Status of Delta-DOR interoperability Pasadena Mar 23 th , 2015 - PowerPoint PPT Presentation

Status of Delta-DOR interoperability Pasadena Mar 23 th , 2015 Mattia Mercolino E SA/ E SOC

Summary  Study on improved Delta-DOR performance  Study on Solar Conjunction impact on Delta-DOR performance  Ka-band Quasar catalogue activties  Full Delta-DOR interoperability validation with JPL / JAXA / FSA / BITTT  Other activities

Study on improved DDOR performance (1)  A study activity on improved DDOR performance for a 1nrad accuracy are were kicked-off in August  The study will address the achievable accuracy in all frequency bands of interest (X/Ka and 25.5-27GHz)  Major error sources for DDOR identified in: Wet troposphere (WVR calibrations assumed)  Thermal noise in S/C/Quasar observations  Receiver phase dispersion  tackled by the study   Preliminary Design Review held in February/March

Study on improved DDOR performance (2)  Phase-ripple estimation performed with lab-testing Most critical element in the chain is the lower frequency/narrower band  equipment, i.e. the LDC (420-640 MHz input, 28 MHz output centred at 70MHz) Tested in lab with two LDC fed to a single receiver scanning the whole band.  Current estimation is between 0.15 – 0.5 deg (pessimistic)  10 8 2 ) Second derivative of phase difference (deg/MHz 6 4 2 0 -2 -4 -6 -8 -6 -4 -2 0 2 4 6 8 Frequency relative to 70.2 MHz

Study on improved DDOR performance (3)  After preliminary evaluation on possible S/C signal structure that could accomplish the goal, the choice discussed at PDR has been the following: Generation of multiple sub-carriers (2 in X-band, 3 in Ka-band,  as per current standard) Freqs of X-band sub-carriers as per current RF&Mod spec  Freqs in Ka-band still TBC  Spreading of the sub-carriers with CDMA Gold codes (TDRSS-  like). Codes would be orthogonal for each tone (no interference) Selectable chip-rate (1.2 – 4.8 Mcps)  Roll-off factor ( α ) TBC  Code length (L) TBC  Filter length TBC 

Study on improved DDOR performance (4) Spectrum made of discrete lines as a function of chiprate and code length L Example of spectrum with 3.2 Mcps and roll-off of 0.5

Study on improved DDOR performance (5)  In order to guarantee flexibility the design foresees the possiblity to select chiprate and mod. index  System can be backward compatible (no code modulation = old solution with DOR tones)  Two different on-board implementations are under evaluation  S/W simulators for the signal generations and on-ground correlation will be developed  This will allow to simulate several scenarios, assess the effectiveness of the phase-ripple removal by this modulation scheme and would help finalising the choice of the critical parameters of the code

Study on effect of solar plasma on DDOR performance  A study activity in the frame of BepiColombo to evaluate the effect of solar plasma on Delta-DOR accuracy close to solar conjunction mission has been started  16 (out of the original 18) VEX DDOR passes were acquired throughout the whole solar conjunction (-10 deg<SEP<10 deg)  Data processing will start this year (TBC) with the objectives of: Check the JPL model below 10 deg and assess the effect of  solar plasma at low SEP on DDOR accuracy Find optimal configuration in terms of correlation parameters for  DDOR operations in solar conjunction

Ka-band Quasar catalogue activities [1]  Activities in MLG PRSR left MLG in July (2-years temporary import over) and was  re-installed in MLG in November with successful 24-hours recording 1 further 10-hours pass taken during first two months of 2015.  Long term IA with JPL finalised  Long term collaboration between ESA/NASA/CONAE also  agreed for the continuation of the activities until 2022 Date for publication of Quasar catalogue?  2015 (TBC with  Chris)

Ka-band Quasar catalogue activities [2]  Proposed activities in CEB JPL requested the possibility of a temporary installation of the  PRSR in CEB to allow frame-tie with Robledo. The PRSR can be temporary installed in CEB (following what  was done in 2012) However at the moment it is not possible to have the same  network arrangement (direct VPN connectivity) that we have with the PRSR in MLG Also, FEC upgrade including star track functionality will not  happen before beginning 2016, therefore scan capabilities are limited to 4-5 sources maximum Way forward TBD 

Full interoperability validation [1]  Preliminary results DOY 187 (1) Configuration IFMS2: wideband (38 MHz BW) IFMS3 narrowband (19MHz BW)

Full interoperability validation [2]  Preliminary results DOY 187 (2) a) IFMS 2 data (spanning 38 MHz) correlated in three ways - WB (wideband) mode: covering the full 38 MHz BW - NB (narrowband) mode: 2channels (2 ch) covering 19 MHz - NB (narrowband) mode: 3channels (3 ch) covering 38 MHz b) IFMS 3 data (spanning 19 MHz) correlated with the standard NB algorithm to check internal data consistency  The clock model is not uniformly removed from the residuals.  Once this is done, results of NB correlation get consistent with the residuals lining up on the uncompesated dynamics, as shown in the following plot.  The residuals in WB (red points in the plot) do not fit as good (not implemented the modification allowing for the single estimation of the clock model (it will be done in the near future))

Full interoperability validation [3]  Preliminary results DOY 187 (3) After consistent removal of the clock offset (common clock offset on all scans) in NB

Full interoperability validation [4]  Preliminary results DOY 208 Configuration IFMS2: wideband (57 MHz BW) IFMS3 wideband(38MHz BW)

Full interoperability validation [5] Summary  Results look quite consistent and in line with the expected accuracies.  These data were also extremely useful for ESA to spot some little inconsistencies in our processing and will make us able to freeze the station configuration to be used for the MRO tests later this year and finally for InSight.  DSN data of DOY 215 for mixed baseline validation needed  Complete delivery of ESA data to JPL for finalisation of data processing (data delivered at the meeting)  Need for OD validation (ESA can perform a pass-through – TBC but OD validation shall be under JPL responsibility)  More passes to come in 2015 on MRO

Full interoperability validation [6] Validation with JAXA: acquisition on Hayabusa-2 has been supported in December Data of DOY 363 provided to JAXA (during the meeting) for further 1) processing Usuda station data needed to complete validation 2) Validation with BITTT Chang’E-3 moon landing supported by NNO. 1) Further DDOR scans taken after landing. Data translated to RDEF and 2) provided to the Chinese. No raw data received from the Chinese. No results of DDOR scans from ESA baseline received from the Chinese. Further tests with GAIA planned in 2015 3) Validation with FSA – TBD

Other activities [1]  New modem generation (TTCP), replacing the IFMS is being developed.  This modem will embed (as was the case for IFMS), among other functions, an open loop receiver with the following characteristics:  Output BW (spec 160 MHz)  IF: L-band (420-640 MHz)  Channels: up to 8  Sample rate/size: from 1kHz to 16 MHz in 1kHz steps, 1 to 16 bits quantisation (16 MHz is with 2 bit max)  Format: RDEF  Initial tests for the modem in 2015  Plans to have it deployed in all ESA DS in the 2016/2018 timeframe

Other activities [2]  Deployment of Microwave radiometers at ESA DS sites  A HATPRO (humidity/temperature profiler) has been deployed in Cebreros in November 2014  Main purpose: to collect attenuation statistics at X/Ka band  Can also be used to provide good estimations of tropospheric wet path delay  This functionality will be tested before summer, and could be applied to have better tropocals  A second instrument is being procured for installation in MLG (current timeframe for installation: beginning 2016)  A third instrument might be also procured for NNO site (with second priority since no Ka-band capability present in NNO)