Detection and time-of-arrival estimation using an IFM receiver

1. An apparatus for confirming a frequency of a received signal comprising:

a receiver for measuring a frequency, f e , of a received signal,

a sampling module for sampling the received signal to form digital samples of data,

a dividing module for partitioning the digital samples of data into blocks of data,

a discrete Fourier transform (DFT) module configured to use a kernel function dependent on the frequency f e ,

the DFT module configured to sum the digital samples of data disposed in a block of data and provide a magnitude, and

a confirmation module for confirming the frequency, f e , of the received signal, if the magnitude exceeds a predetermined threshold value;

wherein the block of data is a first block of data, the magnitude is a first magnitude of data, and the predetermined threshold value is a first predetermined threshold value,

the DFT module is configured to sum the digital samples of data disposed in a second and a third block of data following the first block of data and provide, respectively, a second magnitude and a third magnitude, and

the confirmation module confirms the frequency f e , if the first magnitude exceeds the first predetermined threshold, and the second and third magnitudes each exceeds a second predetermined threshold.

2. The apparatus of claim 1 wherein

the DFT module is configured to obtain the magnitude of the sum of N-sample points of data disposed in the block of data, according to the following equation:

X

⁡

(

k

)

=

∑

n

=

0

N

-

1

⁢

⁢

x

⁡

(

n

)

⁢

ⅇ

-

j

⁢

2

⁢

π

⁢

⁢

kn

N

where k=f e

n is an index for each digital sample, x(n) are input data points and

N is the number of digital samples in the block of data.

3. The apparatus of claim 2 wherein

the N-sample points includes 64-points of data.

4. The apparatus of claim 1 wherein

the first predetermined threshold is larger than the second predetermined threshold.

5. The apparatus of claim 1 wherein

the receiver is configured to estimate the frequency f e of the received signal in a duration of 4 times the duration of the N-sample points.

6. The apparatus of claim 5 wherein

the N-sample points includes 64-points of data, and

the receiver is configured to estimate the frequency f e in a duration of 256 sample points.

7. The apparatus of claim 5 wherein

N-sample points includes one block of data,

the receiver is configured to estimate the frequency f e in a duration of four blocks of data, the four blocks of data defined as a frequency calculation interval,

the DFT module is configured to sequence through sequential blocks of data and obtain the magnitude of each of the blocks of data, and

the first block of data in the sequence begins prior to the start of the frequency calculation interval.

8. The apparatus of claim 7 wherein

the first block of data in the sequence begins two blocks of data prior to the start of the frequency calculation interval.

9. The apparatus of claim 8 wherein

the received signal includes a pulse having a leading edge and a trailing edge, and

if the confirmation module confirms the frequency f e at the start of the frequency calculation interval, then the leading edge of the pulse is defined to be present during a block of data that is two blocks prior to the start of the frequency calculation interval.

10. The apparatus of claim 9 wherein

if the confirmation module does not confirm the frequency f e during one of the sequential blocks of data, after having confirmed the frequency f e prior to the one block of data, then the trailing edge of the pulse is defined to be present during the one block of data.

11. An instantaneous frequency measurement (IFM) receiver comprising:

a receiver module for determining a frequency f e of a received signal,

a discrete Fourier transform (DFT) module configured to sum values of digital samples of data in a block of data and provide a magnitude of the sum values, wherein the values of the digital samples of data are based on the frequency f e , and

a confirmation module for confirming the frequency f e , if the sum has a value greater than a predetermined threshold;

wherein the block of data is a first block of data, the magnitude is a first magnitude of data, and the predetermined threshold value is a first predetermined threshold value,

the DFT module is configured to sum the digital samples of data disposed in a second and a third block of data following the first block of data and provide, respectively, a second magnitude and a third magnitude, and

the confirmation module confirms the frequency f e , if the first magnitude exceeds the first predetermined threshold, and the second and third magnitudes each exceeds a second predetermined threshold.

12. The IFM receiver of claim 11 wherein

the DFT module is configured to obtain the sum of N-sample points of data disposed in the block of data, according to the following equation:

X

⁡

(

k

)

=

∑

n

=

0

N

-

1

⁢

⁢

x

⁡

(

n

)

⁢

ⅇ

-

j

⁢

2

⁢

π

⁢

⁢

kn

N

where k=f e ,

n is an index for each digital sample, x(n) are input data points and

N is the number of digital samples in the block of data.

13. The IFM receiver of claim 12 wherein

the DFT module is configured to sequence through sequential blocks of data and obtain the sum of N-sample points of data disposed in each of the sequential blocks of data.

14. The IFM receiver of claim 13 wherein

the received signal includes a pulse having a leading edge and a trailing edge, and

if the confirmation module confirms the frequency f e at one of the sequential blocks of data, then the leading edge of the pulse is defined to be present in a block of data that is prior to the one of the sequential blocks of data, and

if the confirmation module does not confirm the frequency f e during one of the sequential blocks of data, after having confirmed the frequency f e prior to the one block of data, then the trailing edge of the pulse is defined to be present during the one block of data.