ESA ground antennas and their compatibility with the MORE experiment - PowerPoint PPT Presentation

ESA ground antennas and their compatibility with the MORE experiment

R. Maddè, M. Mercolino

ESA/ESOC

• 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)

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 TT&C and 1 for RSI)

Each input BW: 28 MHz

70 MHz

8400 – 8500

MHz

31800 – 32300

MHz

540-640 MHz

Switch

Switching

Matrix

X-band

D/C

L-band

D/C 1

RHC

RHC

IFMS1

LHC

LHC

C

F

E

GDSP

420-640 MHz

L-band

D/C 2

Ka-band

D/C

GDSP

UCPU

Test

Test

Estrack LAN

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)

• 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

• 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) < 6*10-15
• Other links: σX/X/ σKa/Ka=4; σX/Ka/ σKa/Ka=10
• Requirements on media effects
• Uncalibrated contribution adev (1000 s) < 1*10-14

(or 3*10-15 ??) (all media) for antenna elevation > 15 deg

• Requirements on Ranging performance (all links)
• Ka/Ka ranging calibration error shall be less then than 0.3 ns (1 σ, 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?

• 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)

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

• 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

• 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

Measured Ka-band UC ADEV < 1*10-16

Measured Ka-band DC ADEV of 1*10-16

The MORE X/X adev requirement is 2.4*10-14 @ 1000 s

• 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

• Both the proposed MORE ranging systems (with tone at 20MHz or using PN codes) require the development of a new TT&C 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 TT&C processor
• New wide-band TT&C processor development
• New wide-band TT&C processor procurement
• Procurement of operational units
• Installation and test of new TT&C processor in CEB

• 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)

• The ADEV contribution due to the uncertainty of the station location is required to be less than 1.2*10-15 @ 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.

• 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

• 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

• 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

• 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