Method and system for noise reduction in measurement receivers using automatic noise subtraction

• US 7,266,358 B2
• Filed: 12/15/2003
• Issued: 09/04/2007
• Est. Priority Date: 12/15/2003
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Hillstrom, Timothy L.
• Primary Examiner(s): Le; Thanh Cong
• Application Number:
  US10/737,440
• Publication Number:
  US 20050129152A1
• Time in Patent Office: 1,359 Days
• Field of Search: None
• US Class Current: 455/296
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336

Abstract

An N-element noise model of a receiver is created, with the number of noise elements (N) determined by the equation N=(number of variable gain components+1). The components in the model are grouped into domains with each noise element associated with a domain. The domains are defined so that the noise contributions of the components within each domain are independent of the receiver gain state. A noise value is computed for each noise element. Each noise value is determined with reference to a particular point in the model, and is computed in a reference state. Input-referred noise values are calculated using each noise value and the current gain state data for the receiver. A composite input-referred noise value is computed using the input-referred noise values and subtracted from a measurement signal to reduce noise in the signal. The composite noise value can automatically be re-calculated for any receiver gain state.

Claims

1. A method for automatic subtraction of noise from a signal in a receiver, comprising:

determining a noise value for each of a plurality of noise elements in a noise model of the receiver, wherein a portion of the components in the noise model are grouped into a domain and each noise element is associated with a domain and the noise contributions for the components within each domain are independent of receiver gain state, and wherein each noise value is determined in a reference state and with reference to a particular point in the noise model;

calculating a composite input-referred noise value using the noise values and current gain state data for the receiver; and

subtracting the composite input-referred noise value from the signal in the receiver.

2. The method of claim 1, further comprising generating a noise model of a receiver, wherein the noise model includes the plurality of noise elements.

3. The method of claim 2, wherein the nuber (N) of noise elements in the plurality of noise elements is determined by the equation N=(a number of variable gain components in the receiver −

1.

4. The method of claim 2, wherein determining a noise value for each noise element comprises performing an offline self-claiberation test for receiver gain and noise.

5. The method of claim 4, wherein the self-calibration test comprises:

setting all variable gain components within the receiver to a maximum gain state;

measuring the noise;

setting a first variable gain component to a minimum gain state;

measuring the noise;

deriving a noise value for a noise element associated with the first variable gain component, wherein the noise value is derived in a reference state and with reference to a point in the receiver model; and

repeatedly setting another variable gain component to a minimum gain state and deriving a noise value for a noise element associated with the variable gain components are set to a minimum gain state.

6. The method of claim 1, wherein calculating a composite input-referred noise value comprises:

determining whether each noise value is derived with reference to an input of the receiver;

if a noise value is not derived with reference to the input of the receiver, re-calculating and referring the noise value to the input of the receiver using the current gain state data for the receiver to generate an input-referred noise value;

if a noise value is derived with reference to an input of the receiver, re-calculating the noise value using the current gain state data for the receiver to generate an input-referred noise value; and

adding together all of the input-referred noise values.

7. A method for automatic noise subtraction from a signal in a receiver, comprising:

dividing a noise model of the receiver into a plurality of noise elements;

grouping portions of the components in the noise model into domains, wherein each noise element is associated with a domain, and wherein the noise contributions of the components in each domain are independent of receiver gain state;

determining a noise value for each noise element in the plurality of noise elements, wherein each noise value is determined in a reference state and with reference to a particular point in the noise model;

calculating a composite input-referred noise value using the noise values and the current gain state data for the receiver; and

subtracting the composite input-referred noise value from the signal.

8. The method of claim 7, further comprising generating a noise model of the receiver.

9. The method of claim 7, wherein a number (N) of noise elements in the plurality of noise elements is determined by the equation N=(a number of variable gain components in the receiver+1).

10. The method of claim 7, wherein determining a noise value for each noise element comprises performing an offline self-calibration test for receiver gain and noise.

11. The method of claim 10, wherein the offline self-calibration test comprises:

setting all variable gain components within the receiver to a maximum gain state;

measuring the noise;

setting a first variable gain component to a minimum gain state;

measuring the noise;

deriving a noise value for a noise element associated with the first variable gain component, wherein the noise value is derived in a reference state and with reference to a point in the receiver model; and

repeatedly setting another variable gain component to a minimum gain state and deriving a noise value for a noise element associated with the variable gain component set to a minimum gain state until all of the variable gain components are set to a minimum gain state.

12. The method of claim 7, wherein calculating an input-referred noise value for each noise element comprises:

determining whether each noise value is derived with reference to an input of the receiver;

if a noise value is not derived with reference to the input of the receiver, re-calculating and referring the noise value to the input of the receiver using the current gain state data for the receiver to generate an input-referred noise value;

if a noise value is derived with reference to an input of the receiver, re-calculating the noise value using the current gain state data for the receiver to generate an input-referred noise value; and

adding together all of the input-referred noise values.

13. An apparatus for automatic subtraction of noise from a signal in a receiver, comprising:

means for determining a noise value for each of a plurality of noise elements in a noise model of the receiver, wherein a portion of the components in the noise model are grouped into a domain and each noise element is associated with a domain and the noise contributions for the components within each domain are independent of receiver gain state, and wherein each noise value is determined in a reference state and with reference to a particular point in the noise model;

means for calculating a composite input-referred noise value using the noise values and current gain state data for the receiver; and

means for subtracting the composite input-referred noise value from the signal in the receiver.

14. The apparatus of claim 13, wherein a number (N) of noise elements in the plurality of noise elements is determined by the equation N=(a number of variable gain components in the receiver+1).

15. The apparatus of claim 13, wherein the means for determining a noise value for each noise element comprises:

means for setting all variable gain components within the receiver to a maximum gain state;

means for measuring the noise;

means for setting a first variable gain component to a minimum gain state;

means for measuring the noise;

means for deriving a noise value for a noise element associated with the first variable gain component, wherein the noise value is derived in a reference state and with reference to a point in the receiver model; and

means for repeatedly setting another variable gain component to a minimum gain state and deriving a noise value for a noise element associated with the variable gain component set to a minimum gain state until all of the variable gain components are set to a minimum gain state.

16. The apparatus of claim 13, wherein the means for calculating an input-referred noise value for each noise element comprises:

means for determining whether each noise value is derived with reference to an input of the receiver;

if a noise value is not derived with reference to the input of the receiver, means for re-calculating and referring the noise value to the input of the receiver using the current gain state data for the receiver to generate an input-referred noise value;

if a noise value is derived with reference to an input of the receiver, means for re-calculating the noise value using the current gain state data for the receiver to generate an input-referred noise value; and

means for adding together all of the input-referred noise values.