Abstract: A method of intermediate frequency (i.f.) planning for radio transmitters and receivers involves predicting which i.f. or i.f. range will result in spurious emissions to or response from one or more “avoidance bands” being sources of unwanted signals or frequency bands closed to transmission, whereby to choose an i.f. or i.f. band which minimises such i.f. bands. The method may be carried out by computer software which may be embedded in a transmitter/receiver having means for varying its i.f.

Abstract: A voltage-controlled oscillator (VCO) generates an output signal with adjustable frequency. The VCO circuitry includes a variable capacitor circuitry and a voltage-generator circuitry. In response to a plurality of control signals, the variable capacitor circuitry adjusts the frequency of an output signal of the VCO circuitry. The voltage-generator circuitry generates the plurality of control signals and provides them to the variable capacitor circuitry. The voltage level of each of the plurality of the control signals differs by an offset voltage from the voltage level of the remaining signals in the plurality of signals.

Abstract: The invention relates to a signal source (S) which comprises a local oscillator (5) for generating a reference frequency signal fo.

Abstract: A direct conversion receiver system is provided in which a first input signal at a first frequency is applied to a first input port of a multiplier, a second input signal at a second frequency equal to about {fraction (1/n)} times the first frequency, wherein n is an integer, is applied to a second input port of the multiplier. A first filter coupled to the first input port is configured to substantially filter out any leakage at the second frequency which may be present. A second filter coupled to the second input port is configured to substantially filter out any leakage at the first frequency which may be present. The multiplier is configured to produce a signal at an output port thereof which is derived from the product of the first and second signals. In one embodiment, the output is representative of the product of the filtered first signal and a multiplication factor which switches at n times the second frequency. The output of the multiplier is coupled to a third filter.

Abstract: A method for generating a local oscillation signal comprising two separate frequency converters, of which one frequency converter includes an output unit for generating an internal output signal to be used for its frequency conversion, and the other frequency converter employs the same internal output signal from the output unit as the local oscillation signal.

Abstract: A mobile radio telephone having a minimized tuning bandwidth, based on limiting intermediate frequencies at the highest and lowest expected receive frequencies in each band. A dual band, dual mode mobile phone can be constructed which maintains or improves intermodulation performance using fewer battery cells without additional circuitry.

Abstract: A radar detector including a local oscillator capable of sweeping over a frequency range of sufficient bandwidth to provide a fundamental frequency and, when injected into a multiplier/mixer, harmonics of that fundamental frequency suitable for heterodyning with rf-signals received by an antenna. The heterodyning of the received rf-signals and the local oscillator signal produce an intermediate frequency signal of constant frequency. A sweep controller causes the local oscillator to sweep only through those local oscillator frequencies suitable for heterodyning with those received rf-signals having radio-frequencies which are of interest. The sweep controller causes the sweeping local oscillator not to sweep through those local oscillator frequencies which would heterodyne with received rf-signals that are not of interest.

Abstract: A broadband receiver for converting an input radio frequency signal into output pulses includes provision for expanding the width of the output pulses (50) to permit pulse processing by conventional equipment at slower processing rates. A scanning local oscillator (42) frequency modulates the input signal to create a frequency modulated signal which is compressed into a pulse by a dispersive delay line (40). The width of the output pulse is increased by producing a mismatch or differential in the frequency versus time slopes (52, 54) of the oscillator and dispersive delay line. The slope differential is achieved by a function generator (58, 68) which maintains the frequency versus time slope of the scanning local oscillator at a value different than that produced by the dispersive delay line.

Abstract: An electronic tuning type radio receiver which is designed so that the received electric field intensity distribution in a received frequency band can be known at a glance. When predetermined key information is applied, receiving frequency designating information for determining the broadcasting station to be received is sequentially changed to detect the received electric field intensity of each received frequency. A received frequency vs electric field intensity distribution is produced based on the detected value and the corresponding received frequency and is displayed on a CRT display or the like.

Abstract: An input signal frequency and the output from a local oscillator are applied to a frequency converter to derive therefrom intermediate-frequency signals of frequencies corresponding to the differences between the input signal frequency and the output frequency of the local oscillator and between the former and harmonic frequencies of the latter. The intermediate-frequency signals are amplified by an amplifier, and the output freqeuncy of the amplifier and the oscillation frequency of the local oscillator are simultaneously measured twice. From intermediate frequencies F.sub.i1 and F.sub.i2 and the local oscillation frequencies F.sub.1 and F.sub.2 thus measured, the following calculation is made: ##EQU1## where .alpha. is zero or a decimal. At the same time, it is detected which one of the intermediate frequencies F.sub.i1 and F.sub.