System and method for discovering frequency related spurs in a multi-conversion tuner

1. A method for assisting in the determination of non-interfering local oscillator (LO) frequencies (f 1 , and f 2 ) in a dual conversion tuner system, said method comprising:

determining band edges A, B, C, and D of a system output band and its image using the formulae

A=−f OUT −f BW /2

B=−f OUT +f BW /2

C=f OUT −f BW /2

D=f OUT +f BW /2,

 where f OUT is the system output pass band center frequency and f BW is the bandwidth of the system output pass band;

for a selected harmonic of f 1 , calculating a smallest harmonic of f 2 greater than band edge A, m A , and a smallest harmonic of f 2 greater than band edge D, m D , using the formulae

m A =└( n×f 1 −A )÷ f 2 ┘

m D =└( n×f 1 −D )÷ f 2 ┘,

 where n is the selected harmonic of f 1 ; and

determining if m A =m D .

2. The method of claim 1 , further comprising:

if m A ≠m D , calculating m B using the formula

m B =└( n×f 1 −B )÷ f 2 ┘; and

determining if m A ≠m B .

3. The method of claim 2 , further comprising:

if m A ≠m B , concluding that frequencies f 1 and f 2 result in an interfering spur.

4. The method of claim 2 , further comprising:

if m A =m B , calculating m C using the formula

m C =└( n×f 1 −C )÷ f 2 ┘; and

determining if m C ≠m D .

5. The method of claim 4 , further comprising:

if m C ≠m D , concluding that frequencies f 1 and f 2 result in an interfering spur.

6. The method of claim 4 , further comprising:

if m C =m D , determining if M D ≧n MAX , where n MAX is a maximum harmonic to be considered; and

if M D ≧n MAX , concluding for the selected harmonic of f 1 that frequencies f 1 and f 2 do not result in an interfering spur.

7. The method of claim 6 , further comprising:

if m D <n MAX , selecting a next harmonic of f 1 and repeating, for said next selected harmonic of f 1 , said calculating a smallest harmonic of f 2 greater than band edge A, m A , and a smallest harmonic of f 2 greater than band edge D, m D , and determining if m A =m D .

8. The method of claim 1 , further comprising:

calculating a first f 1 harmonic (n O ) using the formula

n

O

=

⌈

f

2

+

A

f

1

-

f

2

⌉

,

where n 0 is a limit on the harmonics of f 1 considered according to the method.

9. A system for assisting in the determination of non-interfering local oscillator (LO) frequencies (f 1 and f 2 ) in a dual conversion tuner system, said system comprising:

means for determining band edges A, B, C, and D of a system output band and its image using the formulae

A=−f OUT −f BW /2

B=−f OUT +f BW /2

C=f OUT −f BW /2

D=f OUT +f BW /2,

 where f OUT is the system output pass band center frequency and f BW is the bandwidth of the system output pass band;

means for calculating, for a selected harmonic of f 1 , a smallest harmonic of f 2 greater than band edge A, m A , and a smallest harmonic of f 2 greater than band edge D, m D , using the formulae

m A =└( n×f 1 −A )÷ f 2 ┘

m D =└( n×f 1 −D )÷ f 2 ┘

 where n is the selected harmonic of f 1 ; and

means for determining if m A =m D .

10. The system of claim 9 , further comprising:

means for calculating, if m A ≠m D , m B using the formula

m B =└( n×f 1 −B )÷ f 2 ┘; and

means for determining if m A ≠m B .

11. The system of claim 10 , further comprising:

means for concluding if, m A ≠m B , that frequencies f 1 and f 2 result in an interfering spur.

12. The system of claim 10 , further comprising:

means for calculating, if m A =m B , m C using the formula

m C =└( n×f 1 −C )÷ f 2 ┘; and

means for determining if m C ≠m D .

13. The system of claim 12 , further comprising:

means for concluding if, m C ≠m D , that frequencies f 1 and f 2 result in an interfering spur.

14. The system of claim 12 , further comprising:

means for determining, if m C =m D , if m D ≧n MAX , where n MAX is a maximum harmonic to be considered; and

means for concluding, if m D ≧n MAX , for the selected harmonic of f 1 that frequencies f 1 and f 2 do not result in an interfering spur.

15. The system of claim 14 , further comprising:

means for selecting, if m D <n MAX , a next harmonic of f 1 and repeating, for said next selected harmonic of f 1 , said calculating a smallest harmonic of f 2 greater than band edge A, m A , and a smallest harmonic of f 2 greater than band edge D, m D , and determining if m A =m D .

16. The system of claim 9 , further comprising:

means for calculating a first f 1 harmonic (n O ) using the formula

n

O

=

⌈

f

2

+

A

f

1

-

f

2

⌉

,

where n 0 is a limit on the harmonics of f 1 considered.

17. A method for assisting in the determination of non-interfering local oscillator (LO) frequencies (f 1 and f 2 ) in a dual conversion tuner system, said method comprising:

determining band edges A, B, C, and D of a system output band and its image, wherein band edge A comprises a lowest frequency band edge of band edges A, B, C, and D and band edge D comprises a highest frequency band edge of band edges A, B, C, and D;

for a selected harmonic of f 1 , calculating a smallest harmonic of f 2 greater than band edge A, m A , and a smallest harmonic of f 2 greater than band edge D, m D ; and

determining if m A =m D .

18. The method of claim 17 , wherein said determining band edges A, B, C, and D uses the formulae

A=−f OUT −f BW /2

B=−f OUT +f BW /2

C=f OUT −f BW /2

D=f OUT +f BW /2,

 where f OUT is the system output pass band center frequency and f BW is the bandwidth of the system output pass band.

19. The method of claim 17 , wherein said calculating said smallest harmonic of f 2 greater than band edge A, m A , and said smallest harmonic of f 2 greater than band edge D, m D , uses the formulae

m A =└( n×f 1 −A )÷ f 2 ┘

m D =└( n×f 1 −D )÷ f 2 ┘,

where n is the selected harmonic of f 1 .

20. The method of claim 19 , further comprising:

if m A ≠m D , calculating m B using the formula

m B =└( n×f 1 −B )÷ f 2 ┘;

determining if m A ≠m B ; and

if m A ≠m B , concluding that frequencies f 1 and f 2 result in an interfering spur.