Bandpass filter demodulation for FM-CW systems

• US 5,150,124 A
• Filed: 03/25/1991
• Issued: 09/22/1992
• Est. Priority Date: 03/25/1991
• Status: Expired due to Term

• Current Assignee: Alliant Techsystems Incorporated (Northrop Grumman Corporation)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Eickerman, Curtis L., Moore, Gerald J.
• Primary Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US07/674,010
• Time in Patent Office: 547 Days
• Field of Search: 342/68, 342/128, 342/193, 329/314, 329/318, 329/362, 329/341, 329/342
• US Class Current: 342/68
• CPC Class Codes: F42C 13/045 using transmission of F.M. waves
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal

Abstract

A method and device for bandpass filter demodulation for FM-CW systems which includes providing a FM-CW signal to an input of a bandpass demodulator, amplifying the FM-CW signal, timing the bandpass demodulator at an integer multiple of the FM-CW signal frequency, and simultaneously demodulating/filtering the FM-CW signal to produce a signal in baseband containing suppressed carrier-Doppler sideband information from the FM-CW signal. The demodulating/filtering functions are performed in an appropriately biased and clocked switched capacitive filter.

Claims

1. A radar system for processing a FM-CW harmonic signal comprising:

transmitter means comprising a frequency modulation signal input and a transmitter output;

antenna means comprising an antenna output;

coupler/detector means comprising a first coupler/detector input coupled to the transmitter output, a second coupler/detector input coupled to the antenna output, and a coupler/detector output;

bandpass demodulator means comprising a first bandpass demodulator input coupled to the coupler/detector output, a second bandpass demodulator input, and a bandpass demodulator output;

ratio detector fuzing algorithm means comprising a ratio detector fuzing algorithm input coupled to the bandpass demodulator output, and a ratio detector fuzing algorithm output; and

system timing means comprising a first system timing output coupled to the frequency modulation signal input and a second system timing output coupled to the second bandpass demodulator input.

2. A radar system for processing a FM-CW harmonic signal as claimed in claim 1 where the first bandpass demodulator input comprises capacitive coupling means.

3. A radar system for processing a FM-CW harmonic signal as claimed in claim 1 wherein the bandpass demodulator means further comprises:

amplifier means comprising an amplifier input coupled to the coupler/detector output and an amplifier output; and

switched capacitor means comprising a first switched capacitor input coupled to the amplifier output, a second switched capacitor input coupled to the system timing means, and a switched capacitor output coupled to the ratio detector fuzing algorithm input.

4. A radar system for processing a FM-CW harmonic signal as claimed in claim 3 wherein the amplifier means comprises a low noise amplifier.

5. A radar system for processing a FM-CW harmonic signal as claimed in claim 3 wherein the switched capacitor means further comprises:

signal input means coupled to the amplifier output;

clock input means coupled to the system timing means;

a switched capacitor bias input coupled to the switched capacitor means; and

a bias means coupled to the switched capacitor bias input.

6. A radar system for processing a FM-CW harmonic signal as claimed in claim 5 wherein the switched capacitor means further comprises a frequency divider means for maintaining phase coherency between the FM-CW harmonic signal and the frequency modulation signal.