Position locating arrangements

Claim 2

A direction finding arrangement for determining the bearing of a point from which radio frequency electromagnetic radiation is received, comprising: an array of aerial elements for receiving said radiation; modulator means for simultaneously gating for a predetermined period of time signals derived from the respective aerial elements; delay means for delaying the gated signals by different amounts to arrange the gated signals sequentially in time whereby to produce an information signal having a frequency representative of the bearing of said point; and means for determining the frequency of said information signal; said signals derived from each aerial being produced by heterodyning the signals received by each aerial with signals produced by a local oscillator, additively mixing the heterodyned signals received by one aerial with a reference frequency, and subtractively mixing the resultant signal with the heterodYned signals received by each of aerials.

Claim 3

In a direction finding system, in combination: an array of aerial elements disposed individually to receive a wave packet of radio frequency electromagnetic radiation from a distant point at times dependent upon the direction of said point relative to said array; first means for passing radiation received by all of said aerial elements during a short period of time sufficient for reception of said wave packet by all of said elements and for presenting individual output signals corresponding to the individual elements in which the output signals are of a selected frequency much less than that of the received radiation and of phases dependent upon the relative times of reception of the wave packet at the corresponding aerial elements, and including delay means for presenting said output signals in sequential fashion as an information signal extending over an information period of time which is at least equal to nt where n is the number of said output signals and t is said short period of time; and second means for determining the cyclic content of said information signal during said information period of time; the cyclic content of said information signal being determined by feeding said signal to a bank of band pass filters having their bands centred on differing frequencies.

Claim 4

In a direction finding system, in combination: an array of aerial elements disposed individually to receive a wave packet of radio frequency electromagnetic radiation from a distant point at times dependent upon the direction of said point relative to said array; first means for passing radiation received by all of said aerial elements during a short period of time sufficient for reception of said wave packet by all of said elements and for presenting individual output signals corresponding to the individual elements in which the output signals are of a selected frequency much less than that of the received radiation and of phases dependent upon the relative times of reception of the wave packet at the corresponding aerial elements, and including delay means for presenting said output signals in sequential fashion as an information signal extending over an information period of time which is at least equal to nt where n is the number of said output signals and t is said short period of time; and second means for determining the cyclic content of said information signal during said information period of time; the cyclic content of said information signal being determined by feeding said signal to a bank of band pass filters having their bands centred on differing frequencies.

Claim 5

In a direction finding system, in combination: an array of aerial elements disposed individually to receive a wave packet of radio frequency electromagnetic radiation from a distant point at times dependent upon the direction of said point relative to said array; first means for passing radiation received by all of said aerial elements during a short period of time sufficient for reception of said wave packet by all of said elements and for presenting individual output signals corresponding to the individual elements in which the output signals are of a selected frequency much less than that of the received radiation and of phases dependent upon the relative times of reception of the wave packet at the corresponding aerial elements, and including delay for presenting said output signals in sequential fashion as an information signal extending over an information period of time which is at least equal to nt where n is the number of said output signals and t is said short period of time; and second means for determining the cyclic content of said information signal during said information period of time; and including means for off-setting each information period of time in a number of sequential scan periods of time such that a beat of one cycle is obtained over the period of time occupied by that number of sequential scan periods of time.

Claim 6

In a direction finding system, in combination: an array of aerial elements disposed individually to receive a wave packet of radio frequency electromagnetic radiation from a distant point at times dependent upon the direction of said point relative to said array; first means for passing radiation received by all of said aerial elements during a short period of time sufficient for reception of said wave packet by all of said elements and for presenting individual output signals corresponding to the individual elements in which the output signals are of a selected frequency much less than that of the received radiation and of phases dependent upon the relative times of reception of the wave packet at the corresponding aerial elements, and including delay for presenting said output signals in sequential fashion as an information signal extending over an information period of time which is at least equal to nt where n is the number of said output signals and t is said short period of time; and second means for determining the cyclic content of said information signal during said information period of time; and including means for off-setting each information period of time in a number of sequential scan periods of time such that a beat of one cycle is obtained over the period of time occupied by that number of sequential scan periods of time.

Claim 7

In a direction finding system, in combination: an array of aerial elements disposed individually to receive a wave packet of radio frequency electromagnetic radiation from a distant point at times dependent upon the direction of said point relative to said array; first means for periodically passing radiation received by all of said aerial elements only during a short period of time covering many cycles of said radiation sufficient for reception of said wave packet by all of said elements and for presenting individual but overlapping output signals corresponding to the individual elements in which the output signals are of a selected frequency much less than that of the received radiation and of phases dependent upon the relative times of reception of the wave packet at the corresponding aerial elements, and including delay means for delaying said overlapping output signals by different multiples of a delay time at least equal to said short period of time so as to present said output signals in sequential fashion as an information signal extending over an information period of time which is at least equal to nt where n is the number of said output signals and t is said short period of time; and second means for determining the number of zeRo crossings of said information signal within said information period of time and for determining the time lapse between the first and the last zero crossings within said information period of time.

Claim 8

In a direction finding system, in combination: an array of aerial elements disposed individually to receive a wave packet of radio frequency electromagnetic radiation from a distant point at times dependent upon the direction of said point relative to said array; first means for periodically passing radiation received by all of said aerial elements only during a short period of time covering many cycles of said radiation sufficient for reception of said wave packet by all of said elements and for presenting individual but overlapping output signals corresponding to the individual elements in which the output signals are of a selected frequency much less than that of the received radiation and of phases dependent upon the relative times of reception of the wave packet at the corresponding aerial elements, and including delay means for delaying said overlapping output signals by different multiples of a delay time at least equal to said short period of time so as to present said output signals in sequential fashion as an information signal extending over an information period of time which is at least equal to nt where n is the number of said output signals and t is said short period of time; and second means for determining the number of zeRo crossings of said information signal within said information period of time and for determining the time lapse between the first and the last zero crossings within said information period of time.

Claim 9

An arrangement as claimed in claim 4 and wherein the frequency of said information signal is determined by a zero-crossing counter and a device measuring the time between the first and last zero-crossings of the signal.