METHOD FOR IMPLEMENTING CONTINUOUS RADIO FREQUENCY (RF) ALIGNMENT IN ADVANCED ELECTRONIC WARFARE (EW) SIGNAL STIMULATION SYSTEMS

• US 20100194376A1
• Filed: 02/04/2010
• Published: 08/05/2010
• Est. Priority Date: 12/18/2006
• Status: Active Grant

• Current Assignee: AAI Corporation (Textron Inc)
• Original Assignee: AAI Corporation (Textron Inc)
• Inventors: Jaklitsch, James, Markey, Jay, McGrath, Thomas P.
• Granted Patent: US 8,406,718 B2
• Time in Patent Office: Days
• US Class Current: 324/76.12
• CPC Class Codes: G01R 31/2841 Signal generators
• 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

Abstract

A method for characterizing the effect of each step attenuator state, on phase and amplitude, which may include in an exemplary embodiment: activating each step attenuator state as the sole contributor to attenuation, and measuring at least one of a step attenuator amplitude contribution (SAAC) and/or a step attenuator phase contribution (SAPC).

Claims

1. A method for characterizing the effect of each step attenuator state, on phase and amplitude, comprising

activating each step attenuator state as the sole contributor to attenuation, and

measuring at least one of a step attenuator amplitude contribution (SAAC) and/or a step attenuator phase contribution (SAPC).

2. A method for mapping an arbitrary RF Power command into hardware control signals used to produce a commanded RF Power at a Port output for each frequency, the method comprising:

a. providing a level shift that maps an absolute Power Command, in units of dBm, to a relative power command, in units of dBfs;

b. providing a step attenuation state parser that computes the appropriate state for the step attenuator, and subtracts a step attenuator amplitude contribution from said relative power command, to compute an AM DAC attenuation;

c. providing a super-attenuation function that adjusts said AM DAC attenuation command to produce desired attenuation, adding any additional attenuation as required to compensate for non-linear effects of compression, wherein said super-attenuation function is implemented as a stored data table, in octave increments of dB, for each applicable range of step attenuation, with an exact value determined by means of quadratic interpolation at run time;

d. providing a theoretical conversion of said AM DAC attenuation command to hardware bits; and

e. providing a frequency-dependent offset for power leveling.

3. The method of claim 2, wherein said providing said super-attenuation function in said octave increments of dB comprises:

providing said super-attenuation function in said octave increments of dB comprising at least one of 0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, and/or 16.0.

4. A method for mapping an arbitrary RF Phase Command into hardware phase-shift control signals, as required to produce a commanded RF Phase at the Port output for each frequency, the method comprising:

a. computing an aggregate Phase Compensation value from at least one of;

i. a base-state phase error, measured at each sub-band of a synthetic stimulus instrument (SSI),

ii. a filter induced phase contribution (FIPC) measured at closely spaced frequency increments across each sub-band, stored in data tables, and interpolated at run-time using quadratic interpolation,

iii. a step attenuator phase contribution (SAPC), measured at each sub-band of the SSI, and/or

iv. a saturation-induced phase contribution (SIPC), characterizing a non-linear phase shift associated with amplifier compression, wherein SIPC compensation is implemented as a stored data table, in octave increments of dB, for each applicable range of step attenuation, with the exact value determined by means of quadratic interpolation at run time; and

b. subtracting said Phase Compensation value from the RF Phase Command.

5. The method of claim 4, wherein said (a) (ii) comprises closely spaced frequency increments comprising about 200 KHz.

6. The method of claim 4, wherein said (a) (iv) comprises octave increments of dB comprising at least one of 0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, and/or 16.0.

7. A method of using a state-estimation filter comprising:

using a state-estimation filter for computing true values for a step attenuator amplitude contribution (SAAC) and a step attenuator phase contribution (SAPC), in presence of measurement noise.

8. The method of claim 7, wherein said step attenuator amplitude contribution (SAAC) and said step attenuator phase contribution (SAPC) are computed as differentials from a full-power reference measurement comprising amplitude and phase.