Ambiguity elimination in HF FMCW radar systems

Musa, M.; Salous, Sana

doi:10.1049/ip-rsn:20000316

Cited by 14 publications

(5 citation statements)

References 4 publications

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“…The measurement bandwidth cannot be improved by simply increasing the acquisition rate whilst increasing the frequency scan range. We note that the principles of DI-OFDR could also be applied to FMCW radar to solve the × Doppler ambiguity which limits the maximum unambiguously measurable velocity of a target to the range-limiting sweep repetition rate [21][22][23][24]. In other words, the technique could overcome the trade-off between measurable velocity and range in FMCW radar.…”

Section: Discussionmentioning

confidence: 99%

Resolving the range ambiguity in OFDR using digital signal processing

Riesen¹,

Lam²,

Chow³

2014

Meas. Sci. Technol.

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A digitally range-gated variant of optical frequency domain reflectometry is demonstrated which overcomes the beat note ambiguity when sensing beyond a single frequency sweep. The range-gating is achieved using a spread spectrum technique involving time-stamping of the optical signal using high-frequency pseudorandom phase modulation. The reflections from different sections of fiber can then be isolated in the time domain by digitally inverting the phase modulation using appropriately-delayed copies of the pseudorandom noise code. Since the technique overcomes the range ambiguity in OFDR, it permits high sweep repetition rates without sacrificing range, thus allowing for high-bandwidth sensing over long lengths of fiber. This is demonstrated for the case of quasi-distributed sensing.

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Section: Discussionmentioning

confidence: 99%

Resolving the range ambiguity in OFDR using digital signal processing

Riesen¹,

Lam²,

Chow³

2014

Meas. Sci. Technol.

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“…At the 10, 20, 50, and 80 KHz repetition rates, the beat signal demonstrates a resolution of ± 45, 40, 35, and 25 millimeters respectively. Though the theoretical distance resolution of the 47 nm wavelength sweep is approximately 25.6 ȝm 3 , the spectral bandwidth of the beat signal dominates the distance resolution. Furthermore, the spectrum of the beat signal due to a 50 KHz and 80 KHz repetition rate demonstrates an unusual shape.…”

Section: Constructing the Wavelength Sweepmentioning

confidence: 99%

Generation of high speed, linear wavelength sweeps using sampled grating distributed Bragg reflector lasers

O’Connor

Bernacil

Derickson

2008

LEOS 2008 - 21st Annual Meeting of the IEEE Lasers and Electro-Optics Society

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-Wavelength-tunable sampled grating distributed Bragg reflector (SG-DBR) lasers are used for telecommunications applications in which the laser is set to a communication channel and changed infrequently. SG-DBR lasers can be tuned to any wavelength over a 50 nm tuning range with fast transition times using a set of three control currents. This paper demonstrates generation of fast linear wavelength ramps covering the entire tuning range of the laser. Continuous and linear wavelength sweeps are achieved by applying three time synchronized waveforms to the front mirror, back mirror, and phase sections of the laser. Continuous wavelength coverage is achieved by appending 50 separate mode-hop-free tuning segments.The wavelength stitching transitions require a maximum of 60 ns for amplitude, wavelength, and thermal settling time to allow the laser and drive electronics to equilibrate. Full band wavelength ramps with 100 kHz repetition rates have been demonstrated. An example FMCW LIDAR application of this fast wavelength ramp is given.Index Terms -Distributed Bragg reflector lasers, light detection and ranging.

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“…Generally, when the target has a relative velocity, two sweeps, the up-and downsweeps, as shown in Fig. 1 are used to eliminate ambiguity of the distance and the velocity [6,16,17].…”

Section: Outline Of Fmcw Radarmentioning

confidence: 99%

Interference suppression in FMICW radar with staggered pulse repetition interval

Ishihara

2007

Electron. Comm. Jpn. Pt. I

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SUMMARYFMCW (frequency-modulated continuous wave) radar is a radar system which can achieve high resolution by relatively low signal processing load. The authors have reported on clutter suppression by FMICW (FM interrupted CW) radar, where the transmission/reception of FMCW radar in pulse waveform is switched in order to assure transmission/reception isolation and to suppress undesired waves from short distances. This paper proposes the FM staggered PRI system, in which the pulse repetition interval (PRI) is randomized for each pulse in order to suppress the interference when FMICW radars are congested within the search distance. The target-signal in the FM staggered PRI system is formulated. Conditions such as the average PRI and the possible range of staggering are derived from requirements such as the maximum search distance. The output S/I is statistically evaluated by computer simulation, with the average PRI, the pulse width, the number of interference waves, and the input S/I (signal-to-interference ratio) as variables. The effectiveness of the FM staggered PRI system is demonstrated.

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Ambiguity elimination in HF FMCW radar systems

Cited by 14 publications

References 4 publications

Resolving the range ambiguity in OFDR using digital signal processing

Resolving the range ambiguity in OFDR using digital signal processing

Generation of high speed, linear wavelength sweeps using sampled grating distributed Bragg reflector lasers

Interference suppression in FMICW radar with staggered pulse repetition interval

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