1 esa ground antennas and their compatibility with the more experiment r. maddè, m. mercolino...

1

ESA ground antennas and their compatibility with the MORE experiment

R. Maddè, M. MercolinoR. Maddè, M. MercolinoESA/ESOCESA/ESOC

MORE Team meeting, 26-27 February 2007

2

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)


3

Cebreros block diagram


4

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 TT&C and 1 for RSI)

8400 – 8500MHz

RHC

LHC

31800 – 32300MHz

RHC

LHC

X-bandD/C

L-bandD/C 1

SwitchingMatrix

IFMS1

CFE

GDSP

540-640 MHz70 MHz Each input

BW: 28 MHz

L-bandD/C 2

GDSP

Test

Test

UCPU

Estrack LAN

Ka-bandD/C

Switch

420-640 MHz


5

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)


6

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


7

MORE requirements (level 2)

MORE requirements can be split into four main areas:1. Requirements on the needed multi-frequency link2. 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=103. Requirements on media effects

• Uncalibrated contribution adev (1000 s) < 1*10-14

(or 3*10-15 ??) (all media) for antenna elevation > 15 deg4. 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?


8

Current compatibility of MORE requirements with DSA

1. Need for a multi-frequency link– Imply a station Ka-band uplink upgrade (A in the next chart)

2. 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)

3. Requirements on media calibration– Imply the use of an ad-hoc calibration system (which does

not exist in ESA stations) (C)

4. 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)


9

Implementation approach

List of needed activities:

A. Ka-band transmission implementation

B. Assessment of ADEV performance of the station

C. Media calibration

D. WBRS (Wide band ranging) processor

E. Ranging calibration

Ancillary activities

F. Check station location accuracy

G. Extension of station baseband capabilities


10

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


11

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


12

Measured ADEV performances

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


13

Measured ADEV performances

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


14

Measured ADEV performances (CEB X/X)

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

CEB X/X Allan deviation

2.40E-14

1.00E-17

1.00E-16

1.00E-15

1.00E-14

1.00E-13

1.00E-12

1E+00 1E+01 1E+02 1E+03 1E+04

t (s)

s y(t

)

LIN RSS Worst case B-C


15

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


16

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

WBRS processor


17

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)


18

Check station location

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.


19

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


20

Tentative scheduleITEM 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


21

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


22

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


23

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

1 esa ground antennas and their compatibility with the more experiment r. maddè, m. mercolino...

Documents