Spatial combiner for a digital VLF/LF receiver

Claim 2

A spatial combiner for connection to a receiver used in conjunction with a plurality of direction-sensitive antennas for receiving a spread-spectrum communication signal in the presence of interference arriving from directions different than the communication signal being received, said spatial combiner comprising: (a) steering network means for combining N inputs received from N antennas and producing M outputs J 1 , J 2 , . . . , J M , with M being a multiple of K, where K is a positive integer such that each of said M outputs is a weighted sum of said N inputs from said antennas; (b) a plurality of normalizer means, for receiving said M outputs from said steering network, and for normalizing said M outputs to unit energy and producing normalized outputs J 1 , J 2 , . . . , J M ; and (c) a plurality of combiner means for receiving said normalized outputs from said plurality of normalizers and summing the first K of said normalized outputs to produce output C 1 , summing the next K of said normalized outputs to produce output C 2 , and continuing summing of said outputs until summing the last K of said outputs occurs to produce output C M/K .

Claim 3

The spatial combiner of claim 1 wherein said steering network means includes: a plurality of nodes at which preset weights W 11 through W MK are applied to each of said inputs, I 1 , I 2 , . . . , I N ; and a plurality of summers connected to sets of said nodes 24 to produce M outputs, J 1 , J 2 , . . . , J M from said weighted inputs.

Claim 4

The spatial combiner of claim 1 wherein each of said normalizer means includes: a multiplier; a pair of parallel paths connected to said multiplier; a delay interposed in one of said paths; a serial arrangement of a squarer, integrator, and inverter interposed in the other of said paths.

Claim 5

The spatial combiner of claim 1 wherein each of said combiner means is a summer which sums K successive normalized inputs J 1 through J K to form a combined output C.

Claim 6

The spatial combiner of claim 1 further comprising: a receiver operably coupled to said steering network means.

Claim 7

The spatial combiner of claim 5 further comprising: a plurality of antennas operably coupled to said receiver.

Claim 8

The spatial combiner of claim 6 wherein: said plurality of antennas comprise an array of direction sensitive antennas.

Claim 9

In a combination with a plurality of direction-sensitive antennas for receiving a spread-spectrum communication signal in the presence of interference arriving from directions different than the communication signal being received and a receiving having a plurality of signal conditioners connected to said antennas and receiving analog outputs, A 1 , A 2 , . . . , A N , from said antennas and producing N digitized outputs , I 1 , I 2 , . . . , I N , a spatial combiner comprising: (a) a steering network connected to said signal conditioners and receiving and combining said N outputs, I 1 , I 2 , . . . , I N , and producing M outputs J 1 , J 2 , . . . , J M , with M being a multiple of K, K where is a positive integer such that each of said M outputs is a weighted sum of said N inputs from said antennas; (b) a plurality of normalizers connected to said steering network and receiving said M outputs from said steering network, normalizing said M outputs to unit energy and producing normalized outputs J 1 , J 2 , . . . , J M ; and (c) a plurality of combiners connected to said normalizers and receiving said normalized outputs from said normalizers and summing the first K of said normalized outputs to produce output C 1 , summing the next K of said normalized outputs to produce output C 2 , and continuing summing of said outputs until summing the last K of said outputs occurs to produce output C M/K .

Claim 10

In a combination with a plurality of direction-sensitive antennas for receiving a spread-spectrum communication signal in the presence of interference arriving from directions different than the communication signal being received and a receiving having a plurality of signal conditioners connected to said antennas and receiving analog outputs, A 1 , A 2 , . . . , A N , from said antennas and producing N digitized outputs , I 1 , I 2 , . . . , I N , a spatial combiner comprising: (a) a steering network connected to said signal conditioners and receiving and combining said N outputs, I 1 , I 2 , . . . , I N , and producing M outputs J 1 , J 2 , . . . , J M , with M being a multiple of K, K where is a positive integer such that each of said M outputs is a weighted sum of said N inputs from said antennas; (b) a plurality of normalizers connected to said steering network and receiving said M outputs from said steering network, normalizing said M outputs to unit energy and producing normalized outputs J 1 , J 2 , . . . , J M ; and (c) a plurality of combiners connected to said normalizers and receiving said normalized outputs from said normalizers and summing the first K of said normalized outputs to produce output C 1 , summing the next K of said normalized outputs to produce output C 2 , and continuing summing of said outputs until summing the last K of said outputs occurs to produce output C M/K .

Claim 11

The combination of claim 8 wherein said steering network of said spatial combiner includes: a plurality of nodes at which preset weights W 11 through W MK are applied to each of said inputs, I 1 , I 2 , . . . , I N ; and a plurality of summers connected to sets of said nodes 24 to produce M outputs , J 1 , J 2 , . . . , J M from said weighted inputs.

Claim 12

The combination of claim 8 wherein each said normalizer of said spatial combiner includes: a multiplier; a pair of parallel paths connected to said multiplier; a delay interposed in one of said paths; a serial arrangement of a squarer , integrator , and inverter interposed in the other of said paths.

Claim 13

The combination of claim 8 wherein each said combiner of said spatial combiner is a summer which sums K successive normalized inputs J 1 through J K to form a combined output C.