BS ISO 17214 pdf download – Space data and informationtransfer systems-Spacecraft on board interface services —Time access service

BS ISO 17214 pdf download – Space data and informationtransfer systems-Spacecraft on board interface services —Time access service.
service: capability of a layer (service provider) to9ether with the layers beneath it which is provided to the service users.
lime Access Service Access Powit (TASAP): the point at which Time Access
Service is provided by a Time Access Service entity to a Time Access Service user entity.
TASAP address: a Time Access Service address that is used to identify a single TASAP.
1.5.2.3 Terms defined in this Recommended Practice
For the purposes of this Recommended Practice, the following definitions also apply.
accuracy: closeness of the agreement between the times reported by a local time source and the master onboard time source of the spacecraft.
application: component of the onboard software that makes use of the Time Access Service. NOTE — Such components include flight software applications and higher-layer services, error bound: indication of the theoretical error range of a particular time value.
NOTES
1 This is dependent upon the mechanisms of the time source used to obtain the time value. It may be related to the precision and resolution of the time value but also any associated synchronisation mechanisms.
2 Larger values for the error bound indicate less accuracy in the returned time value. precision: smallest significant time increment that can be reported by a time source.
NOTE — For example, a time source that reports time as minutes.seconds:miM’seconds has a precision of ims. The precision of a time source is normally less than the resolution of that time source.
resolution: smallest significant time increment that can be measured by a time source.
NOTE — For example, a time source driven by a 1MHz oscillator has a resolution of ips.
time correlation: process of maintaining coherence between the master time source and each local time source, such that all time sources provide the same time value within some bounded uncertainty.
NOTE — This maximizes the accuracy of each time source with respect to the master onboard time source.
1.6DOCUMENT NOMENCLATURE
The following conventions apply throughout this Recommended Practice:a) the words ‘shall and ‘must’ imply a binding and verifiable specification;b) the word ‘should’ implies an optional, but desirable,specification;c) the word ‘may” implies an optional specification;
d) the words ‘is’ , ‘are’ , and ‘will imply statements of fact.
1.7REFERENCES
The following documents contain provisions which, through reference in this text, constituteprovisions of this Recommended Practice. At the time of publication, the editions indicatedwere valid. All documents are subject to revision, and users of this Recommended Practiceare encouraged to investigate the possibility of applying the most recent editions of thedocuments indicated below. The cCsDs Secretariat maintains a register of currently validccSDS Documents.
NOTE – This document contains no normative references. Informative references are
contained in annex A.