Abstract: A receiver is provided. The receiver includes a first plurality of transistors configured and arranged as diodes connected in series and coupled between an input terminal and an output terminal. A first transistor of the first plurality is configured and arranged for receiving a signal at the input terminal having a voltage exceeding a voltage rating of the first transistor. A second plurality of transistors is configured and arranged as diodes connected in series and coupled between the output terminal and a voltage supply terminal. A second transistor includes a first current electrode coupled to a control electrode and a first current electrode of the first transistor and a control electrode coupled to a voltage source terminal. A third transistor includes a first current electrode coupled to a second current electrode of the second transistor at a first node.

Abstract: There are provided: a first capacitor connected between first and second input/output terminals; a second capacitor connected between the first input/output terminal and a third input/output terminal; a first inductor having one end connected to the first input/output terminal; a second inductor having one end connected to the second input/output terminal and another end connected to another end of the first inductor; a third inductor having one end connected to the first input/output terminal; a fourth inductor having one end connected to the third input/output terminal and another end connected to another end of the third inductor; a first transistor having a drain terminal connected to said another ends of the first and second inductors and a source terminal that is grounded; and a second transistor having a drain terminal connected to said another ends of the third and fourth inductors and a source terminal that is grounded.

Abstract: An apparatus includes a radio frequency (RF) input port, an RF output port, a variable attenuation network, a first filter network, a second filter network, and a third filter network. The variable attenuation network may be coupled between the RF input port and the RF output port. Attenuation of the variable attenuation network is controlled by a first control signal and a second control signal. The first filter network may be connected between the RF input port and the RF output port. The second filter network may be connected between the variable attenuation network and a ground potential. The third filter network may be connected between the variable attenuation network and the ground potential. The first, the second, and the third filter networks modify performance of the variable attenuation network to produce a particular tilt of a radio frequency signal passing through the apparatus between the RF input port and the RF output port.

Abstract: One example includes a superconducting phase-shift system. The system includes an all-pass filter comprising at least one variable inductance element. The all-pass filter can be configured to receive an input signal and to provide the input signal as an output signal that is phase-shifted relative to the input signal based on a variable inductance provided by each of the at least one variable inductance element. The system can further include a phase controller configured to provide a phase-control current to control the variable inductance of the at least one variable inductance element based on a characteristic of the phase-control current.

Abstract: A filter circuit includes: a filter element having a first terminal connected to an antenna, a second terminal connected to a receiving circuit, and a third terminal connected to a transmission circuit; a first inductor, a second inductor, and a third inductor connected in series between the first terminal and the third terminal of the filter element; a fourth inductor that has one end connected to a connecting node connecting the first inductor and the second inductor and that has the other end grounded; and a fifth inductor that has one end connected to a connecting node connecting the second inductor and the third inductor and that has the other end grounded.

Abstract: A transmission medium includes inductive couplers, signal lines and conductors. Each of the signal lines is configured to receive a respective one of multiple input signals. Each of the signal lines extends through at least one of the inductive couplers and is configured to inductively transmit one of the input signals to the at least one of the inductive couplers. Each of the conductors is configured to extend through at least two of the inductive couplers. The conductors include a first conductor and a second conductor. The inductive couplers are configured to inductively transmit the input signals to the conductors to generate a first current and a second current. The first current flows in the first conductor and towards an output of the first conductor. The second current flows in the second conductor and towards an input of the second conductor.

Abstract: An adaptive cable equalizer includes a data signal input unit, a clock signal input unit, a variable equalizer that inputs a data signal input from the data signal input unit, and a transition time measuring portion that measures a transition time of a data signal output from the variable equalizer, with an equalizer control loop being configured that controls characteristics of the variable equalizer based on the output signal of the transition time measuring portion. The adaptive cable equalizer further includes a control circuit that controls response characteristics of the control loop according to the frequency of a clock signal input from the clock signal input unit. This enables a quick response at fast transfer rates by making the relationship between the response time of the control loop and the number of data bits substantially constant even when the transfer rate changes from a slow transfer rate to a fast transfer rate.

Abstract: Exemplary embodiments of the present disclosure provide a method and controller for damping multimode electromagnetic oscillations in electric power systems which interconnect a plurality of generators and consumers. The controller for damping such oscillations includes a phasor measurement unit (PMU) and a power oscillation damper (POD) controller. Each oscillating mode signal is damped and then superposed to derive a control signal. A feedback controller is used to feedback the control signal to a power flow control device in the power system.

Abstract: The present invention relates to a tunable circuit, or admittance, arrangement comprising at least one capacitive branch with at least a tunable first capacitor, and tuning application means. It further comprises at least one resonant branch comprising at least a second capacitor and an inductor, said second capacitor and said inductor being connected in series. Said at least one capacitive branch and said at least one resonant branch are connected in parallel, and said tuning application means are adapted for application of a DC tuning voltage. The capacitance of said first and/or second capacitor and/or the inductance of said inductor are selected such that the frequency dependency of the tunability of a varactor arrangement forming the equivalent varactor arrangement of the admittance arrangement can be controlled at least in a selected frequency range.

Abstract: A method and apparatus are provided for automatic alignment of a notch filter in a receiver. The method comprises the steps of determining a frequency of an interfering signal, monitoring an energy in the interfering signal, tuning the notch filter based on an initial tune value, detecting an energy content in the radio signal after the tuning step, incrementally tuning the notch filter away from the initial tune value while monitoring the energy in the interfering signal, repeating the step of detecting and the step of incrementally tuning until the energy in the interfering signal is minimized, and storing a new tune value as the initial tune value. The notch filter is configured to filter the radio signal. The new tune value indicates a minimized energy in the interfering signal.

Abstract: A circuit topology is configured to flatten out a phase- and amplitude-response over a specified range of frequencies. The circuit topology also provides a large cumulative phase-shift. In one embodiment, the circuit topology cascades a plurality of all-pass sections, with the center-frequencies of each all-pass section staggered to create a substantially flat phase-response over a frequency range. Further, in one embodiment the plurality of all-pass sections has at least one all-pass section that is different from another all-pass section. Each all-pass section includes a tunable capacitor and has a center-frequency that can be varied by electronically tuning the capacitor. Each center frequency is selected to obtain substantially constant amplitude and phase response over a desired frequency range and capacitance tuning range.

Abstract: A tunable bandpass filter is provided that comprises a first shunt-connected ferroelectric (FE) tunable tank circuit having a first node to accept an input signal. A second shunt-connected FE tunable tank circuit has a second node to supply a bandpass filtered signal. A first capacitor is connected in series between the first and second nodes. In one aspect, the first tank circuit comprises a first resonator connected to the first node, and a fourth capacitor connected between the first resonator and a reference voltage. The fourth capacitor is a tunable FE capacitor. Typically, a fifth capacitor is connected between the first node and the reference voltage. Likewise, the second tank circuit comprises a second resonator connected to the second node, and a sixth (FE) capacitor connected between the second resonator and the reference voltage. A seventh capacitor is connected between the second node and the reference voltage.

Abstract: The present invention provides a tunable bandpass filter and method thereof. In a preferred embodiment, the tunable bandpass filter uses variable ferro-electric capacitors to adjust both the passband and the notch across the normal operating range of a wireless communications device. The tunable bandpass filter is capable of providing a tuning range over a desired frequency range with low I.L. and high out-of-band rejections.

Abstract: A tuning circuit for use in an electrical circuit network is disclosed. The tuning circuit includes a bridge circuit. The bridge circuit comprises a first adjustable capacitance grouping, a second adjustable capacitance grouping and a third adjustable capacitance grouping. Each adjustable capacitance grouping includes at least one tunable capacitor and a bias port. In one embodiment, the tunable capacitor is comprised of a tunable thin-film barium strontium titanate (“BST”) capacitor. A first lead and a second lead couple to, or extend from, the bridge circuit. The leads are configured to couple with a coupling element and a shunt element of the electrical circuit network so that when the leads are grounded, one adjustable capacitance group is grounded and the remaining adjustable capacitance group couple with a bias voltage to appropriately tune the electrical circuit to achieve desired electrical characteristics.

Abstract: An integrated RF filter for use at microwave frequencies comprising: an integrated circuit inductor with connected integrated circuit capacitors, arranged as a tank circuit, and an integrated circuit shunt resistor; the inductor, capacitors and resistor being interconnected in a bridge-T filter arrangement.

Abstract: A tuning circuit for use in an electrical circuit network is disclosed. The tuning circuit includes a bridge circuit. The bridge circuit comprises a first adjustable capacitance grouping, a second adjustable capacitance grouping and a third adjustable capacitance grouping. Each adjustable capacitance grouping includes at least one tunable capacitor and a bias port. In one embodiment, the tunable capacitor is comprised of a tunable thin-film barium strontium titanate (“BST”) capacitor. A first lead and a second lead couple to, or extend from, the bridge circuit. The leads are configured to couple with a coupling element and a shunt element of the electrical circuit network so that when the leads are grounded, one adjustable capacitance group is grounded and the remaining adjustable capacitance group couple with a bias voltage to appropriately tune the electrical circuit to achieve desired electrical characteristics.

Abstract: A tunable filter (300) includes first (302) and second (304) “bridged-T” resonators. The first (302) and second (304) resonators are capacitively coupled together via bandwidth control/coupling section (306). A biasing section (314) provides the proper biasing and decoupling for the filter (300). Filter (300) provides for low-side injection mode operation, and provides for a very deep zero on the lower side of the passband resulting in excellent selectivity. Filter (300) provides for excellent selectivity while reducing the number of inductors and varactors needed in the filter circuit. A high side injection mode filter (500) similar to filter (300) is also described in the disclosure.

Abstract: In one form of the invention, a resonant cavity filter (50) is disclosed, comprising an input port (210) for receiving an input signal, a dielectric resonator (204) in a cavity, the dielectric resonator operable to receive an input signal from the input port and further operable to produce an output signal at a resonant frequency of the cavity, an output port (212) operable to receive the output signal and a tuning plate (308) disposed in the cavity, the tuning plate coupled to a control means operable to cause movement of the tuning plate, thereby changing dimensions of the cavity, the control means operable to determine a frequency of the input signal, retrieve an expected tuning plate position from a memory (514) based on the frequency, and move the tuning plate to the expected position. Other systems, devices and methods are disclosed.

Abstract: A high power radio frequency(RF) precision step attenuator includes a trim attenuator, a multi-step attenuator and a calibration/control circuit. The control circuit includes a memory for storing attenuator specific calibration data. The calibration data incorporates attenuator characteristics which are used by the control circuit to adjust the attenuator and compensate for manufacturing variances, temperature variations, and the like.

Abstract: A circuit for controlling the loss of a VCO in a master-slave tuning system includes an envelope detector, an amplitude regulator, a current-mode circuit, and a low-pass filter. The envelope detector receives the VCO output voltage and provides VCO output envelope voltage, V.sub.ENV. The amplitude regulator receives V.sub.ENV and a reference voltage, V.sub.REF, and provides a sourcing current if V.sub.ENV is less than V.sub.REF, and draws a sinking current if V.sub.ENV is greater than V.sub.REF. The current-mode circuit receives V.sub.ENV and provides a control current, I.sub.Q. The low-pass filter has high DC gain for integrating the control current and the sourcing or sinking current to provide the VCO control voltage, V.sub.CON, to the VCO. The control current, I.sub.Q, is proportional to the inverse of V.sub.ENV multiplied by the time derivative of V.sub.ENV.

Abstract: The present invention provides an electronically tunable resonating apparatus which uses a tunable dielectric material which is biased by an electric field to alter the resonant frequency in a resonating cavity. The electrodes which apply the electric field are connected to a variable voltage source. The electrodes can therefore apply a plurality of electric field strengths and provide a range of resonant frequencies in the resonating apparatus. The resonating apparatus is particularly useful for microwave and millimeterwave electromagnetic energy.

Abstract: A circuit is described which maintains the current flowing toward a main circuit within a prescribed limit, regardless of instantaneous voltage or current changes. The circuit includes elements that maintain the current flow in a path toward a main circuit within a prescribed limit by selectively changing the impedance presented in response to any instantaneous change in the voltage flowing toward the main circuit and by introducing into the path a voltage which opposes any such instantaneous change in the current flowing toward the main circuit. Elements may also be provided to protect the main circuit by disconnecting same from a cable leading thereto after signals on the cable have been analyzed and a determination has been made that a signal outside of predetermined upper and lower limit values has been coupled to the cable, for example, from a high altitude electromagnetic pulse.

Abstract: A filter for treating a plurality of channels in a television signal cable distribution system comprises a plurality of paralel bandpass filters having a frequency which is individually controlled by frequency control voltages. A master filter provided with a filtering cell of a type identical to that used in a bandpass filter corresponds to each bandpass filter. For adjusting the central frequency of a master filter, a frequency is applied thereto by a frequency synthesizer and the cell is aligned with this frequency by acting on its frequency control voltage. This voltage is simultaneously applied to a bandpass filter for controlling the frequency, which is thus aligned with the frequency of the synthesizer simultaneously with that of the corresponding master filter. Each couple consisting of a bandpass filter and a corresponding master filter is realized by means of integration on the same semiconductor substrate (IC).

Abstract: An RF plasma system employs frequency tuning to change the frequency of an RF generator within a frequency range to match the impedance of a plasma chamber. Forward power and reflected power magnitudes are obtained from a bidirectional sensor. The ratio of reflected power to forward power is obtained for one frequency, and then the frequency is changed. The tuning algorithm compares the ratio of reflected to forward power at the new frequency with the ratio obtained earlier. If this ratio is smaller, the frequency is changed again in the same direction, but if larger, then the frequency is changed in the other direction. These steps are iterated until the ratio of reflected to forward power reaches a minimum. The tuning algorithm can be implemented in hardware or in software.

Abstract: A method and apparatus for tuning an analog filter that is embodied in a larger circuit in which the analog input signal to the filter is, at some point prior to the filter, in digital form. The digital version of the input signal to the filter is stored in memory. The output signal from the filter corresponding to the stored input signal is digitized and compared to the stored digital input signal to the filter. Based on the known input signal and the known desired frequency characteristics of the filter, the desired output signal is a known quantity. If the actual output signal differs from the expected output signal, the filter is tuned accordingly. The process may be performed continually on all input data or on discrete sections of the input data.

Abstract: A high Q bandpass filter (102) is tuned by applying a transient (204) to the filter to cause it to ring. The ringing of the filter produces an output damped oscillatory waveform (206) whose zero crossings (208) are converted to a pulse train (210) and counted in a digital counter (112) to a predetermined number n. The output (214) of the counter is compared to an accurate timing signal (216) which has a time duration equal to the time of n pulses when the filter is accurately tuned. The output of the comparator (118) is applied to an integrator (122) to generate a control signal V.sub.c to tune the filter. The high frequency tuning problem is thus converted to a low frequency, time domain problem which is readily implemented.

Abstract: A dielectric resonator encased within a pressure enclosure establishes the operating frequency of a microwave circuit. The enclosure is supplied with a pressurized gas and the pressure within the enclosure is varied as a function of the deviation of the operating frequency from a desired value. For more precise control the enclosure is preferably immersed in a cryogenic cooling system.

Abstract: A phase shifter in which the change in phase changes with changes in temperature. The phase shifter includes a plurality of capacitors and inductors connected in series relation to form a filter network. Each of the capacitors has a dielectric material with a temperature coefficient so that the capacitance of the capacitor varies with temperature. Each of the inductors has a ferrite material which has a temperature coefficient so that the inductance of the inductor varies with temperature. The temperature coefficients of the dielectric material of the capacitors and the ferrite material of the inductors have the same sign, i.e, either negative or positive, and preferably are of the same value.

Abstract: An attenuator circuit having three cascaded attenuator stages which become active, one at a time, as an input signal strength increases. In the highest gain state, the three attenuator stages are active. As the input signal increases, the attenuator stages become inactive sequentially starting with the last stage.

Abstract: A spacecraft includes a plurality of paralleled RF amplifiers. Each paralleled power amplifier (206) includes a signal splitter (222) which produces two nominally equal-amplitude signals, and a signal combiner (242) which combines appropriately phased signals to produce a sum signal at a sum port (250). The signal combiner also includes a null output port (248). A pair of elemental amplifiers (236, 238) is coupled between the splitter outputs and the combiner inputs. In order to allow for phase drift of the elemental amplifiers, at least one phase shifter (258) is associated with one of the elemental amplifiers. A phase control loop is coupled from the null output of the combiner, around the paralleled amplifier arrangement, and controls the phase shifter to maintain the phase within bounds, to maximize the signal at the sum port of the combiner.

Abstract: An integrated circuit includes a single pole double throw switch including a transmitting and receiving port, a transmitting port, and a receiving port. A transmission switch is coupled between the transmitting port and the transmitting and receiving port. A reception switch is coupled between the receiving port and the transmitting and receiving port. The reception switch includes a field effect transistor having a gate, a drain and a source. A voltage generating circuit receives first and second power supply voltages. The first power supply voltage is greater than the second power supply voltage. The voltage generating circuit generates a third voltage lower than the second power supply voltage and applies the third voltage to the gate of the field effect transistor of the reception switch during transmission.

Abstract: A phase adjusting circuit for adjusting phases of output powers from two high frequency power generators in a plasma processing apparatus comprises first and second synthesizing circuits for generating first and second high frequency signals of a predetermined waveform with frequencies of f0 and f0.+-..DELTA.f (.DELTA.f<<f0), a phase difference detection circuit for detecting a phase difference between detection signals of plate electrodes, a third waveform synthesizing circuit for generating a high frequency signal with frequency and waveform same as the first frequency signal which has a phase determined from a phase error between a set phase difference and an output from the phase difference detection circuit and a phase adjusting circuit which determines output powers of the two high frequency power generators base on outputs of the first and third waveform synthesizing circuits.

Abstract: A method is provided for automatically adjusting the output signal level from a transmitting apparatus, in which the transmitting apparatus recognizes the distance to a receiving apparatus and automatically adjusts the signal output level. In a system in which a signal is transmitted from a transmitting apparatus via a coaxial cable to a receiving apparatus, the signal output from the transmitting apparatus is gradually changed, a judgment being made as to whether or not reception of the signal is possible at the receiving apparatus. When this condition is achieved, notification of the condition is made to the transmitting apparatus which when receiving this notification, sets the signal level to the signal level at that time, thereby setting the signal level to the level which is the receiving limit at the receiving apparatus.

Abstract: A device and a method for adjusting a bandpass filter, especially a combiner filter. The method includes deriving an RF sample signal proportional to the power of a modulated RF signal which is one of: passing forward to the bandpass filter, reflected from the input of the bandpass filter and passed through the bandpass filter; down-converting the sample signal by another RF signal; detecting the signal strength of the mixing result; adjusting the center frequency of the passband of the bandpass filter on the basis of the detected signal strength. There is an essential frequency or modulation difference between the signals to be mixed, and so the mixing result is an AC signal of a lower frequency. No accurate adjustment of the phase relation of the signals to be mixed is required. Preferably, the frequency or phase difference between the signals to be mixed is accomplished by utilizing the phase modulation contained in the transmission when one of the signals is unmodulated.

Abstract: A communication device (100) including an antenna (110) for receiving a signal. A receiver circuit (12) is coupled to the antenna (110) and demodulates the signal which is received by the antenna (110). A signal strength measuring circuit (126) is coupled to the antenna (110) and generates a signal strength indicator signal representing a strength of the signal received by the antenna (110). A controller (130) is coupled to the receiver circuit (120) for receiving the signal strength indicator signal and generating a tuning signal in response thereto. An antenna tuning circuit (140) is coupled to the controller (130) and is responsive to the tuning signal for tuning the antenna (110) to a reduced gain level when the strength of the signal received by the antenna (110) is indicative of strong signal conditions.

Abstract: The invention relates to a directional coupler arrangement and measurement of radio frequency electric power with a directional coupler arrangement, which arrangement comprises a directional coupler, in which a terminal impedance, a detector element and a control circuit are connected between the end of the second conductor element and the earth potential. The impedance value of the terminal impedance can be altered by means of an electric control signal and said control circuit produces said control signal on the basis of the signal provided by the detector element. When the detected power level is low, the control circuit increases the impedance value of the terminal impedance, whereby the peak voltage of the signal applied to one end of the directional coupler increases and the arrangement yields a measurement result that is larger than ordinary, which improves the accuracy and reliability of the arrangement at low power levels.

Abstract: In one form of the invention, a resonant cavity filter (50) is disclosed, comprising an input port (210) for receiving an input signal, a dielectric resonator (204) in a cavity, the dielectric resonator operable to receive an input signal from the input port and further operable to produce an output signal at a resonant frequency of the cavity, an output port (212) operable to receive the output signal and a tuning plate (308) disposed in the cavity, the tuning plate coupled to a control means operable to cause movement of the tuning plate, thereby changing dimensions of the cavity, the control means operable to determine a frequency of the input signal, retrieve an expected tuning plate position from a memory (514) based on the frequency, and move the tuning plate to the expected position. Other systems, devices and methods are disclosed.

Abstract: A transceiver system for interfacing digital modems with radio frequency signals including an antenna, an antenna interface system and a modem interface system separated by a cable. The antenna is placed in a location having optimal reception and in close proximity to the antenna interface system. The cable couples the antenna interface system to the modem interface system. The modem interface system includes a two state variable attenuator and an attenuation register that are configured to either reduce the strength of the receive (Rx) signal when the modems are located near a base station, or to transmit the Rx signal without attenuation when the concentrated subscriber unit is at a more distant location. The outgoing, or transmit (Tx), signal is also attenuated in a similar manner to the incoming signal. A signal loss detection system includes a detector located in the modem interface system that receives an oscillating signal transmitted from the antenna interface system through the coaxial cable.

Abstract: Tuning a combiner filter, which includes two separate tuning modes: coarse adjustment applied when the combiner is taken into use by utilizing a measuring branch for forward power and a coarse measuring branch for reflected power; and fine adjustment applied in continuous operation by utilizing the measuring branch for forward power and a fine measuring branch for reflected power. The two-stage adjustment decreases the mutual interference of the filters during tuning. The correct tuning frequency of the combiner filter is obtained as the average point of the reversing points obtained in the adjustment process, the filter being driven to the average position. This so-called positional average tuning has two advantages: the effect of noise present in the power measuring line is reduced, and the tuning error caused by the termination of the dynamics of the A/D converter positioned after the detector at low power levels and good combiner filter settings is diminished.

Abstract: The present invention relates to a for coupling Plain Old Telephone Service (POTS) signals and Asymmetric Digital Subscriber Line (ADSL) signals to a common line (TL). In order to avoid saturation of inductances (L1,L2,L3,L4) of a low pass POTS filter (LPF) located between the POTS transmitter/receiver (PTR) and this common line (TL) when the POTS signal is not sufficiently attenuated by this common line (TL), a variable impedance (SL) is inserted between the POTS transmitter/receiver (PTR) and this low pass POTS filter (LPF). The value of this variable impedance (SL) is controlled by a control signal (CS) supplied by the ADSL transmitter/receiver (ATR) which measures the attenuation caused by this common line (TL).

Abstract: An accurate estimate of the amplitude of a sparsely sampled sinusoidal signal is obtained by filtering the squares of the sampled values of the sinusoidal signal with an adjustable notch filter in order to remove a double-frequency component at twice the frequency of the sinusoidal signal. This amplitude estimate, for example, is used for automatic gain control of the amplitude of the sinusoidal signal. Preferably, the notch filter is a digital filter for computing an output signal (v) from successive samples (x.sub.n, x.sub.n-1, x.sub.n-2) of an input signal (x) according to: v.sub.n =x.sub.n -.beta.x.sub.n-1 +x.sub.n-2. The frequency control parameter (.beta.) is computed, so as to automatically track the frequency of the sinusoidal signal, by integrating a product of a derivative (x.sub.n-1 -x.sub.n-2) of the input signal (x) and a derivative (v.sub.n -v.sub.n-1) of the filtered signal (v).

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: A system which integrates "intelligent" electronic feedback into the structure of vacuum electronic devices whose subcomponents are electronically and/or electro-mechanically adaptive. By "vacuum electronic device," is meant any source of microwave (or millimeter-wave) power generation which is driven by electron beams. Such a device is divided into the following main subsections: an electron emitter, an electron beam shaping & acceleration region, an rf signal input coupler (for amplifiers), an electron-beam drift region, at least one rf/beam interaction region where beam energy is converted to an rf signal, a beam-dump region, and the rf signal output coupler. Some of those subsections are instrumented with electronic sensors. The data collected by those sensors will feed into an "on-board" microcomputer (logic unit subsection 8) which will compare it to "ideal" set of values for those parameters.

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: A multistate electronic transfer standard provides electronic conditions to at least one of two ports of a vector network analyzer. One embodiment of the multistate electronic transfer standard includes a plurality of semiconductor interconnected by transmission lines. Each of the semiconductor devices are biased to generate different conditions at each of the two ports. A control computer controls the biasing of devices according to a predetermined procedure and compares impedance values measured for at least one of the two ports of the network analyzer to known values stored by the control computer. The control computer thereby derives calibration coefficients that are used by the network analyzer in performing further measurements.

Abstract: A device for tuning a combiner filter. The measuring signals (P.sub.rl . . . P.sub.rn, P.sub.F1 . . . P.sub.Fn) of a number of different combiner filters are multiplexed to the same detectors. Multiplexing allows the measuring and adjusting electronics required by the tuning and adjusting means of combiner filters to be simplified considerably especially with a high number of combiner filters. Multiplexing of measuring signals is used primarily to select the sample signals of the forward and reflected power of one and the same combiner filter to be tuned for the measuring electronics. In the invention selectors for reflected power and forward power are independent of each other, which allows isolation measurement between different channels. The sample signal of the forward power of one combiner filter and the sample signal of the reflected power of another combiner filter are thus connected to the measuring electronics.

Abstract: A method and circuit for detecting and reducing the impedance mismatch between the directional coupler and the antenna of an RF communications system exposed to externally generated RF signals. The impedance mismatch is detected by the quadrature multiplication of the signal passing through a directional coupler in the forward and reverse directions with the detection being enhanced by the use of a forward direction signal substantially devoid of externally generated RF signal components.

Abstract: The invention relates to a method for fine tuning the resonant frequency of a filter in a combiner, which is provided for combining signals from several radio channels, to the carrier frequency of an input signal to the filter. The power of the output signal from the filter is measured in a narrow frequency band around the carrier frequency of said input signal. Furthermore, the power of the signal reflected by the filter is measured in a narrow frequency band around the carrier frequency of the input signal. Thereafter a measure of the ratio between the two power measurements is formed. The resonant frequency of the filter is adjusted so as to maximize this measure.

Abstract: A method for tuning an RF bandpass filter, especially a combiner filter (10.sub.1, 10.sub.2. . . 10.sub.n) belonging to a GSM system, in which an RF signal having a certain nominal carrier frequency (f.sub.c) is inputted into the RF bandpass filter and a medium frequency of a pass band of the RF bandpass filter is tuned depending on an RF power propagating through the bandpass filter or on an RF power reflected from an input of the bandpass filter. For an easier tuning of the filter and for a tuning accuracy better than before, (a) a carrier is modulated by a signal causing a first predetermined offset (+.DELTA.f), of the carrier frequency, (b) a medium frequency, at which the power propagating through the filter is at the maximum or the power reflected from the input of the filter is at the minimum, is searched for for the bandpass filter, (c) the first medium frequency obtained at stage (b) is stored, (d) the carrier is modulated by a signal causing a second predetermined offset (-.DELTA.

Abstract: An automatically tuned filter apparatus having as input a signal of constant or slowly varying but unknown frequency superimposed on a second signal of rapidly varying frequency with a first output attenuating the first signal by implementation of a narrow band rejection filter and the second output rejecting all but the first signal by implementation of a narrow band pass filter in which the characteristics of both filters are controlled by the relative amplitudes and phase differences of the two outputs.