Data processing: measuring – calibrating – or testing – Measurement system – Dimensional determination
Reexamination Certificate
2002-02-26
2004-09-28
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Dimensional determination
C342S061000, C342S192000, C342S204000, C345S158000, C345S163000
Reexamination Certificate
active
06799141
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to emission and reception of signals and to obtaining information regarding the signal path by obtaining information regarding the emitted and/or the received signals.
More particularly the present invention relates to a method for determining channel gain, wherein the received signal is transformed by means of a linear transform. The present invention further relates to a number of applications of the method, such as position determination of an emitter or of a reflective or refractive object, a pointing device for a computer, a door opening device, a remote control for e.g. an audio system, and reduction of “cross talk” in electrical components.
BACKGROUND
It is known to use wavelet transforms for transforming emitted and/or received signals. U.S. Pat. No. 5,384,725 (Coifman et al.) discloses a method and apparatus for encoding and decoding using wavelet-packets. This reference is concerned about the process of encoding/decoding a video or audio signal as such in order to compress/decompress the information contained in the signal. In particular this reference is concerned about finding the best basis for the wavelet transform to be used. The wavelet transform is used to transform an unknown signal.
Pointing devices for computers, such as the conventional “computer mouse” or so-called “touch screens” are known. However, the known devices require the hand of the user to be in a particular area in order to operate the device. This area is normally positioned in such a way that the user's arm is put in a more or less awkward position, and the continuous use of such devices frequently results in overstrain of the muscles and/or other parts of the user. Furthermore, conventional pointing devices are normally confined to being moved in only two dimensions. Three dimensional movements of the pointer on the computer screen may be performed by means of such pointing devices. However, this is very difficult since it is not natural to perform three dimensional movements by moving a device in only two dimensions. So-called “touch screens” require the user to actually touch the computer screen, thereby applying grease and/or other kinds of unwanted dirt to the screen.
It is desirable to be able to use a chosen linear transform to generate a particular signal, and to use the transform to obtain information relating to elements of the signal path. It is thus an object of the present invention to provide a method for obtaining such information when emitting and receiving signals. It is a further object of the present invention to provide an improved method of determining channel gain between one or more emitter(s) and one or more receiver(s), the method being fast as wells robust. It is an even further object of the invention to provide a method of determining channel gain between one or more emitter(s) and one or more receiver(s), wherein the battery power required is reduced as compared to known systems the received signal still being resolvable, even if it is very noisy. It is an even further object of the invention to provide a method for determining the position of an object placed in the signal path. It is an even further object of the present invention to provide a pointing device for a computer, the pointing device overcoming the above mentioned problems, in particular providing a more natural way of performing three dimensional movements on the computer screen. It is an even further object of the present invention to provide a method for eliminating or at least to a certain extend reducing the unintentional occurrence of a signal in one conductor of electronic equipment, the signal being intentionally present in another conductor of the equipment (so-called “cross talk”).
SUMMARY
Thus, according to the present invention is provided a method for determining the channel gain(s) between one or more emitter(s) and one or more receiver(s), the method comprising the steps of
emitting a first output signal by means of a first emitter, the first output signal being deterministic and containing an interval of frequencies,
receiving a first input signal by means of a first receiver,
determining a transformed first input signal by transforming said first input signal by means of a predetermined linear transform,
determining a first channel gain by means of comparison of said transformed first input signal and a predetermined original first signal being equal to said first output signal being emitted and received noiselessly with a known channel gain and being transformed by means of said linear transform.
The first output signal is deterministic, i.e. it is not a completely random signal (such as “white noise”). It may, however, be a pseudo-random signal Preferably, the first output signal is a generated signal sequence which is generated before the emission step. The same sequence may be used every time the method is performed. The first output signal contains an interval of frequencies as opposed to a signal containing only a single frequency or a finite number of frequencies, such as a signal of the kind being emitted from conventional door openers, e.g. such as the ones known from super markets etc.
The linear transform is predetermined, i.e. it is chosen before the step of determining a transformed first input signal. The transform may be chosen initially, such as once and for all, so that the same transform is always used. Alternatively or additionally, a transform may be chosen each time the method is performed, i.e. the transform may be chosen dynamically based on the conditions of the current emission/reception of signals.
The comparison of the transformed first input signal and the original first signal may be a simple comparison of the signals, such as overlaying the signals and visually comparing them, or spectral subtraction of one signal from the other. It may alternatively or additionally be obtaining the inner product between the two signals.
The original first signal is equal to the first output signal being emitted and received noiselessly with a known channel gain and being transformed by means of the linear transform. The original first signal is thus preferably a synthetic signal which has been generated. This generated signal is then transformed by the inverse transform of the predetermined linear transform, emitted by the emitter (at this point it has “become” the first output signal), and received by the receiver (at this point it has “become” the first input signal). Thereby the comparison gives a measure of the noise which has been applied to the original signal from the emission (e.g. electrical noise in electrical components of the emitter), the transmission (e.g. reflection and/or refraction and/or absorption of at least part of the signal when travelling through a gas (e.g. atmospheric air or any other suitable gas) or when hitting one or more refractive and/or reflective and/or partially absorbing object(s)), and the reception (e.g. electrical noise in electrical components of the receiver). When in the present context the term “noise applied” is used, it should be understood as the intentional as well as the unintentional components being added to the signal during emitting/transmitting/receiving the signal. That is, it should be interpreted as comprising “wanted” information regarding the signal path, such as information originating from objects inserted in the signal path as well as “unwanted” regular noise, such as noise originating from external noise sources. The “noise applied” may even comprise the gain of the system, e.g. in form of a damping or an amplification.
Systematic errors (such as reflections from walls, or noise originating from external noise sources, such as remote controls, the sun, artificial light etc.) may be eliminated, or at least to a great extend reduced, by using the knowledge thus obtained, and information may be obtained regarding one or more object(s) which is/are inserted into the signal path. Most preferably, information relating to the reflective and/or refractive and/
Cour-Harbo Anders La
Stoustrup Jakob
Beamcontrol APS
Harness Dickey
Le John H
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