Doppler-improved polyphase pulse expander-compressor

In a polyphase-coded expansion and compression system, a method of reducing cyclic variation in the amplitude of the compressed pulse waveform due to doppler shift, comprising:

• generating kN.sup.2 phase coded elements by phase filtering clocked pulses, each of said elements from a phase characteristic corresponding to a consecutive sample of a chirp waveform with an information bandwidth B, sampled at a rate having a frequency S, with k=S/B and where N is an integer;
• sequencing said phase coded elements by delaying them consecutively over a period corresponding to T=N.sup.2 /B to form an expanded polyphase-coded signal;
• conjugating an echo of said expanded polyphase-coded signal to form conjugated phase coded elements, and
• combining said conjugated phase coded elements by filtering and delaying them to form a compressed output signal of amplitude N.sup.2 k and width 1/B.

In a polyphase-coded, peak-power limited radar system, an expander/compressor for polyphase-coded pulses comprising:

• signal generation means for generating kN.sup.2 phase coded elements, each of said elements having a phase corresponding to a phase characteristic of a consecutive sample of a chirp waveform with an information bandwidth B, sampled at a rate having a frequency S, with k=S/B and where N is an integer;
• sequencing means for sequencing said phase coded elements consecutively over a period corresponding to T=N.sup.2 /B to form an expanded polyphase-coded signal;
• conjugating means for conjugating an echo of said expanded polyphase-coded signal to form conjugated phase coded elements;
• and
• combining means for combining said conjugated phase coded elements to form a compressed output signal of amplitude N.sup.2 k and width 1/B.

In a polyphase-coded, peak-power limited radar system, an expander/compressor for polyphase-coded pulses comprising:

• signal generation means for generating kN.sup.2 elements with a clocking circuit, a pulse generator and a phase filter, each of said elements having a phase corresponding to a consecutive sample of a chirp waveform with an information bandwidth B, sampled at a rate having a frequency S, with k=S/B and where N is an integer;
• sequencing means, including storage elements comprising a delay network system, for sequencing said phase coded elements consecutively over a period corresponding to T=N.sup.2`B to form an expanded polyphase-coded signal;
• conjugating means for conjugating an echo of said expanded polyphase-coded signal to form conjugated phase coded elements;
• and
• combining means, including a phase filter and storage elements comprising a delay network system for combining said conjugated phase coded elements to form a compressed output signal of amplitude N.sup.2 K and width 1/B.