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1024-MHz vs 512-MHz Bands for VLBI2010?

1024-MHz vs 512-MHz Bands for VLBI2010?. East Coast VLBI Meeting Feb. 23-24, 2011, Haystack Observatory Bill Petrachenko. Method for comparing 1024 and 512-MHz BW Systems. Compare performance of a variety of 1024- and 512-MHz sequences.

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1024-MHz vs 512-MHz Bands for VLBI2010?

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  1. 1024-MHz vs 512-MHz Bands for VLBI2010? East Coast VLBI Meeting Feb. 23-24, 2011, Haystack Observatory Bill Petrachenko

  2. Method for comparing 1024 and 512-MHz BW Systems • Compare performance of a variety of 1024- and 512-MHz sequences. • Figure of merit for comparison is minimum SNR/band for 5-σ broadband delay detection (lower is better) – see next slide. • Sequence variations • 4 use 512-MHz bands. • 5 use 1024-MHz continuous bands. • 2 use 1024-MHz bands with possible spaces. • Some ensure full overlap with both S and X-band (green shading), which is beneficial for S/X compatibility modes. • Some avoid the Direct Broadbast Satellite (DBS) bands (purple shading) to avoid possible RFI problems. • Some use high frequencies to access lower source structure. • Some assume 50% power at high frequency (darkened bands) to emulate feed/LNA roll-off.

  3. 2 4 6 8 10 12 14 VLBI2010 Frequency Sequences SNR/band for 5-σ detection (Min flux (10-s, 16-Gbps)) X-band S-band DBS DBS Relative data volume 9.0 (221) – 2.33 11.6 (286) – 3.87 512-MHz bands 11.5 (284) – 3.80 11.8 (290) – 4.00 6.4 (157) – 1.18 6.8 (168) – 1.33 1024-MHz bands 7.3 (179) – 1.53 7.4 (183) – 1.57 7.6 (190) – 1.56 5.9 (145) – 1.00 Split bands 7.2 (179) – 1.49 GHz

  4. Compatibility Concern: RDBE (2x512-MHz) vs DBBC2010 (1x1024-MHz) • Six possible modes were considered • 4 of 6 are compatible (See following slides) • Some cases assume digital sideband flipping • Easy to implement (flipping the sign of alternate samples).

  5. Sampling/BW Compatibility2048-Gsps vs. 2x1024-Gsps Nyquist filter Nyquist filters 512 2560 512 2560 512 2560 512 2560 1024-Gsps Samplers 2048-Gsps 512 2560 512 2560 512 2560

  6. Sampling/BW Compatibility2048-Gsps vs. 2x1024-Gsps Nyquist filter Nyquist filters 512 2560 512 2560 512 2560 512 2560 1024-Gsps Samplers 2048-Gsps 512 2560 512 2560 512 2560

  7. Sampling/BW Compatibility2048-Gsps vs. 2x1024-Gsps Nyquist filter Nyquist filters 512 2560 512 2560 512 2560 512 2560 1024-Gsps Samplers 2048-Gsps 512 2560 512 2560 512 2560

  8. Sampling/BW Compatibility2048-Gsps vs. 2x1024-Gsps Nyquist filters 512 2560 Sum 512 2560 512 2560 512 2560 1024-Gsps Samplers 2048-Gsps 512 2560 512 2560 512 2560

  9. Sampling/BW Compatibility2048-Gsps vs. 2x1024-Gsps Nyquist filters 512 2560 Sum 512 2560 512 2560 512 2560 1024-Gsps Samplers 2048-Gsps 512 2560 512 2560 512 2560

  10. Sampling/BW Compatibility2048-Gsps vs. 2x1024-Gsps Nyquist filters 512 2560 Sum 512 2560 512 2560 512 2560 1024-Gsps Samplers 2048-Gsps 512 2560 512 2560 512 2560

  11. Extra slides

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