Abstract: Apparatus and methods are provided to allow multiple, possibly overlapping, regions of interest within a frequency spectrum to be defined, and managed. Each of these regions of interest may be selected for further testing or identification. Unselected regions are allowed to collapse into narrow bars so as not to interfere with the selected region. Multiple rows are provided to allow for the definition and selection of overlapping regions of interest. Furthermore, in some embodiments aid is provided for identifying the signal type by providing a list of signal type candidates based upon such parameters as region of interest bandwidth, region of interest center frequency and geographic location.

Abstract: A method and apparatus for residual spur avoidance is disclosed. One embodiment comprises a method of generating a first local oscillator signal, mixing the first local oscillator signal with a radio frequency signal to generate an intermediate frequency signal, filtering the intermediate frequency signal at a band-pass frequency, mixing the filtered intermediate frequency signal with a second local oscillator signal having a first frequency offset from the band-pass frequency to generate an output intermediate frequency signal, and switching the second local oscillator signal to a second frequency offset to avoid a spur generated from the first frequency offset, wherein the second frequency offset is the opposite sign but same magnitude offset from the band-pass frequency.

Abstract: Apparatus and methods are provided to allow multiple, possibly overlapping, regions of interest within a frequency spectrum to be defined, and managed. Each of these regions of interest may be selected for further testing or identification. Unselected regions are allowed to collapse into narrow bars so as not to interfere with the selected region. Multiple rows are provided to allow for the definition and selection of overlapping regions of interest. Furthermore, in some embodiments aid is provided for identifying the signal type by providing a list of signal type candidates based upon such parameters as region of interest bandwidth, region of interest center frequency and geographic location.

Abstract: An apparatus and method for characterizing a loading pattern of a twisted pair telecommunications transmission line includes a variable frequency signal generator and a measurement receiver connected to the twisted pair line. The signal generator applies a variable frequency signal to the twisted pair line and the measurement receiver acquires magnitude values representative of the impedance of the twisted pair line. A controller, operating under program control, models a plurality of baseline transmission line and twisted pair lines to generate magnitude values representative of the models. Error values are generated between the acquired magnitude values and the modeled magnitude values. The error values are compared to each other to determine the model with the minimum error value which is used as the model for charactering the twisted pair transmission line.

Abstract: An improved time domain reflectometer (TDR) includes a capacitor coupled in series between a transmission medium under test and the TDR receiver input. A switch, operating under microprocessor control, selectively couples and uncouples the capacitor to a voltage reference, such as ground. During the generation of interrogating pulses from the TDR and the acquisition of data from the transmission medium under test, the capacitor is uncoupled from the voltage reference and acts as a DC blocking capacitor. During periods of non-TDR activity, the capacitor is coupled to voltage reference and acts as a load for low frequency interference appearing on the transmission medium. The capacitor-switch operation blocks low frequency interference signals from the receiver input of the TDR.

Abstract: An error corrected wide dynamic range amplifier has a transimpedance amplifier where the input signal node is used as a monitoring point for providing an error correction voltage to a combining circuit that also receives the voltage on the output node of the transimpedance amplifier. The combining circuit subtracts the input signal node voltage from the output signal voltage to produce a resultant voltage substantially free of errors produced by non-ideal characteristics of the transimpedance amplifier. The combining circuit may be implemented using analog or digital circuity. The digital combining circuit may also add digital correction values representative of circuit component errors of the wide dynamic range amplifier. Such a wide dynamic range amplifier is usable in high sensitivity, wide dynamic range optical receivers, such as found in optical time domain reflectometers or other optical measurement instruments.