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Multistatic Sonar Simulation* P. Willett

January, 2011

Supported by the Office of Naval Research

Contract: N00014-10-10412

Program Managers: Keith Davidson & John Tague

* help from R. Georgescu, S. Schoenecker, S. Coraluppi, O. Erdinc, W. Blanding

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What is it?

• Most MSTWG datasets are high-fidelity but one-shot.– some need for Monte Carlo results

• This simulation is medium fidelity– same scenario can be run multiple times with

different noises (detections and clutter)

• Scenario– can be specified by GUI– scenario can be specified by matfile

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Targets• motion is described via waypoints

– as many as you like (e.g., “W” needs 5)

• as many targets as you want– presently there is no “appear” or “disappear”

• future work, easy

– aspect dependent SNR– Gaussian-shaped pedestal, =10o

• can be set

– pedestal is 10dB• can be set

– specify in terms of received monostatic SNR at broadside at 1 km

• can be set

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Platforms• as many as desired• specified as waypoints, same as targets• each can be a source, receiver or both• platforms are acoustically observable

– same model as target– can turn this off

• bistatic observations model– azimuth, time delay and Doppler

• input ’s– attenuation with distance

• loss proportional to distance2 below 1km, and to distance beyond 1km• loss product of source-target and target receiver losses

• sound velocity must be input– no multipath

• future work, easy but nontrivial• specify ping rates and total simulation time

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Clutter

• presently three types, user-specified– Rayleigh– log-normal (choose parameter)– K-distributed (choose parameter)

• detection threshold input (nominally 13dB)• formed in angle/delay space

– more dense near receiver

• all resolution cells’ returns are formed and compared to the threshold– no Pfa input, although it is internally calculated

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How to use it?• scenario setup mode:

– invoke “multistatic_simulation” in MATLAB– decide whether want GUI or matfile input

• output is in “simulation_output.mat”

• Monte Carlo mode:– assume “parameterfile.mat” was created in scenario

setup mode or is given– [newobs,newcontact,data]= …

multistatic_simulation(‘parameterfile.mat’)– output given for one whole simulation run

• suitable to be called within loop• first call simulation• then call tracker• compare output to truth (from parameterfile.mat)

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What is the Output?• each run (invocation of multistatic_simulation)

gives three outputs– “obs” – in Cartesian space– “contact” – in time/bearing space– “data” – in NURC format that MSTWG has been using

(see NURC Technical Memo RL-JUN03-01 “Abel Multistatic sonar information processing chain” by Rene Laterveer, also the presentation “New ARLUT Data Set” by Brian LaCour, MSTWG 3rd Meeting)

• these are very redundant, use what you want– obs & contact are cell arrays

• given in form useful for a tracker

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contact data format• contact{i_scan,i_pair}.az(i_contact)

– azimuth (degrees, counter-clockwise from east)• contact{i_scan,i_pair}.delay(i_contact)

– travel time of ping (s)• contact{i_scan,i_pair}.doppler(i_contact)

– bistatic Doppler (m/s)• contact{i_scan,i_pair}.time(i_contact)

– return time of ping from start of simulation (s)• contact{i_scan,i_pair}.power(i_contact)

– level of contact (dB)• contact{i_scan,i_pair}.source(:,i_contact)

– [x; y] values of position of source at the time of emission of ping.• contact{i_scan,i_pair}.receiver(:,i_contact)

– [x; y] values of position of receiver at the time of reception of return.• contact{i_scan,i_pair}.provenance(i_contact)

– zero if clutter, otherwise is index of target that return came from.• contact{i_scan,i_pair}.truth(:,i_contact)

– [x; y] values of position of reflecting target at the time of reflection. If clutter: zeros(2,1).• contact{i_scan,i_pair}.number_contacts

– number of threshold-exceedances for this ping/pair.• contact{i_scan,i_pair}.source_platform_index(i_contact)

– the index of the source platform for contact i_contact, to distinguish multistatic pairs when it is necessary to estimate (say) SNR.

• contact{i_scan,i_pair}.receiver_platform_index(i_contact)– the index of the receiver platform for contact i_contact, to distinguish multistatic pairs when

it is necessary to estimate (say) SNR.

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obs data format• obs{i_scan}.meas(i_meas).time

– return time of ping from start of simulation (s)• obs{i_scan}.meas(i_meas).z(:)

– [x; y; Doppler] values of centroid of contact (measurement Cartesian space).• obs{i_scan}.meas(i_meas).R(:,:)

– covariance matrix for z.• obs{i_scan}.meas(i_meas).snr

– power of contact (dB).• obs{i_scan}.meas(i_meas).provenance

– zero if clutter, otherwise is index of target that return came from.• obs{i_scan}.meas(i_meas).truth(:,i_contact)

– [x; y] values of position of reflecting target at the time of reflection. If clutter, this is zeros(2,1).

• obs{i_scan}.meas(i_meas).source_platform_index(i_contact)– the index of the source platform, to distinguish multistatic pairs when it is

necessary to estimate (say) SNR.• obs{i_scan}.meas(i_meas).receiver_platform_index(i_contact)

– the index of the receiver platform, to distinguish multistatic pairs when it is necessary to estimate (say) SNR.

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• dat{i_scan,i_pair}.header.svel– sound velocity (m/s)

• dat{i_scan,i_pair}.buoy.compass– heading of receiver, clockwise from east in degrees

• dat{i_scan,i_pair}.buoy.lat(1)– latitude of receiver at time of ping (obs & contact use time of reception)

• dat{i_scan,i_pair}.buoy.lon(1)– longitude of receiver at time of ping (obs & contact use time of reception)

• dat{i_scan,i_pair}.buoy.lat(2)– latitude of source at time of ping

• dat{i_scan,i_pair}.buoy.lon(2)– longitude of source at time of ping

• dat{i_scan,i_pair}.clust.range(i_contact)– zero for all contacts

• dat{i_scan,i_pair}.clust.mean(i_contact).range– the time in seconds between transmission of the ping and the reception of contact

number i_contact• dat{i_scan,i_pair}.clust.mean(i_contact).doppler

– the bistatic Doppler in m/s• dat{i_scan,i_pair}.clust.mean(i_contact).beam

– the angle, clockwise from east in degrees, of contact number i_contact

dat data format