1. LFR Calibration Activities
(sub-system level)
LFR team at LPP
Thomas Chust
Lead Co-I (CNRS)
science, calibration, tests
Paul Leroy
Technical Manager (CNRS)
flight software development + SGSE
Alexis Jeandet
Lead Engineer (CNRS)
hardware development, GSE + SGSE
Jean-Christophe Pellion
Engineer (CDD)
VHDL developement
Vincent Leray (20%)
product assurance hardware
William Recart (20%)
product assurance software
Bruno Katra
Engineer (CNRS)
software developement, calibration, tests, GS
Véronique Bouzid
flight software specification / validation
Fouad Sahraoui
Co-I (CNRS)
science
Alessandro Retino
Olivier Le Contel
science + SCM calibration

2. Outline
Presentation of the LFR products
On-ground LFR sub-system calibration
Current LPP

3. RPW Instrument Overview
Will allow the characterization of the electric and magnetic fields associated
to the dynamics of the near-Sun heliosphere from near DC up to 20 MHz
Main Electronic Box (MEB)
Electric Antennas (ANT)
3xV V LF
Bias Unit V Sp W 1
1HF
Floating volt
age dr
iver V
5xV
BIAS
2HF V
3HF
3xV HF
TNR-HFR V
Auto & cr
oss-spectr a Sp W
1LF
1xB
(4kHz-20MHz) V HF
2LF V V V 2
3LF 3
3xV
Nom. SpW HF
TDS
to/from S/C
1xB HF
Wavefor
500kS/s Sp W
3xV
BIAS
+ LFR Redundancy
RPW-DPU
Search Coil Magnetometer
3xB LF
(SCM)
Red. SpW
to/from S/C B
2LF
5xV
LFR
BIAS
Waveform up
to 25kS/s
3xV Sp W B HF
3LF +
Auto &
cross-
spectr a
3xB LF + k-
vector
(~DC-10kHz) B
1LF
3.3V 2. 5V 5V +/ -1 2V B
1HF
28 V
LVPS-PDU
from S/C
Low Frequency Receiver

4. LFR 11 analogue inputs

5. LFR Decimation and Processing Strategy
8 ADCs @ Hz
decimation
down to ß Hz
( f0 )
(14 bits ideally)
:32 :3
(16 bits)
(15 bits)
(16 bits)
(16 bits) Hz
4 096 Hz
16 Hz
256 Hz
shaping :3 :2
:64 :4
[20 bits ?]
[18 bits ?]
( f1 )
( f3 )
( f2 ) :4
( f0 )
2  E
3  B
1  V
2  E
3  B
2  E
3  B
1  V
2  E
3  B
1  V
2  E
(3  B)
2  E
3  B
1  V
2  E
3  B
FFT
FFT
FFT
(15 bits)
Spectral matrices
(ASM)
Waveforms
(WF)
Spectral matrices
(ASM)
Waveforms
(WF)
Waveforms
(WF)
Spectral matrices
(ASM)
Waveforms
(WF)
Basic parameters
(BP)
Basic parameters
(BP)
Basic parameters
(BP)

6. BIAS 5 analog inputs and the R-parameters
DC V
(G=1/15)
DC dV ~ E (G=1)
AC dV ~ E (G=5 or 100, cutoff~8Hz) R2

9. LFR Normal Mode (1) Basic Parameters sampling frequency ...
BP: bps
WF: bps
ASM: bps
TM: bps
Basic Parameters
sampling frequency
BP1
&
BP2
BP1
&
BP2
BP1
BP1
BP1
ASM
BP1
4 SMs
64 SMs
384 SMs
4 SMs
64 SMs
384 SMs
4 SMs
64 SMs
384 SMs
4 SMs
64 SMs
384 SMs
4 SMs
64 SMs
384 SMs
4 SMs
64 SMs
384 SMs
4 SMs
64 SMs
384 SMs
f0 = Hz
...
TBP1_0= 4 s
...
f1 = 4096 Hz
...
TBP1_1= 4 s
...
f2 = 256 Hz
...
TBP1_2= 4 s
...
...
4 s
continuous WF
...
f3 = 16 Hz
20 s
time

10. WaveForms & Averaged Spectral Matrices
LFR Normal Mode (2)
WaveForms & Averaged Spectral Matrices
TASM= 3600 s
sampling frequency
TWF= 300 s WF
BP1
ASM
BP1 WF
384 SMs
384 SMs
384 SMs
f0 = Hz
1/12 s
...
...
...
64 SMs
64 SMs
64 SMs
f1 = 4096 Hz
1/2 s
...
...
...
4 SMs
4 SMs
4 SMs
f2 = 256 Hz
8 s
...
...
...
2048 pts
...
4 s
...
continuous WF
...
f3 = 16 Hz
time

11. LFR Selected Burst Mode 1
BP: bps
WF: bps
ASM: bps
TM: bps
sampling frequency
BP1
&
BP2
BP1
&
BP2
BP1
BP1
BP1
BP1
BP1
24 SMs
24 SMs
24 SMs
24 SMs
24 SMs
24 SMs
24 SMs
f0 = Hz
...
TBP1_0= 0,25 s
...
0,25 s
f1 = 4096 Hz
...
continuous WF
...
1 s
time

12. LFR Selected Burst Mode 2
BP: bps
WF: bps
ASM: bps
TM: bps
sampling frequency
BP1
&
BP2
BP1
&
BP2
BP1
BP1
BP1
BP1
BP1
96 SMs
96 SMs
96 SMs
96 SMs
96 SMs
96 SMs
96 SMs
f0 = Hz
...
TBP1_0= 1 s
...
16 SMs
16 SMs
16 SMs
16 SMs
16 SMs
16 SMs
16 SMs
f1 = 4096 Hz
...
TBP1_1= 1 s
...
f2 = 256 Hz
...
1 s
continuous WF
...
5 s
time

13. On-ground LFR sub-system calibration
LFR will be calibrated on-ground in a standalone configuration across the entire frequency and amplitude range to properly characterize the :
analogue to digital conversions
filter responses
gain factors
reference voltage levels
uncertainties in the on-board computation of spectral products
In particular, the aim is to determine for each frequency channel (f0, f1, f2, and f3) :
the frequency response (amplitude & phase) associated to the analog and digital filters
the group delay between the input signals and the output data
the relative gain and phase shift for all pairs of input channels;
the maximum measurable level associated with the saturation of electronics;
the minimum measurable level associated with the electronics noise and the finite number of bits
the large (near-saturation) narrow-band signal dynamic range
...

15. On-ground LFR sub-system measurements
Measurement of the noise floors of the waveforms
Measurement of the noise floors of the spectral matrices
Measurement of the transfer functions to be applied to the waveforms
Measurement of the transfer functions to be applied to the spectral matrices
Measurement of the dynamic ranges of the waveforms
Measurement of the dynamic ranges of the spectral matrices
Measurement of the white noise responses in terms of waveforms
Measurement of the white noise responses in terms of spectral matrices
Measurement of the uncertainties in the computation of the wave parameters

16. LFR Engineering Model (EM1)
FPGA
ADCs
(RTAX4000
emulator)
November 2013

17. Noise floors of the waveforms (1)
Long continuous waveforms of output signals will be recorded (in count unit) with LFR inputs let free.
Set of waveform data representing all possible working configurations of the receiver for continuous measurements.
The waveform data are then analyzed in order to retrieve the main characteristics of the noise observed for each of these output signals.
One will compute their offset, their standard deviation and their frequency power spectrum; one will also check their stability in time.
Same for a large number of successive waveform snapshots ...

19. Noise floors of the spectral matrices
Successive and a large number of spectral matrices will be recorded (in count unit) with LFR inputs let free.
Set of spectral data representing all possible working configurations of the receiver for auto- & cross-correlation measurements.
It will constitute reference noise measurements for the LFR on-board spectral computation. The stability in time will also be checked.
Results obtained from the original spectral matrices (ASM_F0, ASM_F1, and ASM_F2, respectively), will be compared with those obtained from the normalized ones (BP2_F0, BP2_F1, and BP2_F2, respectively).

20. Transfer functions for waveforms (1)
Constant input signals
One will start by measuring the scale factors that allow to convert count unit to Volt unit for constant input signals (zero frequency).
In a first time, one will inject a +1.0 V amplitude signal in all possible input channels and will record the corresponding waveform data with all possible working configuration of the receiver.
The configurations to be used are thus the same as for the noise floor measurements of the waveforms.
In a second time, one will redo the same but with a -1.0 V amplitude signal.
The comparison between the two cases allows for the determination of the offsets and thus getting rid of them.
(or one will inject a very low frequency rectangular signal ...)

21. Transfer functions for waveforms (2)
Sinusoidal input signals
One will inject 2.0 Vpp sinusoidal signals and sweep over the full frequency range.
Again all possible input channels will be considered and the corresponding waveform data will be recorded with all possible working configuration of the receiver.
Thus, same configurations as for the noise floor measurements of the waveforms.
For continuous waveform measurements the frequency resolution is not limited and can be as good as 0.01Hz :
CWF_F1 : frequency range of analysis = [0.01Hz-2048Hz]
CWF_F2 : frequency range of analysis = [0.01Hz-128Hz]
CWF_F3 : frequency range of analysis = [0.01Hz-16Hz]
For waveform snapshot measurements the frequency resolution is limited by the number of samples (2048) recorded by snapshot :
SWF_F0 : frequency range of analysis = [12Hz-12288Hz]
SWF_F1 : frequency range of analysis = [2Hz-2048Hz]
SWF_F2 : frequency range of analysis = [1/8Hz-128Hz]

22. Transfer functions for waveforms (3)
Sinusoidal input signals (continued)
Frequency responses in amplitude
For each considered frequency, the responses in amplitude will be determined by computing the standard deviations of the output signals.
The offsets will be determined by computing the averages, which should be independent from the frequencies. Time stability will also be investigated.
(or by computing the FFT ...)
Frequency responses in phase
Necessitate a synchronization between the input and output signals. This will be done by triggering the start of the input signals by a pulse synchronized with the receiver. This procedure is on going.
Meanwhile (or as second procedure) we will consider the addition of two sinusoidal signals where one of them will be considered as the reference signal (at a given frequency fref ).
The measurement of the phase shift between the two output sinusoidal signals will allow for the determination of the response in phase relative to the reference signal

23. Experimental facility for LFR calibration
On going ...
4 x
trigger
Mini-LFR
= up to 8 analog signals EM

24. Transfer functions for waveforms (4)
Sinusoidal input signals (continued)
Relative gains and phase shifts
Ideally it would be interesting to perform the measurements for all pairs of input channels. For practical reason we will consider the most important ones, which are sufficient for reconstructing all possible relative gains and phase shifts.
This set of input pairs will be associated to all possible working configuration of the receiver
One will inject 2.0 Vpp sinusoidal signals in these pairs and sweep over the same frequency ranges as for the determination of the frequency responses.
For each considered frequency, the corresponding pair of output waveform data will be recorded. Their relative gain and phase shift will be determined by computing their cross-correlation. Time stability will again be investigated.

25. Transfer functions for spectral matrices
One will inject simultaneously five 2.0 Vpp sinusoidal signals, with same phase, on the LFR inputs. And sweep over the full frequency range with multiple of the on-board frequency resolution (f0/256, f1/256 or f2/256).
One will use all possible working configurations of the receiver for auto- & cross-correlation measurements.
These are the same as defined for the determination of the noise floors of the spectral matrices.
Successive and a large number of the corresponding spectral matrices will be recorded (in count unit).
They will constitute reference sinusoidal signal measurements for the LFR on-board spectral computation. The stability in time will also be checked.
Results obtained from the original spectral matrices (ASM_F0, ASM_F1, and ASM_F2, respectively), will be compared with those obtained from the normalized ones (BP2_F0, BP2_F1, and BP2_F2, respectively).
(indeed one more signal is needed if the dependency with VHF_1 has to be taken into account ...)

26. Dynamic ranges of the waveforms (1)
Measurements will be done with constant and triangular signals.
(BW=1, R0=1, R1=1, SP0=0, SP1=0)
9 Vpp
F = Hz
counts B1
counts B2

28. Dynamic ranges of the spectral matrices
Measurements will be done with two superposed sinusoidal signals. One with large amplitude, the second one with small amplitude.

29. Dynamic ranges of the spectral matrices
The smallest sinusoidal signal detectable with the ASM_F1 is presently (to my best knowledge) :
~ 1 mVpp => ~ 9 counts pic to pic
Tbw ...

30. White noise responses
Another way to measure the frequency response in amplitude ...
Another way to evaluate saturation levels ...
Again both in terms of waveforms and spectral matrices ...

31. Uncertainties on the wave parameters
Concern the uncertainties in the on-board computation of the wave parameters (BP1) derived from the ASM
Tbw ...

32. Expected calibration parameters
For each frequency channel of data products (f0, f1, f2 or f3), the on-ground LFR calibration will determine :
the transfer functions to be applied to the waveforms (WF) and the spectral matrices (ASM and BP2)
the large (near-saturation) narrow-band signal dynamic ranges of the waveforms (WF) and the spectral matrices (ASM and BP2)
the noise floors of the waveforms (WF) and the spectral matrices (ASM and BP2)
the white noise broadband responses in terms of waveforms (WF) and spectral matrices (ASM and BP2)
the uncertainties in the on-board computation of the wave parameters (BP1) derived from the ASM

33. Additional slides

34. LFR operational modes data produced and sent to DPU: data subsequently
transmitted to S/C:   NM
all
(SW In-Situ) BM
LFR
~10 min
all NM
(Shock) SBM1
~15 min NM
all
(Type III) SBM2
min

35. LFR block diagram

36. LFR processus chain

37. LFR processus chain

38. BIAS configuration