Status of Delta-DOR interoperability Colorado Springs April 20 th , 2009 Mattia Mercolino E SA/ E SOC,
Summary � Results of ESA Δ DOR support to Hayabusa � ESA-JAXA Δ DOR tracking on VEX � Status and plans of ESA enhanced Wideband Δ DOR for future supports to JPL � ESA-JPL wideband Δ DOR interoperability testing � Way forward to ESA possible Δ DOR support to MSL
Results of ESA Δ DOR support to Hayabusa
Hayabusa observations (1) � Acquisitions: � 2 acquisitions of Hayabusa were made during 2008 � During the first tracking there were problems in DSN antenna pointing for the uplink of ranging tones to the S/C, therefore only quasar and carrier signal were acquired � The second tracking was successful � Data translation: � JAXA translated some sample of quasar data of the first acquisition in VSR format � Such Quasar data were successfully correlated with ESA data � JAXA provided all data of the second acquisition translated into both VSR and MK-V formats
Hayabusa observations (2) Data processing – S/C � � The two datasets (JAXA-VSR and JAXA-MKV) were translated, for each acquisition, in the ESA-CDF format and processed with the ESA - Δ DOR s/w correlator. � The S/C correlation of the S/C acquisition produced a correlation peak at 0Hz, with a phase of about -1.5 rad different from the expected value of 0 rad.
Hayabusa observations (3) � Data processing – Quasar (1) � The two datasets were translated, for each acquisition, in the ESA-CDF format and processed with the ESA - Δ DOR s/w correlator. � The quasar correlation produced a correlation peak of 0.82 for both acquisition Q1 and Q3 � This value is lower than expected, since the two samples streams, representing the same signal, should almost equal
Hayabusa observations (4) Data processing – Quasar (2) � � Direct comparison between the CDF samples obtained from the JAXA VSR file and those obtained from the JAXA VLBI file was made. � The I streams were almost the same (only 1.000 samples over 2.000.000 differ, i.e. the 0.05%) � The Q streams differed by more than 1.000.000 samples over 2.000.000, i.e. more than 50% of samples. � JAXA VSR data were also translated in VLBI format using the ESA- Δ DOR format converter. Again a comparison wrt the VSR samples was performed. � The I streams were almost the same (only 1.000 samples over 2.000.000 differed). � The Q streams differed by about 233.000 samples over 2.000.000 (11%). This amount of noise is consistent with what has been measured up to now, and is due to the quantization error affecting the reconstruction process of the analytic signal during the VLBI � CDF translation.
Hayabusa observations (5) Data processing – Quasar (3) � � Finally, a direct comparison of the JAXA VLBI file with the ESA VLBI file obtained with the ESA- Δ DOR format converter. The result was that the two real streams differed by more than 1.000.000 samples over 4.000.000. � Looking this difference more in details, it was discovered that the differences between the JAXA and DIAA VLBI quasar files involved the odd samples. � The I samples of the JAXA VLBI � CDF translation derive from the VLBI real stream, which is under-sampled by taking one every two samples (i.e. the even samples). � On the contrary, the Q samples of the JAXA VLBI � CDF translation are obtained by a signal reconstruction process involving all the VLBI real stream. � Since the stream includes also the odd samples, the Q-samples cannot be reconstructed in a proper way. This might explain why the correlation process produced a low correlation peak on the Quasar files, and an unexpected non-zero correlation phase on the S/C files.
ESA-JAXA Δ DOR tracking on VEX
VE X observations � VEX is currently being observed monthly (once per month) by ESA in order to provide JPL with plane-of-the-sky measurement of the S/C � ESA provided JAXA with the dates for a VEX tracking in the 2009 timeframe � JAXA to identify suitable dates for the support
enhanced Wideband Δ DOR Status and plans of ESA
SA enhanced wideband Δ DOR (1) E � From Phoenix support experience, the limiting factor of ESA Δ DOR accuracy is the total spanned bandwidth at the receiver (maximum 28 MHz) that allows the reception of only one of the Δ DOR tones at X-band (19 MHz wrt the carrier) � ESA is undergoing an activity to upgrade its Δ DOR receiving capabilities for wideband Δ DOR (i.e. use of both 19 MHz tones and/or 2 nd harmonics of such tones) � The activity foresees some rewiring of the back-end at both Cebreros and New Norcia DSA plus some new developments for the correlator in order to be able to cope with such modifications
SA enhanced wideband Δ DOR (2) E � In order to be able to acquire the spectrum � The wiring will be upgraded as follows
SA enhanced wideband Δ DOR (3) E � The cabling will be installed in Cebreros during week 18, but not connected to the L-band downconverter due to station freeze for the launch of Herschel-Planck. � Once the freeze is over, the new wiring will be connected and validated. � For New Norcia the installation is foreseen for weeks 23/24, depending on H-P launch. � By the end of June the system should be ready for operational validation (with VEX since passes are already foreseen for the remaining of 2009).
Δ DOR interoperability testing ESA-JPL wideband
MRO observations � In order to fully validate the ESA wideband Delta-DOR functionality the following options are foreseen: � First functional validation of the acquisition with one station only � First end-to-end validation on ESA S/C (VEX in the frame of th eactivity already foreseen) � Real-scenario validation using a S/C with DOR tones at X-band � candidate MRO. Is this feasible in the frame of the mutual agreement between JPL and ESA for Delta-DOR operations? Any other S/C that could be used? � Two are the configuration to be tested: � Delta-DOR from ESA stations only � Delta-DOR in mixed-baseline mode Since data translation from/to VSR has already been proven, the � observations on MRO would: � Validate ESA wideband raw data capture � Validate ESA capability of correctly correlate data acquired in wideband at its stations � Validate ESA capability of correctly correlate data acquired in wideband in mixed-baseline mode
Tentative schedule � ESA-JPL MRO Delta-DOR tentative schedule: April 2009 Sept. 09 March 10 TBD 10 HW upgrades readiness SW upgrades readiness Tracking and data processing and validation � JPL to confirm whether a ESA is allowed to track MRO
Way forward to ESA possible Δ DOR support to MSL
Δ DOR support to MSL? � Results of Phoenix Delta-DOR tracking by ESA were not as accurate as expected due to bandwidth limitations � This could be seen as a potential problem for future Delta-DOR support by ESA � ESA is undertaking an upgrade to wideband Delta-DOR in order to be able to support recordings up to 100 MHz wide (the limitation in this case is the diplexer) in the band 8.4 – 8.5 GHz � This should enhance the Delta-DOR accuracy of the ESA system to the same level of the JPL system � Once the capability is installed, verified and tested in a real-case scenario (i.e. with MRO), JPL and ESA could jointly produce and distribute to the MSL project a Memo outlining the obtained results
Recommend
More recommend
