US 11,726,119 B2
Fractional Fourier Transform-based spectrum analyzer
Seema Sud, Reston, VA (US); and Timothy Jones, Purcellville, VA (US)
Assigned to THE AEROSPACE CORPORATION, El Segundo, CA (US)
Filed by The Aerospace Corporation, El Segundo, CA (US)
Filed on Jan. 10, 2020, as Appl. No. 16/739,187.
Prior Publication US 2021/0215747 A1, Jul. 15, 2021
Int. Cl. G01R 23/165 (2006.01); H04B 1/10 (2006.01); G06F 17/14 (2006.01); H03H 17/02 (2006.01)
CPC G01R 23/165 (2013.01) [G06F 17/141 (2013.01); H03H 17/0213 (2013.01); H04B 1/1027 (2013.01)] 32 Claims
OG exemplary drawing
 
1. A method for performing fractional Fourier transform (FrFT)-based spectrum analysis, comprising:
receiving radio frequency (RF) signals for a portion of an RF spectrum at a sampling rate ƒs, by a receiver;
collecting a block of M samples from the received RF signals, by a spectrum analyzer;
applying the FrFT to the block of M samples, by the spectrum analyzer, to rotate axes for a time domain and a frequency domain by an initial rotational parameter a, producing a rotated portion of the RF spectrum; and
responsive to the one or more signals not being detected above the noise floor for the initial value of a:
incrementing a by an amount Δa, by the spectrum analyzer,
performing the FrFT on the block of M samples, by the spectrum analyzer, for the incremented a, and
passing the M samples through a bandpass filter that removes other signals outside a bandpass filtering bandwidth, wherein
the incrementing of a by Δa and the performing of the FrFT for the incremented a are repeated until the one or more signals are detected above the noise floor or the incremented a equals a final value of a.