 Scan type radar device |
| A first object of the present invention is to solve the problems in the above-mentioned on-vehicle ... |
|
| Interference suppression circuit and method thereof for multi-channel receivers |
| OF THE DRAWINGS A better understanding of the present invention may be realized by considering the ... |
|
| Electric generator arrangement |
| What is claimed is: 1. An electric generator arrangement comprising at least two wheels arranged to ... |
|
| Fluid driven power producing apparatus |
| What is claimed is: 1. An apparatus for use in converting the kinetic energy of an accelerated ... |
|
| Aerodynamic lifting mechanisms |
| What I claim is: 1. An aircraft comprising: a body with two sides; an engine mounted within said ... |
|
| Apparatus for controlling a plurality of electrical devices |
| It is, therefore, an object of the present invention to provide an apparatus for controlling a ... |
|
| Field control for wind-driven generators |
| We have now discovered a method and apparatus for precisely controlling the field current on a wind-... |
|
| Alternating comparator circuitry for improved discrete sampling resistance control |
| In accordance with the invention, an alternating comparator circuit, as e.g. for realizing an ... |
|
| Stress-crack resistant ethylene-perhaloethylene terpolymers |
| I claim: 1. Terpolymers of from about 40 to 60 mol percent ethylene, from about 60 to about 40 mol ... |
|
| Nitrile rubber hydrogenation |
| The nitrile rubber hydrogenated in this invention is a polymer comprising a conjugated C.sub.4 -C.... |
|
|
Method and system for determining the integrity of a received signal
| Details |
Inventors: Daughtry, Jr., Earl A.; Ruff, Mark A.;
Assignee: Matsushita Communications Industrial Corporation (Peachtree City, GA)
Primary Examiner: Cangialosi; Salvatore
Assistant Examiner:
Attorney, Agent or Firm: Smith, Esq.; Gregory Scott Troutman Sanders LLP
A method for determining the integrity of a received signal in a frequency tracking environment so that a determination can be made whether Automatic Frequency Control (AFC) can be utilized. Several samples of the frequency are taken (205). At least one statistic based on these frequency samples is calculated for use in determining whether the received signal may be used for AFC operation. These statistics may include, for example, the mean, the mean deviation, the standard deviation, and the variance of the measured frequency. A strong signal limit and a weak signal limit are used to determine whether AFC operation should be disabled. If the calculated statistic is less than the strong signal limit (210) then AFC operation is enabled. If the calculated statistic is also greater than the weak signal limit (220) then AFC operation is disabled (225). This allows the receiver to continue AFC operation until the signal level is so weak as to cause erroneous frequency measurements. If the calculated statistic is between the strong signal limit (210) and the weak signal limit (220) then the signal strength is tested (230). If the signal strength is below a minimum value then AFC operation is enabled but if the signal strength is above this minimum value then AFC operation is disabled because a strong interfering signal may be present. |
|
DETAILED DESCRIPTION The present invention satisfies the above described needs by providing an improved system and method for determining the integrity of a received signal in a frequency tracking environment.
Briefly described, the present invention is directed to a method and system for determining the quality, or integrity, of a received signal in a frequency tracking environment so that a determination can be made whether Automatic Frequency Control can be utilized.
Several consecutive measurements of the frequency of the limited IF output of a receiver are taken.
These frequency measurements are used to calculate statistics on the frequency of the limited IF output.
These statistics are then evaluated to determine if an adjustment in the receiver timebase/oscillator frequency is allowable.
These statistics may include the mean, mean deviation, variance and standard deviation, among other statistics.
The mean deviation of the measured frequency of the limited IF output signal increases as the received signal level decreases, that is, as the RSSI falls.
Ultimately, as the received signal level decreases to zero, the mean deviation will be determined by the characteristics of the receiver itself, such as the IF bandwidth of the receiver.
Also, the average (mean) frequency of the limited IF output changes as the received signal level decreases.
Ultimately, as the received signal level decreases to zero, the mean frequency will be determined by the characteristics of the receiver itself, such as the IF center frequency of the receiver.
A weak signal deviation limit is used as the threshold for disabling AFC operation.
If the mean deviation calculated is greater than the weak signal deviation limit, then the controller disables AFC operation.
Therefore, the present invention allows the receiver to continue AFC operation until the signal level is so low that the frequency measurements will be erroneous and the AFC will be ineffective.
This also provides for disabling AFC operation in a changing signal environment such as fading
|
| Related patents |
|
|
Method for detecting weak signals in a non-gaussian and non-stationary background
A method is described for detecting weak signals in a non-Gaussian and non-stationary background using a hidden Markov parameter estimator. The method comprises the ...
|
|
|
Phaselock threshold correction
In accordance with the present invention, there is provided a noise estimator for threshold correction of phaselock in a receiver where a noise estimating circuit ...
|
|
|
Adaptive control of the detection threshold of a binary integrator
The present invention achieves technical advantages as an apparatus, method and system of dynamically estimating a coefficient of variation of the fluctuation of a ...
|
|
|
Communications receiver arrangement
In accordance with a first aspect of the invention, there is provided a communications receiver arrangement for the receipt of digital data, comprising: means for ...
|
|
|
Guided wave radar level transmitter with automatic velocity compensation
In accordance with the invention there is provided a guided wave radar transmitter with automatic velocity compensation. Broadly, in accordance with one aspect of the ...
|
|
|
Methods and apparatus for providing robust synchronization of radio transceivers
The present invention fulfills the above-described and other needs by providing a multi-part digital preamble for use in transmitting digital data packets. A...
|
|
|
Noncontact position and orientation measurement system and method
Accordingly, a need has arisen for an improved technique having greater flexibility and applications for position measurement than prior systems. In accordance with the ...
|
|
|
Airborne biota monitoring and control system
OF THE DRAWINGS The instant invention combines knowledge of physical and behavioral characteristics of insect pests, beneficials, and neutrals, as well as other biota, ...
|
|
|
Multilateration auto-calibration and position error correction
The Multilateration Auto-Calibration & Position Error Correction System of the present invention is a truly passive method of error detection and correction. The system ...
|
|
|
Method and apparatus for correlating flight identification data with secondary surveillance radar data
The present invention includes hardware, software, and a methodology for correlating flight identification data with aircraft registration numbers. In a first embodiment ...
|
|
|
Radio 
