TEST STATION FOR WIRELESS DEVICES AND METHODS FOR CALIBRATION THEREOF

• US 20130187674A1
• Filed: 12/06/2012
• Published: 07/25/2013
• Est. Priority Date: 12/06/2011
• Status: Active Grant

• Current Assignee: Ether Capital Corporation
• Original Assignee: EMSCAN Corporation
• Inventors: Rada, Patrick, Patton, Ruska
• Granted Patent: US 9,316,714 B2
• Time in Patent Office: Days
• US Class Current: 324/750.02
• CPC Class Codes: G01R 35/005 Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references G01R33/0035, G01R35/002 take precedence
• CPC Class Codes: H04B 17/11 for calibration
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements

Abstract

A test station for wireless devices and methods for calibration thereof. The test station includes a signal generator, a calibrator, a scanner having receiving and transmitting antennas, a signal analyzer, and a computer. Under the direction of the computer, the signal generator generates a calibration signal in accordance with a programmable calibration signal script. The calibrator may be used to emulate either a wireless device in transmit mode by transmitting the calibration signal to the scanner for analysis by the signal analyzer, or a wireless device in receive mode by receiving the calibration signal from the scanner for analysis by the signal analyzer. The behavior of the test station is calibrated by correlating signal parameters of the calibration signal as specified by the calibration signal script and as measured at the signal analyzer.

Claims

1. A method for calibrating a test station for testing a wireless device in transmit mode, the test station comprising a receiving antenna, a calibrator with a calibrator antenna, a signal generator, and a signal analyzer, the method comprising the steps of:

(a) providing a signal path comprising a conducted path from the signal generator to the calibrator antenna, a wireless path from the calibrator antenna to the receiving antenna, and a conducted path from the receiving antenna to the signal analyzer;

(b) providing a calibration signal script encoding for a calibration signal having a target transmit power level at the calibrator antenna;

(c) using the signal generator to generate the calibration signal through the signal path;

(d) using the signal analyzer to measure the power level of the calibration signal; and

(e) correlating the target transmit power level of the calibration signal to the measured power level of the calibration signal.

2. The method of claim 1 wherein the calibration signal script additionally specifies one or more of the following parameters of the calibration signal:

frequency;

modulation and data rate;

error vector magnitude;

spectral mask and flatness;

occupied bandwidth;

phase noise;

I-Q imbalance;

clock frequency offset;

center frequency leaking;

or timing.

3. A test station for testing a wireless device in transmit mode, the test station comprising:

(a) a signal generator for generating a conducted calibration signal;

(b) a calibrator comprising at least one calibrator antenna conductively connected to the signal generator for wirelessly transmitting the calibration signal;

(c) at least one receiving antenna for wirelessly receiving the calibration signal;

(d) a signal analyzer conductively connected to the receiving antenna for receiving and measuring the power level of the calibration signal;

(e) a computer comprising;

(i) a memory for storing a calibration signal file encoding for a target transmit power level of the calibration signal at the calibrator antenna, and a set of program instructions implementing the method of claim 1;

(ii) a processor operatively connected to the memory, the signal generator, and the signal analyzer, the processor configured for executing the set of program instructions.

4. The test station of claim 3 wherein the calibrator may be selectively positioned on or away from the wireless scanner.

5. The test station of claim 3 wherein the calibrator further comprises an enclosure for protecting the calibrator antenna.

6. The test station of claim 3 wherein the calibrator antenna is conductively connected to the signal generator via a calibrator signal path having:

(a) a port that may be selectively conductively connected to the signal analyzer;

(b) a calibrator antenna switch for selectively connecting the calibrator antenna to and disconnecting the port from the calibrator signal path, or disconnecting the calibrator antenna from and connecting the port to the calibrator signal path.

7. The test station of claim 6 wherein the calibrator antenna switch is operatively connected to the computer.

8. The test station of claim 3 wherein the receiving antenna is comprised in a near-field scanner.

9. The test station of claim 3 wherein the memory storing the calibration signal file is modifiable.

10. A method for calibrating a test station for testing a wireless device in receive mode, the test station comprising a transmitting antenna, a calibrator with a calibrator antenna, a signal generator, and a signal analyzer, the method comprising the steps of:

(a) providing a signal path comprising a conducted path from the generator to the scanner antenna, a wireless path from the scanner antenna to the calibrator antenna, and a conducted path from the calibrator antenna to the signal analyzer;

(b) providing a calibration signal script encoding for a calibration signal having a target receive power level and a corresponding target BER at the signal analyzer;

(c) using the signal generator to generate the calibration signal through the signal path;

(d) setting the power level of the calibration signal received at the signal analyzer to the target receive power level;

(e) measuring the BER of the calibration signal received at the signal analyzer;

(f) as necessary, varying the power level of the calibration signal generated by the signal generator to converge the measured BER to the target BER;

(g) correlating the target receive power level and the target BER to the power level of the calibration signal generated by the signal generator at which the measured BER converges to the target BER.

11. The method of claim 10 wherein the calibration signal script additionally specifies one or more of the following signal parameters of the calibration signal:

frequency;

modulation and data rate;

error vector magnitude;

spectral mask and flatness;

occupied bandwidth;

phase noise;

I-Q imbalance;

clock frequency offset;

center frequency leaking;

or timing.

12. A test station for testing a wireless device in receive mode, the test station comprising:

(a) a signal generator for generating a conducted calibration signal;

(b) at least one transmitting antenna conductively connected to the signal generator for wirelessly transmitting the calibration signal;

(c) a calibrator comprising at least one calibrator antenna for wirelessly receiving the calibration signal;

(d) a signal analyzer conductively connected to the calibrator antenna for receiving and measuring the power level of the calibration signal;

(e) a variably controllable generator amplifier or attenuator operatively connected to the signal generator for varying the amplitude of the calibration signal generated by the signal generator;

(f) a variably controllable analyzer amplifier or attenuator operatively connected to the signal analyzer for setting the amplitude of the calibration signal received by the signal analyzer;

(g) a bit error detector operatively connected to the signal analyzer for measuring the BER of the calibration signal received by the signal analyzer;

(h) a computer comprising;

(i) a memory for storing a calibration signal file encoding for a target receive power level and a corresponding target BER of the calibration signal at the signal analyzer, and a set of program instructions implementing the method of claim 10;

(ii) a processor operatively connected to the memory, the signal generator, the signal analyzer, the generator amplifier or attenuator, the analyzer amplifier or attenuator, and the bit error detector, the processor configured for executing the set of program instructions.

13. The test station of claim 12 wherein the calibrator may be selectively positioned on or away from the wireless scanner.

14. The test station of claim 12 wherein the calibrator further comprises an enclosure for protecting the calibrator antenna.

15. The test station of claim 12 wherein the memory storing the calibration signal file is modifiable.