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This interim report covers the progress of the acoustic telemetry project during the period 12/1/88 to 5/15/89. In general, the work followed the format specified in WHOI proposal No. 5674.1. The major exception was the deletion of the transmitter array development task and a corresponding funding decrease from $242,242 to $170,000. In addition, the period for the funding was extended to June 30, partly due to a two month delay in project startup. The telemetry project was centered around the construction, programming and testing of a digital receiver prototype capable of supporting future signal processing algorithms in real-time over ocean acoustic channels. The baseline receiver consists of a two-channel analog quadrature demodulator, and interface to a multiprocessor receiver for digital signal processing. The software developed includes routines for command and control of the analog demodulator, data handling and formatting, and minimal software to digitally implement an incoherent MFSK demodulator, synchronizer and data decoder. Data storage and display programs were also completed to facilitate the performance analysis of the unit during testing. The system was tested in Woods Hole harbor at data rates up to 4800 bits/sec. The acoustic channel was time-dispersive Rayleigh fading, and performance close to theoretical expectations was achieved. We are confident that the system error behavior is arising from channel-caused effects and known deficiencies in system performance, such as excessive synchronizer steady-state jitter., Funding was provided by the Office of Naval Research under contract Number N00014-86-K-0751, and by the Charles Stark Draper Laboratory Inc.

Contains table of contents for Section 2, an introduction and reports on fourteen research projects., U.S. Navy - Office of Naval Research Grant N00014-91-J-1628, Defense Advanced Research Projects Agency/U.S. Navy - Office of Naval Research Grant N00014-89-J-1489, MIT - Woods Hole Oceanographic Institution Joint Program, Lockheed Sanders, Inc./U.S. Navy Office of Naval Research Contract N00014-91-C-0125, U.S. Air Force - Office of Scientific Research Grant AFOSR-91-0034, AT&T Laboratories Doctoral Support Program, National Science Foundation Fellowship

This report describes a multiple CZ acoustic telemetry experiment conducted off the coast of California 1/28/90-2/2/90. The goal was to design a maximally robust high speed underwater modem suitable for data telemetry for submerged platforms and moorings. Six modulation methods were used to transmit data at rates from 1 to 1000 baud corresponding to bit rates up to 3kbit/sec. In addition, a large number of channel probe sequences was transmitted in order to estimate channel multipath, fluctuation dynamics and spatial diversity characteristics relevant to acoustic data telemetry. The data was transmitted from a 1 kHz source suspended from the R/V McGaw, and received on a multichannel vertical array tended by the RV Point Sur. The multichannel data was digitally recorded using floating-point digitizers and stored on optical disk for further processing. Approximate transmission ranges were 70, 140, 200 and 250km. Approximtely 8 hrs of transmission were recorded at each data range., Funding was provided by the Office of Naval Technology under Grant No. N00014-90-C-0098.

This report describes the March 1994 Arctic deployment undertaken by the Acoustic Telemetry Group of WHOI. The deployment was a part of the 1994 Sea Ice Mechanics Initiative (SIMI) project and was based at the west SIMI camp, approximately 150 nautical miles north-east of Prudhoe Bay, Alaska. The goal of the deployment was to install a network of six high-performance acoustic modems, developed at WHOI, and to obtain a data set demonstrating the communications and acoustic monitoring capabilties of the network. The six modems in the network were deployed over an area of 22 square km and communicated via radio Ethernet with a computer at the SIMI camp. Each model had a global positioning system, an acoustic source and an 8 element receiving array. The network was operated in a round-robin broadcast mode (i.e., each modem in turn transmitted a packet of data while the others received). The transmissions were 5000 bits-per-second QPSK with a 15kHz carrier. An extensive data set including raw acoustic data source localization information, and modem position was collected during the deployment. An additional function of the acoustic network was to communicate with, and track, the Odyssey, an autonomous underwater vehicle operated by the MIT group at the SIMI camp. To this end, the Odyssey was equipped with a Datasonics modem configured for periodic QPSK transmission to the network. A data set was obtained from which both the up-link communication and localization capabilties of the network can be determined., Funding was provided by the Office of Naval Research under Contract No. N00014-93-1-0988 and the Advanced Research Projects Agency under Contract Nos. MDA972-91-j-1004 and MDA972-93-1-0019.

A real-time spetrogram instrument has been developed to provide an inexpensive and field-portable instrument for the analysis of animal sounds. The instrument integrates a computer graphics display package with a PC-AT computer equipped with an A/D board and a digital signal processing board. It provides a real-time spectrogram display of frequencies up to 50kHz in a variety of modes: a running display, a signal halted on screen, successive expanded views of the signal. The signal amplitude may also be displayed. Portions of the scrolled data may be saved to disk file for future viewing, or as part of a database collection. The screen display may be manipulated to adapt to special needs. Program source listings are included in the text., Funding was provided by the Office of Naval Research through Grant Nos. N00014-88-K-0273 and N00014-87-K-0236, the National Institutes of Health through Grant No.1 R29 NS25290, and the Andrew W. Mellon Foundation.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1987., Includes bibliographical references., by Josko A. Catipovic., Sc.D.

The Office of Naval Research is sponsoring the development of acoustic communication modems for unmanned undersea vehicles. This effort is an enhancement to the Acoustic Communications (ACOMMS) ATD, focusing on a demonstration of UUV to SSN acoustic connectivity. The long term goal is to determine whether ACOMMS is sufficiently mature to warrant use on Navy UUVs currently under development, and to demonstrate the usefulness of the technology for data telemetry, bidirectional communication and UUV control., See also ADM002252. Prepared in collaboration with Woods Hole Oceanographic Institute, Woods Hole, MA and Florida Atlantic University, Boca Raton, FL.

This report describes the March 1994 Arctic deployment undertaken by the Acoustic Telemetry Group of WHOI. The deployment was a part of the 1994 Sea Ice Mechanics Initiative (SIMI) project and was based at the west SIMI camp, approximately 150 Nautical miles north-east of Prudhoe Bay, Alaska. The goal of the deployment was to install a network of six high-performance acoustic modems, developed at WHOI, and to obtain a data set demonstrating the communications and acoustic monitoring capabilities of the network. The six modems in the network were deployed over an area of 22 square km and communicated via radio Ethernet with a computer at the SIMI camp. Each modem had a global positioning system, an acoustic source and an 8 element receiving array. The network was operated in a round-robin broadcast mode (i.e., each modern in turn transmitted a packet of data while the others received). The transmissions were 5000 bits-per-second QPSK with a 15kHz carrier. An extensive data set including raw acoustic data, source localization information, and modem position was collected during the deployment. An additional function of the acoustic network was to communicate with, and track, the Odyssey, an autonomous underwater vehicle operated by the Mff group at the SIMI camp. To this end, the Odyssey was equipped with a Datasonics modem configured for periodic QPSK transmission to the network. A data set was obtained from which both the up-link communication and localization capabilities of the network can be determined. (KAR) P. 5, Sponsored in part by Contract MDA972-93-1-0019.

The results of an experiment examining the forward propagation of an acoustic signal through a buoyant plume are discussed. Two distinct testing sights were used. One made use of a small fresh water tank in NUWC to provide a controlled plume. The other us

This report describes a multiple CZ acoustic telemetry experiment conducted off the coast of California 1/28/90 - 2/2/90. The goal was to design a maximally robust high speed underwater modem suitable for data telemetry for submerged platforms and moorings. Six modulation methods were used to transmit data at rates from 1 to 1000 baud, corresponding to bit rates up to 3kbit/sec. The modulation formates were: (1) Multiple Frequency Shift Keying (MFSK) and Binary Expurgated Modulation (BEX-PERM); (2) Duobinary Frequency Shift Keying; (3) Quadrature Phase - Shift Keying (QPSK); (4) Quadrature Amplitude Modulation (8QAM); (5) Continuous Phase Modulation (CPM) 2DPM4 and 2CPFSK4; and (6) Trellis coded 8PSK. In addition, a large number of channel probe sequences was transmitted in order to estimate channel multipath, fluctuation dynamics and spatial diversity characteristics relevant to acoustic data telemetry. The data was transmitted from a 1 kHz source suspended from the R/V McGaw, and received on a multichannel vertical array tended by the R/V Point Sur The multichannel data was digitally recorded using floating-point digitizers and stored on optical disk for further processing. Approximate transmission ranges were 70, 140, 200 and 250 km. Approximately 8 hrs of transmission were recorded at each data range., Prepared in cooperation with Trondheim Univ., (Norway).

A real-time spectrogram instrument has been developed to provide an inexpensive and field-portable instrument for the analysis of animal sounds. The instrument integrates a computer graphics display package with a PC-AT computer equipped with an A/D board and a digital signal processing board. It provides a real-time spectrogram display of frequencies up to 50kHz in a variety of modes: a running display, a signal halted on screen, successive expanded views of the signal. The signal amplitude may also be displayed. Portions of the scrolled data may be saved to disk file for future viewing, or as part of a database collection. The screen display may be manipulated to adapt to special needs. Program source listings are included in the text. Keywords: Computer systems, Spectrography, Computer programs.

This work studies the application of current communication engineering methods to underwater acoustic telemetry. The underwater channel is modelled with data collected from channel probe experiments in Woods Hole Harbor and the Marginal Ice Zone. The experimental results indicate that the short range underwater acoustic channel may be modelled as a time dispersive fully saturated channel. In all cases the received signal phase is fully random for time intervals longer than 10 msec, and the envelope is characterized by a fully fading Nakagami PDF. It is shown that PSK modulation methods are ineffective because of the rapid phase fluctuations of received transmissions, and that the performance of the optimal partially coherent FSK receiver is almost identical to the suboptimal incoherent FSK demodulator. Adaptive equalization and impulse response measurement techniques for the underwater acoustic channel are presented. Performance of convolutional codes and sequential decoders on the Rayleigh fading channel is discussed, and complexity bounds for sequential decoding on the memoryless fading channel are discussed as a function of optimal and/or available system diversity. It is shown that sequential decoding of convolutional codes is a viable technique given the contemplated data rates and currently available decoding hardware. (KT)

The acoustic telemetry project was centered around the construction, programming and testing of a digital receiver prototype capable of supporting future signal processing algorithms in real-time over ocean acoustic channels. The baseline receiver consists of a two-channel analog quadrature demodulator, and interface to a multiprocessor receiver for digital signal processing. The software developed includes routines for command and control of the analog demodulator, data handling and formatting, and minimal software to digitally implement an incoherent MFSK demodulator, synchronizer and data decoder. Data storage and display programs were also completed to facilitate the performance analysis of the unit during testing. The system was tested in Woods Hole harbor at data rates up to 4800 bits/sec. The acoustic channel was time-dispersive Rayleigh fading, and performance close to theoretical expectations was achieved. We are confident that the system error behavior is arising from channel-caused effects and known deficiencies in system performance, such as excessive synchronizer steady-state jitter. (jhd)

The results of an experiment examining the forward propagation of an acoustic signal through a buoyant plume are discussed. Two distinct testing sights were used. One made use of a small fresh water tank in NUWC to provide a controlled plume. The other us, http://archive.org/details/forwardscatterin1094539913