ESA ground antennas and their compatibility with the MORE experiment

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ESA ground antennas and their compatibility with
the MORE experiment
R. Maddè, M. Mercolino ESA/ESOC
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ESA deep space network

• ESA deep space network consists of two stations
• New Norcia (NNO) DSA-1, operational since 2001,
  western Australia
• S- and X- band uplink and downlink capabilities
• Ka-band downlink optional (not yet taken)
• Currently supporting Mars Express (MEX) and
  Rosetta
• Cebreros (CEB) DSA-2, operational since 2005,
  Spain.
• X- band uplink and downlink, Ka- band downlink
  capabilities
• Ka-band uplink optional (not yet taken)
• Currently supporting Venus Express (VEX)
• Cebreros will be the station supporting
  BepiColombo
• Future deep space station
• DSA-3 mat be located in the southern hemisphere
  at American longitudes (Chile or Argentina)
• X- band uplink and downlink (baseline), Ka- band
  downlink (optional)

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Cebreros block diagram
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Detail of the back-end (Rx side only)

• Ka-band D/C output BW 220 MHz
• X-band D/C output BW 100 MHz
• L-band D/C output BW 30 MHz
• 3L-band D/Cs per station
• 3 IFMS per station (2 for TTC and 1 for RSI)

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Back end Receiver (IFMS)

• IFMS characteristics
• Input BW 28 MHz (High-speed mode)
• IF at 70MHz
• CFE (common front end) samples at 280 Ms/s
• Open loop capabilities
• Sampling rate from 1kHz to 4MHz
• Quantisation levels 1,2,4,8,16 bits
• Up to 4 channels per each DSP card
• Ranging capabilities
• Maximum ranging tone frequency at 1.5 MHz (as per
  ECSS and CCSDS standards)

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MORE requirements (generals)

• Unlike most scientific experiments mounted on ESA
  missions, MORE heavily involves both space and
  ground segment
• Different requirement levels can be defined
• PI level 1 performance requirements are the
  end-to-end requirements
• A set of level 2 performance requirements has
  been prepared by the PI, with the intention to
  apportion them to the space and ground segments
• Some level 2 requirements are related to media
  calibration

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MORE requirements (level 2)

• MORE requirements can be split into four main
  areas
• Requirements on the needed multi-frequency link
• Requirements on Doppler performance (all links)
• Ka/Ka link adev (1000 s) lt 610-15
• Other links sX/X/ sKa/Ka4 sX/Ka/ sKa/Ka10
• Requirements on media effects
• Uncalibrated contribution adev (1000 s) lt 110-14
  
• (or 310-15 ??) (all media) for antenna
  elevation gt 15 deg
• Requirements on Ranging performance (all links)
• Ka/Ka ranging calibration error shall be less
  then than 0.3 ns (1 s, 1-w) over half a day (X/Ka
  and X/X 1.5 ns)
• Ka/Ka, X/X and X/Ka ranging signals shall be as
  defined in the SGICD (WBRS either with tone or
  PN codes)
• Question for PI are ageing requirements
  intended for the Ground Segment as well?

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Current compatibility of MORE requirements with
DSA

• Need for a multi-frequency link
• Imply a station Ka-band uplink upgrade (A in the
  next chart)
• Requirements on Doppler performance (all links)
• Imply the adev characterisation of the station on
  all links (B)
• Imply the evaluation of the mechanical noise
  contribution (B)
• Requirements on media calibration
• Imply the use of an ad-hoc calibration system
  (which does not exist in ESA stations) (C)
• Requirements on ranging performance
• Imply the development, deployment and validation
  of a wide-band ranging processor (D)
• Imply the development of a proper calibration
  strategy the conduction of related test
  campaign (E)

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Implementation approach

• List of needed activities
• Ka-band transmission implementation
• Assessment of ADEV performance of the station
• Media calibration
• WBRS (Wide band ranging) processor
• Ranging calibration
• Ancillary activities
• F. Check station location accuracy
• G. Extension of station baseband capabilities

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Ka-band transmission

• What has been done
• High stability Ka-band up- and down-conv. are
  available
• Ka-band feed, mirrors and dichroic are in
  production
• Development of a movable mirror, to squint Ka-Tx
  beam respect Ka-Rx beam, on going
• What needs to be done
• Development of the transmitter HPA
• Production and procurement of 2 operational units
• Installation of all Ka-band uplink elements in
  CEB
• Test and validation campaign
• Verification of the Ka-band uplink stability

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Assessment of ADEV performances of the station

• An end-to-end assessment on all the three links
  is required
• What has been done
• At station level, a tool has been developed to
  compute the ADEV of the station, given the
  measurements of each of the equipment (X/X link
  only)
• ADEV characterisation has been performed in both
  NNO and CEB (not taking into account the antenna
  mechanical noise)
• Development of system able to assess antenna
  mechanical noise (to be deployed and validated in
  a test antenna in Villafranca)
• What needs to be done
• Evaluate CEB mechanical noise
• Evaluate overall adev of X/X link, once
  mechanical noise is known
• Evaluate overall adev of X/Ka link, once
  mechanical noise is known
• Evaluate overall adev of the Ka/Ka link, once the
  antenna is upgraded

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Measured ADEV performances
Measured Ka-band UC ADEV lt 110-16
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Measured ADEV performances
Measured Ka-band DC ADEV of 110-16
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Measured ADEV performances (CEB X/X)
The MORE X/X adev requirement is 2.410-14 _at_
1000 s
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Media calibration

• The effect of dispersive media will be almost
  totally cancelled by means of the multifrequency
  link
• Requirements on the level at which troposphere
  effects have to be calibrated have to be frozen
• The current requirements are not enough to define
  the needed system
• There is the need to define the system in terms
  of
• Technical performance
• Station interfaces
• Interfaces to the final user
• What has been done
• Nothing
• What needs to be done
• Study and assessment of technical specification
  of the needed media calibration system
• Development and procurement of the operational
  system
• Installation, testing and long term calibration
  of the operational system

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WBRS processor

• Both the proposed MORE ranging systems (with tone
  at 20MHz or using PN codes) require the
  development of a new TTC platform
• This platform shall anyhow be developed due to
  obsolescence of the current IFMS (in operation
  since 2001)
• What has been done
• Nothing
• What needs to be done
• Study on new wide-band TTC processor
• New wide-band TTC processor development
• New wide-band TTC processor procurement
• Procurement of operational units
• Installation and test of new TTC processor in CEB

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Ranging calibrations

• Requirements on ranging calibration need some
  further clarifications
• ESA has never faced requirements on ranging
  calibration so stringent. Therefore, ranging
  calibration achievable accuracies have to be
  further characterised
• What has been done
• Some preliminary test campaigns on the existing
  links (X/X, X/Ka)
• What needs to be done
• Requirement analysis and test with the current
  available equipment
• Based on the outputs of the characterisation of
  the current ranging calibration system, one may
  consider further activities (if needed i.e.
  On-line ranging calibration)

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Check station location

• The ADEV contribution due to the uncertainty of
  the station location is required to be less than
  1.210-15 _at_ 1000 s. This means a sub-centimetre
  accuracy (0.9 cm) in the station location.
• The declared accuracy of ESA deep space antennas
  is in the order of 1-2 cm over short time
  periods.
• Over long time periods, the effect of the
  tectonics movement must be taken into account.
• Too little data available to characterise the
  tectonics movement in CEB.
• A survey using DDOR/VLBI techniques for
  evaluating the station coordinates may be
  considered. This possibility is at the moment TBD.

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Extension of station baseband capabilities

• The advent of a new ranging processor has high
  impact on baseband station integration
• The number of receiving/transmitting chains (and
  related connectivity to the RF equipment) shall
  be reviewed, depending upon the final mission
  operational requirements
• Once this is clear, and the new processor
  produced, an upgrade of the baseband
  configuration shall take place

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Tentative schedule
ITEM Timeline
A. Ka- band Tx implementation Development 2007/08
A. Ka- band Tx implementation Production 2009/10
A. Ka- band Tx implementation Ka- u/l installation in CEB 2011/12
B. Assessment of ADEV - ADEV of mechanical noise 2008
B. Assessment of ADEV - ADEV of CEB in al llinks 2008/2012
C. Media calibration Study 2007/08
C. Media calibration System development 2009/10
C. Media calibration Installation, verfication, calibration 2011/12
D. WBRS Ranging processor architectural study 2008
D. WBRS Ranging processor development 2009/10
D. WBRS Ranging processor procurement 2011
D. WBRS Ranging processor integration 2012
E. Ranging calibration System characterisation 2008
E. Ranging calibration On-line ranging calibration TBD
F. Check of station location 2008
G. Baseband integration 2012
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Schedule assumptions

• The main assumption is to have the station ready
  6 months before launch
• Launch is currently scheduled for August 2013
• It has to be noted that the station is
  operational, and would require major upgrade
  (i.e. a considerable down-time)
• ? In order to minimise operational impacts, all
  integration activities shall be grouped in the
  same time period

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Costs

• This presentation does not talk about costs
• It just shows how MORE needs can be mapped in the
  existing ESA infrastructure
• However, it has to be noted that
• All that has been mentioned under what has been
  done has been covered by ESA
• Most of what has been mentioned under needs to
  be done is currently not financed
• The PI is invited to acknowledge the
  above-presented current status

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Final remarks

• ESA CEB station would welcome to host the ground
  segment of the MORE experiments
• CEB is an operational station, used to support
  several missions. Therefore
• Station configuration is ruled by ESA
• Station operation is restricted to ESA
• Interfacing to experiment data has to be done
  through ESA
• CEB station will provide in any case routine
  operations to the BC mission