Planck Pre-Launch Status Papers - APC - Université Paris Diderot ...
Planck Pre-Launch Status Papers - APC - Université Paris Diderot ... Planck Pre-Launch Status Papers - APC - Université Paris Diderot ...
M. Bersanelli et al.: Planck pre-launch status: Design and description of the Low Frequency InstrumentFig. 22. Schematics of the grounding scheme of LFI.Table 11. LFI characteristic internal frequencies.Fig. 23. Schematics of the cryoharness serving HEMT biasing, phaseswitch biasing, and temperature sensors. Heat loads on the 20 K stageare minimised by intercepting heat with the V-grooves.compression (by a factor of 2.4 for at least the 95% of thepackets) performed in the REBA SPU (Sect. 4.5), the sciencedata volume is 36.12 Kbps, increased to 37.88 Kbps by packetingoverheads. An additional contribution of up to 5.06 Kbpscomes from the so-called “calibration channel”: for diagnosticpurposes, one LFI channel at a time will be transmitted to theground without compression. Adding 2.57 Kbps of housekeepingleads to a total budget of 45.41 Kbps for LFI, well withinthe allocated 53.5 Kbps (see Table 12). It is critical that the (average)2.4 compression factor be achieved with an essentiallylossless process, which requires careful optimisation of the parametersthat control the on-board compression algorithm in theSPU (Maris et al. 2009). After telemetry transmission, the datawill be treated through LFI DPC “Level 1” (Zacchei et al. 2009)for real-time assessment, housekeeping monitoring, and data decompression.Then the time-order information (TOI) will beν Origin Unit1Hz ........... Housekeepingacquisition frequency DAE BEU1Hz ........... Synchronisationsignal DAEBEU,REBA10 Hz . . . . . . . . . . Internal timer SCS1kHz.......... Lockingclocks SCS4096 Hz . . ..... PhaseSwitch FEM,DAEBEU100 kHz . . . . . . . 5 V & 12 V DC/DC SCS131 072 Hz . . . . . DC/DC converters DAE Power box131 072 Hz . . . . . On-board clock signal DAE BEU, REBA131 072 Hz . . . . . LOBT clock SCS200 kHz . . . . . . . 12 V DC/DC SCS1MHz ......... CommandlinkfromtheBEUbox DAEpowerbox1MHz ......... Internaltransferofdigitaldata DAEBEU,REBA8MHz ......... ADCclock SCS10/80 MHz . . . . . 1355 serial data digital interface DAE BEU, REBA16 MHz . . . . . . . . DSP processor clock SCS17.46 MHz . . . . . Clock frequency of the DSP REBA20 MHz . . . . . . . . Sequencer internal clock DAE BEUTable 12. LFI data rate summary.30 GHz 44 GHz 70 GHzNumber of detectors . . . . . . . . . . . . . . . . . 8 12 24Angular resolution (nominal) ......... 33 ′ 24 ′ 14 ′Beam crossing time [ms] . . . . . . . . . . . . . 92 64 39Sampling rate [Hz] . . . . . . . . . . . . . . . . . . 32.51 46.55 78.77Science data rate [Kbps] . . . . . . . . . . . . . 8.32 17.87 60.49Total science data rate . . . . . . . . . . . . . . . 86.69 Kbpsafter compression . . . . . . . . . . . . . . . 36.12 KbpsTotal LFI data rate . . . . . . . . . . . . . . . . . . 45.41 Kbpsgenerated and processed by the successive analysis steps in theDPC pipeline.Page 19 of 21
Table 13. Principal requirements and design solutions in LFI.A&A 520, A4 (2010)Requirement/ConstraintHigh sensitivityLow residual 1/ f ,immunityfromreceiversystematicsSingle telescopeModularity, cryo testing.Low power dissipation at the 20 K stage.Waveguide mechanical routing.Design solutionCryogenically cooled (∼20 K) HEMT amplifiers.Pseudo-correlationdifferential design. Cryogenic reference load (∼4K).Offsetremoval by gain modulation factor in post-processing. Fast switching (4 KHz)of sky and reference signal to suppress backend 1/ f noise.“Internal” reference load.Phase switch in frontend modules.Two amplification stages (cold frontend, warm backend). Low loss and thermalconductivity interconnecting waveguides.Phase switch and second hybrid in the frontend (avoids need of phase-matchedwaveguides.)7. Optical interfacesThe optimisation of the optical interface between the combinedLFI-HFI focal plane and the Planck telescope was coordinatedthroughout the various development phases of the project.Rejection of systematic effects arising from non-ideal opticalcoupling has been a major design driver for LFI (Mandolesi et al.2000b; Villa et al. 2009b). Minimisation of main beam ellipticityand distortion, particularly relevant for the off-axis LFI feeds,has been a key element in the optical design (Burigana et al.1998; Sandri et al. 2010). An upper limit of
- Page 37 and 38: A&A 520, A2 (2010)Table 5. Inputs u
- Page 39 and 40: A&A 520, A2 (2010)Fig. 16. Three cu
- Page 41 and 42: A&A 520, A2 (2010)Table 7. Optical
- Page 43 and 44: A&A 520, A2 (2010)Fig. A.1. Dimensi
- Page 45 and 46: A&A 520, A2 (2010)5 Università deg
- Page 47 and 48: A&A 520, A3 (2010)Horizon 2000 medi
- Page 49 and 50: A&A 520, A3 (2010)Fig. 1. CMB tempe
- Page 51 and 52: A&A 520, A3 (2010)Ω ch 2τn s0.130
- Page 53 and 54: A&A 520, A3 (2010)Fig. 6. Integral
- Page 55 and 56: A&A 520, A3 (2010)Table 2. LFI opti
- Page 57 and 58: 3.3.1. SpecificationsThe main requi
- Page 59 and 60: A&A 520, A3 (2010)Fig. 11. Schemati
- Page 61 and 62: A&A 520, A3 (2010)features of the r
- Page 63 and 64: A&A 520, A3 (2010)Fig. 13. Level 2
- Page 65 and 66: A&A 520, A3 (2010)Fig. 15. Level 3
- Page 67 and 68: A&A 520, A3 (2010)GUI = graphical u
- Page 69 and 70: A&A 520, A3 (2010)23 Centre of Math
- Page 71 and 72: A&A 520, A4 (2010)In addition, all
- Page 73 and 74: A&A 520, A4 (2010)Table 2. Sensitiv
- Page 75 and 76: A&A 520, A4 (2010)Fig. 2. Schematic
- Page 77 and 78: A&A 520, A4 (2010)Fig. 6. LFI recei
- Page 79 and 80: A&A 520, A4 (2010)Fig. 9. Schematic
- Page 81 and 82: A&A 520, A4 (2010)Table 4. Specific
- Page 83 and 84: A&A 520, A4 (2010)Fig. 15. DAE bias
- Page 85 and 86: A&A 520, A4 (2010)Fig. 19. Picture
- Page 87: A&A 520, A4 (2010)Table 10. Main ch
- Page 91 and 92: A&A 520, A5 (2010)DOI: 10.1051/0004
- Page 93 and 94: A. Mennella et al.: LFI calibration
- Page 95 and 96: A. Mennella et al.: LFI calibration
- Page 97 and 98: A. Mennella et al.: LFI calibration
- Page 99 and 100: A. Mennella et al.: LFI calibration
- Page 101 and 102: A. Mennella et al.: LFI calibration
- Page 103 and 104: A. Mennella et al.: LFI calibration
- Page 105 and 106: D.1. Step 1-extrapolate uncalibrate
- Page 107 and 108: A&A 520, A6 (2010)DOI: 10.1051/0004
- Page 109 and 110: F. Villa et al.: Calibration of LFI
- Page 111 and 112: F. Villa et al.: Calibration of LFI
- Page 113 and 114: F. Villa et al.: Calibration of LFI
- Page 115 and 116: F. Villa et al.: Calibration of LFI
- Page 117 and 118: F. Villa et al.: Calibration of LFI
- Page 119 and 120: F. Villa et al.: Calibration of LFI
- Page 121 and 122: A&A 520, A7 (2010)DOI: 10.1051/0004
- Page 123 and 124: M. Sandri et al.: Planck pre-launch
- Page 126 and 127: A&A 520, A7 (2010)Fig. 8. Footprint
- Page 128 and 129: -30-40-30-6-3-20A&A 520, A7 (2010)0
- Page 130 and 131: A&A 520, A7 (2010)Table 4. Galactic
- Page 132 and 133: A&A 520, A7 (2010)Fig. A.1. Polariz
- Page 134 and 135: A&A 520, A8 (2010)inflation, giving
- Page 136 and 137: A&A 520, A8 (2010)estimated from th
Table 13. Principal requirements and design solutions in LFI.A&A 520, A4 (2010)Requirement/ConstraintHigh sensitivityLow residual 1/ f ,immunityfromreceiversystematicsSingle telescopeModularity, cryo testing.Low power dissipation at the 20 K stage.Waveguide mechanical routing.Design solutionCryogenically cooled (∼20 K) HEMT amplifiers.Pseudo-correlationdifferential design. Cryogenic reference load (∼4K).Offsetremoval by gain modulation factor in post-processing. Fast switching (4 KHz)of sky and reference signal to suppress backend 1/ f noise.“Internal” reference load.Phase switch in frontend modules.Two amplification stages (cold frontend, warm backend). Low loss and thermalconductivity interconnecting waveguides.Phase switch and second hybrid in the frontend (avoids need of phase-matchedwaveguides.)7. Optical interfacesThe optimisation of the optical interface between the combinedLFI-HFI focal plane and the <strong>Planck</strong> telescope was coordinatedthroughout the various development phases of the project.Rejection of systematic effects arising from non-ideal opticalcoupling has been a major design driver for LFI (Mandolesi et al.2000b; Villa et al. 2009b). Minimisation of main beam ellipticityand distortion, particularly relevant for the off-axis LFI feeds,has been a key element in the optical design (Burigana et al.1998; Sandri et al. 2010). An upper limit of