101st Meeting of the
Satellite Telemetry Interagency Working Group (STIWG)
Virginia Beach, Virginia
Wednesday, March 24, 2004
Minutes
Call to Order and
Welcome
The STIWG meeting was called to order at 9:00 a.m. by Ernest Dryer of the U.S.G.S., who is the Chairperson for 2004. It was announced that the morning would by given to technical presentations and would be open to non-STIWG members. The normal STIWG meeting was to begin after lunch.
Welcome from the
NOAA National Ocean Service
The host of the STIWG meeting, the NOAA national Ocean Service, welcomed the STIWG members.
Presentations of DCS Project Studies Sponsored by
NOAA/NESDIS
GOES DCS Backup
Study
Mark Bailey and Jean Pohl of AC Technologies presented the results of their work on a viable DCS backup system concept that would ensure continuation of data processing if Wallops should ever fail. The Power Point presentation is included as an attachment to these minutes. Two backup scenarios were mentioned: (1) a centralized one which would be conceptually like Wallops only in reduced scope, and (2) a distributed backup design that would utilize multiple users’ data DRGS data sources rather than directly acquiring the data from GOES. Data distribution would otherwise be the same for both concepts. AC Tech. emphasized the distributed system during the STIWG discussion. Secure Internet data feeds would be emphasized and the Domsat link would be continuously monitored for failures. There would also be continuous monitoring of the LRIT link (which could be relaying DCS message data). Phil Whaley said that the LRIT link is already backed up at the Wallops image backup site located at the Goddard Spaceflight Facility in Greenbelt, Maryland. Test messages will be used to verify the DCS backup link prior to data distribution. There would be a rapid deployment of Wallops CDA staff to the backup facility if there was a primary system failure.
A question was asked regarding the planned backup system database and how frequently the system updates would occur, for instance to the PDTs. It was stated that the database would never be more than 24 hours behind the primary system. A more serious concern would be getting changes that have been made to the database while the primary system was down back to Wallops. Data base operations at the backup site will be scaled back versions of that done on the primary system.
The selected site for the facility would be the new NSOF (NOAA Satellite Operations Facility) building that is under construction in Suitland, MD. There were opinions from users indicating that the chosen site was too near the existing Wallops location. The guidelines that NOAA gave to AC Tech. only specified at least 50 miles separation. It was also pointed out that if Suitland was down, there would be no spacecraft control anyway, and therefore no data to be processed. However, it was stated that at least, Fairbanks could control the GOES West. AC Tech. mentioned that the report represents the findings of a study and is not a final design.
AC Tech. is recommending that quarterly fail-over drills be part of backup system standard operations.
A final report from AC Tech. is due in April, 2004, and will be posted on the DCS Internet site. AC Tech estimated a ROM backup system cost of $2.5 million.
LRIT Development
Status
Jeff Manning of Science and Technology Corp. presented the status of the transition from the analog WEFAX to the digital LRIT service. LRIT has an allocated maximum bandwidth of 256 Kb, and it currently using 128 Kb. Plans were to begin the service with GOES N, but transition has begun with the current GOES East satellite and will begin on the GOES West sometime this spring (2004). Current LRIT products include charts, imagery, and EMWIN. Beginning last October, the alternating transmissions of WEFAX and LRIT were begun with 29 minutes of LRIT alternating with 31 minutes of WEFAX. It is planned to continue this schedule through October 2004. DCS data are also being inserted into the data stream. There were questions from users about the latency and priority level for DCS message data. He reported that no latency tests had been performed, and that the priority level for DCS data has not yet been determined. He said that a 1.2 meter dish was working fine there at Virginia Beach and without accurate alignment. Volunteers are needed for testing the DCS data stream for determining properties such as latency.
Jeff invited users to come and witness a demonstration of the system that he had installed there in the hotel.
Interested users can find more information at http://noaasis.noaa.gov/LRIT and provide comments to lrit@noaa.gov. The URL for additional operational information was listed as http://www.osdpd.noaa.gov/cob/cob.html.
Duane Prebel, representing Morecom International presented the status of the investigation to determine the applicability of CDMA technology to the DCS environment. The scope of the study covers the concept of a coexisting CDMA system overlaying the existing 400 KHz DCS band. Theoretical studies are completed and Morecom is working with Microcom Design on a CDMA DCP design that will soon be ready for testing using the Microcom DRGS. The next phase of testing is planned to be using the Wallops CDA facility for a test which will more closely resemble true DCS operations. The DCS RF links being studied for possible CDMA functions consist of both the DCPI and the DCPR. Duane said that the DCPI would only be modeled and not physically tested.
An absolute requirement of the CDMA study is that there must not be any interference with the existing FDMA/TDMA system. Duane referenced one study that indicated maximum RF efficiency could be achieved by using a mixed CDMA and TDMA/FDMA system. Data rates for the CDMA system will probably be about 100 to 200 bps. System management should be much different from that which is currently in use. A guideline being used is to have the data ingest phase at the Wallops CDA look just like the current data.
Richard Schwarz of Microcom Design next presented engineering details of the software/hardware approach that is being used on the CDMA study. He said that they are nearing Phase 2 of the study which is prototype implementation. They intend to utilize the latest technology chips and subsystems that are available. Code will be primarily portable C++. Low power chips will be utilized, some as low as 1 volt to minimize power drain. The design will also utilize existing Microcom boards/subsystems that can be adapted to the system. The actual software radio will be able to implement TDMA and/or CDMA signals. The initial goal is for 50 CDMA simultaneous users at a 37 dBm power (EIRP) with a noise floor 29 dB below the 1200 bps transmitters operating at a 50 dBm level. There will be tests to determine the CDMA limits against 1200 bps transmissions (which are the most prone to interference).
Kay proposed use of CDMA for the random channels which would thus free 30 channels that currently have random transmission assignments. The group adjourned for lunch at this point.
Afternoon Session Call
to Order and Welcome
The afternoon session of the STIWG was called to order by Ernest Dryer, the Chairperson for 2004. The STIWG officers for 2004 were announced: Ernest Dryer is the Chairperson and Alan Pilak of the NOAA/ERG is secretary. Since Alan Pilak 2004 was absent, Jim Wydick, who was one of the NESDIS support personnel, was doing the minutes for this meeting. Next were introductions of supporting personnel which included Letecia Reeves who is now officially Carol Green’s replacement in NESDIS, and Peter Woolner of Mitretek Systems who has been doing advanced DCS telecommunications studies in support of the DCS.
Afternoon Session
Welcome from the NOAA National Ocean Service
Mark Bushnell of the National Ocean Service, the host of the meetings, provided a presentation explaining the various aspects of the NOS’s work that is supported by the DCS. It was interesting to learn of how the East Coast harbors are becoming more shallow and the link between DCS monitoring to predict draft depth clearance for ships.
Mark showed how sweeping microwave sensors are being used to monitor water level in addition to the more traditional water level gauges. Water level is important for determining bridge clearance. Mark explained how six minute observations are needed for current observation allowing timely predictions.
Review of Agenda
The agenda was reviewed and approved. Ernest said that most of the topics should be short and that additional topics would include a report on DAPS II progress and a discussion of the mornings 3 technical presentations.
Approval of
Previous Meeting Minutes
The minutes from the last meeting were reviewed and approved. They are available at the following web site: http://water.usgs.gov/datarelay/stiwg/meetings/stiwg_meetings.html
Action Item Review
Action items from the last meeting were reviewed and discussed:
Action: DOMSAT contract extension. Status: Complete.
Action: DOMSAT Funding Plan. Status: Incomplete.
This action generated substantial discussion regarding how the costs would be born by various agencies. The National Ocean Service will be added to the existing list as a major user and DOMSAT funding source. It is estimated now that each of the nine funding agencies will be asked to contribute from $7,000 to $9,000.
New Action: Ernest Dryer will
determine the exact DOMSAT payment for each agency. Also Ernest will authorize the next payment.
Action: Letter to NTIA. Status: Incomplete
There was a
continuation of last meeting’s discussion regarding continued RF interference
within the DCS band. There seems to be
no easy solution for locating and eliminating bogus RF signals. But it was felt that the NTIA is the agency
charged with handling problems like this, so a new action was generated.
New Action: Ernest Dryer will work with the Wallops CDA
to draft a letter
with supporting details to the NTIA which will point out
the frequent abuse of the GOES DCS RF band and specify the continuing
interference in DCS channels 65 and 66.
The relationship of the DCS to homeland security will also be
emphasized.
Treasurer’s Report
Doc Carver of the OFCM who is the treasurer was not present. However, it was reported that the DOMSAT funding had been spent on the contract renewal. Members expressed the need for regular STIWG treasury reports. It was hoped to get Doc Carver to come to the meetings. No change to the treasury was known other than about $27,000 that was paid for DOMSAT leaving about $60,000 to pay the $52,944 which will be due for the next DOMSAT payment.
New Action: Ernest Dryer is to
contact Doc Carver to determine what level of participation the STIWG can
expect.
STIWG Terms of Reference
Discussion of the Terms of Reference centered on the matter of absent members voting by email. There were pros and cons expressed by the attendees. It was determined that the new wording that would allow email voting had not been added to the document. It was taken as an action by Ernest Dryer to amend the terminology and complete the action that was generated at the previous meeting.
New Action: Ernest Dryer to modify the Terms of Reference to allow email
voting at special meetings for viewing on the Internet and forward the Terms of
Reference to the parent organizations
for review and approval.
The Terms of Reference may be viewed at the following URL:
http://water.usgs.gov/datarelay/StiwgTor-new.html
HDR Demod Status
Kay presented the current status of the DCS HDR demodulators. She said that there had been discussions regarding an emergency procurement for sixty or more high data rate demods within ninety days from Microcom Design. Al Mcmath added that these demods will use a new interface to communicate with the current Data General DAPS. Kay remarked that she is still limited by the number of channels that are available for assignments. Kay reported that the random channels are preventing her from making more assignments. She also reported that she is trying to get permission to use the international channel allocation for random channel assignments, but approval is required from the CGMS whose next meeting is in May of this year in Russia.
HDR User Transition Subcommittee
Report
All requested changes have been made to the draft and the GOES High Data Rate Transition Plan is ready for member voting. Kolleen Shelly distributed copies of the document for review. There were no objections to the plan so Ernest Dryer declared the plan as accepted.
Kay Metcalf requested users to transition from the higher channels first and to start as soon as possible.
The letter complaining about the DCS interference was mentioned again, and it was emphasized that it needed to be written. There was also some discussion about the former TLS study and demonstration. Kay Metcalf explained that there were no NESDIS funds that would allow the current development of a TLS system. The timely completion of a letter to the NTIA is covered in an above action item for Ernest Dryer.
Kay reported on the question of whether the contractor (ISI) will upgrade DAPS II to the latest Oracle version or not, and who will pay for it. The DAPS II PAT (acceptance test) had been delayed from December 2003 to allow the Oracle upgrade. It was also mentioned that the contractor’s view of the acceptance test was that no users would be allowed on the system during the test period. STIWG members said that they needed to see some DAPS II documentation and Kay Metcalf replied that the documentation that has been received from ISI was not acceptable and she did not want to distribute it. To answer a question, she said that the backup system was scheduled to follow DAPS II and not precede it. She also answered an Oracle question saying the current Oracle version on the system is 9Ias release 1. She estimated a DAPS II transition preparation by sometime in FY 2005.
New Action: The STIWG will generate a letter to the OFCM and/or Hydrology Working Group detailing their GOES DCS Backup System concerns.
The STIWG is still looking at the LRIT stream as a backup to the DOMSAT. However DCS is not considered primary within the LRIT data stream at this time. Data latency, complexity, and capacity are all concerns to the STIWG. The STIWG will continue to monitor the development of the LRIT service.
CDMA
Ernest Dryer expressed the concern about safeguards for the DCS system during the CDMA development. Peter Woolner expressed doubts about the level of interference that can be expected within the DCS by CDMA transmissions. Random channels with low power CDMA DCPs were advocated. The STIWG will continue to watch this issue as it develops.
Manufacturers’ Meetings Review
Ernest Dryer reviewed the previous two days’ manufacturers meetings for the group. The meetings had been held to discuss proposed changes to the DCS DCP certification standards in the GOES-R era which should begin in 2012. It is being proposed that the channel spacing would be halved from 1.5 KHz to 0.75 KHz for the 300 bps service. That change would result in a doubling of the 300 bps channel capacity. A similar band reduction would be applied to the 1200 bps service which now utilizes two channels, or 3.0 KHz band width.
The next topic reported on was the DCPI service. It was revealed that if the DCS community does not start using the interrogate DCS band, there is a probability that it will be not be included in the GOES R generation of spacecraft. Ernest Dryer asked the STIWG members if there was justification to keep the DCPI. There were suggestions for using the DCPI to potentially control DCP power and control, for instance to stop the transmission of an errant DCP. It could also be used for accurate timing functions. Ernest requested user input for support of the DCPI service. It was pointed out that the DCPI frequencies can only be used in the interrogate direction and not the reverse. There are currently 3 DCPI channels (47 KHz) available. There was enough spontaneous support for the service that Peter Woolner said that he would report back to NESDIS that the DCPI service should be continued on GOES R.
New Action: DCS members are requested to determine future
uses of the DCPI that would justify the continued existence of the service. Peter will tell Dave Maginnis, who represents
NESDIS in RF matters, that he attended the meeting and that the STIWG supports
the continuation of the DCPI. Member input
on this action is to sent to: ptippett@usgs.gov
Next meeting: The next meeting is planned to be in conjunction with another manufacturers conference dealing with the certification standards during the first week of August in Seattle, Washington.