Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-02-09
2001-01-16
Eisenzopf, Reinhard J. (Department: 2745)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S575100
Reexamination Certificate
active
06175748
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to improvements in wireless communications. More particularly, the present invention relates to methods and apparatus for determination of a power level in an RF booster for wireless communications.
BACKGROUND OF THE INVENTION
Cellular telephone systems are widely used in a variety of applications and locations, including for communication from automobiles. In order to provide the greatest possible portability, the handset, or Personal Station, of a cellular telephone system is typically self-contained, receiving power from its own internal battery. The power provided by the battery is limited, particularly due to the need for a small battery in order to reduce the size and weight of the Personal Station.
In order to increase the operational power of the Personal Station, many users install booster stations in their automobiles. A further advantage of such an installation is that it takes advantage of the electrical power produced by the automobile. This increased power can greatly extend the range of the Personal Station.
According to the standards governing cellular equipment, all Personal Stations are classified according to the level of RF power they transmit. The goal of the booster's design is to convert the Personal Station (usually a Class II unit) into a higher class (usually a Class I) combination. At the same time, according to the same standards, each class of Personal Stations is divided into a number of power levels. To meet the standards requirements, the booster has to provide a required value of output power for each power level.
In order to keep an RF signal at a predetermined level, the value of the output RF is typically converted to a DC voltage. This voltage is applied to a first input of an operational amplifier. The second input of the operational amplifier is kept at a constant reference level voltage. Under these conditions, the signal from the output of the operational amplifier is controlled as necessary. In order for this system to operate, the power level of the input signal supplied to the first input of the operational amplifier must be supplied or predetermined. The reference level at the second input of the operational amplifier is chosen to correspond to that power level.
If the level of the RF input signal changes, the operational amplifier reference level should change accordingly. Thus, each of the RF output power levels should have a specific corresponding DC value to be used as an operational amplifier reference level.
In RF boosters of the prior art, the operational amplifier reference level is set by the Personal Station. This has the advantage of simplicity of implementation, as the level information is readily available from the Personal Station. However, setting the reference level at the Personal Station makes the booster dependent on a specific telephone model. It is difficult to adapt the booster to other types of telephones. Moreover, setting the reference level at the Personal Station provides the values of the “desired” signal. There is no provision to make sure that the RF signal transmitted by the Personal Station actually reaches the input of the booster.
There exists, therefore, a need in the art for a booster in which the reference level is easily adaptable to different types of telephones, and which provides that the signal transmitted by the Personal Station reaches the input of the booster.
SUMMARY OF THE INVENTION
In one aspect, the invention may suitably comprise a booster which sets a DC reference level of an operational amplifier according to a power level of an RF signal received from a mobile station. The booster includes a level determination device receiving as an input a signal derived from the RF signal produced by a mobile station. The level determination device produces a DC voltage which is supplied to the reference input of an operational amplifier. The operational amplifier also has a variable input which is received from the output RF signal of a mobile station. The output of the operational amplifier is supplied as an input of a variable attenuator, which supplies its output to an RF power amplifier.
The level determination device may suitably include a step voltage circuit receiving an input corresponding to the input RF signal of the mobile station. The step voltage circuit produces a plurality of outputs, with the input determining how many outputs are set at a step voltage and how many outputs are set at a zero voltage. The output of the step voltage circuit is supplied to a resulting voltage circuit which sums the voltages to determine an output level.
A more complete understanding of the present invention, as well as further features and advantages of the invention, will be apparent from the following Detailed Description and the accompanying drawings.
REFERENCES:
patent: 5146614 (1992-09-01), Furuno
patent: 5471654 (1995-11-01), Okazaki et al.
patent: 5493707 (1996-02-01), Kamitani
patent: 5507016 (1996-04-01), Okuhara
patent: 5585786 (1996-12-01), Clark et al.
patent: 5659893 (1997-08-01), Enoki et al.
patent: 5901346 (1999-05-01), Stengel et al.
Aboukhalil Joseph C.
Aleiner Boris
Bark Boris A.
Eisenzopf Reinhard J.
Law Offices of Peter H. Priest, PLLC
Lucent Technologies - Inc.
Mehrpour Naghmeh
LandOfFree
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