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DDC Personality Status

DDC Personality Status. October 2011 – Matt Luce. Overview. Block Diagram Version 1.0 Problems Version 1.1 PFB Weaver Future Improvements Version 1.2 and beyond. DDC Block Diagram. 1.0 Typical Spectrum. 1.0 Problems w/PFB. PFB is generating large spurious tones

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DDC Personality Status

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  1. DDC Personality Status October 2011 – Matt Luce

  2. Overview • Block Diagram • Version 1.0 Problems • Version 1.1 • PFB • Weaver • Future Improvements • Version 1.2 and beyond

  3. DDC Block Diagram

  4. 1.0 Typical Spectrum

  5. 1.0 Problems w/PFB • PFB is generating large spurious tones • PFB sub-band edges are too soft • >32MHz dead-zones between sub-bands to avoid aliasing

  6. 1.0 Problems w/down-converters • Weaver IR filter is not sharp enough and is creating aliases. • Cleanup/weaver filters are creating too many ripples in the pass-band.

  7. 1.0 Problems w/Decimation • Limited BW support • 64MHz and 16MHz are the only completely functional • CIC output truncation is critical!

  8. What is version 1.1? • Architecture: 2 down-converters • Improved filter responses • Poly-phase • Weaver image reject • CIC cleanup • Improved down-converters • Supported Bandwidths: 64MHz, 32MHz, 16MHz…62.5kHz • Mark5B • Format select: 1 or 2 streams • Bug fixes!

  9. Large Spurious Signals 1.0 (append) 1.1 (sign extend)

  10. Improved Poly-phase Filter Bank 1.0 (80) 1.1 (128)

  11. Improved Weaver IR Filter Old (20) New (128)

  12. SB-SB Aliasing (1.1) 636MHz 650MHz

  13. Improved CIC Cleanup Filter 1.0 (40) 1.1 (128)

  14. DSP Slice Budget: 640 Available • Channelization (2) • 128 per IF • DC (2): • Mixers (DDS + multipliers) • 6 per DC • Image reject FIR • 68 per DC • CIC & cleanup FIR: • 34per DC • 216 total • TOTAL: 472 (~70%)

  15. Spectrum: 488 FFT Bench

  16. Spectrum: Bench 0Baseline

  17. Spectrum: VLBA Single station auto-correlationsTD023C

  18. The Future • 1.1.1 (Experimental version) • Hilbert SSB • 1.2 • Partial support for128MHz BW • 512-640MHz • 896-1024MHz • Tsys (w/ quantizer) • 1.3 • Full support for 128MHz BW • Pipeline delay correction

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