1. GoetzFIELDS Quarterly – 18 July 2013 SPP/FIELDS Modes and Operations Stuart D. Bale, Keith Goetz 18 July 2013 1

2. GoetzFIELDS Quarterly – 18 July 2013 FIELDS Clocks FIELDS instrument to use unified clocking –Receivers, sampling, power supplies, clocks FIELDS HF instrument relies on picket-fence for RF sensitivity –Power supplies chop – making lines noise as a function of frequency –Un-avoidable but controllable chopping at controlled frequencies All power supplies must be controlled N * 50kHz with N starting at 3 – e.g. 150kHz, 200kHz and so on Frequencies are crystal controlled (±100PPM) –Make observations as a function of frequency in between lines of noise In earlier analog super-heterodyne receivers, we used sharp crystal filters to create the picket fence –Observing in between lines of noise 2

3. GoetzFIELDS Quarterly – 18 July 2013 Picket Fences 3

4. GoetzFIELDS Quarterly – 18 July 2013 FIELDS Clocks In the past, we used sharp crystal filters to create the picket fence With our new all-digital receiver, we implement sharp picket- fence filtering with simple time series and poly-phase filtering Samples must be in sync with FIELDS’ and S/C power supplies FIELDS/HFR high end is about 20MHz – sampling at ~40MSa/s –Exact frequency must fall on the picket fence with room for an FFT Master sampling frequency is thus of the form 150kHz * 2^N Master sampling frequency is 150,000 * 256 Hz is 38,400,000Hz 4

5. GoetzFIELDS Quarterly – 18 July 2013 FIELDS Clocks Master clock is 38,400,000Hz (±4kHz) Power supply chopping frequency is 150,000Hz –38,400,000Hz / 256 Other FIELDS instruments will be operated in synchronization with master clock and power supply chopping frequency (SWEAP too?) For low frequencies we’ll shift down by powers of two to ~293 Sa/s –150,000kHz / 512(292.968750Sa/s) However, making convenient and compressible packets still requires a packet size and cycle time corresponding to a power of 2 samples –A standard packet should start with 256 vectors Giving a FIELDS internal cycle time of.87 seconds/cycle –131,072 / 150,000 Hz –FIELDS’ New York second 5

6. GoetzFIELDS Quarterly – 18 July 2013 FIELDS DC MAG Two DC MAGs – in-board and out-board –Designed and built at GSFC Two units are to be identical –Identical drive frequencies –Identical range and resolution – 3 ranges up to ±64knT –Identical AC heater frequencies (150kHz) –Identical sampling rates: ~293 Sa/s or 292.96875 Sa/s or 150,000/512 Sa/s Sync’ed to overall FIELDS master clock Sync’ed to SWEAP clock? –Common hardware interfaces to FIELDS’ DCB and TDS –Common flight software modes MAGs produce chunks/packets at 256 vectors per cycle MAGs produce samples at ~293 vectors per second –Out-board MAG survey data down-sampled by 8 to ~36.3 vectors/second –In-board MAG survey data down-sampled by 128 to ~2.3 vectors/second 6

7. GoetzFIELDS Quarterly – 18 July 2013 FIELDS DC MAG MAGs produce samples at ~293 vectors per second –Out-board MAG survey data down-sampled at ~36.3 vectors/second –In-board MAG survey data down-sampled at ~2.3 vectors/second MAG telemetry chunks/messages/packets –Continuous B(t) - edge to edge –.87 seconds/cycle (131,072/150,000Hz ) –Powers of 2 vectors in length – nominally 256 vectors/packet –Powers of 2 cycles (.87s) in length –Ranges from 256 vectors at 293Sa/s covering.87s and 1 cycle in duration – highest resolution 256 vectors at 36.3Sa/s covering 7s and 8 cycles in duration – out-board nominal 256 vectors at 2.3Sa/s covering 111s and 128 cycles in duration – in-board nominal 256 vectors at 1.2Sa/s covering 222s in 256 cycles in duration – lowest resolution MAG range/gain changes –Allowed between cycles (256 vector samples or.87s) 7

8. GoetzFIELDS Quarterly – 18 July 2013 FIELDS AC SCM AC Search-Coil Magnetometers (SCM) –Designed and built at Orleans 3 Low Frequency axes - 1 Mid Frequency axis FIELDS DFB – can sample all 4 SCM axes and all 5 electric axes –Sampled at 150,000Sa/s –Down sampled in powers of two –Lowest rate is ~293 Sa/s or 292.96875 Sa/s or 150,000/512 Sa/s –SCM telemetry chunks – continuous time series - edge to edge Nominally 2 V(t), 3 E(t) and 3 B(t) –.87 seconds/cycle (131,072/150,000Hz ) –Powers of 2 samples in length –Powers of 2 cycles (.87s) in length –Low frequency DFB packets 256 vectors at 293Sa/s covering.87s and 1 cycle in duration – lowest resolution DFB samples in sync with DC MAGs 8

9. GoetzFIELDS Quarterly – 18 July 2013 FIELDS AC SCM DFB can sample from all 4 SCM axes and all 5 electric axes –Sampled at 150,000Sa/s DFB low-frequency spectra –4 spectra – 2 cross spectra - 112 log-spaced channels up to 9.4kHz –1 cycle –.87s per spectrum – continuous coverage DFB mid-frequency spectra –4 spectra – 2 cross spectra – 112 log-spaced channels up to 75kHz –60 cycles – 52s per spectrum continuous coverage DFB mid-frequency select time series –Nominally 3 E(t) and 3 AC B(t) –Sampled at 150,000Sa/s –Burst triggered based on programmable quality –Recorded at 1% duty cycle in FIELDS’ internal memory throughout perihelion –Later selected and sent to telemetry by command 9

10. GoetzFIELDS Quarterly – 18 July 2013 FIELDS AC SCM TDS – 1 SCM axis –Time series triggered bursts sampled at ~2MSa/s –Burst snapshots simultaneous with V, E and SWEAP counts RFS – 1 SCM axis –Sampled at ~40MSa/s –Spectra downsampled to 1MHz (~2MSa/s) 10