System and method for power control of an over-the-air RF environment emulator

• US 10,542,498 B2
• Filed: 04/11/2018
• Issued: 01/21/2020
• Est. Priority Date: 05/01/2017
• Status: Active Grant

• Current Assignee: Ets-Lindgren Incorporated (ESCO Technologies, Inc.)
• Original Assignee: Ets-Lindgren Incorporated (ESCO Technologies, Inc.)
• Inventors: Foegelle, Michael David
• Primary Examiner(s): Ahn, Sung S
• Application Number:
  US15/950,256
• Publication Number:
  US 20180317179A1
• Time in Patent Office: 650 Days
• CPC Class Codes: H04B 17/13 of power amplifiers, e.g. gain or non-linearity
• CPC Class Codes: H04B 17/29 Performance testing
• CPC Class Codes: H04B 17/3912 Simulation models, e.g. distribution of spectral power density or received signal strength indicator [RSSI] for a given geographic region
• CPC Class Codes: H04W 52/04 TPC

Abstract

Methods, tests systems and computers for controlling power delivered to a test volume are provided. According to one aspect, an electromagnetic test system has at least one operational path having a channel emulator output, an amplifier, an attenuator and an antenna. A method includes, for a given desired output power level, C, setting a channel emulator output power to a power level B, and setting the attenuator to a setting A, such that C is a function of B and A. In such embodiments, the attenuation A is calculated based on an upper limit output power of the channel emulator and the desired output power C.

Claims

1. A method of controlling power in an electromagnetic test system, the electromagnetic test system having at least one operational path having a channel emulator output, at least one of an amplifier/attenuator combination and a variable gain amplifier, VGA, and an antenna, the method comprising:

for a given desired output power level, C, setting a channel emulator output power to a power level B, and setting one of the attenuator and the VGA to achieve an attenuation setting A, such that C is a function of B and A;

the attenuation setting A being calculated based on an upper limit output power of the channel emulator and the desired output power level C.

2. The method of claim 1, wherein C is offset from B minus A by a constant that includes an insertion loss of the attenuator.

3. The method of claim 1, wherein a sequence in which the setting of the channel emulator output power level B and the setting of the attenuation setting A are made depends upon whether the desired output power level C is less than a current output power level.

4. The method of claim 1, wherein the amplifier output is one of disabled and reduced during a setting of the attenuation setting A and channel emulator output power B.

5. The method of claim 1, wherein a setting of the attenuation setting A is calculated to reduce a range over which the channel emulator output power, B, is adjusted to achieve the desired output power level.

6. The method of claim 1, wherein at least one of the channel emulator output power B and attenuation setting A are further adjusted to compensate for an insertion loss of the attenuator.

7. The method of claim 1, wherein at least one of the channel emulator output power B and attenuation setting A is further adjusted to compensate for a residual error arising from the determination of the attenuation setting A.

8. The method of claim 1, wherein the attenuation setting A is based on a difference between a maximum output power of the channel emulator output, P_Max, and the target power level, C.

9. A method of controlling power in an electromagnetic test system, the electromagnetic test system having at least one operational path having a channel emulator output, one of an amplifier/attenuator combination and a variable gain amplifier, VGA, and an antenna, the method comprising:

determining a target power level, C, to be delivered by an antenna to a test volume;

determining an attenuation value A based on the target power level, C; and

when the determined attenuation value A differs from a previously set attenuation value, then;

if C is less than a current power level output by the antenna, adjust the channel emulator output power to B and then set one of the attenuator and the VGA to achieve an attenuation value A, where B is a function of C plus A; and

if C is greater than the current power level, set the attenuation value A and then adjust the channel emulator output power to B, where B is a function of C plus A.

10. The method of claim 9, wherein C is offset from B minus A by a constant that includes the insertion loss of the attenuator.

11. The method of claim 9, wherein the amplifier is one of disabled and reduced during a setting of the attenuation value A and channel emulator output power B.

12. The method of claim 9, wherein a setting of the attenuation value A is calculated to reduce a range over which the channel emulator output power B is adjusted to achieve the desired output power level.

13. The method of claim 9, wherein at least one of B and A are further adjusted to compensate for insertion loss of the attenuator.

14. The method of claim 9, wherein at least one of the channel emulator output power B and attenuation setting A is further adjusted to compensate for a residual error arising from the determination of the attenuation setting A.

15. The method of claim 9, wherein the attenuation value A is based on a difference between an upper limit output power of the channel emulator output, P_max, and the target power level, C.

16. The method of claim 9, further comprising one of disabling and reducing the amplifier prior to setting the attenuation value A and re-enabling the amplifier after setting the attenuation value A.

17. The method of claim 9, wherein, when the determined attenuation value A equals a previously set attenuation value, adjust the channel emulator output power to B, where B is a function of C plus A.

18. An electromagnetic test system having at least one operational path having a channel emulator output, one of an amplifier/attenuator combination and a variable gain amplifier, VGA, and an antenna, comprising:

a controller configured to;

control an output power C of an operational path of the electromagnetic test system by setting one of the attenuator and the VGA to achieve an attenuation value A; and

setting the channel emulator output to a value B, such that A is a function of a predetermined upper output power limit of the channel emulator and the target power level C, and B is a function of the sum of C and A.

19. The electromagnetic test system of claim 18, further comprising a switch to switch the attenuator out of the circuit during adjustment.

20. The electromagnetic test system of claim 18, wherein the attenuator is a step attenuator with fixed steps.

21. A test automation computer for controlling power and attenuation in an electromagnetic test system, comprising:

a memory configured to store a target output power C, an attenuation A, and a channel emulator output power B; and

a processor in communication with the memory and configured to;

control an output power C of an operational path of the electromagnetic test system by setting one of an attenuator and a variable gain amplifier, VGA, to achieve an attenuation value A and setting a channel emulator output to a value B, such that A is a function of a predetermined upper output power limit of the channel emulator and the target power level C, and B is a function of the sum of C and A.