Lunar Astro-Track


Engineering

   Details of the Lunar Astro-Track design are described in this section.  Here you will find link-budgets, data rates, and other technical information.

   Design Topics:


       System Summary


       RFID Link Budget (Nominal)

       RFID Link Budget (Emergency)

       RFID Components

       

       Lunar Lander Link Budget

       Lunar Link Components


       Radio Location Accuracy

            Range Ring Accuracy
            DF System Accuracy
           

       Power Systems

           


                    
            

Radio Location Accuracy

Range Ring Accuracy


The range ring accuracy is dependent on:

    1) Accurate Clock Timing and Time Stamping
    2) Accurate Knowledge of 'Time-Delay' through RFID
    3) Signal to Noise Ratio ( Cross-Correlation Peak Fidelity)

Given that we are using a high bandwidth signal, the cross correlation peak of the matched filter will be very narrow (meaning less time ambiquity).  

Anticipated accuracy:  < 5 meter 3 sigma


DF System Accuracy


Unfortunately after much study, the DF System accuracy will not be quite as accurate.  If we restrict ourselves to a four element array, the 3dB beamwidth is quite large.  Because of this limitation, the resolution of the angle of arrival estimate will be rough.  This system will be able to easily identify which quadrant the RFID is with repect ot the range ring. Given that the RFID will nominally be within 20 meters, this is an acceptable limitation.