USING DME FOR TERRESTRIAL TIME TRANSFER

摘要

Techniques for allowing a remote or fielded receiver to derive a precise time reference (such as Coordinated Universal Time (UTC)) when the fielded receiver is not able to derive time directly from received GPS signals. One or more fixed DME reference stations are located within range of DME beacon signals from an existing DME beacon station, the DME reference stations also having the capability to receive GPS signals and derive UTC therefrom. Based on the known distance between the DME reference station and the DME beacon station, the DME reference station can determine the time of transmission from the DME beacon station of each DME beacon signal. This time tag information is then provided to the fielded receiver, which is also within range of DME beacon signals from the DME beacon station. With this time tag information, the fielded receiver can correlate that with the received DME beacon signals and derive UTC to within an acceptably small margin.;GLOSSARY3GPPThird Generation Partnership ProgramAWGNadditive white Gaussian noiseASFAdditional Secondary Factoralphafilter roll off factorBCCHbroadcast control channelCcarrier powerCCCHcommon control channelCIcoherent integrationdBdecibelDMEDistance Measuring EquipmentE911Enhanced 911EbEnergy per bitEcEnergy per chipEsenergy per symbolEIRPeffective isotropic radiated powerIFIntermediate FrequencyFCCFederal Communications CommissionGHZgigahertzGNSSglobal navigation by satellite systemGNSSGlobal Position SystemKHzkilohertzKmkilometerLTELong Term EvolutionMHzmegahertzmmetermsmillisecondsN0noise power spectral densityNCInon coherent integrationnsnanosecondNTPNetwork Time ProtocolOCXOoven-controlled crystal oscillatorPTPPrecision Time ProtocolRxreceiveSNRsignal to noise ratiospcsamples per chipspssamples per symbolSVsatellite vehicleTCXOtemperature-controlled crystal oscillatorTxtransmit

主权项

1. A method for deriving a precise time reference when GNSS signals are not directly available, comprising:
determining that GNSS signals are not directly available; receiving a plurality of DME beacon signals from a DME beacon station; receiving precise timing information from a DME reference station, the precise timing information including time tags for each DME beacon signal received by the DME reference station from the DME beacon station, the time tag including a precise time reference for the time that the DME beacon station sent the respective DME beacon signal; and deriving a precise time reference from the DME beacon signals received from DME beacon station and the time tags received from the DME reference station corresponding to the received DME beacon signals.