Authenticating a signal based on an unknown component thereof

1. An arrangement in an environment that includes a plurality of sources, where source C i of said sources outputs a carrier modulated signal c i that includes a signal component that is modulated by a first code pertaining to source C i and a signal component that is modulated by a second code pertaining to source C i , where the first code is a known code, i=1, 2, . . . n, the arrangement comprising:

a processor;

a first apparatus that is configured to

receive a signal S A that contains a plurality of comingled signals, where signal S i A of said plurality of comingled signals is a replica of signal c i that is altered by a Doppler frequency shift f i,D A and a time delay τ i A that are related to attributes of source C i and to global location of said first apparatus, the second code being secret to said first apparatus, index i in said first apparatus running 1, 2, . . . , n1, where n1<n,

develop signal S A by processing said signal S A to at least convert said carrier signals to intermediate frequencies, where bandwidth of signal S A is not markedly lower than bandwidth of signal S A , and

apply signal S A to said processor, which is geographically removed from said first apparatus;

a second apparatus that includes a module that is configured to

receive a signal S B comprising a second comingled plurality of signals, where signal S i B of said second plurality of comingled signals is a replica of signal c i that is altered by a Doppler frequency shift f i,D B and a time delay τ i B that are related to attributes of source C i and to global location of said second apparatus, index i in said second apparatus running 1, 2, . . . , n2, where n2<n

develop signal S B by processing said signal s B to at least convert said carrier signals to intermediate frequencies, where bandwidth of said signal S B is not markedly lower than bandwidth of signal s B , and

apply signal S B to said processor;

where

(a) said processor computes cross-correlation of signals S A ({circumflex over (f)} i,D A ) with signals S B ({circumflex over (f)} i,D B ), to obtain a set of delays δ i , i=1, 2, . . . n, and employs said set of delays to authenticate a statement relative to said first apparatus, where

index i in said processor running 1, 2, . . . , n3, where n3≦n1 and n3≦n2,

S A ({circumflex over (f)} i,D A ) is said signal S A that is processed to compensate for Doppler frequency shift f i,D A by an estimate of the Doppler frequency shift {circumflex over (f)} i,D A , and

S B ({circumflex over (f)} i,D S ) is said signal S B that is processed to compensate for Doppler frequency shift f i,D B an estimate of the Doppler frequency shift {circumflex over (f)} i,D B ,

(b) from a set that consists of said first code and said second code, the arrangement generates only the first code.

2. An arrangement that operates in an environment that includes a plurality of sources, where source C i of said sources outputs a carrier modulated signal c i that includes a signal component that is modulated by a first code pertaining to source C i and a signal component that modulated by a second code pertaining to source C i where the first code is a known code, i=1, 2, . . . , n, which arrangement includes (A) a first apparatus that receives a signal s A that contains a plurality of comingled signals, where signal s i A of said plurality of comingled signals is a replica of signal c i that is altered by a Doppler frequency shift f i,D A and a time delay τ i A that are related to attributes of source C i and to global location of said first apparatus, said second code being secret to said first apparatus, index i in said first apparatus running 1, 2, . . . , n1, where n1<n, (B) a second apparatus that receives a signal S B that contains a second plurality of comingled signals, where signal s i B of said second plurality of comingled signals is a replica of signal c i that is altered by a Doppler frequency shift f i,D B and a time delay τ i B that are related to attributes of source C i and to global location of said second apparatus, index i in said second apparatus running 1, 2, . . . , n2, where n2<n, where said first apparatus is distinct from said second apparatus, and (C) a processor that operates on signals applied by said first apparatus and by said second apparatus, index i in said processor running 1, 2, . . . , n3, where n3≦n1 and n3≦n2, the improvement comprising:

said first apparatus develops, and delivers to said processor, a signal S A that includes a plurality of comingled altered-received signals S i A , where each altered-received signal S i A i=1, 2, . . . , n is related to signal s i A , and each signal Shd i A includes a portion that is (i) related to said secret code, (ii) has a bandwidth that is not markedly lower than bandwidth of signal s i A , and (iii) is devoid of said carrier signal;

said second apparatus develops, and delivers to said processor, a signal S B that includes a second plurality of comingled altered-received signals, where altered-received signal S i B is related to signal s i B , and each signal S i B includes a portion that is (i) related to said secret code, (ii) has a bandwidth that is not markedly lower than bandwidth of signal s i B , and (iii) is devoid of said carrier signal; and

said processor, being remote from said first apparatus, performing cross-correlation on signals related to signals S A with signals related to signals S B to develop a plurality of delay measures the are used to authenticate a statement pertaining to said first apparatus.

3. The claim 2 arrangement where first apparatus includes a means that communicates said statement to the processor and both said first apparatus and said second apparatus are devoid of means for generating said secret code.

4. The claim 2 arrangement where the processor is contained within said second apparatus.

5. The claim 2 arrangement where said signal S i A also includes Doppler frequency shift estimates {circumflex over (f)} t,D A or time delay estimates τ i A , or both, developed in said first apparatus.

6. The claim 2 arrangement where

said signal s A is related to

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where

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f L1 is the carrier frequency,

f i,D A is the Doppler shift,

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x Y i is said secret code used by source C i ,

K 2 i is a term that modulates x Y i , which term is related to said data signal and is delayed by transit delay from source C i , τ i A ; and

said signal S A is related to

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where f IF is a preselected intermediate frequency that is significantly lower than f L1 and θ 1 is a phase.

7. The arrangement of claim 2 arrangement where

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where

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f L1 is the carrier frequency,

f i,D A is the Doppler shift,

φ 1 is a phase,

x Y i is said secret code used by source C i ,

K 2 1 is a term that modulates x Y i , which term is related to said data signal and is delayed by transit delay from source C i , τ i A ; and

said signal is related to

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where PH i (f iD A ) is a phasor related to Doppler frequency shift relative to source C i , f i,D A .

8. The arrangement of claim 2 where said signals related to signal S A are signals S A ({circumflex over (f)} i,D A ) and said signals related to signal S B are signals S B ({circumflex over (f)} i,D B ), i=1, 2, . . . n, where S A ({circumflex over (f)} i,D A ) is said signal S A that is processed to compensate for Doppler frequency shift f i,D A by an estimate of the Doppler frequency shift {circumflex over (f)} i,D A , and signal S B ({circumflex over (f)} i,D B ) is said signal S B that is processed to compensate for Doppler frequency shift f i,D B by an estimate of the Doppler frequency shift {circumflex over (f)} i,D B .

9. The arrangement of claim 2 where said processor is located with a party that is other than a first party that is in control of said first apparatus and other than a second party that is in control of said second apparatus.

10. The arrangement of claim 2 where from said plurality of delay measures said processor determines whether all of said signals s i do arrive from sources c i , respectively.

11. The arrangement of claim 3 where from said plurality of delay measures said processor determines bona fide of the statement.

12. The arrangement of claim 2 where said first apparatus is contained in a portable device.

13. The arrangement of claim 2 where said first apparatus includes a memory for storing time delimited signal segments of said signals s i for future, non-real time processing into said signal S A .

14. An arrangement, in an environment with a plurality of satellites that transmit signals which are received by a first apparatus and a second apparatus, where satellite i transmits signal c i , i=1, n, the improvement comprising:

said first apparatus

receives a signal s A that is a comingled plurality of the signals transmitted by the satellites, each of the comingled signals, s i A , originating from satellite i and being burdened by a Doppler frequency shift and a delay, relative to the satellite i, the Doppler frequency shift and the delay being related to satellite i and of the and location of said first apparatus, and

develops, and delivers to a processor, a signal S A that includes a plurality of comingled altered-received signals S i A , where each altered-received signal S A , i=1, n, is (i) related to signal s i A , (ii) includes a portion that is related to a known code plus a portion that is related to a code that is secret to the first apparatus, (iii) has a bandwidth that is not markedly lower than bandwidth of signal s i A , and (iv) is devoid of a carrier frequency contained within signal s i A ;

said second apparatus

receives a signal s B that is a comingled plurality of the signals transmitted by the satellites, each of the comingled signals, s i B , originating from satellite i and being burdened by a Doppler frequency shift and a delay, relative to the satellite i, the Doppler frequency shift and the delay being related to satellite i and of the and location of said second apparatus,

develops, and delivers to said processor, a signal S B that includes a second plurality of comingled altered-received signals S i B , where each altered-received signal S i B , i=1, n, is (i) related to signal s i B (ii) includes a portion that is proportional to said secret code (iii) has a bandwidth that is not markedly lower than bandwidth of signal s i B , and (iv) is devoid of a carrier frequency that is contained within signals s i B ; and

said processor correlates signals S A ({circumflex over (f)} i,D A ) with signals S B ({circumflex over (f)} i,D B ) to obtain delay measures δ i , i=1, 2, . . . n, that are used to authenticate a statement about the first apparatus, where signal S A ({circumflex over (f)} i,D A ) corresponds to signal S A with the Doppler frequency shift f i,D A compensated by an estimate of the Doppler frequency shift {circumflex over (f)} i,D A , still including a signal component that is related to said secret code, and signal S B ({circumflex over (f)} i,D B ) corresponds to signal S B with the Doppler frequency shift f i,D B compensated by an estimate of the Doppler frequency shift {circumflex over (f)} i,D B still including a signal component that is related to said secret code.

15. The claim 2 arrangement where said second apparatus receives said signal s B via an antenna arrangement that is designed to insure that received signal s B indeed originates from said plurality of sources.

16. The claim 2 arrangement where said processor is co-located with said second apparatus.