Method and system for noise reduction in measurement receivers using automatic noise subtraction
View Patent ↗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.
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.