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UHE Particle Requirements. R. Ekers, C. James, J. Bray, P. Roberts, C. Phillips, R. Protheroe. Alternatively: buffer element voltages (sensitivity +2-3%) (but may increase trigger dead-time). Data path. B. B. B. Dedispersion Filter (or equivalent operations). V b (t). V b (t). V b (t).
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UHE Particle Requirements R. Ekers, C. James, J. Bray, P. Roberts, C. Phillips, R. Protheroe
Alternatively: buffer element voltages (sensitivity +2-3%) (but may increase trigger dead-time). Data path B B B Dedispersion Filter (or equivalent operations) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) One PAF Beam only! Elements PAF BEAM Moon Buffer TO GERALDTON Primary beams from central antennas (only if part of the tied-beam sub-array) Trigger! Trigger Logic Tied Array Beam-former Form beams on lunar limb only.
Key Points Must be able to reconstruct full time resolution voltage tied-array beams in offline processing. 9 (pref 10) effective bits per offline tied beam = ( ) ~6 (pref 7) per antenna. B B B Dedispersion Filter (or equivalent operations) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Vb(t) Elements PAF BEAM Moon Buffer TO GERALDTON Primary beams from central antennas (only if part of the tied-beam sub-array) Black box: - Outputs tied-array beams - Dedispersed - Formed from a sub-array - Covering the lunar limb - full-time resolution voltage - 8 effective bits Question: - how many beams? Trigger! Trigger Logic Tied Array Beam-former Form beams on lunar limb only.
How many tied-array beams? We can detect a ~9.2 signal in offline processing. What is the expected strength ( ) in real time ? What is the trigger rate per tied array beam? What is the total rate? What is the max dead-time for this rate? (5% loss) What is the chance of a false trigger per sample? How many tied array beams do we need? Data Rate: # antennas (36) x # polarisations (2) x bits/sample (6) x sample length (600) =260kb/trigger 40 Gb/s -> Geraldton Max rate: 150 kHz
The x-axis • Form tied-array beams using x antenna. • y is the solid angle covered with sensitivity >z (at zenith). • For given z (=17 here), which x maximises y?
Note on sampling • Nyquist criteria fine for off-line processing. • Not ideal for real time. • 0-3 GHz transient • 0.7-1.0 GHz band limited • Sampled at 700 MHz 1.4 GHz 700 MHz