Loren Data's SAM Daily™

FBO DAILY ISSUE OF MAY 14, 2011 FBO #3458
SOLICITATION NOTICE

A -- Develop Internal Beam-Forming Software

Notice Date

5/12/2011
 

Notice Type

Combined Synopsis/Solicitation
 

NAICS

541511 — Custom Computer Programming Services
 

Contracting Office

Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), Western Acquisition Division-Boulder, 325 Broadway - MC3, Boulder, Colorado, 80305-3328, United States
 

ZIP Code

80305-3328
 

Solicitation Number

NFFS71001103850DLZ
 

Archive Date

5/20/2011
 

Point of Contact

Donald L. Schartz, Phone: 3034977363
 

E-Mail Address

donald.l.schartz@noaa.gov
(donald.l.schartz@noaa.gov)
 

Small Business Set-Aside

Total Small Business
 

Description

COMBINED SYNOPSIS/SOLICITATION Develop Internal Beam-Forming Software for the Extended Nadir Augmentation Sonar (I) This is a combined synopsis/solicitation for commercial items prepared in accordance with the format in FAR Subpart 12.6, as supplemented with additional information included in this notice and in accordance with the simplified acquisition procedures authorized in FAR Part 13. This announcement constitutes the only solicitation; proposals are being requested and a written solicitation will not be issued. (II) This solicitation is issued as a request for quotation (RFQ). Submit written quotes on RFQ Number NFFS7100-11-03850DLZ. (III) The solicitation document and incorporated provisions and clauses are those in effect through Federal Acquisition Circular 2005-¬¬51. (IV) This solicitation is being issued as a Total Small Business Set-Aside. The associated NAICS code is 541511. The small business size standard is $25.0 million. (V) This combined solicitation/synopsis is for purchase of the following commercial services: CLIN 0001 -Services, non-personal, to provide all equipment, labor and materials (unless otherwise provided herein) necessary for Development of Internal Beam-Forming Software in accordance with the statement of work. (VI) Description of requirements is as follows: See attached statement of work and Department of Labor Wage Rates: WD 05-2563, Revision No. 12, dated Aug 17, 2010 which can be found on www.wdol.gov. (VII) Period of performance shall be: Starting May 25, 2011 through August 8,2011 (VIII) FAR 52.212-1, Instructions to Offerors -- Commercial Items (June 2008), applies to this acquisition. Inquiries (Apr 2010). Offerors must submit all questions concerning this solicitation in writing to Donald Schartz either through email donald.l.schartz@noaa.gov or faxed at 303-497-7719 no later than 12:01 p.m. MST, May 17, 2011. (IX) FAR 52.212-2, Evaluation - Commercial Items (Jan 1999), applies to this acquisition. Offers will be evaluated based on price and the factors set forth in paragraph (a), and award will be made to the firm offering the best value to the Government. Paragraph (a) is hereby completed as follows: Evaluation will be based on 1) Technical Capability - quote shall include documentation of a project of similar scope. 2) Price. The Government intends to award a firm-fixed price purchase order on an all or none basis to the responsive and responsible offeror. (X) The offeror must submit a completed copy of the provision at FAR 52.212-3, Offeror Representations and Certifications - Commercial Items (Oct 2010), with its quote. The offeror shall complete the annual representations and certifications electronically at http://orca.bpn.gov. (XI) The clause at FAR 52.212-4, Contract Terms and Conditions - Commercial Items (June 2010) applies to this acquisition. (XII) The clause at FAR 52.212-5, Contract Terms and Conditions Required to Implement Statutes or Executive Orders - Commercial Items (Apr 2011) applies to this acquisition. The following clauses under subparagraph (b) apply: (4) 52.204-10, Reporting Executive Compensation and First-Tier Subcontract Awards (Jul 2010) (Pub. L. 109-282) (31 U.S.C. 6101 note) (Effective March 1, 2011). (10)(i) 52.219-6, Notice of Total Small Business Set-Aside (June 2003) (15 U.S.C. 644). (20) 52.219-28, Post Award Small Business Program Rerepresentation (Apr 2009) (15 U.S.C. 632(a)(2)). (21) 52.222-3, Convict Labor (June 2003) (E.O. 11755). (22) 52.222-19, Child Labor-Cooperation with Authorities and Remedies (July 2010) (E.O. 13126). (23) 52.222-21, Prohibition of Segregated Facilities (Feb 1999). (25) 52.222-26, Equal Opportunity (Mar 2007) (E.O. 11246). (26) 52.222-36, Affirmative Action for Workers with Disabilities (Oct 2010) (29 U.S.C. 793). (28) 52.222-40, Notification of Employee Rights Under the National Labor Relations Act (Dec 2010) (E.O. 13496). (33) 52.223-18, Contractor Policy to Ban Text Messaging While Driving (Sep 2010) (E.O. 13513). (35)(i) 52.225-3, Buy American Act-Free Trade Agreements-Israeli Trade Act (June 2009) (37) 52.225-13, Restrictions on Certain Foreign Purchases (June 2008) (E.O.'s, proclamations, and statutes administered by the Office of Foreign Assets Control of the Department of the Treasury). (42) 52.232-33, Payment by Electronic Funds Transfer-Central Contractor Registration (Oct 2003) (31 U.S.C. 3332). The following clauses under subparagraph (c) apply: (1) 52.222-41, Service Contract Act of 1965 (Nov 2007) (41 U.S.C. 351, et seq.). (2) 52.222-42, Statement of Equivalent Rates for Federal Hires (May 1989) (29 U.S.C. 206 and 41 U.S.C. 351, et seq.). (XIII) The following clauses are also applicable to this acquisition: 52.252-1 Solicitation Provisions Incorporated by Reference (Feb 1998) 52.252-2 Clauses Incorporated By Reference (Feb 1998). This contract incorporates on or more clauses by reference, with the same force and effect as if they were given in full text. Upon request, the Contracting Officer will make their full text available. Also, the full text of a clause may be accessed electronically at this address: https://www.acquisition.gov/far/index.html (End of Clause) The following additional FAR terms and conditions apply: 52.214-34, Submission of Offers in the English Language (Apr 1991) 52.214-35, Submission of Offer in U.S. Currency (Apr 1991) 52.217-8, Option to Extend Services (Nov 1999) 52.228-5, Insurance - Work on a Government Installation (Jan 1997) Department of Commerce Clauses: 1352.201-70, Contracting Officer's Authority (Apr 2010). The Contracting Officer is the only person authorized to make or approve any changes in any of the requirements of this contract, and, notwithstanding any provisions contained elsewhere in this contract, the said authority remains solely in the Contracting Officer. In the event the contractor makes any changes at the direction of any person other than the Contracting Officer, the change will be considered to have been made without authority and no adjustment will be made in the contract terms and conditions, including price. 1352.237-71 Security processing requirements-low risk contracts. Security Processing Requirements-Low Risk Contracts (APR 2010) (a) Investigative Requirements for Low Risk Contracts. All contractor (and subcontractor) personnel proposed to be employed under a Low Risk contract shall undergo security processing by the Department's Office of Security before being eligible to work on the premises of any Department of Commerce owned, leased, or controlled facility in the United States or overseas, or to obtain access to a Department of Commerce IT system. All Department of Commerce security processing pertinent to this contract will be conducted at no cost to the contractor. (b) Investigative requirements for Non-IT Service Contracts are: (1) Contracts more than 180 days-National Agency Check and Inquiries (NACI). (2) Contracts less than 180 days-Special Agency Check (SAC). (c) Investigative requirements for IT Service Contracts are: (1) Contracts more than 180 days-National Agency Check and Inquiries (NACI). (2) Contracts less than 180 days-National Agency Check and Inquiries (NACI). (d) In addition to the investigations noted above, non-U.S. citizens must have a background check that includes an Immigration and Customs Enforcement agency check. (e) Additional Requirements for Foreign Nationals (Non-U.S. Citizens). Non-U.S. citizens (lawful permanent residents) to be employed under this contract within the United States must have: (1) Official legal status in the United States; (2) Continuously resided in the United States for the last two years; and (3) Obtained advance approval from the servicing Security Officer in consultation with the Office of Security headquarters. (f) DOC Security Processing Requirements for Low Risk Non-IT Service Contracts. Processing requirements for Low Risk non-IT Service Contracts are as follows: (1) Processing of a NACI is required for all contract employees employed in Low Risk non-IT service contracts for more than 180 days. The Contracting Officer's Representative (COR) will invite the prospective contractor into e-QIP to complete the SF-85. The contract employee must also complete fingerprinting. (2) Contract employees employed in Low Risk non-IT service contracts for less than 180 days require processing of Form OFI-86C Special Agreement Check (SAC), to be processed. The Sponsor will forward a completed Form OFI-86C, FD-258, Fingerprint Chart, and Credit Release Authorization to the servicing Security Officer, who will send the investigative packet to the Office of Personnel Management for processing. (3) Any contract employee with a favorable SAC who remains on the contract over 180 days will be required to have a NACI conducted to continue working on the job site. (4) For Low Risk non-IT service contracts, the scope of the SAC will include checks of the Security/Suitability Investigations Index (SII), other agency files (INVA), Defense Clearance Investigations Index (DCII), FBI Fingerprint (FBIF), and the FBI Information Management Division (FBIN). (5) In addition, for those individuals who are not U.S. citizens (lawful permanent residents), the Sponsor may request a Customs Enforcement SAC on Form OFI-86C, by checking Block #7, Item I. In Block 13, the Sponsor should enter the employee's Alien Registration Receipt Card number to aid in verification. (6) Copies of the appropriate forms can be obtained from the Sponsor or the Office of Security. Upon receipt of the required forms, the Sponsor will forward the forms to the servicing Security Officer. The Security Officer will process the forms and advise the Sponsor and the Contracting Officer whether the contract employee can commence work prior to completion of the suitability determination based on the type of work and risk to the facility ( i.e., adequate controls and restrictions are in place). The Sponsor will notify the contractor of favorable or unfavorable findings of the suitability determinations. The Contracting Officer will notify the contractor of an approved contract start date. (g) Security Processing Requirements for Low Risk IT Service Contracts. Processing of a NACI is required for all contract employees employed under Low Risk IT service contracts. (1) Contract employees employed in all Low Risk IT service contracts will require a National Agency Check and Inquiries (NACI) to be processed. The Contracting Officer's Representative (COR) will invite the prospective contractor into e-QIP to complete the SF-85. Fingerprints and a Credit Release Authorization must be completed within three working days from start of work, and provided to the Servicing Security Officer, who will forward the investigative package to OPM. (2) For Low Risk IT service contracts, individuals who are not U.S. citizens (lawful permanent residents) must undergo a NACI that includes an agency check conducted by the Immigration and Customs Enforcement Service. The Sponsor must request the ICE check as a part of the NAC. (h) Notification of Disqualifying Information. If the Office of Security receives disqualifying information on a contract employee, the Sponsor and Contracting Officer will be notified. The Sponsor shall coordinate with the Contracting Officer for the immediate removal of the employee from duty requiring access to Departmental facilities or IT systems. Contract employees may be barred from working on the premises of a facility for any of the following reasons: (1) Conviction of a felony crime of violence or of a misdemeanor involving moral turpitude. (2) Falsification of information entered on security screening forms or of other documents submitted to the Department. (3) Improper conduct once performing on the contract, including criminal, infamous, dishonest, immoral, or notoriously disgraceful conduct or other conduct prejudicial to the Government regardless of whether the conduct was directly related to the contract. (4) Any behavior judged to pose a potential threat to Departmental information systems, personnel, property, or other assets. (i) Failure to comply with security processing requirements may result in termination of the contract or removal of contract employees from Department of Commerce facilities or denial of access to IT systems. (j) Access to National Security Information. Compliance with these requirements shall not be construed as providing a contract employee clearance to have access to national security information. (k) The contractor shall include the substance of this clause, including this paragraph, in all subcontracts. (End of clause) [75 FR 10570, Mar. 8, 2010; 75 FR 14496, Mar. 26, 2010] (XIV) Defense Priorities and Allocations System (DPAS) and assigned rating do not apply. (XV) Quotes are required to be received in the contracting office no later than 12:01 P.M. Mountain Standard Time on May 19, 2011. All quotes must be faxed or emailed to the attention of Donald Schartz. The fax number is (303) 497-7719 and the email address is donald.l.schartz@noaa.gov. (XVI) Any questions regarding this solicitation should be directed to Donald Schartz through the email address: donald.l.schartz@noaa.gov or fax (303) 497-7719. CAR Clause 1352.239-70 SOFTWARE LICENSE ADDENDUM (APR 2010) (a) This Addendum incorporates certain terms and conditions relating to federal procurement actions. The terms and conditions of this Addendum take precedence over the terms and conditions contained in any license agreement or other contract documents entered into between the parties. (b) Governing Law: Federal procurement law and regulations, including the Contract Disputes Act, 41 U.S.C. Section 601 et. seq., and the Federal Acquisition Regulation (FAR), govern the agreement between the parties. Litigation arising out of this contract may be filed only in those fora that have jurisdiction over federal procurement matters. (c) Attorney's Fees: Attorney's fees are payable by the federal government in any action arising under this contract only pursuant to the Equal Access in Justice Act, 5 U.S.C. Section 504. (d) No Indemnification: The federal government will not be liable for any claim for indemnification; such payments may violate the Anti-Deficiency Act, 31 U.S.C. Section 1341(a). (e) Assignment: Payments may only be assigned in accordance with the Assignment of Claims Act, 31 U.S.C. Section 3727, and FAR Subpart 32.8, "Assignment of Claims." (f) Invoices: Invoices will be handled in accordance with the Prompt Payment Act (31 U.S.C. Section 3903) and Office of Management and Budget (OMB) Circular A-125, Prompt Payment. (g) Patent and Copyright Infringement: Patent or copyright infringement suits brought against the United States as a party may only be defended by the U.S. Department of Justice (28 U.S.C. Section 516). (h) Renewal of Support after Expiration of this Award: Service will not automatically renew after expiration of the initial term of this agreement. (i) Renewal may only occur in accord with (1) the mutual agreement of the parties; or (2) an option renewal clause allowing the Government to unilaterally exercise one or more options to extend the term of the agreement. (End of clause) STATEMENT OF WORK BACKGROUND: RACE Division of the Alaska Fisheries Science Center requires a means of performing beam forming/processing, at a real-time rate, on post-recorded data from the Extended Nadir Augmentation Sonar (ENAS) sub-system of their Long Range Side Scan Sonar (LRSSS). Results from the ENAS beamforming/processing will be used: (1) to make informed at-sea decisions impacting the acquisition of scientific data for fisheries research, (2) for post-cruise analyses of scientific data for fisheries research and (3) to infer pertinent information related to Essential Fish Habitat. The ENAS and computational requirements are described in Attachment I. OBJECTIVE: The objective of this agreement is to develop, test and deliver source code and compiled code for performing ENAS beamforming/processing with a graphics accelerator board to be installed in a Government Furnished Dell computer. SCOPE OF WORK: The contractor shall provide all manpower, facilities and materials necessary to develop, test, and deliver documented source and compiled code to perform ENAS beam forming/processing and to run on a graphics accelerator, which is also a separate deliverable. The technical requirements for ENAS beam forming/processing are described in Attachment I. Also develop debug code for extracting geo-located bathymetry and radiometric adjusted backscatter information from post-recorded data in "SDF2" format and recording same in "SDFX" format. The C&A requirements of clause 73 do not apply and a Security Accreditation Package is not required. PERIOD OF PERFORMANCE: The period of performance for this contract is 25 May 2011 through 8 August 2011, unless extended by written mutual agreement. CONTRACTOR PERFORMANCE REQUIREMENTS: The ENAS beam forming/processing as described in Attachment I must be performed at a real-time rate on 181 acoustic data channels, at ping intervals of one-second, with a sample rate of 12 kHz, and a sample length of 8000. SPECIFIC OBJECTIVES/TASKS: 1. Prepare pseudo-code outlining the functional steps and/or special purpose-built subroutines necessary to perform the ENAS beam forming/processing. 2. Develop debug code for extracting geo-located bathymetry and radiometric adjusted backscatter information from post-recorded data in "SDF2" format and recording same in "SDFX" format. 3. Test the debug code on a synthetic data set. 4. Document the functional (tested) source code. 5. Compile the source code for the graphics accelerator installed in the GFE computer. 6. Demonstrate real-time thru-put by running the compiled code on a synthetic data set. 7. Ship contract deliverables. 8. Return GFE materials. PROJECT DELIVERABLES and DEADLINE FOR EACH 1. Pseudo-code for taking post-recorded data in "SDF2" format and producing: (a) geo-located bathymetry and (b) radiometric adjustments to backscatter measurements made coincident with the bathymetry; 7 June 2011. 2. Debug code for extracting geo-located bathymetry and radiometric adjusted backscatter information from post-recorded data in "SDF2" format and recording same in "SDFX" format; 25 June 2011. 3. Results from processing a synthetic test data set; 3 August 2011. 4. Graphics accelerator board with functional (compiled) code installed; 8 August 2011 5. Documented source code; 8 August 2011. Attachment I Description of the ENAS and the ENAS real-time rate computational requirements ENAS - A SUBSYSTEM OF THE LRSSS The ENAS is one of the two backscatter measuring sub-systems of the Klein 7180 Long-Range Side Scan Sonar (LRSSS). The LRSSS was designed and developed to increase the productivity of backscatter surveys in support of fisheries research. Productivity is judged on survey coverage rate, which is the product of survey speed and usable cross-track range. The LRSSS was designed for a nominal survey speed of 6 knots with a maximum speed of 12 knots. The LRSSS was designed to provide continuous, equivalent, radiometric and quantitative backscatter information across the full swath from port to starboard, a distance of 1 kilometer. The full swath coverage requires two acoustic sub-systems. Equivalent backscatter over the swath was addressed by having both acoustic sub-systems operate in a "narrow" band around 180 kHz. The two acoustic backscatter measurement sub-systems in the LRSSS are: (1) multibeam side scan sonar (MBSS) and (2) extended nadir augmentation sonar (ENAS), where the second is the collective grouping of three separate near-nadir (gap-filling) multi-beam sonars and one vertical beam echo sounder. In order to meet the high signal-to-noise required for long range side scan sonar, the MBSS employs a "long" frequency swept transmission (chirp). In order to reduce the negative impact of cross-talk between the several LRSSS acoustic sub-systems, both frequency-division multiplexing and time-division multiplexing are employed in the transmission of acoustic energy. ENAS BACKGROUND: The purpose of the ENAS is determine the Backscatter Angular Response Function (BARF) of the local seabed along the LRSSS survey track line and contribute to the Cascade Calibration schema for the LRSSS. The ENAS transducers consist of two ELAC-LSE324 and three ELAC-LSE325. The mounting geometry of the two ELAC-LSE324 transducers is a Mills Cross configuration, pointing downward. The mounting geometry for each of the three ELAC-LSE325 transducers is unique. One ELAC-LSE325 transducer is mounted on the tow fish with its MRA pointing 50 degrees from horizontal to the port side. One ELAC-LSE325 transducer is mounted on the tow fish with its MRA pointing 50 degrees from horizontal to the starboard. The third ELAC-LSE325 transducer is mounted on the tow fish with its MRA pointing down toward nadir. Two of the 62 elements in an ELAC-LSE325 transducer are transmit elements. Their function is to convert electrical energy to acoustic energy (NOTE: Only one is active on any given ping). Sixty of the 62 elements in an ELAC-LSE325 transducer are used as receive elements (converting acoustic pressure into electrical voltage). In general, the ENAS receive function includes beam forming, either computational or mechanical (FFT or Mills Cross). To facilitate radiometric adjustment of the ENAS measurements of BARF, each transmit element will be characterized in terms of source level (TVR) and beam width. To facilitate radiometric adjustment of the ENAS measurements of BARF, each receive element will be characterized in terms of beam width and OCVR (transform from acoustic pressure to electrical voltage). The several TVG operators in the system, which act on the gain functions of any ENAS receive element, will also be characterized in terms of fixed gain and time-varying gain. One element in the Mills Cross configuration of two ELAC-LSE324 arrays will transmit a short (0.333 ms) CW-pulse at 180 kHz. The output from the receive element of the Mills Cross configuration of two ELAC-LSE325 arrays will be recorded at a complex sample rate of 12 kHz onto the LRSSS RAID (data storage array). It is also important to recognize that the nadir pointing Mills Cross Array primarily receives bottom echoes resulting from the acoustic energy propagating from the Mills Cross Array transmitter. One transmit element in each of the three ELAC-LSE325 transducers will emit simultaneous 8 msec chirps with 6 kHz bandwidth. The nominal acoustic frequency for the two ELAC-LSE325 transducers, whose MRA point either toward port or toward starboard, will be 177 kHz. It is important to recognize due to the coordinated time multiplexed nature of transmissions by the ENAS and the MBSS, the port and starboard pointing ENAS-transducers arrays are primarily receiving bottom echoes resulting from either acoustic energy propagating from the transmitter in each of those "177 kHz" arrays, or acoustic energy propagating from the transmitter in each of the MBSS arrays. The nominal acoustic frequency for the one ELAC-LSE325 transducer, whose MRA points toward nadir, will be 183 kHz. It is important to recognize that the Nadir facing ENAS primarily receives bottom echoes resulting from acoustic energy propagating from the transmitter in the "183 kHz" array. The acoustic energy received on the three ELAC-LSE325 transducers will be digitally sampled and recorded at a complex sample rate of 12 kHz onto the LRSSS RAID. The ENAS recorded raw data format will be an extension of the Fishpac SDF2 format. It will contain the sampled signals from each receive stave, as well as the ping time, sound speed measured at the tow fish, depth of the tow fish, altitude of the tow fish, attitude of the tow fish, ship position and tow fish position. The ENAS processed data will be recorded in an extension of the Klein SFX format. Those records will contain beam slant range travel times from the tow fish to the seabed, beam angles relative to local vertical, backscatter amplitudes after radiometric adjustments, and a data quality parameter representing at least 4 states of 4 different factors (co-linearity of cross track bathy solutions and associated backscatter amplitudes, signal-to-noise of backscatter amplitude, and dispersion of bathy phase solution) ENAS BEAM FORMING: The beam forming and subsequent extraction of information necessary to develop the BARF will operate on recorded data files after they have been closed (subsequent to being written to the LRSSS RAID). The ENAS will produce 204 independent bottom detections per ping that are reported as one-way travel time to the bottom and angle relative to local vertical from the tow fish to the location of the bottom detection. The ENAS will produce 204 independent BARF backscatter measurements that are reported as "flat bottom" radiometric adjusted amplitudes at the time of the bottom detection. The ENAS will produce 204 independent estimates of the quality of the bottom detection. The number of "204" is based on there being one ENAS array (ELAC-LSE325 transducers) providing BARF information on 91 beams, two ENAS arrays (ELAC-LSE325 transducers) which each provide BARF information on 56 beams and one ENAS array (Mills Cross of two ELAC-LSE234 transducers) providing BARF information on 1 beam. The first processing step for each ping of ENAS raw data from the LRSSS RAID will be to leading edge detect the receive signals from the Mills Cross ENAS to establish the altitude of the tow fish above the seabed, as well as, determine the radiometric adjusted backscatter amplitude of the returning echo for recording onto the LRSSS RAID (in SDF2 format). There is no computational beam forming to be performed because the beam forming is inherent to the Mills Cross configuration. The radiometric adjustments to the backscatter amplitude are to be based on the transmit source level, receive sensitivity, transmit beam pattern, receive beam pattern, footprint size at the time of the amplitude determination and gain (both fixed and time-varying). The information bearing signals that are received on the three ELAC-LSE325 transducers result from echoes of a swept-frequency transmission (linear chirp); therefore beam forming starts with pulse compression using a replica of the respective transmit chirp waveform. It is expected that the beam forming for the three ELAC-LSE325 transducers will be accomplished using "zero-padded" FFTs across the 60 receive elements of the those transducers, followed by interpolation, and/or across multiple sub-arrays comprised of less than 60-elements, followed by interpolation. BOTTOM DETECTION: The technique for making the required detection of the bottom and subsequent determination of the backscatter amplitude for any given beam depends on the length of the echo return (number of samples in the "elevated" echo return) in a particular beam, which in turn is determined by the angle at which acoustic energy associated with the particular beam intersected with the local seabed. In those instances where there are two recommended bottom detection techniques, the reported value should be the average of the two solutions. Transitions from one bottom solution to two bottom solutions, or vice versa, should use a tapered 3-element weighted average of the two bottom solutions. When the beam projection is within 17 degrees from perpendicular to the nominal seabed, the bottom detection should be performed by detecting the "leading edge" of the most significant increase of the received signals in each of the specific beams. In this approach, the determination of backscatter pulse amplitude for each beam is made starting at the time of the bottom detection for that beam. The radiometric adjustments to the backscatter amplitudes are to be based on the ENAS transmit source level, ENAS receive sensitivity, transmit beam pattern, receive beam pattern, footprint size at the time of the bottom determination, and gain (both fixed and time-varying). When the beam projection is greater than 13 degrees, but less than 49 degrees, from perpendicular to the nominal seabed, the bottom detection should be performed via a weighted mean time of arrival technique (WMT) (deMoustier, 1993). Travel times are estimated using the sound speed that is observed at the tow fish. In this approach, the backscatter amplitude determination for each beam is made at the time of the bottom detection for that beam. The radiometric adjustments to the backscatter amplitudes are to be based on the ENAS transmit source level, ENAS receive sensitivity, transmit beam pattern, receive beam pattern, footprint size at the time of the bottom determination, and gain (both fixed and time-varying). When the beam projection to the seabed is greater than 41 degrees from perpendicular to the nominal seabed, the bottom detections and subsequent determinations of backscatter amplitudes should be made via the "phase" technique which uses phase difference between overlapping beams formed via FFTs performed on multiple sub-arrays. The "phase" technique is regularly employed when the bottom returns are greatly elongated due to the geometry of beams at large off-nadir angles. The phase technique equates the time of the bottom detection to the time of zero phase difference between spatially overlapping beams. In the phase technique: (Hammerstad et. al., 1991) the "time" of bottom detection is determined by fitting a curve to the trend in the differential phase time series between two spatially overlapping beams. Depending on the coherence of the phase data, the bandwidth of the received signal may need to be limited in order to achieve a reasonably robust estimate of the time of the zero-phase crossing epochs. (Kraft and de Moustier, 2004) In this approach, the backscatteramplitude determination for each beam is made at the time of the bottom detection for that beam. The radiometric adjustments to the backscatter amplitudes are to be based on the ENAS transmit source level, ENAS receive sensitivity, transmit beam pattern, receive beam pattern, and footprint size at the time of the bottom determination, and gain (both fixed and time-varying). Computations (Beaudoin, et. al., 2004) to determine the WGS84 geo-locations of the bottom detections and the backscatter determinations must utilize the tow body attitude and locations from the raw data SDF2 files on the system RAID. ENAS CONTRIBUTIONS TO LRSSS CASCADING CALIBRATION ENAS backscatter is an integral part of the LRSSS Cascading Calibration. The two large 3-m side scan arrays on the LRSSS tow body are difficult to calibrate, even when each is disassembled into its three 1-m component (ELAC-LSE327) transducers. This presents a problem, considering that backscatter measurements from all of the LRSSS subsystems are intended to be quantitative and equivalent rather than simply providing qualitative information. The two ELAC-LSE324 transducers which comprise the nadir pointing Mills Cross Array are simple two terminal devices, which can readily be removed from the LRSSS tow body and be subjected to classical tank calibration techniques. Spatial discrimination of the effective backscatter measurement area on the sea bed is provided by the Mills Cross orthogonal mechanical mounting orientations of the two ELAC-LSE324 transducers. Backscatter measurements from a nadir pointing Mills Cross transducer are reliable and robust. The backscatter values from a nadir pointing Mills Cross transducer are easy to analyze for the relative backscatter in dB per square meter, provided that the fixed and range (time) varying gain properties of the receive channel are well known. Accurate and precise backscatter values can be computed for the observed nadir aspect of BARF, which are based on tank measurements of: (1) the 2-D beam patterns for the ELAC-LSE324 transducers, (2) the TVR for the ELAC-LSE324 transducers, (3) the OCVR for the ELAC-LSE324 transducers, and (4) transmitted pulse length. The physical mounting arrangement of the ENAS transducers on the LRSSS tow body results in spatial overlap of the areas on the sea bed where BARF can be individually measured by different ENAS transducers. The downward pointing Mills Cross Array, composed of two ELAC-LSE324 transducers, provides information on BARF at nadir. After beam forming is performed on signals received on the nadir pointing ELAC-LSE 325 transducer, an independent measurement of BARF at nadir is obtained. Comparisons between the two independent measurements of BARF at nadir provides information that can be used to "force" the BARF value at nadir from the ELAC-LSE325 transducer into correspondence with the BARF value at nadir from the Mills Cross Array composed of two ELAC-LSE324 transducers. As the de facto system standard, the "superior knowledge" of the ELAC-LSE324 characteristics justifies the backscatter from other transducers in the cascading calibration process being forced to "statistically" agree with the data obtained with the ELAC-LSE324. The comparison statistics will be the mean and standard deviation in the linear domain and the median in the dB domain. The calibration cascade continues with comparisons between backscatter measurements resulting from electronic beam forming applied to the receive signals on the nadir, port and starboard pointing ELAC-LSE325 transducers. Common angles in the BARF may be associated with beams that are steered differently relative to an array's face- normal, therefore the beam footprints may not coincide. Nevertheless, with appropriate adjustments for the differing beam widths, the BARF measurements from the off-nadir beams of the downward facing ELAC-LSE325 transducer can be used to force "statistical" agreement between itself and the BARF measurements from the port and starboard pointing ELAC-LSE325 transducers. The forcing will be based on comparisons between the mean and standard deviation in the linear domain and the median in the dB domain. EXTENSION OF LRSSS CALIBRATION CASCADE The ENAS processing does not extend to the Multi-Beam Side Scan (MBSS) subsystem of the LRSSS, however, the LRSSS Calibration Cascade does extend to the MBSS. This section is for completeness only. Although it is beyond the scope of ENAS processing, the LRSSS Calibration Cascade continues by forcing agreement between backscatter measurements from the port and starboard pointing ELAC-LSE327 transducers of the MBSS and from the port and starboard pointing ELAC-LSE325 transducers of the ENAS. There are differences in sizes and shapes of the ENAS footprints compared to the sizes and shapes of the MBSS footprints, but those differences are known and can be overcome to force the MBSS measurements of BARF to "statistically" agree with spatially overlapping sections of BARF measurements from the port and starboard ENAS arrays. The comparison statistics will be the mean and standard deviation in the linear domain and the median in the dB domain. At slant ranges beyond reach of the port and starboard pointing ENAS arrays, the MBSS will also carry the cascading calibration imprint of the nadir pointing Mills Cross array, the nadir facing ENAS array and the port and starboard pointing ENAS arrays. It is important to recognize due to the coordinated time multiplexed nature of transmissions by the ENAS and the MBSS, the port and starboard pointing ENAS transducers arrays are primarily receiving bottom echoes resulting from either acoustic energy propagating from the transmitter in each of those arrays, or acoustic energy propagating from the transmitter in each of the MBSS arrays. COMPUTATIONAL LOAD The ENAS computations are always performed on post-recorded data. However, based on the LRSSS at-sea operational practices, the ENAS computational requirements must be performed at a real-time rate on 181 acoustic data channels, at ping intervals of one-second, with a sample rate of 12 kHz, and a sample length of 8000. The computational requirements include: (1) Poll the RAID to determine which, if any, raw data files are closed and ready for ENAS processing. (2) Read raw data from Klein-SDF2 files on the system RAID. (3) Perform bottom detection, amplitude determination and WGS84 geo-location for the data from the single receive element in the ENAS Mills Cross. (4) Perform pulse compression on the 180 ENAS data channels (60 each in three separate transducers) where the information bearing echoes are expected to be swept frequency signals. (5) Form 203 beams (91+56+56) using FFT's across the ENAS multi-element arrays (nadir pointing, port pointing and starboard pointing, respectively). (6) Perform bottom detection, amplitude determinations, quality parameters, and WGS84 geo-location for the 203 beams formed in 5 (7) Perform radiometric adjustments to the amplitude determinations in 3 and 6. (8) Determine the calibration cascade factors using information from 3, 6, and 7. (9) Write the results as processed Klein-SDFX files to the system RAID. REFERENCES: Beaudoin, J., Hughes Clarke, J., and Bartlett, J., 2004, Application of Surface Sound Speed Measurements in Post-Processing for Multi-Sector Multibeam Echosounders: International Hydrographic Review, v.5, no.3, p.26-31. Kraft, B.J., and de Moustier, C., 2004, Variable Bandwidth Filter for Multibeam Echosounding Bottom Detection, IEEE Oceans, Kobe, Japan, Nov 09 - Nov 12, Conference Proceedings, p. 1154-1158. deMoustier, C., 1993, Signal processing for swath bathymetry and concurrent seafloor acoustic imaging: in Acoustic Signal Processing for Ocean Exploration, eds. Moura and Louttie, p.329-354. Hammerstad, E., Pohner, F., Parthiot, F. and Bennett, J., 1991, Field testing of a new deep water multibeam echosounder: Proc. IEEE Oceans '91, 2, 743-749.
 

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