System and a method for determining an image rejection characteristic of a receiver within a transceiver
A method for determining an image rejection characteristic of a receiver within a transceiver is provided. The transceiver uses a common local oscillator. The method includes generating a test signal having a spectral peak and generating a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak. Further, the method includes down-mixing the test signal in the receiver using the local oscillator signal to generate a down-mixed signal. The method further includes calculating a first value of a signal characteristic of the down-mixed signal in a first frequency range corresponding to a desired signal component of the down-mixed signal and calculating a second value of the signal characteristic of the down-mixed signal in a second frequency range corresponding to an undesired signal component of the down-mixed signal. Further, the method includes comparing the first value and the second value to generate the image rejection characteristic.
1. A method for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
generating a test signal having a spectral peak;
generating a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak;
down-mixing the test signal in the receiver using the local oscillator signal to generate a down-mixed signal;
calculating a first value of a signal characteristic of the down-mixed signal in a first frequency range corresponding to a desired signal component of the down-mixed signal;
calculating a second value of the signal characteristic of the down-mixed signal in a second frequency range corresponding to an undesired signal component of the down-mixed signal; and
comparing the first value and the second value to generate the image rejection characteristic.
2. The method of claim 1 , wherein a center frequency of the first frequency range has an offset from an intermediate frequency, and wherein the second frequency range is mirror-inverted to the first frequency range with respect to the intermediate frequency.
3. The method of claim 2 , wherein the intermediate frequency is zero.
4. The method of claim 1 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal.
5. The method of claim 4 , wherein the test signal comprises a plurality of equidistant spectral peaks.
6. The method of claim 1 , wherein the first value of the signal characteristic is related to an energy of the down-mixed signal in the first frequency range and the second value of the signal characteristic is related to an energy of the down-mixed signal in the second frequency range.
7. The method of claim 1 , wherein comparing the first value of the signal characteristic and the second value of the signal characteristic comprises calculating a ratio of the first value of the signal characteristic and the second value of the signal characteristic.
8. A method for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
generating a test signal having a spectral peak, a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak and a second local oscillator signal comprising a frequency being mirror-inverted to the local oscillator signal with respect to the center frequency of the spectral peak;
down-mixing the test signal in the receiver using the local oscillator signal to generate a down-mixed signal and down-mixing the test signal in the receiver using the second local oscillator signal to generate a second down-mixed signal;
calculating a value of a signal characteristic of the down-mixed signal and a value of the signal characteristic of the second down-mixed signal in a frequency range corresponding to a desired signal component of the down-mixed signal; and
comparing the value of the signal characteristic of the down-mixed signal and the value of the signal characteristic of the second down-mixed signal to generate the image rejection characteristic.
9. The method of claim 8 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal, and wherein the test signal does not have another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of second local oscillator signal.
10. The method of claim 9 , wherein the test signal comprises a plurality of equidistant spectral peaks.
11. The method of claim 8 , wherein the value of the signal characteristic of the down-mixed signal is related to an energy of the down-mixed signal in the frequency range and the value of the signal characteristic of the second down-mixed signal is related to an energy of the second down-mixed signal in the frequency range.
12. The method of claim 8 , wherein comparing the value of the signal characteristic of the down-mixed signal and the value of the signal characteristic of the second down-mixed signal comprises calculating a ratio of the value of the signal characteristic of the down-mixed signal and the value of the signal characteristic of the second down-mixed signal.
13. A system for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
a signal generator configured to generate a test signal having a spectral peak;
wherein the local oscillator is configured to generate a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak, wherein the receiver is configured to down-mix the test signal using the local oscillator signal to generate a down-mixed signal, and
an analysis unit configured to calculate a first value of a signal characteristic of the down-mixed signal in a first frequency range corresponding to a desired signal component of the down-mixed signal, to calculate a second value of the signal characteristic of the down-mixed signal in a second frequency range corresponding to an undesired signal component of the down-mixed signal, and to compare the first value and the second value to generate the image rejection characteristic.
14. The system of claim 13 , wherein a center frequency of the first frequency range has an offset from an intermediate frequency, and wherein the second frequency range is mirror-inverted to the first frequency range with respect to the intermediate frequency.
15. The system of claim 14 , wherein the intermediate frequency is zero.
16. The system of claim 13 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal.
17. The system of claim 16 , wherein the test signal comprises a plurality of equidistant spectral peaks.
18. The system of claim 13 , wherein the first value of the signal characteristic is related to an energy of the down-mixed signal in the first frequency range and the second value of the signal characteristic is related to an energy of the down-mixed signal in the second frequency range.
19. The system of claim 13 , wherein the analysis unit is configured to compare the first value of the signal characteristic and the second value of the signal characteristic by calculating a ratio of the first value of the signal characteristic and the second value of the signal characteristic.
20. The system of claim 13 , wherein the signal generator comprises a frequency multiplier configured to generate the test signal by multiplying a frequency of a reference signal used for the local oscillator.
21. A system for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
a signal generator configured to generate a test signal having a spectral peak;
wherein the local oscillator is configured to generate a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak and a second local oscillator signal comprising a frequency being mirror-inverted to the frequency of the local oscillator signal with respect to the center frequency of the spectral peak,
wherein the receiver is configured to down-mix the test signal using the local oscillator signal to generate a down-mixed signal and to down-mix the test signal using the second local oscillator signal to generate a second down-mixed signal, and
an analysis unit configured to calculate a value of a signal characteristic of the down-mixed signal and a value of the signal characteristic of the second down-mixed signal in a frequency range corresponding to a desired signal component of the down-mixed signal, and to compare the values of the signal characteristic of the down-mixed signal and the second down-mixed signal to generate the image rejection characteristic.
22. The system of claim 21 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal, and wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of second local oscillator signal.
23. The system of claim 22 , wherein the test signal comprises a plurality of equidistant spectral peaks.
24. The system of claim 21 , wherein the value of the signal characteristic of the down-mixed signal is related to an energy of the down-mixed signal in the frequency range and the value of the signal characteristic of the second down-mixed signal is related to an energy of the second down-mixed signal in the frequency range.
25. The system of claim 21 , wherein the signal generator comprises a frequency multiplier configured to generate the test signal by multiplying a frequency of a reference signal used for the local oscillator.