[Css-csts] Tracking Data CSTS

[John Pietras]

David,

I'm finally able to get back to working on the draft TD-CSTS
specification. 

 

In Noordwijk, we struggled a bit with getting everyone on the same page,
and because I was presenting at the front of the room during the joint
NavWG/CSTSWG meeting, I was not able to record all of the issues and
nuances that came up. However, as I recall it, there were a few issues
with the way I had proposed that the service operate: (1) the approach
of creating Contemporaneous Segments with a predefined interval's worth
of tracking data was overly complicated, (2) as specified the service
required that all users of the service get all available tracking data
(e.g., a TD-service user could not get just antenna angles if that was
all that she was interested in), and (3) the approach implies that every
TD service instance as access to all of the tracking data generated for
a space link session, whereas some Complexes may implement the service
in a distributed fashion (i.e., one TD service instance may have access
to only the antenna angles, and another instance has to be used to get
Doppler values). 

 

I'd like to propose a variation that I think resolves these issues. I
describe that approach below, and hopefully you and the members of the
CSTSWG can tell me if it makes sense to you and resolves any issues that
you know of regarding the previous version. Please feel free to forward
this to the members of the NavWG for their comments also.

 

A.	In negotiating the Service Agreement for support between a
mission and a Complex (i.e., a TT&C network), the mission and Complex
mutually agree on what kinds of tracking data can be reported, from the
following set of tracking data types: CARRIER_POWER,
DOPPLER_INSTANTANEOUS, DOPPLER_INTEGRATED, PC_N0, PR_N0, RANGE,
RECEIVE_FREQ, TRANSMIT_FREQ, TRANSMIT_FREQ_RATE, and ANGLES.

 

NOTE 1:   This list is consistent with your recommendations for the TDM
data types that are appropriate for "real time" transmission.

NOTE 2:   For data types that require further qualification (e.g., angle
type and range units), the qualifications are also recorded as part of
the Service Agreement, and are considered to be static for that Service
Agreement. For example, if the Service Agreement specifies the angle
type to be AZ-EL, all angle measurements reported by that Complex to TD
services users of that mission get reported as AZ-EL.

               

B.	When a Service Package is scheduled to provide tracking
services, that Service Package is also configured to provide TD service
instances. Each TD service instance is configured to provide one or more
of the tracking data types. 

NOTE:     Some Complexes may implement TD services that only provide
different subsets of the tracking data types. These limitations are
reflected in the tracking data types allowed for those instances. 

 

C.	When a Service Package containing tracking services starts
executing, the tracking data measurements associated with those tracking
services are taken at whatever frequencies are appropriate and/or
negotiated for those services (different data types may be generated at
different intervals. The Tracking Data Merge and Segmentation production
process takes the measurements and wraps them in Atomic Segments. Each
Atomic segment contains *one and only* of the following: 

-          A single carrier power measurement and the metadata
associated with it;

-          A single instantaneous Doppler measurement and the metadata
associated with it;

-          A single integrated Doppler measurement and the metadata
associated with it;

-          A single carrier power to noise spectral density measurement
and the metadata associated with it;

-          A single ranging power to noise spectral density measurement
and the metadata associated with it;

-          A single receive frequency measurement and the metadata
associated with it;

-          A single transmit frequency measurement and the metadata
associated with it;

-          A single transmit frequency rate measurement and the metadata
associated with it; or

-          A single pair of angle measurements and the metadata
associated with them.

 

NOTE:     In the cases where receive frequencies, transmit frequencies,
and/or transmit frequency rates are measured for multiple participants
(e.g., using the TRANSMIT_FREQ_n data type), a subscription to the
tracking data type (e.g., TRANSMIT_FREQ) gets all measurements of that
type that are available to the TD service instance.

 

D.	For each TD service instance, after binding to the service
provider the user sends a START invocation that subscribes the service
instance to one or more of the tracking data types. If the invocation
attempts to subscribe to one or more tracking data types that are not
configured for that service instance, the START fails and the provider
returns a START negative result with diagnostic "invalid parameter type"
and the name(s) the invalid type(s). If the subscribed tracking data
types are all valid, the provider returns a START positive result that
contains the TDM Header. 

 

E.	Whenever an Atomic Segment becomes available for a tracking data
type to which the TD service instance is subscribed, the TD service
instance transfers that Atomic Segment.

 

What do you think of this approach? 

 

Thanks.

 

Best regards,

John

 

John Pietras

GST, Inc. 

7855 Walker Drive, Suite 200

Greenbelt, MD 20770

240-542-1155 

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