Notes from South Pole TDRSS Relay (SPTR) Mtg/Telcon held on 1/6/98

Participants:  GSFC (450, Eng Team, NISN)
               SP User Rep at GSFC (Troy Ames)
               MSFC (Kevin Takada)
               WSC (Jim Edgington, Bob Gonzales)


SPTR OPERATIONAL USE - SPTR IMPLEMENTATION IS TO THE POINT WHERE ITS
CONSIDERED OPERATIONAL AS OF JANUARY 5TH 1998 - ALL SP USERS ARE ENCOURAGED
TO USE THE COMMUNICATIONS DURING SPTR SCHEDULED PERIODS AND LET US KNOW IF
THEY ARE HAVING ANY PROBLEMS (IT AIN'T PERFECT JUST YET, BUT WE'RE GET'N
CLOSER) - ALSO LET US KNOW YOUR SUCCESSES AS WELL!


NISN/MSFC ITEMS

- MSFC (Kevin Takada) reported there is a CISCO router S/W bug related to
redistribution of routes (BGP protocol) that affects all SPTR routers
(SP/WSC) being used. MSFC/AMES (NSI) is working with CISCO to
demonstrate/isolate/resolve the problem. Work around router configurations
have been put in place in the interim. There is still router tweaking going
one as problems are reported. The following are the know problem areas
remaining.

       -- Asymmetrical routing is currently being done at the SP during
co-ops (TDRS/GOES). This results, on occasion, in SP return IP traffic
being routed via GOES even though TDRS is handling the traffic transmitted
to the SP (SSAF). A SP GINKO router change needs to be implemented once
Chris Liljenstolpe returns to McMurdo on 1/8.

       -- During TDRS only mode of operation, there can be no e-mail
traffic to/from the ATSVAX at Malabar. This can only be resolved by
implementing "policy" routing. It is intending to implement policy routing
once the T1 circuit is in to Malabar and the CISCO 4700 routers have been
installed at both UofM and Malabar. Paul Eden is requested to e-mail the
sptr collective to advise us when the T1 and 4700's has been installed.

- MSFC (Kevin Takada) reported there is a potential Intra-Facility Link
(IFL) problem between STGT and WSGT at WSC that may preclude using WSGT for
F1 SPTR operations after the handover to WSGT on February 1st (post Shuttle
WOW).  It was intended to use fiber optic modem transceivers on the fiber
IFL but there may be an RS422 compatibility issue. MSFC has ordered 3
Ethernet modems (single mode transceivers) to span the 6Km distance. Kevin
was unsure of the priority and ETRO expected on these modems. GSFC
(NISN-Stan Rubin) will check if any can be obtained elsewhere.(Late news -
StanR indicates that he has located 2 xceivers & will be shipped as loaners
- see below). The second
WSC SPTR router (being integrated into the second TDI at GSFC) will be sent
to WSC ASAP to test the current F/O modems for compatibility. WSC (Jim
Edgington) will also see if other alternative transceiver interface
equipment might be available that could be tested and used until the
ordered E/N modems can be installed.

NOTE-POST MEETING - GSFC (NISN) has located two 10-Base-T xceivers here at
GSFC
and will ship these to WSC on 1/9 for temporary use. They should arrive at
WSC on 1/14 (Wednesday).


SPTR ENGINEERING STATUS

- WSC (Bob Gonzales) reported monitoring of the K-Band frequency indicates
a fairly consistent frequency 12-15 KHz higher that nominally scheduled.
Bob will advise Tri Thai after further data reduction the best frequency to
have implemented within the SPTR SHO. WSC will FAX to Dave Israel the SSAR
signal strength (Eb/No) info for further S-Band fade evaluation.

- Miteq is building another S-Band LNA to be sent to the SP in a week to 10
days. A temporary LNA (spare GOES LNA) is currently being use at the SP to
allow the SSAF link to work. Getting the LNA swapped-out will be addressed
once the Miteq LNA is at the SP. Its anticipated the last flight into the
SP will occur 1st week in February.

- New K-Band encoder chips are being fabricated by ATSC. Tests will be
scheduled within the next two week using the RFSOC/F1/WSC to check
compatibility before shipment to SP. The KSAR file transfers are being used
in an uncoded configuration with Bi-Phase-L modulation. A new SHO config
code (P03) was fabricated to support this link configuration. EIRP margins
are consider good to run uncoded and very few transmission errors in the
transfer process have been observed thus far.

- New SPTR MCS S/W has been FTP'ed and installed at SP to resolve interface
problems with the SP fileserver. This appears to be working now but will be
under close observation to assess possible slowdown's that have occurred.

- The backup K-Band TWTA (#2) has a bad Standby status indication which
precludes its current automatic use (turn-on) via MCS S/W control. A
request will be made to swap the cables between TWTA's to isolate a
possible cable problem. If not, it may be possible to modify the MCS S/W to
better control its turn-on. This particular TWTA has an existing HV timer
problem that must be observed for proper warm up, in the event its needed.
TWTA-1 is configured as the prime right now and is working fine.

- Dave I. is formulating and will be adding soon a "Frequently Ask
Questions" (FAQ) feature to the SPTR Web page to dispel any
misunderstandings that may have been derived from some of the recent email
traffic on just what to expect from SPTR.


SPTR OPERATIONS

- The SPTR schedule has been modified to add the daily time of maximum
elevation angle for SPTR support. The initial S-Band signal strength
(fading) data taken thus far has indicated that good solid IP
communications can be obtained plus/minus 1 hour about this max elevation
time. The 45 minutes prior (and 45 mins after) this "prime" SPTR 2-hour
window will be intermittent (3-10 minute) signal fades but is certainly
usable for most IP traffic activity. Currently, the comm support phasing
between TDRS and GOES allows continuous comm during the later portion of
the TDRS view period/fades, when GOES is also available. Dave I. will add a
graphic representation of a typical TDRS comm contact on the SPTR web page
to illustrate/explain the usable period(s) for communications.

- Andre F. has reported via email a problem with the methodology used on
the K-Band file transfers which precludes transferring files onto the SP
fileserver, during a TDRS contact, while the SP fileserver is transmitting
files to the WSC fileserver. Its a matter of SPFS loading/processing speed
to keep the data moving at a 2MB rate via the TDRS link. Until this is
resolved (or an appropriate work around is developed), users are requested
to place their files on the SPFS during periods other that when TDRS is
scheduled.

- A TDRS-1 E/W maneuver was performed on 6 Jan as it approached one end of
its mandatory position box. Future E/W maneuvers will occur on 55-58 day
cycles to maintain TDRS-1 within plus/minus 0.3 degrees centered at 49.0W
(311.0E) longitude. SPTR signal strengths will be monitored closely for the
next 3-4 months to ensure optimum SP SPTR antenna pointing was obtained.

- The SPTR OIP document is through CCB now and has been made available on
the SPTR web page (new items area). DCN-001, reflecting as-built, should be
completed by 1/9 and will be incorporated within the OIP and place on the
SPTR web page as soon as its completed.