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TSI Incorporated Copyright© 2008 TSI Incorporated Signal Processing TSI LDV/PDPA Workshop & Training Presented by Joseph Shakal Ph.D.

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Presentation on theme: "TSI Incorporated Copyright© 2008 TSI Incorporated Signal Processing TSI LDV/PDPA Workshop & Training Presented by Joseph Shakal Ph.D."— Presentation transcript:

1 TSI Incorporated Copyright© 2008 TSI Incorporated Signal Processing TSI LDV/PDPA Workshop & Training Presented by Joseph Shakal Ph.D.

2 TSI Incorporated Copyright© 2008 TSI Incorporated Outline Nature of the Signal Processor Requirements FSA Architecture- Front End & Burst Detector FSA Architecture- Samplers FSA Architecture- Firmware Processor Burst Centering Dynamic Sampling Rate Selection Other Features Conclusion

3 TSI Incorporated Copyright© 2008 TSI Incorporated Nature of Doppler Signals Amplitude not constant Lasts for only a short time, which itself varies Amplitude varies from burst to burst Presence of noise High frequency Random arrival

4 TSI Incorporated Copyright© 2008 TSI Incorporated Signal Processor - Key Requirements Use multi-bit sampling up to a high maximum frequency Detect and validate bursts based on SNR and amplitude Automatically optimize the sampling rate for each burst –Gives the best resolution in processing, even for a wide range of velocities –This will ensure the maximum number of cycles are used Detect the burst center, before processing –Use the data from the middle portion of the burst first –Use this value as the arrival time of the particle –Detect burst duration separately Digitize and record additional analog and digital signals, including cyclic markers and the burst amplitude

5 TSI Incorporated Copyright© 2008 TSI Incorporated FSA Signal Processor Uses 8 bit sampling up to a 800MHz Detects and validates bursts based on patented real-time SNR measurement, and also amplitude Automatically selects the optimum sampling rate for each burst, which is also a patented technique Detects the burst center, since processing is done after sampling process is complete The FSA EB option digitizes and records additional signals, including cyclic markers Burst amplitude is measured as part of the patented Intensity Validation technique

6 TSI Incorporated Copyright© 2008 TSI Incorporated Nature of Input Signal Out of PMT Detector Out of PDM Noisy Signal

7 TSI Incorporated Copyright© 2008 TSI Incorporated Impact of Type of Burst Detection SignalMethod of Burst Detection Source AmplitudeAmplitude/ Envelope Based SNR Based Small ParticlesSmallIgnoresDetects Large ParticlesLargeDetects Surface Reflections LargeDetects Ignores Other Noise, Spikes, etc. AnyDetects some Ignores

8 TSI Incorporated Copyright© 2008 TSI Incorporated The FSA Signal Processor

9 TSI Incorporated Copyright© 2008 TSI Incorporated FSA Processor Burst Detector Subsection LUT/DFT Amplitude Threshold Controller Signal Out Burst Gate Downmixer Downmix Frequency Ch 1 Frequency Estimate Dynamic Optimum Sampling Rate Selection Burst Gate Filters

10 TSI Incorporated Copyright© 2008 TSI Incorporated FSA Processor Burst Sampling Subsection Controller Multibit A/D Sample Memory Signal Out Burst Gate Downmix Frequency Frequency Estimate Burst Gate Optimally Sampled Data Firmware Processing LUT/DFT Ch 1 Filters

11 TSI Incorporated Copyright© 2008 TSI Incorporated FSA Processor Firmware Processing DSPs Burst Processing Firewire Interface Optimally Sampled Data Burst gate & Burst center to PC

12 TSI Incorporated Copyright© 2008 TSI Incorporated FSA Block Diagram Summary to PC Signals from PDM Downmixer Downmix frequency generator Amplitude threshold Controller 8 bit A/D s Sample Memory DSPs Signal Out Burst Gate Firewire Interface Bandpass filters Ch 1 Ch 2 Ch 3 Frequency estimate Burst gate EIC/EB pressure, temp OPR or Shaft Encoder LUT/DFT

13 TSI Incorporated Copyright© 2008 TSI Incorporated Burst Detection and Sampling Burst Detector –Determines the approximate burst frequency –Determines the beginning, end, and center of the burst Burst Sampler –Dynamically selects the optimum sampling frequency (using the approximate frequency value) so that each and every burst is sampled at the optimum rate –Obtains the 8 bit digital values, and passes them on to the Firmware Processing subsection

14 TSI Incorporated Copyright© 2008 TSI Incorporated Burst Centering Burst centering is automatically done by the FSA, and it helps give higher quality data by using only the high-SNR portion of the signal for processing. The center point of the burst is identified. From this reference point, samples are used out to a certain noise threshold, until the FSAs data block is filled. Gate Time (transit time) is still based on the actual time the particle was in the measurement region, regardless of the portion of the signal used for processing. Beginning End Center of burst This portion used for processing

15 TSI Incorporated Copyright© 2008 TSI Incorporated Dynamic Sampling Rate Selection Example Burst gate Particle 1 velocity = u sampling rate: F Particle 2 velocity = 2u sampling rate: 2F Particle 3 velocity = 4u sampling rate: 4F Burst gate

16 TSI Incorporated Copyright© 2008 TSI Incorporated Flow and Size Analyzer (FSA) Other unique features and benefits of the FSA Built in input buffer, for high data rate situations Size measurement validation –Patented intensity validation uses an independent measured quantity to validate the diameters. We do not need receiver masks, and we can see what is being rejected and what is being accepted. –Phase validation, uses the degree of agreement between the two independent phase measurements to discriminate between reflection and refraction Short transit time flows (50ns minimum gate time) –Particle size measurements in dense sprays, where we need very small measuring volumes, resulting in short-transit-time burst signals –Size measurements in (pulsed) high velocity sprays –Velocity measurements in supersonic flows

17 TSI Incorporated Copyright© 2008 TSI Incorporated Measured Parameters Ch. 1 Velocity Mean (m/sec) Velocity RMS (m/sec) Turbulence Intensity (%)7.01 Frequency Mean (MHz) Frequency RMS (MHz) Frequency TI (%)7.01 Gate Time Mean (usec)2.26 Gate Time RMS (usec)1.32 Data Rate (Hz)43245 Valid Count2663 Invalid Count0 Elapsed Time (sec) Statistics Plots

18 TSI Incorporated Copyright© 2008 TSI Incorporated Conclusions Examined the nature of Doppler signals Looked at processor requirements FSA Architecture- Front End & Burst Detector FSA Architecture- Samplers FSA Architecture- Firmware Processor Saw how burst centering works and its benefits Looked at how dynamic sampling rate selection is done and its benefits Other benefits of the FSA, like high-speed capabilities for dense sprays and high speed flows, and FireWire connectivity


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