September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 1 MORE EGSE IF & BB EGSE Allan Variance & RF EGSE

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 2 Phase A/B1- EGSE Activities-1  Beginning in January 2007: EGSE system definition including:  Analysis of EGSE functional and performance requirements  Analysis of the Radio-Science Experiment applicable documentation.  Definition of EGSE overall architecture and of the interfaces between main EGSE components (RF equipment, digital and power equipment, MMI workstations, etc.)  Establishment of an overall EGSE development plan and schedule  Produce the design specification WBRS preliminary study including:  Analysis of the requirements related to the deep space ranging system with focus on the wideband ranging signaling system (WBRS).  Integrate the EGSE level simulation with system level simulations (developed by University of Rome).

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 3 Phase A/B1- EGSE Activities-2 EGSE RF system definition including:  Analysis of EGSE RF functional and performance requirements  Definition of RF EGSE architecture  Contribute to overall EGSE development plan and schedule  Analyze the Radio-Science Experiment applicable documentation.  Analyze the requirements related to Allan Variance.  Produce the Allan Variance Test Set design specification  Implement the Allan Variance Test set to be used for B/B testing

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 4 BB Heritage Hardware Platform Industrial PC equiped with: IF receiver (up to 3) IF Modulator (up to 2) BPSK Dem. (up to 3) Frame Synch +Vit. Dec. + RS Dec. (up to 3) RNG Processor TC Generator IRIG-B receiver Frequency Distributor CPU Hard Disk Software Platform Operating System Red Hat Linux v.9.0

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 5 Main Features: RANGING (1/2 cont.) Ranging function  Code ranging ESA standard  interface the RF system by means the IF Receiver in down-link (the same as for the TLM link) and the IF Modulator for the Up-link link (the same as for the TLC link)  generate the ranging tone and the code for ranging measurements being the tone signal BPSK modulated by the ranging code; the tone frequency and code length are programmable whilst the Code Repetition Period may be computed by  the maximum usable code length is 2 Exp. 24  supply the ranging signal to the IF Modem (the same of the TLC system) for PM modulation with the correct modulation index  receive from the IF receiver the down linked ranging signal for ranging measurements  solve code ambiguity due to the propagation delay  perform accurate range measurement by measuring the time elapsed between emitted and received code  store in mass memory the ranging measurements data  transmit to the SCC all the stored data by means of TCP/IP link according to the communication protocol

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 6 Summary of characteristics Ranging tone100 KHz to 1,5 MHz Ranging modulation index0,1 to 2 rad. (down-link) Tone mod. two selectable phase (programmable from 10° to 90°) Modulation schemePCM/PSK/PM Maximum code length2 Exp 24 Ranging accuracy1ns STC protocolMKII (modified) on TCPIP (IEEE 802.3) M&C protocolEDEN protocol on TCPIP (IEEE 802.3) Main Features: RANGING (2/2)

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 7 WBRS migration  Main Improvements needed WBRS standard 20 MHz tone Improved accuracy Integration of post processing SW  Modification in architecture Possible trough reconfiguration in FPGA Possibility to change IF front end

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 8 Allan Variance test set-up 1/2 The test bench is designed in order to measure the Allan variance of frequency standards and it is known as Dual-Mixer Time Difference (DMTD) scheme The L.O. frequency is set in order to have a residual frequency of 1 Hz, the time interval counter measures the time difference between the two signals, from the fluctuation of the time difference it is possible to calculate the Allan variance. DUT FILTER + ZCD TIME INTERVAL COUNTER L.O. REFERENCE OSCILLATOR FILTER + ZCD DUAL MIXER METHOD

September 2005 backnext All rights reserved © 2005, Alcatel Alenia Space Page 9 Allan Variance test set-up 2/2 FILTER + ZCD TIME INTERVAL COUNTER L.O. REFERENCE OSCILLATOR FILTER + ZCD DUAL MIXER METHOD (NOISE FLOOR EVALUATION) REFERENCE The uncertainty sources are :  Reference oscillator residual phase noise.  Noise introduced from the ZCD ( Zero Crossing Detector ) Measurement from “noise floor evaluation” test setup will allow to understand the real accurarcy of the test set up.