• CPC Class Codes: H04L 27/2334 using filters

Abstract

A demodulator apparatus for demodulating a data bearing broadcast signal in the absence of mixers and without incurring quantization errors. The apparatus incorporates a receiver for receiving a broadcast signal and producing therefrom a predetermined intermediate carrier frequency (F_IF), transversal filter connected to receive the intermediate carrier frequency F_IF has N active stages and tap weight means at each of said stages for entering a tap weight sequence to yield maximum correlation energy when desired alignment occurs to thereby make phase and frequency agreement between local timing and the received signal, and the frequency F_IF is sampled at a clock rate (F_s) of: ##EQU1## wherein F_IF is the intermediate frequency and K is a scaling factor which is related to the number of carrier cycles per stage, the transversal filter includes a charge coupled device having the N active stages.

Claims

1. Demodulator apparatus for demodulating a data bearing broadcast signal, comprising means for receiving a broadcast signal and producing therefrom a predetermined intermediate carrier frequency having analog signals therein,

a charge coupled device connected to receive said intermediate carrier frequency and having N active stages and tap weight means at each of said stages for entering a tap weight sequence to yield maximum correlation energy when a predetermined alignment occurs to thereby mark phase and frequency agreement between local timing signals and the received signals.

2. Demodulator apparatus as defined in claim 1 including an analog-to-digital converter connected to said charge coupled device for digitizing analog signals after passing through said charge coupled device.

3. Demodulator apparatus for demodulating a data bearing broadcast signal in the absence of mixers and without incurring quantization errors, comprising:

a) means for receiving a broadcast signal and producing therefrom a predetermined intermediate carrier frequency (F_IF),

b) charge coupled device connected to receive said intermediate carrier frequency F_IF and having N active stages and tap weight means at each of said stages for entering a tap weight sequence to yield maximum correlation energy when desired alignment occurs to thereby mark phase and frequency agreement between local timing and the received signal, and the frequency F_IF is;

space="preserve" listing-type="equation">(N.sub.stage /4)(D.sub.R /2)(K)(1/α

)

where;

N_stage correspond to the number of active stages,

D_R /₂ and α

defines the relationship between the number of active stages and symbol rate of the received signal,

K₁ is a scaling factor which specifies the number of carrier cycles per four stage block and it is and odd integer ≧

1,

α

denotes the portion of a symbol, that said transversal charge coupled device spans,

c) means for sampling said intermediate frequency at a clock rate (F_s) of;

##EQU2## wherein F_IF is said intermediate frequency and K is a scaling factor which is related to the number of carrier cycles per stage.

4. The demodulator apparatus defined in claim 3 wherein said transversal filter is a charge coupled device having N stages having demodulator aliasing frequencies F_ALS and said carrier frequency F_IF is:

##EQU3##

5. A method for demodulating a data bearing broadcast signal in the absence of mixers and without incurring quantization errors, comprising:

a) receiving a broadcast signal and producing therefrom an intermediate carrier frequency (F_IF),

b) providing a charge coupled device (CCD) having N active stages and tap weight means at each of said stages for entering a tap weight sequence to yield maximum correlation energy when desired alignment occurs to thereby mark phase and frequency agreement between local timing and the received signal, and the frequency of F_IF is;

space="preserve" listing-type="equation">(N.sub.stage /4)(D.sub.R /.sub.2)(K)(1/α

)

where;

N_stage correspond to the number of active stages,

D_R /₂ and α

defines the relationship between the number of active stages and symbol rate of the received signal,

K₁ is a scaling factor which specifies the number of carrier cycles per four stage block and it is and odd integer ≧

1,

α

denotes the portion of a symbol that said transversal filter spans,

c) sampling said intermediate frequency at a clock rate (F_s) of;

##EQU4## wherein F_IF is said intermediate frequency and K₂ is a scaling factor related to the number of carrier cycles per stage.

6. The method defined in claim 5 wherein said charge coupled device (CCD) having N stages has a demodulation aliasing frequency F_ALS and said carrier frequency F_IF is:

##EQU5##