DDC Personality Status October 2011 – Matt Luce 1

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

DDC Block Diagram 3

1.0 Typical Spectrum 4

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 5

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. 6

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

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! 8

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

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

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

SB-SB Aliasing (1.1) 636MHz650MHz 12

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

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: 34 per DC – 216 total TOTAL: 472 (~70%)

Spectrum: 488 FFT Bench 15

Spectrum: Bench 0Baseline 16

Spectrum: VLBA Single station auto-correlations TD023C 17

The Future (Experimental version) – Hilbert SSB 1.2 – Partial support for128MHz BW MHz MHz – T sys (w/ quantizer) 1.3 – Full support for 128MHz BW – Pipeline delay correction 18