1. A method for compensating for a residual frequency offset in an orthogonal frequency division multiplexing system, comprising the steps of:
a) performing a fast Fourier transform for an input signal to convert the input signal into a serial signal;
b) detecting signal power of the serial signal to control the pass through of a signal greater than a predetermined critical value;
c) selecting a section of a quadrant for each passed signal;
d) estimating a phase error in each section of the quadrant for one orthogonal frequency division multiplexing symbol with respect to the selected section of the quadrant; and
e) frequency-oscillating a signal based on the estimated phase error, generating the input signal by multiplying an oscillated signal by a band-passed signal, and returning to step a).
2. The method as claimed in claim 1, wherein step a) includes the steps of:
f) converting the input signal into a digital signal;
g) converting the digital signal into parallel signals; and
h) performing a fast Fourier transform on the parallel signals and converting the parallel signals into a serial signal.
3. The method as claimed in claim 1, wherein the power detection in step b) is performed by,
|Ym(k)|2>\u03c4,
where Ym(k) represents an kth subcarrier signal of an mth orthogonal frequency division multiplexing symbol and \u03c4 represents a critical value.
4. The method as claimed in claim 2, wherein the power detection in step b) is performed by,
|Ym(k)|2>\u03c4,
where Ym(k) represents an kth subcarrier signal of an mth orthogonal frequency division multiplexing symbol and \u03c4 represents a critical value.
5. An apparatus for compensating for a residual frequency offset in an orthogonal frequency division multiplexing system, the apparatus comprising:
a fast Fourier transform unit for performing a fast Fourier transform for an input signal to convert the input signal into a serial signal;
a power detector for detecting signal power of an output signal of the fast Fourier transform unit to control the passthrough of a signal greater than a predetermined critical value;
a quadrant detector for selecting a section of a quadrant for each passed signal;
a phase error estimation unit for estimating a phase error in each section of the quadrant for one orthogonal frequency division multiplexing symbol with respect to the selected section of the quadrant; and
a voltage controlled oscillator for frequency-oscillating a signal based on the estimated phase error, generating the input signal by multiplying an oscillated signal by a band-passed signal, and inputting the input signal to the fast Fourier transform unit.
6. The apparatus as claimed in claim 5, wherein the phase error estimation unit estimates the phase error by using a SNR signal greater than a predetermined critical value and a representative signal located on a diagonal axis of a constellation plot.
7. A computer program device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform the method steps for a method for compensating for a residual frequency offset in an orthogonal frequency division multiplexing system, comprising the steps of:
a) performing a fast Fourier transform for an input signal to convert the input signal into a serial signal;
b) detecting signal power of the serial signal to control the pass through of a signal greater than a predetermined critical value;
c) selecting a section of a quadrant for each passed signal);
d) estimating a phase error in each section of the quadrant for one orthogonal frequency division multiplexing symbol with respect to the selected section of the quadrant; and
e) frequency-oscillating a signal based on the estimated phase error, generating the input signal by multiplying an oscillated signal by a band-passed signal, and returning to step a).
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
I claim:
1. A vacuum line socket and dental saliva ejector tube assembly, comprising in combination:
a. a dental saliva ejector tube having a first end for being inserted into a patient’s mouth and having an opposing second end, the dental saliva ejector tube including a sidewall;
b. a vacuum line socket having first and second opposing ends and a central passage extending therebetween, the first end including a port for being coupled to a source of a vacuum, and the second end including a central bore forming a socket for receiving the second end of the dental saliva ejector tube;
c. a lever secured to said vacuum line socket, said lever including a first end, the first end of said lever being selectively movable toward the sidewall of said dental saliva ejector tube for retaining said dental saliva ejector tube within said vacuum line socket, and the first end of said lever being selectively movable away from the sidewall of said dental saliva ejector tube for allowing said dental saliva ejector tube to be inserted within, or released from, the second end of said vacuum line socket.
2. The assembly recited by claim 1 wherein said lever is pivotally secured to said vacuum line socket about a pivot axis, said lever including a second end opposite the first end thereof, wherein movement of the second end of said lever toward said dental saliva ejector tube rotates the first end of said lever away from said dental saliva ejector tube.
3. The assembly recited by claim 2 wherein the first end of said lever includes a sharpened tip for selectively engaging the sidewall of said dental saliva ejector tube.
4. The assembly recited by claim 2 including a biasing member urging the first end of said lever toward said dental saliva ejector tube.
5. A vacuum line socket and dental saliva ejector tube assembly, comprising in combination:
a. a dental saliva ejector tube having a first end for being inserted into a patient’s mouth and having an opposing second end, the dental saliva ejector tube including a sidewall;
b. a vacuum line socket having first and second opposing ends and a central passage extending therebetween, the first end including a port for being coupled to a source of a vacuum, and the second end including a central bore forming a socket for receiving the second end of the dental saliva ejector tube;
c. a retaining member movably secured to said vacuum line socket, said retaining member selectively engaging the sidewall of said dental saliva ejector tube, said retaining member being capable of assuming a first position wherein said retaining member does not contact the sidewall of said dental saliva ejector tube for allowing said dental saliva ejector tube to be inserted within, or released from, said vacuum line socket, and being capable of assuming a second position wherein said retaining member does contact the sidewall of said dental saliva ejector tube for retaining said dental saliva ejector tube in said vacuum line socket.
6. The assembly recited by claim 5 wherein said retaining member includes a sharpened tip, and wherein the sharpened tip of said retaining member does not engage the sidewall of said dental saliva ejector tube when said retaining member is in its first position, and wherein the sharpened tip of said retaining member engages the sidewall of said dental saliva ejector tube when said retaining member is in its second position.
7. The assembly recited by claim 5 wherein said retaining member is a lever pivotally secured to said vacuum line socket.
8. The assembly recited by claim 5 wherein said vacuum lines socket includes a slot extending therethrough, and wherein said retaining member is a slide member that slides through the slot extending within said vacuum line socket.
9. The assembly recited by claim 5 including a biasing member for urging said retaining member toward its second position.