Naval Research Laboratory, Attn: Code 3230, 4555 Overlook Avenue, SW, Washington, DC 20375-5326

58 -- ACOUSTIC PROJECTION SYSTEM FOR ACTIVE MEASUREMENTS SOL N00173-00-R-CB02 POC Contact, Contract Specialist, Cheri R. Burkhardt, Code 3230.CB (202) 767-6542, Contracting Officer, Carol A. Parnell, Code 3230, (202) 767-6542 WEB: http://heron.nrl.navy.mil/contracts/rfplist.htm, http://heron.nrl.navy.mil/contracts/rfplist.htm. This notification is in response to questions that came about from the previous synopsis, which appeared in the May 11, 2000 edition of the Commerce Business Daily. The following are the stated questions with the answer to each question: Question 1: The specification requires conductor pairs for each element in the array. Would an alternative scheme such as a shared common conductor that reduces the size and cost of the electromechanical cable be considered acceptable if it does not lead to unacceptable array performance? Answer to Question 1: No. We would not favor the proposed alternative scheme. The government wants to be able to control the beam, and so the amplitude and phase of each array element individually. Furthermore, if the common conductor breaks, the array is out of operation: whereas, if one of the conductor pairs breaks, the array is still operable (though at reduced source level). Question 2: Is a slip-ring assembly for each cable conductor required for the winch? Answer to Question 2:No. A slip-ring assembly is not required. Question 3: Is a level-wind mechanism required for the winch? Answer to Question 3: No. A level-wind mechanism is not required. Question 4: Paragraph 8.3 is titled "Winch and Handling System". The winch requirement is defined but is there a requirement for a Handling System such as an A-frame? Answer to Question 4: No. There is not a requirement for a handling system. Paragraph 8.3 of the specification should be titled "Winch". Question 5: What primary power will be available to power the Power System of Paragraph 3.3 and Winch 8.3? Answer to Question 5: The projection system will be used on research-grade vessels which generally have a full range of power systems. It can be assumed that 220/440 VAC 3-phase @ 50 amps available. Question 6: In para. 3.1.b -- Towability -- "towable in a stable vertical configuration ". Define parameters for vertical stability and vertical positioning of the tow body (projector source). Do you have requirements for roll, pitch and yaw? Is there any tolerance for movement of the tow body (projector source)? Is the towed body (projector source) allowed to rotate? Answer to Question 6: The projector system will be used to make a variety of scientific measurements included among them is the measurement of bottom backscatter as a function of angle. For the measurements to be of value, the projector beam pattern must be known, and it must remain reasonably stable throughout the measurement period. The government, therefore, has a "stable vertical configuration" requirement. The projector beam pattern has a vertical axis and is azimuthally omnidirectional therefore not necessary to describe in terms of roll, pitch, and yaw. The government will specify in terms of (a) a maximum deviation of the beam pattern from vertical and (b) the maximum rate at which the deviation may vary. The projection unit, accordingly, should remain vertical to within 4 degrees to a nominal tolerance of 1 degree when towed at speeds of up to 4 knots in the absence of currents. As to movement of the tow body, the government has no strong tolerances on its vertical excursions -- 1 to 2% of the water depth is a typical tolerance. The projector beam pattern is to be omnidirectional azimuthally, therefore there is no acoustic reason to constrain the tow body from rotating to some degree. Rotational forces must not be such that the mechanical integrity of the system is jeopardized; the tow body may not be permitted to rotate to the point of damaging the tow cable or the electrical or mechanical connections. Question 7: What is the current profile in the area where acoustic measurements will be taken: In other words, what is the maximum current that the towed body (projector source) will see? Answer to Question 7: The majority of our measurements will be in water currents where it would range from 0 to 1 knots. Question 8: What is the configuration of the anchor? Is it hydrodynamically shaped? Answer to Question 8: No particular anchor in mind. The government so determine,in the technical specifications, that some amount of tensioning weight will be required to achieve and maintain vertical stability of the sonar projection unit, when towed at speeds up to 4 knots. The size, weight, and shape of any anchor required to achieve this stability will be influenced by the design of the projection system itself. The offeror must provide guidance on what sort of anchor is required to meet the specification and state any requirement in the Deployment and Recovery Plan. It must be consistent with the specification Sonar Projector construction 3.2.e.4 and Tow Cable Strength 3.4.a. Question 9: What type(s) of vessels will be towing the projector source? Answer to Question 9: The ships will primarily be oceanographic research vessels and be 100 to 300 feet in length, typically. Ship will be outfitted to deploy and recover oceanographic equipment of this size and larger and have ample deck space to work and accommodate any winch and handling system this projection system requires. Laboratory space to house shipboard computers, amplifiers, etc. and similarly there is provision for powering scientific equipment. The precise characteristics vary from platform to platform. Question 10: In para. 3.2.b -- Source Level -- Is the 210 dB re uPa at 1 m a "band level" for 70% of 1.5 -- 5 kHz ( and 200 dB for 85% of the same range)? Answer to Question 10: The source level figures are source spectrum levels. The source level of the projection unit must be at least 210 decibels re 1 micropascal @ 1 meter as measured in a 1-Hz band over at least 70% of the interval from 1.5 to 5 kHz, and at least 200 decibels re 1 micropascal @ 1 meter as measured in a 1-Hz band over at least 85% of the interval from 1.5 to 5 kHz. Question 11: At what Sea State will the towed body be operating in? Answer to Question 11: The government plans to deploy and recover the projection system in sea states between 0 and 3. Question 12: Section 3.2. Is there any tolerance on verticality of the projectors while under tow? Answer to Question 12: The projection unit should remain vertical to within 4 degrees to a nominal tolerance of 1 degree when towed at speeds of up to 4 knots in the absence of currents. Question 13: Section 3.2 (c) Part 3. Please confirm there is no side lobe level specification for the array when steered through plus minus 30 degrees. Answer to Question 13: The only side-lobe level specification is for horizontal steering. It is desirable, although, to maintain side-lobe control over as a broad a range of frequencies and steering angles as possible. Question 14: Section 8.6. Confirm that optional calibration at USN Seneca Lake is for the single elements only and not for the acoustic projector array, in the case where an array of elements is offered. Answer to Question 14: Optional in-water calibration is for single elements only, the case where an array of elements is offered. Question 15: Indicate whether a single (RS-232 type) digitized signal carried on a single conductor pair from the ESM is an acceptablealternate. Answer to Question 15: A single digital signal for each engineering sensor carried on a single conductor pair from the ESM is an acceptable alternative. The digital signals must be isolated to prevent coupling into the analog source signals. Question 16: The CBD posting indicates that the government reserves the right to exercise options 3 through 6 up to a quantity of eight times. (a) For Option 3 ESM, does this imply pricing is required for a quantity of 1 through 8 ESM, or a quantity of 2 through 16 (i.e. the technical specification speaks to "pairs" of ESMs). (b) For Option 3 ESM, confirm the additional quantities are for spares and do not require signal conductors in the tow cable and deck cable, (c) Option 4 -- Projection elements does this imply bidder must provide pricing for 9 baseline system variants (i.e. baseline, baseline plus 1 additional element, baseline plus 2 additional elements . . .) and /or some of the up to quantity 8 of this option for spares purposes and not installed inthe base line system, (d) Option 5 -- Power amplifier, same question as (c) above. Answer to Question 16: (a) Pricing is required for a pair of ESMs. The government has the option to purchase up to 8 pairs. (b) The tow cable and deck cable have to include all the wiring for power and signal for a pair of ESMs as described in Option 3 (0006). The additional ESMs would be spares. (c) Option 4 (CLIN 0007), if exercised, will be only one time. Offerors may provide pricing for as many potential baseline configurations as they wish. (d) The government may exercise Option 5 (CLIN 0008) up to 8 times for individual amplifiers. Question 17: The CBD refers to inspection and acceptance 30 days after completion of training. As this solicitation only comprises a portion of a full towable system, confirm that inspection and acceptance does not include at sea performance testing. Answer to Question 17: Inspection and acceptance does not include at-sea performance testing. Question 18: In Section 3.1 paragraph 3. Operational depth, there is reference to meeting the depth specification without cavitation or compensation. Would you define compensation? Is this a reference to motion/heave compensation? Answer to Question 18: Compensation refers to maintaining a constant output-level calibration during projection unit motion, including heave and tidal effects. The government prefers not having to use active depth compensation, such as a SCUBA bottle. Question 19: In Section 3.4 regarding the Electromechanical Tow Cable, it indicates that the cable must be double armored. One option to consider is a Kevlar armor package and use two layers of served Kevlar strands the same way that steel armor would be applied. Is double Kevlar armor acceptable or do you require steel armor? Answer to Question 19: The government requires steel armor. Question 20: Section 8.3 (Option) there is no mention of a slip-ring associated with the winch. Assume option exercised, the government will want a slip-ring assembly and want the offeror to install and terminate the tow cable on the winch. Is this correct? Answer to Question 20: A slip-ring is not required. If the option were exercised, the government would want the successful offeror to install and terminate the tow cable on the winch. URL http://heron.nrl.navy.mil/contracts/rfplist.htm Posted 06/12/00 (W-SN463823). (0164)

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