Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Amplitude control
Reexamination Certificate
1998-08-18
2001-01-30
Ton, My-Trang Nu (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Amplitude control
Reexamination Certificate
active
06181188
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for stabilizing the level of transmission output.
The apparatus for stabilizing the level of transmission output is used, in radio communications, to reduce signal interference between channels and simplify receiver processes. The apparatus must be simple and low cost and must stabilize, in particular, a rise of an output signal when a power source is turned on or when burst communication starts.
2. Description of the Related Art
An apparatus for stabilizing transmission output according to a prior art employs integrating circuits to remove noise or the influence of modulation from a control signal that is used to feedback-control an output control unit, thereby stabilizing the level of an output signal transmitted from the output control unit.
The control signal of the prior art, however, becomes zero or nearly zero when a power source is turned on or when burst signal transmission starts. The control signal at zero or nearly zero is unable to stabilize the level of transmission output.
SUMMARY OF THE INVENTION
An object of the present invention is to stabilize a rise of a transmission output signal and subdue fluctuations in an input signal.
In order to accomplish the object, according to a first aspect of the present invention, there is provided an apparatus for stabilizing the level of an output signal by controlling an output control unit according to a control signal. The apparatus has a switching unit and a smoothing unit. The switching unit may be a switching circuit to switch initial value data and reference value data from one to another. The initial value data determines an initial value of the control signal when an input signal to the output control unit rises. The average value data is obtained from a moving average of the difference between reference value data and level data detected from the output signal of the output control unit after the input signal rises. The smoothing unit smoothes the difference between the initial value data and the average value data both provided through the switching unit, for a predetermined period and generates the control signal for the output control unit accordingly.
According to a second aspect of the present invention, the apparatus for stabilizing transmission output has a level detecting unit for detecting the level of the output signal of the output control unit and providing the level data; a difference detecting circuit for calculating a moving average of the difference between the level data and the reference value data or average value data and providing difference data; a differential value detecting circuit for detecting a variation in the difference data and providing differential data; and a switching circuit for switching the initial value data to the average value data when the differential data decreases to below a predetermined value. According to the second aspect, the smoothing unit smoothes the difference between the initial value data and the average value data both provided through the switching circuit, for the predetermined period and generates the control signal for the output control unit accordingly.
According to a third aspect of the present invention, the apparatus for stabilizing transmission output has an average value data holding circuit for holding the difference data as the average value data and a structure for providing the smoothing unit with the average value data after the differential value detecting circuit determines that a variation in the difference data has increased to above the predetermined value and then decreased to below the predetermined value.
According to a fourth aspect of the present invention, the apparatus for stabilizing transmission output has a structure for determining whether or not the average value data held in the average value data holding circuit and difference data that is provided by the difference detecting circuit after the predetermined period exceed a predetermined range, and if they exceed the predetermined range, setting the difference data as new average value data in the average value data holding circuit and providing the new average value data as current data to the smoothing unit.
According to a fifth aspect of the present invention, the smoothing unit has a multiplier for multiplying the difference between previous and current data provided through the switching circuit by function data that changes during the predetermined period; an adder for adding the product calculated by the multiplier to the previous data; and a switching unit for providing the output of the adder to generate the control signal for the output control unit for the predetermined period, and after the predetermined period, providing the current data to generate the control signal for the output control unit.
According to a sixth aspect of the present invention, the apparatus for stabilizing transmission output has a comparator for comparing the difference data from the difference detecting circuit with difference tolerance data, and if the difference data is above the difference tolerance data, controlling the switching unit to provide the initial value data to the smoothing unit.
REFERENCES:
patent: 5396652 (1995-03-01), Kunitomo
patent: 5566363 (1996-10-01), Haruyasu
patent: 5697074 (1997-12-01), Hannu et al.
patent: 5752171 (1998-05-01), Akiya
patent: 5768694 (1998-06-01), Kumagai
patent: 5854971 (1998-12-01), Nagoya et al.
patent: 5995811 (1999-11-01), Watanabe
patent: 681 375 (1995-11-01), None
patent: 786 859 (1997-07-01), None
Fujitsu Limited
Helfgott & Karas P.C.
Nu Ton My-Trang
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