Flexible Filter Bank Based on an Improved Weighted Overlap-Add Algorithm for Processing Wide Bandwidth Radio Astronomy Signals

Wang, Xianhai; Meng, Qiao; Han, J. L.; Liu, Wei; Zhang, Jianwei

doi:10.1086/684435

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…The output of the WOLA filter bank involves real-and complex-valued signals, and the number of the independent output sub-channels is K/2 + 1 (where K is the number of sub-bands); thus, the processing complexity and consumption of hardware resources is increased. To simplify the hardware implementation of the algorithm, the IWOLA algorithm [22] was proposed, which shifts the centre frequencies of every sub-band of the WOLA filter bank by π/K along the positive frequency axis. In particular, the expression of the IWOLA filter bank is as follows:…”

Section: Basic Algorithm Principlementioning

confidence: 99%

“…Therefore, their computational and hardware complexity is equivalent. In comparison with the expressions of the IWOLA filter bank and the WOLA filter bank [22], the expression of the IWOLA filter bank involves two terms more: (−1) l and e -jπp/K . It is obvious that the first term does not increase the computational and hardware complexity; the second term only necessitates one complex multiplication operation and two block RAMs (BRAMs) in the FPGA.…”

Section: Basic Algorithm Principlementioning

confidence: 99%

“…In this paper, a spectral analysis algorithm with an ultra-high-frequency resolution is first proposed for broadband real-valued signals. This algorithm uses an improved WOLA (IWOLA) [22] channelised filter bank to channelise the broadband signals preliminarily, and decimates the output data from the IWOLA filter bank appropriately. The IWOLA algorithm applies an equivalent Hilbert transform to the normal WOLA filter bank by shifting the centre frequency of every sub-band by half of the frequency bin, such that the IWOLA filter bank provides K/2 independently output complex sub-bands for real-valued signals instead of the general K/2 + 1 sub-bands, thus reducing the subsequent processing units by one set.…”

Section: Introductionmentioning

confidence: 99%

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Broadband Spectral Analysis Algorithm with High-Frequency Resolution for Elimination of Overlap Interference between Adjacent Channels

Wang

Yin

et al. 2021

Applied Sciences

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Spectral lines can be analysed to determine the physical properties of molecular clouds and the astrochemical processes in the formation area of massive stars. To improve the observation technology of radio astronomy, this paper proposes and compares two spectral analysis algorithms (improved weighted overlap-add (IWOLA) + FFT and IWOLA + weighted overlap-add (WOLA)). The proposed algorithms can obtain an ultra-high-frequency resolution for real-valued wideband signals, eliminate the signal overlapping interference between adjacent channels, substantially decrease the required hardware resources, especially multipliers, adders, and memory resources, and reduce the system design complexity. The IWOLA + FFT algorithm consists of an improved weighted overlap-add (IWOLA) filter bank, fast Fourier transform (FFT), a specific decimation for the output data from the IWOLA filter bank, and a selection for part of the output data from the FFT. The IWOLA + WOLA algorithm consists of the same modules as the IWOLA + FFT algorithm, with the second-stage FFT replaced by the modules of the weighted overlap-add (WOLA) filter bank and the accumulation for each sub-band. Based on an analysis of the underlying principles and characteristics of both algorithms, the IWOLA + FFT algorithm demonstrated a spectrum with a high frequency resolution and a comparable performance to an ultra-large-scale FFT, based on two smaller FFTs and a flexible architecture instead of a ultra-large-scale FFT. The IWOLA + WOLA algorithm contains the same function as the IWOLA + FFT algorithm and demonstrates a higher performance. The proposed algorithms eliminated the interference between the adjacent channels within the entire Nyquist frequency bandwidth. The simulation results verify the accuracy and spectral analysis performances of the proposed algorithms.

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Section: Basic Algorithm Principlementioning

confidence: 99%

Section: Basic Algorithm Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Broadband Spectral Analysis Algorithm with High-Frequency Resolution for Elimination of Overlap Interference between Adjacent Channels

Wang

Yin

et al. 2021

Applied Sciences

Self Cite

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show abstract

“…In effect, a full spectrum is generated by stitching the FFT response from each of these sub-bands 12 . A combination of these approaches has also been proposed, e.g., the weighted overlap-add method, which uses polyphase pre-processing over a larger window, multiple times the FFT length, and subsequent addition of those sub-blocks before FFT 16 , 17 . Moreover, FPGA based design renders high flexibility in terms of future modifications for spectrum generation methodology, bandwidth, and spectral resolution.…”

Section: Introductionmentioning

confidence: 99%

Wideband digital multi-channel merge-split fast Fourier transform spectrometer: design and characterization

Sharma

Singh

Chakraborty

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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We developed a wideband multi-channel merge-split fast Fourier transform spectrometer (FFTS) using analog-to-digital convertors (ADC) for signal sampling and field-programmable gate arrays (FPGA) for real-time spectrum generation. The FFTS constitutes the backend of the sub-mm wave heterodyne spectroscopy telescope to observe emitted radiations from rotational transitions of CO (J: 2 → 1 and J: 3 → 2) with 50 arc sec angular resolution, aiming to provide the first comprehensive survey of molecular clouds in the Milky Way and nearby galaxies from the northern hemisphere (Hanle, India) at these frequencies. The FFTS provides 8 GHz instantaneous bandwidth at 1.6 MHz spectral resolution (extendable to 0.8 or 0.4 MHz) comprising four channels (spanning 218.898 to 220.898 GHz, 229.038 to 231.038 GHz, 329.087 to 331.087 GHz, and 344.295 to 346.295 GHz frequency bands) belonging to two receiver chains at 230 and 345 GHz operating in a double side band configuration. The channel placement for these four channels is done to cover 13 CO (J:2 → 1) transition at 220.398 GHz, 12 CO (J:2 → 1) transition at 230.538 GHz, 13 CO (J:3 → 2) transition at 330.588 GHz, and 12 CO (J:3 → 2) transition at 345.796 GHz with 1.5 GHz margin for red-shifts. Spectrometer design is presented along with spectral line profile simulations, hardware configuration, proposed methodology, system specifications, and scalable field-programmable gate arrays (FPGA) implementation architecture. Elements in the instrument design leverage simultaneous multi-channel acquisition for optimized FPGA utilization by merging the channel pair from the sideband separating (2SB) second stage intermediate frequency (IF) mixer during Fourier transform and subsequently splitting the generated spectra. System characterization results are presented, confirming instruments capable of stable spectroscopy with a wide bandwidth (instantaneous 8 GHz with four 2 GHz channels) and high-spectral sampling (1∕0.5∕0.25 MHz corresponding to scalable fast Fourier transform length of 4k∕8k∕16k respectively) that provides adequate spectral resolution for the science case. Wide dynamic range (49.3 dB) and fine radiometric resolution required for relative spectroscopic measurements is realized by sampling IF signals with 12-bits ADCs. Variable spectral accumulation time facilitates improvements in the signal to noise ratio proportional to the square root of the number of coherent averaged cycles, covering various target dependent (longer dwell time for a single target) or scanning dependent (e.g., drift scanning mode matching earth's rotation) dwell time requirements.

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A Wideband Digital FFT Spectrometer System for ground based Sub-mm Wave Telescope

Sharma

Bhadoria

Chakraborty

et al. 2020

2020 IEEE International Conference for Innovation in Technology (INOCON)

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Flexible Filter Bank Based on an Improved Weighted Overlap-Add Algorithm for Processing Wide Bandwidth Radio Astronomy Signals

Cited by 3 publications

References 8 publications

Broadband Spectral Analysis Algorithm with High-Frequency Resolution for Elimination of Overlap Interference between Adjacent Channels

Broadband Spectral Analysis Algorithm with High-Frequency Resolution for Elimination of Overlap Interference between Adjacent Channels

Wideband digital multi-channel merge-split fast Fourier transform spectrometer: design and characterization

A Wideband Digital FFT Spectrometer System for ground based Sub-mm Wave Telescope

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