Water Resources of the United States

Frequently Asked Questions
Platform Assignment and Scheduling System (PASS):
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1. When splitting windows for additional 100-baud assignments,

• What is the typical turnaround Time that can be expected on receiving the new windows?
• Should the field users expect delay in receiving the assignments as opposed to the PASS system, which assigned windows as requested?

Response:  Do Not Know. We are working on the first batch this week (May 25) -- there is a lot of hand work involved. We will have a better idea after going through this exercise.

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2. Has the error in PASS that allowed for duplicate registrations been resolved?

• When DCP ID's are erroneously reused, there are several field trips involved by both offices in trying to resolve what appears to be an errant transmitter. Several man-days, not to mention frustration, are wasted on this problem.

Response:  N0 -- This error has occurred twice. Can not reproduce and can not see where in the code that the problem occurs, in fact it appears to be impossible to happen but obviously it does. It happens when two persons simultaneously request the same registration. Fail safe, go back, and review later. Code will be reviewed again as other updates are made to try to locate the problem.

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3. At times PASS give out antennae azimuths that are erroneous when applying for new ID's or changing existing site information.

• Experienced technicians will quickly recognize that the direction that an antenna is pointing is incorrect, but there are some offices that do not have the luxury of sending out experienced crews for DCP installations.

Response:   Code has been reviewed once with no problem found. In queue for more through review.

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4. The total number of 100 baud windows that will be needed, based on a survey that followed a conference call on the availability of DCP id's, showed an estimated 322 additional assignments will be needed over the next year. This number was based on replies from 20 states. If one was to extrapolate this number out, there is a potential for an estimated 800 plus assignments for all 50 states. In addition to the number of 100-baud DCP's sitting on shelves, many 100-baud DCP's may be purchased with end of year money.

Response:  Will be getting 120-140 new ids. All assigned but not implemented need to be used. Steve Blanchard is heading up a group to prioritize assignment of codes. Districts that split time slots have been getting the benefit of the split.

Based on the information above:

1. Should the USGS WRD impose a moratorium on 100-baud DCP's?
Response:  
2. Are there a finite number of 100-baud assignments left?
Response:  YES
3. If so what's the number?
Response:  What we have plus the 120-140 new ids.
4. Will we be limited in the number of 100-baud assignments that we can split?
Response:  NO

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5. As there have been two transmitters certified as HDR's and the "clock" is ticking, will we still be able to split windows after May 31, 2002?

Response:  We believe so, but this is one of the topics being discussed this week (May 21).

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6. What manufacturers will supply the new transmitters?

Response:  Currently, I know of 3 that are actively developing HDR transmitters:  Seimac, Sutron, and Handar. Seimac is a Canadian company that is teamed with Campbell Scientific. So Campbell Scientific will use their data loggers with a Seimac transmitter as their DCP.

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7. What changes will have to be made to the LRGS units at the District level to accommodate multiple baud rates?

Response:  None. The LRGS s are oblivious to the baud rates of the DCPs. DAPS receives the DCP transmissions from GOES and rebroadcasts them to the LRGSs using DOMSAT. So all the messages look the same to the LRGS.

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8. Will our current DCP's be able to be retrofitted with the new transmitters, and if so which models?

Response:  Some will; some will not. Here are excerpts from replies from several manufacturers who were asked this question.

Handar:

Any Handar 555 DCP product will be able to be updated to HDR by replacing the Signal Engineering 100b transmitter assembly with a new transmitter.

... All products prior to the 555 will not have an upgrade path. This includes any model 540, 560, 530 or 520.

Sutron:

Software:
• 8210 will upgrade via PCMCIA card or front panel serial port.
• 8200A will upgrade via ROM change only. These chips are socketed so it is fairly easy though you will have to go inside the unit to make the change.
Hardware:
• 8210. The goal is to fit inside the 8210. We need 2 more months to verify if we accomplished or not. If it goes outside it will communicate via the RS-232 port.
• 8200A. Will have to be external via RS-232 port.

I am fairly certain that any Campbell recorders can be upgraded because Campbell has always isolated the transmitter interface from their recorder so that they could use other manufacturer's transmitters. (Other manufacturers now do this also with their current models so it is their older models where the transmitter was integrated with the recorder that cannot be upgraded . )

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9. Will HQ be able to assist the Districts in funding for the instrumentation changes?

Response:  I have been informed that the Office of Surface Water is considering a subsidy for the purchase of HDR transmitters, but a final decision has not been made. OSW says that it depends on how the appropriation increase for FY 2001 is distributed.

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10. The Central Region Advisory Committee for Data Operations (CRACD) has been receiving requests for clarification of the transition to the HDR GOES transmitters. Additionally we cannot get assignments for the western satellite, as we are to use the 500+/- ID's that the USGS currently has.
• Is there some way that we could access a master-list of these ID's so we can start using them, or do they have to be relinquished by the responsible party prior to us using them?

Response:  We have started a process of reclaiming all inactive assignments. In the future, an assignment should only be requested if it will be deployed within 3 months. When assignments were plentiful, many were obtained and warehoused for future use. We can no longer afford to allow this. We shall now monitor the use of assignments and reclaim them if the assignments are not used within 9 months. All reclaimed assignments will be made available via PASS.

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11. Is PASS set up to make assignments for HDR windows?

Response:  NO

• If not, how does one get an HDR window now?

Response:  Contact Don Dolnack ddolnack@usgs.gov on 703-648-6819, currently getting IDs for two Districts.

• Will PASS be setup to make the assignments in the future, or will another system be developed to make the assignments?

Response:  PASS will be updating.

• Are any Districts currently transmitting/receiving with HDR's?

Response:  HDR is still in test mode.

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12. If we were to all buy into 300-baud radios this summer, would one channel for each satellite be sufficient to cover all of the requested windows?

Response:  Several more DEMODs are on order. Delivery from the supplier has been delayed.

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13. Will the change to HDR radios increase the number of available ID's?

Response:  Yes.  The capacity of GOES is not close to saturation. It just requires more reception hardware ( DEMODs ) to make use of the many channels that are still available. The HDR DEMODs will increase the number of available assignments.

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14. What is the time limit on keeping 100-baud radios?

Response:  The NESDIS policy for supporting GOES assignments is keyed to the date that two manufacturers have certified HDR DCPS available. The policy will be as follows:

1. NESDIS will quit making assignments for 100-baud DCPs one year after two manufacturers have certified HDR DCPS available.
2. NESDIS will support current 100-baud assignments for at least 10 years after two manufacturers have certified HDR DCPS available. They guarantee 10 years, but will continue as long as their 100 baud demods do not fail. After the 10 year period, if a 100-baud demod fails, it can only be replace with a HDR demod.

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15. If we use up all of the ID's prior to the implementation of the HDR's, will more assignments be available from NESDIS? If not it may be very difficult to get people to release their ID's.

Response:  We shall work to get assignments for any DCPS that are ready to be deployed. NESDIS is reserving channels for use with the new HDR transmitters, and will not give us new assignments as long as we have so many inactive ones. When we have deployed all our current assignments, we shall work with NESDIS to make sure that we get sufficient assignments for our needs. Currently, NESDIS is checking to see if their 100 and 300 baud demodulators can monitor the same channel. If so, we could start getting assignments on some of the channels reserved for the HDR DCPs for use by 100-baud DCPS as long as the transmissions from the 100 baud DCPs fit within a 15-second window. This will be true for a number of 100 baud DCPs. So this is one of the ways that we might use to obtain more 100 baud assignments.

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16. Not long ago we received a message that the HDR demodulators had caused problems and that NESDIS took them offline in order to keep the system up.
• Have the faulty DEMODS for the HDRs been repaired/replaced?
• What if any problems do we face in moving to the HDR's?

Response:  Don Dolnack did not believe that the problem is correctly stated. As with any new technology, you work through problems in the test phase. Ernest Dreyer will have much more current information after this week (May 21).

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17. Will we have to reapply to NESDIS to change the transmission interval each time we upgrade one of our current assignments to a HDR radio?

Response:  Yes.  you might be able to keep the same id, but the channel ill have to change. DCPs will be moved from a 100-baud channel to a HDR channel until the 100-baud channel can be completely freed. It will then be converted to a HDR channel. If fact, any change made to a DCP should be reported via PASS to NESDIS. We have a memorandum of understanding (MOU) with NESDIS that requires us to keep accurate information about our DCPs in their Platform Description File. We do this by transferring information to them from our PASS database which has everything that they currently need. Updating PASS has often been neglected when changes are made to assignments. This is becoming a sore point with NESDIS and the NWS which uses the PDTs to garner information about our network. For example, NESDIS requires a local operational contact. At the last GOES TWG meeting NESDIS complained that the contacts that they recently tried to reach about DCP problems had incorrect phone numbers. They didn't say which agency had the incorrect phone numbers, but I am sure that some of ours are not up-to-date. So we need to do a better job of keeping the information in PASS up-to-date.

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18. Do you know what the additional costs will be for GPS chips for 300-baud radios?

Response:  Sutron and Campbell include the chip in their hardware. Not sure what Handar does.

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19. When will DAPS be ready for the HDR transmissions?

Response:  It has 4 HDR demods installed and ready to go. They are waiting on the HDR DCPs.

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20. Will we have options as to the baud rate we purchase, 300-1200?

Response:  We shall use the 300 baud transmitters. The 1200 baud transmitters were designed for special cases. They require more band width than the 300 baud transmitters which translates into having to use 2 of the current GOES channels for their operation. So getting 1200 baud assignments will not be easy and will require a justification that NESDIS can accept.

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21. Will we have options as to the transmission interval, or will we be restricted to hourly?

Response:  We shall have flexibility in designing the operational use of the HDR transmitters which would include transmitting as frequently as we can as long as we develop a plan that will insure that 1) we can manage a channel without inter-transmission interference and 2) we can use the channel efficiently, i.e. we would probably have to have >240 DCPs per channel. However, initially the norm will be hourly transmissions. Exceptions will be considered if there is a strong justification for more frequent transmissions. Changing the transmission frequency of a single DCP on a channel obviously affects the entire channel so we would have to carefully design the channel configuration to accommodate this.

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22. What sizes will the windows be and will the baud change compensate for the compressed window, or will we have to change transmission formats to binary to accommodate the difference?

Response:  The maximum window that will be allowed for HDR assignments is 20 seconds; however, I think almost everyone wants to use 15-second windows. This will allow hourly transmissions with the same channel loading that we have now. You should be able to keep the same transmission mode that you are currently using except possibly the amount of redundant data that is transmitted. Transmitting hourly, you probably only need to transmit two hours worth of data, i.e. one set of redundant values. This would cut the size of the current transmissions by a factor of 4 if you are currently transmitting redundant values. That combined with tripling the speed of the transmission should allow transmissions to easily fit within a 15-second window. One manufacture thinks that we could use less than 5-second windows if the DCPs had a clock source ( a GPS receiver for example ) and I think that most, if not all, will.

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