Abstract: An FM intermediate-frequency circuit into which there is integrated at least a limiter-amplifier (1A) and a phase-locked loop which contains a VCO (4). The limiter-amplifier also includes a level detector. The dynamic range of the level detector is expanded without having to use excessive limiter-amplifier amplification, which would cause oscillation problems, by placing in parallel with the limiter-amplifier (1A) at least a second limiter-amplifier (1B), in connection with which there is also a level detector. The level of the input signal of the second limiter-amplifier (1B) is dropped as compared with that of the first limiter-amplifier (1A) by means of a dividing circuit (R1, R2). The signals (1A, 1B) obtained from the level detectors are combined to form one level detection signal (ITOT). If the signals are in the form of current, the combining can be carried out directly by summing the signals.
Abstract: A circuit arrangement allows either analog (ANAL) modulation or (DIG) digital modulation to be selected by means of couplers (K1, K2) for transmission over a radio channel. The analog or digital signals are applied to I,Q generators to form I, Q wave shapes (I.sub.A, Q.sub.A or I.sub.D, Q.sub.D), which modulate a possible intermediate frequency in a stage (3) and upon summation, modulate a transmission frequency in a stage (4).
Abstract: A control voltage generator in a transmitter arrangement for, e.g., QAM signals comprising a class C output amplifier (AMP). The control voltage generator (CVG) comprises a memory with a look up table (ROM), whereby the I,Q-signals (I,Q) of the modulating signal (DM) address a cell in the look-up table (ROM), the information of which is used as a control signal (CS) to control the amplifier output level (RF). The information is modified to compensate for temperature variations and other non-linearities.
Abstract: A radio transmitter arrangement for e.g. QAM signals comprising a class C output transistor amplifier (AMP). The control voltage generator (CVG) comprises a memory, whereby the I,Q-signals (I,Q) of the modulating signal (DM) address the control voltage generator (GEN), the information of which is used as a control signal (CS) acting as the collector voltage to control the amplifier output level (RF). The information can be modified to compensate for temperature variations and other non-linearities.
Abstract: A method and circuit for automatically controlling the frequency of a radio telephone. According to this method, the frequency of the signal detected at the receiver of a radio telephone is mixed with the output frequency of a phase-locked loop in a first mixer. The output frequency of the first mixer is mixed in a second mixer with the frequency derived from a local oscillator. The frequency of the phase-locked loop is controlled on the basis of the frequency deviation of the output frequency of the second mixer. This frequency deviation can be determined by counting the pulses generated by the second mixer during a predetermined time interval, the time interval being equal to the amount of time which elapses when a specified number of pulses generated by the local oscillator is counted. The reference frequency of the phase-locked loop is derived from the frequency of the local oscillator.
Abstract: A matrix display for the display of alphanumeric characters one of the elements of the basically 5.times.3 matrix divided into two parts (P5a, P5b). The matrix can also be applied to a printer.
Abstract: Balanced mixers with respect to their output stages are created by making the differential mixer output (A, B) a single-ended output (C) without a matching transformer. The circuitry can be used in all balanced transistor mixers, provided that both sides of the differential output are available for use.
Abstract: The invention relates to a dividing network in the support station in a radio telephone network, wherein the received multi-channel antenna signal (ANT) is divided among separate receivers (CH1-CHn) by means of a dividing unit. The dividing unit is made up of a filter (2), an amplifier (3) and a dividing network (1). According to the invention it has, in a cascade (11; 21), N directional couplers (H1-Hn; B1-Bn), there being branched out from the cascade in succession to each of the N receivers (CH1-CHn) a share, according to the coupling (k1-kn) of the directional coupler, of the filtered and amplified antenna signal (4).
Abstract: In a circuit arrangement for the generation of I,Q waveforms, an incoming analog signal controls a voltage-controlled oscillator (1), whose output signal (U1) is frequency-modulated. This signal (U1) is mixed with unmodulated signals by using mixers that are switches (6,7). The signals controlling the switches are either modulated or oscillator-generated rectangular waves. The circuit arrangement can be implemented as an integrated circuit.
Abstract: Mounting base for the transceiver of a mobile telephone for use in vehicles, the transceiver having a rigid boxlike enclosure. The mounting base (10) comprises a baseboard (12) having a main surface (20) and at least four sides (21, 22, 23, 24), at least three resilient brackets (14, 14', 14") extending from the sides of the baseboard. The brackets (14, 14', 14") have clips (16, 16', 16") at their free ends pointing inwardly over the baseboard. For mounting, the transceiver enclosure (110) is placed against the brackets and the transceiver bottom plate (112) against the baseboard (12) so that the bracket clips tightly snap on the transceiver upper edges. Pins (30) and recesses (40) cooperate with corresponding recesses and supports in the enclosure preventing the transceiver enclosure form moving relative the baseboard. The mounting base (10) is well suited for automatic production.
Abstract: Method of mounting a printed circuit board and securing the earthing to a casing. The method includes providing the printed circuit board with projecting parts and an earthing connection on at least one face, providing the casing with corresponding recesses, mounting the printed circuit board so that the projecting parts fit into the recesses to support the board, attaching a flexible sealing strip of electrically conducting material, and placing a lid on the sealing strip, whereby the earthing connection contacts the casing and the sealing strip, securing the earthing connection.
March 1, 1989
Date of Patent:
August 7, 1990
Pekka Hakanen, Lassi Lahti, Jari Suutari, Eero Sirkia, Timo Kallioinen, Heikki Nieminen, Seppo Alaspaa, Kari Salo, Harri Halonen, Markku Rauhanummi
Abstract: Circuitry for compensating for the temperature drift of a phase detector (1) in a phase-locked loop which comprises a phase detector (1), a loop filter (2) and in the feedback branch a voltage controlled oscillator (3) coupled to the phase detector (1). The phase detector (1) is provided with a differential output (I and II), which is coupled to the input terminals (- and +) of the operational amplifier (4) in the loop filter (2), whereby the common-mode temperature drift of the phase detector (1), appearing in the input poles of the operational amplifier, is substantially eliminated in the output of the amplifier (Uout).
Abstract: The invention relates to an RF-shielded hybrid circuit which comprises a printed circuit board (1) of an insulating material, with foils on both sides, components placed on one side of the printed circuit board, and an RF-shield housing (5) made of metal sheet and fitted around at least part of the circuit. It is the object of the invention to provide an RF-shield which can be manufactured automatically and which at the same time ensures a relatively simple and compact structure. In order to achieve this, the RF-shield for the circuit is made up on the one hand of a cup-like cover (5) the peripheral area of which extends substantially around the edge of the printed circuit board (1), with the exception of the area of the connectors (2) of the printed circuit board, and which is placed over the components, and on the other hand of an earth foil (2a) which faces away from the components of the printed circuit board and is soldered by its edge to the peripheral area (5a) of the cover (5).
Abstract: The invention relates to a method for the use of a portable radio telephone, which has a processor (4) controlling and supervising the operation, a keyboard (7) and a display (6), and a card reader (3), in which case, when the radio telephone is being used, the user identification data required by the radio telephone system are read from the card (1). The identification data (21) of the card (1) of the user authorized to use the radio telephone concerned are recorded in the non-erasable memory (5) of the processor (4), whereupon the radio telephone shifts into a mode locked to this card in such a way that its use is possible with only a certain card (1). By means of this method, protection is achieved against unauthorized use of the radio telephone.
Abstract: A circuitry in a diversity unit of an FM receiver for a telephone system having at least two channels for receiving signals, and at least one phase-lock loop. The signals received by the channels which possibly differ from each in amplitude and frequency. Each channel comprises a mixer and a band-pass filter for forming an intermediate-frequency signal. The phase-lock loop has phase-lock branches operably connected between each mixer of the channels which comprises a frequency-phase comparator. The phase-lock loop equalizes the channel signals in phase and amplitude. The phase-lock loop further has a summation circuit for adding the channel signals which have been equalized. The frequency-phase comparator has a single phase-lock branch exiting therefrom along with a voltage-controlled oscillator connected to one of the mixers of one of the channels. The voltage-controlled oscillator has a switch on an input side thereof.