Tuning a station

• US 7,403,747 B2
• Filed: 06/27/2002
• Issued: 07/22/2008
• Est. Priority Date: 06/27/2001
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Savolainen, Jorma, Salmi, Ville, Kuiri, Tapio
• Primary Examiner(s): Phu; Sanh D.
• Application Number:
  US10/183,720
• Publication Number:
  US 20030053561A1
• Time in Patent Office: 2,217 Days
• Field of Search: 455/77, 455/161.1, 455/161.2, 455/161.3, 455/166.1, 455/166.2, 455/182.3, 455/185.1, 455/186.1, 455/126, 455/115.1, 455/115.2, 455/182.1, 375/130, 375/141
• US Class Current: 455/77
• CPC Class Codes: H03C 3/406 using a feedback loop containing mixers or demodulators
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control
• CPC Class Codes: H04L 2027/0016 Stabilisation of local oscillators
• CPC Class Codes: H04L 27/364 Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels

Abstract

A method of tuning a station is disclosed, wherein a first pilot signal is applied on a circuit of the station and the resulting output power of the signal circuit is subsequently detected. A second pilot signal is then applied to the circuit and the resulting output power of the circuit is detected. The offset of the circuit is then tuned based on information of the resulting output power detected for the first and second signals. A station that is adapted to implement the method may be tuned by the manufacturer thereof or later after having already been taken into use. The tuning may occur automatically as response to a predefined event.

Claims

1. A DC offset compensation circuit configured to output a first test signal to one of an in-phase (I) branch or a quadrature phase (Q) branch of a modulator circuit and to output a second test signal to the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, the second test signal being of opposite polarity to the first test signal, said DC offset compensation circuit further configured to respond to values of first and second power measurements made at an output of the modulator circuit, said first and second power measurements corresponding to said first and second test signals, respectively, and to modify a DC offset signal of the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, where the DC offset signal is modified to have a value determined to minimize a difference between said values of said first and second power measurements.

2. The DC offset compensation circuit of claim 1, wherein the first and second power measurements are obtained at an output of an amplifier having an input coupled to an output of said modulator circuit.

3. The DC offset compensation circuit of claim 1, further configured to output a third test signal to the other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit and to output a fourth test signal to the same other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, the fourth test signal being of opposite polarity to the third test signal, said DC offset compensation circuit further configured to respond to values of third and fourth power measurements made at an output of the modulator circuit, said third and fourth power measurements corresponding to said third and fourth test signals, respectively, and to modify a second DC offset signal of the same other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, where the second DC offset signal is modified to have a value determined to minimize a difference between said values of said third and fourth power measurements.

4. The DC offset compensation circuit of claim 1, further configured to apply the DC offset signal to the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit.

5. The DC offset compensation circuit of claim 1, embodied in a digital signal processor.

6. The DC offset compensation circuit of claim 1, embodied in a mobile communication device configured to communicate with a wireless communication system.

7. The DC offset compensation circuit of claim 1, wherein the DC offset compensation circuit is configured to modify the DC offset value in response to an event.

8. The DC offset compensation circuit of claim 7, wherein the event comprises at least one of:

expiry of a predefined time period;

a change in an operational status;

a change in an operational environment;

receiving a message; and

an action taken by a user.

25. An apparatus comprising a DC offset compensation circuit according to claim 1.

9. A method comprising:

outputting a first test signal to one of an in-phase (I) branch or a quadrature phase (Q) branch of a modulator circuit;

outputting a second test signal to the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, the second test signal being of opposite polarity to the first test signal;

responding to values of first and second power measurements made at an output of the modulator circuit, said first and second power measurements corresponding to said first and second test signals, respectively; and

modifying a DC offset signal of the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, where the DC offset signal is modified to have a value determined to minimize a difference between said values of said first and second power measurements.

10. The method of claim 9, comprising obtaining said first and second power measurements at an output of an amplifier having an input coupled to an output of said modulator circuit.

11. The method of claim 9, further comprising:

outputting a third test signal to the other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit;

outputting a fourth test signal to the same other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, the fourth test signal being of opposite polarity to the third test signal;

responding to third and fourth power measurements made at an output of the modulator circuit, said third and fourth power measurements corresponding to said third and fourth test signals, respectively; and

modifying a second DC offset signal of the same other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, where the second DC offset signal is modified to have a value determined to minimize a difference between said values of said third and fourth power measurements.

12. The method of claim 11, further comprising:

applying the DC offset signal to the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit.

13. The method of claim 9, as carried out in a digital signal processor.

14. The method of claim 9, as carried out in a mobile communication device configured to communicate with a wireless communication system.

15. The method of claim 9, comprising modifying the DC offset value in response to an event.

16. The method of claim 15, wherein the event comprises at least one of:

expiry of a predefined time period;

a change in an operational status;

a change in an operational environment;

receiving a message; and

an action taken by a user.

17. A DC offset compensation circuit comprising:

means for outputting a first test signal to one of an in-phase (I) branch or a quadrature phase (Q) branch of a modulator circuit;

means for outputting a second test signal to the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, the second test signal being of opposite polarity to the first test signal;

means for responding to first and second power measurements made at an output of the modulator circuit, said first and second power measurements corresponding to said first and second test signals, respectively; and

means for modifying a DC offset signal of the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, where the DC offset signal is modified to have a value determined to minimize a difference between said values of said first and second power measurements.

18. The DC offset compensation circuit of claim 17, wherein the first and second power measurements are obtained at an output of an amplifier having an input coupled to an output of said modulator circuit.

19. The DC offset compensation circuit of claim 17, comprising:

means for outputting a third test signal to the other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit;

means for outputting a fourth test signal to the same other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, the fourth test signal being of opposite polarity to the third test signal;

means for responding to third and fourth power measurements made at an output of the modulator circuit, said third and fourth power measurements corresponding to said third and fourth test signals, respectively; and

means for modifying a second DC offset signal of the same other of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit, where the second DC offset signal is modified to have a value determined to minimize a difference between said values of said third and fourth power measurements.

20. The DC offset compensation circuit of claim 19, further comprising:

means for applying the DC offset signal to the same one of the in-phase (I) branch or the quadrature phase (Q) branch of the modulator circuit.

21. The DC offset compensation circuit of claim 17, as embodied in a digital signal processor.

22. The DC offset compensation circuit of claim 17, as embodied in a mobile communication device configured to communicate with a wireless communication system.

23. The DC offset compensation circuit of claim 17, comprising means for modifying the DC offset value in response to an event.

24. The DC offset compensation circuit of claim 23, wherein the event comprises at least one of:

expiry of a predefined time period;

a change in an operational status;

a change in an operational environment;

receiving a message; and

an action taken by a user.

26. An apparatus comprising a DC offset compensation circuit according to claim 17.