MODIFICATION
A -- Ultra Light Dropsonde System
- Notice Date
- 9/27/2006
- Notice Type
- Modification
- NAICS
- 334511
— Search, Detection, Navigation, Guidance, Aeronautical, and Nautical System and Instrument Manufacturing
- Contracting Office
- Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), Mountain Region Acquisition Division, 325 Broadway - MC3, Boulder, CO, 80305-3328
- ZIP Code
- 80305-3328
- Solicitation Number
- RA133R-06-RP-0180
- Response Due
- 10/12/2006
- Archive Date
- 12/31/2006
- Description
- This is Amendment 3 to the RFP. Responses to submitted technical questions are hereby being provided to all potential offerors. Please note that the proposal due date of Thursday, October 12, 2006 is NOT being extended as a result of this amendment. Additional responses are being prepared for other solicitation questions that were submitted. These responses will also be posted by amendment. RESPONSES TO SOLICITATION QUESTIONS 1. Refer to 4.1.2.1 External Interfaces ... The prototype ODRP unit has a physical and electrical interface to some type of aerial vehicle. The physical attachment shall be by two tie points located near the two ends of the longest side of the package. These points shall be such that they can be securely attached by suitable fasteners with necessary characteristics to perform for at least 10 days in the high-altitude environment. The prototype ODRP unit shall be powered by 12 volt DC normally supplied from the aerial vehicle. After contract award, the Government will entertain discussion on possible no-cost changes to either the physical or electrical external interfaces for the prototype ODRP unit. Q1. "We need better understanding on the ODRP mechanical interface. Would the government please provide a drawing or sketch of the proposed ODRP mechanical interface? Two tie points seems perhaps like not enough. For example, is the ODRP intended to be external or internal to the UAV? Where can we mount antennae?" R.1. As stated in the RFP, the Government has not selected an aerial vehicle for this application. For purposes of the ODRP mechanical interface, assume that the vehicle is a super pressure balloon with a payload that is a one meter cube with vertical and horizontal sides capable of supporting the ODRP. Q2. "For the sonde release mechanism, we have the same mechanical interface questions (e.g. is the UAV external skin curved? Is it thin aluminum? What sort of backing is available for tie points? Can we tie to the frame rather than the skin?) A suggested drawing would help" R.2. Delivery of a sonde release mechanism is not called for in this RFP. The only requirement relating to a sonde release mechanism is a conceptual design. For this conceptual design, assume flat surfaces oriented horizontally and vertically are available to mount to. Q3: "Could you provide a target for the expected G-forces on landing/takeoff of the UAV? This relates to statements that our ODRP needs to accommodate the temp/vibration environment on a UAV. Temperature seems pretty well defined, but vibration is not. Please define expected vibration environment." R.3. The flight tests of the Ultra-light Dropsonde System will be conducted using hand-launched lighter-than-air balloons and the maximum acceleration and vibration forces will normally be less than 4 G. Q4. "For the receiver on the UAV how much current is available at 12Vdc and at what duty cycle?" R.4. Current specification is part of the design for the UDS and the requirement should be given in the proposal. The Government will assure that capability is provided for the testing. Q5. "What is the AC ripple on UAV 12Vdc power?" R.5. The maximum AC ripple that the proposed UDS can tolerate should be given in the proposal and the Government will assure that the voltage supplied during testing has AC ripple less than this. Q6. "What is the +/- DC voltage tolerance on UAV 12Vdc power?" Typical satellite data modems have very tight limits on DC supplies. We may need a bulky/expensive DC-DC converter if the UAV power is not clean and stable. Need more information on DC power available from UAV. R.6. The proposer should provide the voltage tolerance that is required by the proposed UDS and the Government will assure that the voltage used in testing has this tolerance. Q7. "A 300km range is stated for RF. Why such a long range? Is it to let another loitering aircraft (i.e. P3 or Gulfstream-V) cruising very high up can contact the data receiver on the UAV? Sitting on the earth's surface, 300km is far beyond the range of any UAV at realistic flight altitudes. If it is intended to provide adequate data link margin? If yes, could you provide a SNR specification or bit error rate, rather than range? At issue is how to aim the UAV antenna at the ground station as the UAV moves around. Also, related to this, for unlicenced point-to-point telemetry links, low power unlicenced operation will not work to 300km. Does the government propose to get a licensed frequency for this link and if so could they suggest a suitable UHF data modem?" R.7. If a direct radio link to the surface is used, the Government desires to be able to receive data from ranges at least 300 km from shore stations. This is well within the approximately 500 km line of sight from 60,000 feet altitude to the horizon. The design of this communication link is part of the proposal process and it is not appropriate for the Government to ?suggest? specific equipment or configurations. The Government will obtain experimental frequency allocations for testing. Q8. "A maximum height of 25000 meters is stated for altitude. Getting altitude via GPS is no problem, however, that altitude is far, far higher than a UAV can fly [see U2/ER-2]. And even much higher than required for hurricane sounding work. Later in the RFP, chamber testing is discussed simulating conditions to 25000m. This appears to be aimed at for balloon verification/testing to extreme latitudes. However, the design target is not for a balloon sonde (radiosonde) but rather it needs to be highly weight/size-optimized for lower tropospheric hurricane work (hence the "utlralight" in UDS!) Why is this height spec set so high? will we be expected to fly this on a balloon for testing to 25000m or is it simply for GPS height." R.8. Super pressure, zero pressure or latex balloons can fly at 25000 meters and above. The flight testing done by the Government will involve flying latex balloons to heights near 25000 meters. Q9. "Temperature specification of RMS 0.3 on the sonde, first is it +/- 0.3? And does this include solar radiation effects? What are the actual conditions, a lab test in a temp chamber? What about radiative cooling if sensor is wet? R.9. RMS stands for root-mean-square and is, generally, not considered to be negative. All error sources normally encountered in atmospheric measurements should be included in the analysis and design. Q10: "It is stated that the sonde sensors, including temperature will be verified in an environmental test chamber. How can one make simulate air temperatures to this level somehow ensuring air homogeneity to better than 0.03 degrees? If no, how are we to verify our temp sensor performance? In nearly all commercial temperature chambers is nearly impossible. In our experience the only valid method to intercompare thermistors is to use a NIST-traceable liquid bath for calibration, not a chamber air temperature measurement which will change across the box. Even with fan mixing, chambers experience inhomogenietes due to radiation and thermal convection. Also, how large in dimensions is the environmental test chamber window? This matters as it needs to be large enough for RF telemetry wavelengths need to make it out." R.11. There will be no need to have ?air inhomogeneity to better than 0.03 degrees? to verify temperature measurement accuracy of 0.3 degrees C. The Government will use sensor proximity to verify temperature accuracy. The size of the environmental test chamber window is 22 x 22 inches. No Q11 in list of questions. Q12: "Would we be unresponsive if we could not meet the sonde temperature measurement accuracy spec?" R.12. The Government expects the requirements of the RFP to be met. Q13: "Why is the temperature resolution so high (0.1)? " R.13. A smaller than desired resolution in any of the measured parameters will increase the data rate requirements of the communication links. Q14: "Would we be unresponsive if we could not meet this resolution spec but got near it, and the sonde was light/cheap?" R.14. The Government expects the requirements of the RFP to be met. Q15: "From a end user perspective, why is the barometric spec so tight (0.1 hPa)? This spec is very difficult to meet in a lightweight design using MEMS technology. What is driving this tight spec?" R.15. Pressure is a key parameter in characterizing hurricanes and the Government wants to be able to accurately characterize the pressure field in the vicinity of hurricanes. Q16: "Similar to Q14, would we be unresponsive if we could not meet the pressure specification but got near it, and the sonde was light/cheap? We can provide pressure via GPS attitude, but we do realize that unlike a radiosonde, GPS pressure is not valid in a hurricane. But we feel the combination of a MEMS sensor and GPS altitude might get us to an 'accurate enough' pressure measurement at low weight/cost." R.16. The Government expects the requirements of the RFP to be met. Q17: "All of these last questions can be summed up as if we do not meet any one of the measurement resolution or accuracy specs, will we still get paid under the contract? Is this best effort contract or are those hard targets that we must meet in order to fulfill the contract? " R.17. The Government expects the requirements of the RFP to be met. Q18: "Is 800-1000 MHZ band range acceptable for the ODRP-to-ground station UHF telemetry? Are their FCC and international guidelines that we must accommodate? R.18. The design of the ODRP-to-Ground Station communications link is the responsibility of the proposer and the Government cannot provide advice during the proposal stage of the procurement. The Government will acquire experimental frequency authorizations for the testing phase. If the proposal only has Non-Government frequency bands listed, the Government will be unable to award this contract to that proposer. Q19: "If the government uses the UHF data ODRP-to-ground data link (rather than satcom), will the ground station operator be able to manually aim the telemetry antenna in the general direction of the UAV or must we use omni directional vertical antennae? If "no", how are we to accomplish this aiming, as VHF/UHF is a line-of-sight problem and the UAV will obviously move within the field-of-view?" R.19. The ground stations will generally be unmanned. The design of the communication links is under the purview of the proposer and the Government can not make recommendations on specific approaches. Q20: "Is digital Cyclical Redundancy Checking sufficient to protect the integrity of the dropsonde-to-ODRP telemetry data link? Would CRC technology be responsive ?" R.20. Cyclical Redundancy Checking, as generally practiced, does not ?protect the integrity? of a communications link. If CRC technology meets the requirements of the RFP, it will be considered responsive. Q21: "Common commercial satcom modems have a minimum burst transmit rate of 20 seconds. This means that even if the sonde acquires 1 second data it will take a minimum of 20-25 seconds for it to arrive to the ground station for display (whereupon 1 Hz data will be displayed). Will we be non-responsive if our satcom takes 20 seconds to reach the end user's ground display? R.21. The Government understands that there are inherent delays when data are sent through the internet. Q22: "Our dropsonde ( see http://www.yesinc.com/products/data/XDR-928/index.html ) can work at -70F, however, battery life at -70F becomes a significant issue if the dropsonde and battery is 'cold-soaked' waiting on a high altitude loitering UAV. How long do you expect the UAV to be on station and could we expect that the UAV will have provision to preheat the sonde release compartment so as to keep the batteries at a warmer temperature? Or can we build such a heater into the release mechanism?" R.22. As previously pointed out, a release mechanism is not a deliverable under this contract. If the dropsonde proposed requires preheating at altitude, that fact should be pointed out in the proposal. Q23: "On tower drop testing, how will the government ensure that the dropsonde will not hit the 950' tower on the way down? Further, how will the tower not interfere with the weak GPS signals the dropsonde needs to get a lock on? We have performed such testing on our dropsonde via a 165' tower and these are very challenging test issues. We would prefer a drop test via one of NOAA's aircraft, not via a 'tower drop'." R.23. If, during the tower drop test, the dropsonde strikes any part of the tower, that test will be repeated. Prior to the test, the GPS satellite constellation will be analyzed to determine which side of the tower has the most satellites in view. A test GPS receiver will be used to verify that proper operation is possible on that side of the tower. Q24: "Several requirements are made about minimum acceptable dropped telemetry packets. However, it is not clear how this will actually be simulated and tested. How will this be verified? Can the government assert that this is a 'best effort' issue, (i.e. bit error rate specifications need not apply)? The technical issue is that the RF environment is a severe challenge aboard almost any aircraft, especially an undefined one, and meeting that dropepd telemetry spec might be impossible unless we understand the target UAV quite intimately." R.24. The Government expects that during the training, the capability to detect bad telemetry packets will be shown to the training attendees by the contractor. How this capability is realized is the contractor?s responsibility. Q25: "For many practical and cost-driven reasons, for our dropsonde-to-ODRP link we are planning on using 403-405.9 MHZ telemetry, not 1.6Ghz (as on NOAA's RRS). This is because of the inherent difficulty with operating near GPS and Iridium frequencies nearby. Would we be unresponsive to use this 403-406 MHZ band? If "yes," where do you suggest we move our telemetry band to, and then, how will we achieve license authorization operating in international waters?" R.25. The selection of frequency bands is the responsibility of the proposer and any suggestions by the Government would be inappropriate until after a contract is in place.
- Record
- SN01155676-W 20060929/060927220231 (fbodaily.com)
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