SN User's Guide - ESC Home - NASA

headers supported are the Standard Formatted Data Unit (SFDU), Advanced X-ray
Astrophysics Facility – Imagery (AXAF-I), Advanced Composition Explorer (ACE), Low
Earth Orbit-Terminal (LEO-T), and the IP Data Unit (IPDU).
DAS transmits Customer service data, both real-time and playback, as asynchronous
data streams encapsulated in TCP/IP without any CCSDS processing or encapsulation
unless otherwise specified by the Customer in a service request. In this case, the PTP
is used to simply archive the data and to stream it as TCP/IP packets for delivery. With
TCP/IP reliability, this method provides the highest assurance that the data received by
the Customer MOC is exactly the same as the data received by the DAS demodulator.
DAS provides telemetry data with the least manipulation for Customers with their own
PTPs.
H.3.3 Customer Interactions with DAS
The Customer can interact with DAS in two time frames: Planning/Scheduling prior to
an event or events, and during an event. During the planning/scheduling phase, the
Customer schedules resources for service by interacting with DAS through SNAS.
During an event, the Customer can monitor the status of communications from the
Customer platform and, if necessary, modify parameters that control the
communications during the event.
H.3.3.1 The Planning/Scheduling Phase
DAS service support begins with planning sequences. Planning sequences include
interaction between DAS and the Customer to set up a resource allocation request
within the context of the available DAS MAR resource times and the resource utilization
objectives. This customer interaction provides DAS with the time window(s) in which
the Customer requests DAS resources. DAS in turn provides the Customer with the
available service time(s) and the associated TDRS(s) available for the support within
the specified time window. The customer can then vary parameters of their request
derived from this information.
NOTE:
If a dedicated customer preempts a non-dedicated customer,
DAS will attempt to reschedule the non-dedicated
customer’s preempted support at another time within the
requested window.
The customer sends a request via SNAS for the resources desired, including customer
identification and location (ephemeris), identification of the TDRS(s) requested,
parameters of resources requested, period of the request, demodulator parameters,
archive and retrieval requests, and data forwarding requirements. DAS will interact with
the Customer via SNAS to establish and confirm a customer request.
Upon receipt of a specific request for resources, DAS will examine the parameters
required to set up the request and determine if they are feasible. If DAS determines
that the request is not within the capability of the system, DAS will notify the customer to
this effect.
Revision 10 H-16 450-SNUG