Generation of dopplerized, aspect dependent, highlighted simulated echoes

Claim 2

In apparatus for generating, from a source of signals having frequency characteristics of sonar transmission signals, simulated sonar echoes having doppler and target aspect dependent highlight characteristics, the apparatus including problem computer means for providing signals representative of simulated target range, range rate, and target aspect, doppler effects generator means, and aspect dependent target highlight echo generator means, the improvement comprising: said doppler effects generator means connected to receive said sonar transmission signals and responsive to said range rate signals to provide output signals the frequencies of which are all proportional in the same ratio to corresponding frequencies of said transmission signals; said doppler effects generator means comprising data storage means; means for reading data representative of said sonar transmission signals into said storage means at a first predetermined rate; and means for reading said data out of said storage means at a second rate which is a function of said range rate.

Claim 3

In apparatus according to claim 1, said doppler effects generator means comprising: analog to digital conversion means operative to convert said sonar transmission signals to digital data form; parallel in parallel out shift register means; first AND gate means for connecting said analog to digital conversion means to the input of said shift register means; digital to analog conversion means; second AND gate means for connecting the output of said shift register means to said digital to analog conversion means; and timing circuitry operative to provide sampling and enabling signals at a predetermined first frequency to said analog to digital conversion means and to said first gate means respectively, to effect sampling and read in at said first rate and for a period of time determined by the duration of said sonar transmission signal, said timing circuitry being operative to provide to said shift register shift signals at a rate which is a function of said predetermined first frequency, and said timing circuitry being operative to provide enabling signals to said second gate means, whereby read out from said shift register to said digital to analog conversion means is effected at a second rate which is a function of said range rate.

Claim 4

In apparatus according to claim 2, said timing circuitry comprising: gate pulse generator means responsive to said sonar transmission signals to provide gate pulses each having a duration just exceeding the length of a sonar transmission; read in clock means for providing an output of said predetermined first frequency; first one shot means for shaping the output of said read in clock means to a series of pulses at said predetermined first frequency, said pulses being applied as said sampling signals to said analog to digital conversion means; first switching means responsive to each of said gate pulses to connect said read in clock means to said first one shot means for the duration of the gate pulse; third and fourth AND gate means having outputs connected as inputs to control said first and second AND gate means, respectively, said third AND gate means being connecTed to receive said gate pulses as a first input; delay means connected to receive the output of said first one shot means so as to provide as an output delayed pulses at said first frequency, said delayed pulses being applied as a second input to said third AND gate means to effect read in to said shift register; second one shot means connected to receive said delayed pulses and operative to trigger on the trailing edges thereof to provide a series of further delayed pulses at said first frequency; n pulse generator means connected to receive said further delayed pulses and to generate as an output a series of n pulses for each input pulse thereto, said output of said n pulse generator being applied as said shift signals to said shift register; a variable frequency read out clock responsive to said range rate signal to provide an output at a second frequency which is a function of said range rate; a variable time delayed trigger pulse generator connected to receive said sonar transmission signals and said range signals and operative to provide as an output trigger pulses each following the inception of a corresponding transmission signal by a time period which is a function of range; first flip-flop means connected to receive said trigger signals and to change from a reset condition to a set condition in response thereto; second switching means for connecting the output of said variable read out clock means to the input of said first one shot means in response to said set condition of said first flip-flop means, whereby said one shot means provides an output at said second frequency to said delay means for the duration of said set condition and said delay means provides delayed pulses at said second frequency as one input to said fourth AND gate means; said fourth AND gate means being connected to receive a set condition output from said first flip-flop as a second input thereto so as to effect read out of said shift register to said digital to analog conversion means at a rate corresponding to said second frequency, whereby the output of said digital to analog conversion means is a signal having doppler characteristics and all frequencies of which bear the same ratio to corresponding frequencies in the transmission signal.

Claim 5

In apparatus for generating, from a source of signals having frequency characteristics of sonar transmission signals, simulated sonar echoes having doppler and target aspect dependent highlight characteristics, the apparatus including problem computer means for providing signals representative of simulated target range, range rate, and target aspect and aspect data as functions of cos theta and of sin theta where theta is the aspect angle of the target, doppler effects generator means, and aspect dependent target highlight echo generator means, the improvement wherein said echo generator means comprises: analog to digital converter means connected to receive the output of said doppler effects generator means and responsive to sample command signals to provide a digital representation thereof in the form of a plurality of parallel digital outputs; parallel in/parallel out shift register means; first parallel AND gate means for connecting the parallel outputs of said analog to digital converter means to said shift register means; said shift register means being responsive to shift signals to shift said inputs in groups therealong to a plurality of group output positions, each group output position being representative of a highlight along the target length; a plurality of digital to analog converter means each corresponding to one of said group output positions; second parallel AND gate means for connecting parallel outputs from said group output positions of said shift register means to respective ones of said digital to analog converter means; a plurality of attenuator means each corresponding to one of said digital to analog cOnverter means; analog voltage signal summing means connected to said attenuator means for summing analog voltage signals from said attenuator means to provide a composite echo simulating signal; a plurality of bow gate means for connecting the outputs of predetermined ones of said digital to analog converter means to respective ones of said attenuator means in response to bow aspect signals from said problem computer means; a plurality of stern gate means for connecting the outputs of predetermined ones of said digital to analog converter means to respective ones of said attenuator means in response to stern aspect signals from said problem computer means; and timing means responsive to aspect data signals from said problem computer means to generate enabling signals for said first and second parallel AND gate means and to generate said shift signals for said shift register means.

Claim 6

In apparatus for generating, from a source of signals having frequency characteristics of sonar transmission signals, simulated sonar echoes having doppler and target aspect dependent highlight characteristics, the apparatus including problem computer means for providing signals representative of simulated target range, range rate, and target aspect and aspect data as functions of cos theta and of sin theta where theta is the aspect angle of the target, doppler effects generator means, and aspect dependent target highlight echo generator means, the improvement wherein said echo generator means comprises: analog to digital converter means connected to receive the output of said doppler effects generator means and responsive to sample command signals to provide a digital representation thereof in the form of a plurality of parallel digital outputs; parallel in/parallel out shift register means; first parallel AND gate means for connecting the parallel outputs of said analog to digital converter means to said shift register means; said shift register means being responsive to shift signals to shift said inputs in groups therealong to a plurality of group output positions, each group output position being representative of a highlight along the target length; a plurality of digital to analog converter means each corresponding to one of said group output positions; second parallel AND gate means for connecting parallel outputs from said group output positions of said shift register means to respective ones of said digital to analog converter means; a plurality of attenuator means each corresponding to one of said digital to analog cOnverter means; analog voltage signal summing means connected to said attenuator means for summing analog voltage signals from said attenuator means to provide a composite echo simulating signal; a plurality of bow gate means for connecting the outputs of predetermined ones of said digital to analog converter means to respective ones of said attenuator means in response to bow aspect signals from said problem computer means; a plurality of stern gate means for connecting the outputs of predetermined ones of said digital to analog converter means to respective ones of said attenuator means in response to stern aspect signals from said problem computer means; and timing means responsive to aspect data signals from said problem computer means to generate enabling signals for said first and second parallel AND gate means and to generate said shift signals for said shift register means.

Claim 7

In apparatus according to claim 4, said timing means comprising: clock means for providing a predetermined frequency output; filtered noise source means for providing noise frequencies; count and hold circuit means; gate means for connecting said clock means output and said noise source output to the input of said count and hold circuit means in response to either of said aspect data functions; a multiplier circuit connected to receive said predetermined frequency from the clock means and to provide a predetermined multiple thereof as an output; counter means connected to receive the output of said multiplier circuit; comparator means connected to said count and hold circuit means and to said counter means and adapted to render an output signal each time the count in said counter means equals the count in said count and hold circuit means, said output signals of said comparator means being applied to said analog to digital converter means as said sample command signals; delay means connected to receive said output signals of said comparator means and connnected to provide delayed signals as enabling signals to said first and second parallel AND gate means; one shot means connected to receive said delayed signals and operative to trigger on the trailing edges thereof to provide output signals of predetermined duration; an n pulse generator operative to provide n pulses as an output for each output signal of said one shot means, said output of said n pulse generator being applied as shift signals to said shift register means.

Claim 8

In apparatus according to claim 4, at least one of said attenuator means comprising: second shift register means connected to receive the output of said gate means as shift signals, said second shift register means comprising a plurality of output taps; second delay means connected to receive the output of said gate means and to provide a delayed output as a data input to said second shift register means; a plurality of attenuator resistors each connected to one of said output taps on said second shift register means; second summing means connected to said resistors for providing a composite voltage output; and voltage controlled resistor means connected in series with said first summing means and responsive to said composite voltage output to vary said analog voltage signals.