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. VLBI2010 Frequency Sequences 2468101214 GHz 9.0 (221) – 2.33 11.6 (286) – 3.87 11.5 (284) – 3.80 11.8 (290) – 4.00 6.4 (157) – 1.18 6.8 (168) – 1.33 7.3 (179) – 1.53 7.4 (183) – 1.57 7.6 (190) – 1.56 5.9 (145) – 1.00 7.2 (179) – 1.49 SNR/band for 5-σ detection DBS X-band DBSS-band (Min flux (10-s, 16-Gbps)) Relative data volume 512-MHz bands 1024-MHz bands Split bands

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 Compatibility 2048-Gsps vs. 2x1024-Gsps 51225605122560 51225605122560 1024-Gsps Nyquist filters 5122560 5122560 Nyquist filter 5122560 2048-Gsps Samplers

6. Sampling/BW Compatibility 2048-Gsps vs. 2x1024-Gsps 51225605122560 51225605122560 1024-Gsps Nyquist filters 5122560 5122560 Nyquist filter 5122560 2048-Gsps Samplers

7. Sampling/BW Compatibility 2048-Gsps vs. 2x1024-Gsps 51225605122560 51225605122560 1024-Gsps Nyquist filters 5122560 5122560 Nyquist filter 5122560 2048-Gsps Samplers

8. Sampling/BW Compatibility 2048-Gsps vs. 2x1024-Gsps 51225605122560 51225605122560 1024-Gsps Nyquist filters 5122560 5122560 5122560 2048-Gsps Sum Samplers

9. Sampling/BW Compatibility 2048-Gsps vs. 2x1024-Gsps 51225605122560 51225605122560 1024-Gsps Nyquist filters 5122560 5122560 5122560 2048-Gsps Sum Samplers

10. Sampling/BW Compatibility 2048-Gsps vs. 2x1024-Gsps 51225605122560 51225605122560 1024-Gsps Nyquist filters 5122560 5122560 5122560 2048-Gsps Sum Samplers

11. Extra slides

12. BWf1f2f3f4snr1snr2Smin ΔτΔτ ΔτΔτ 0.52.24.25.79.29.07.92218.42.2 0.52.24.28.08.511.610.32868.31.5 0.52.25.26.712.711.55.32843.62.2 0.52.25.26.712.711.86.82905.42.7 1.02.24.26.711.76.26.41577.92.0 1.02.25.77.712.76.85.91686.51.9 1.02.26.28.212.77.36.21796.41.8 1.02.24.77.212.77.47.21838.52.4 1.02.25.77.912.77.67.71908.82.1 1.02.2 3.2 4.7 5.7 8.2 8.7 12.7 13.7 5.9 1457.31.9 1.02.2 3.2 4.7 5.7 8.2 8.7 12.7 13.7 7.2 1798.42.2