Abstract: A radiotelephone unit for conducting time division mutiplex receiving includes a two intermediate-frequency filters provided with the same performance, and switches for switching alternately the two intermediate-frequency filters every time when a receive slot is changed. First and third receive slots are associated with one IF filter and second and fourth receive slots are associated with the other IF filter.

Abstract: A detachable keyboard for a telephone set is provided in the form of a keyboard card clipped to the headset, which is completely detached from the body when unclipped. Wireless communication between the handset body and keyboard is used when the card is unclipped, while contacts are activated in the clipped position so that the wireless handset then functions as in the case of a non detachable keyboard.

Abstract: A method for measuring by means of a mobile auxiliary device, quality determining parameters of a communications transmission link which is firmly connected to at least one end thereof and includes a central measuring system. Precise determination of the quality determining parameters in one partial link (7) of the communications transmission link, the invention provides for the auxiliary device (12) to transmit a control signal to the measuring system (25). After receipt of the control signal in the measuring system (25), the communications transmission link is subdivided into two partial links (7, 8). Subsequently, it is verified in the measuring system (25) which of the partial links the auxiliary device (12) is connected to, after which the quality determining parameters of the verified partial link (7) of the communications transmission link are measured.

Abstract: In a radio communication apparatus, a switch circuit is connected between a transmitter and first and second antennas. A control circuit is connected to the first antenna and the switch circuit and controls the switch circuit in accordance with a standing wave ratio measured from the first antenna. That is, when the standing wave ratio of the first antenna exceeds a predetermined value, the connection between the transmitter and the first antenna is switched to the connection between the transmitter and the second antenna.

Abstract: Radiotelephones having retractable antenna systems include an antenna, a housing with a transceiver and user interface disposed therein and a non-radiating antenna feed coupled to both the antenna and the transceiver. The non-radiating feed is movably mounted within and extendible from the housing so as to have an extended position and a retracted position. In one embodiment, the antenna is physically supported by the non-radiating feed and is thus mounted in an extended state when the non-radiating feed is in an extended position. and is mounted in a retracted state when the non-radiating feed is in the retracted position. Preferably, the antenna exhibits approximately the same electrical length in both the extended and retracted states, and the antenna is substantially isolated from the housing of the radiotelephone when the antenna is in the extended state.

Abstract: A method and apparatus for improving the quality and transmission rates of speech is presented. Upon connection of a call with a receiving terminal, a communication unit (12, 26, 28, 42, 57, 54, 60) reads a dynamic user-specific speech characteristics model (SCM) table and user-specific input stimulus table and sends them to an appropriate point in the connection path with the receiving terminal. As normal voice conversation begins, the user's speech is collected into speech frames. The speech frames are compared to input stimuli entries in the user-specific input stimulus table, and are used to calculate SCMs which are compared to dynamic user-specific SCM table entries in the dynamic user-specific SCM table to generate an encoded bit stream. Simultaneously, speech characteristics statistics are collected and analyzed in view of multiple available generic SCMs to update and improve the dynamic user-specific SCM table during the progress of the call to closely track changes in the user's voice.

Abstract: A portable speech communication apparatus, preferably a radio telephone, has a flip (14) which is swingable from the apparatus (10). A sound channel is arranged in the flip for guiding sound from at least one speech opening (54, 62) in the flip to a microphone (24) located in the apparatus. The sound channel is formed as a recess (52) in a plate means (50, 60), which is arranged on an essentially even inside (40) of the flip (14).

Abstract: A direct conversion receiver (DCR)(10) comprises amplitude modulated interference (AMI) nulling circuitry (32) for achieving enhanced cancellation of AMI. The AMI nulling circuitry (32) includes a first signal processor (42) and a second signal processor (44) for processing first and second differential output signals, respectively, from a mixer (24a). The first signal processor (42) includes an adjustable transfer function that is controlled by a controller (50). The controller (50) adjusts the transfer function of the first signal processor (42) to equalize the magnitudes of AMI components in the first and second differential output signals. The first and second differential output signals are then combined in a manner which cancels the equalized AMI components.

Abstract: A high frequency apparatus for receiving digital modulated high frequency signal which withstands vibration and is easy to adjust for tuning, yet presents clear oscillation signal. The invented apparatus has an input terminal(101), a mixer(104) which receives at one input the signals supplied to input terminal(101) and at the other input an output signal of local oscillator(103), and output terminals(107,108) to which the output signal of mixer(104) is delivered. A voltage controlled oscillator constituting said local oscillator(103) has an oscillating section and a tuning section; the tuning section has a movable conductive member(119) and a gluing agent(120) for maintaining a state after adjustment. Control loop has a high loop band width which is large enough so as the noise of local oscillator(103) is not dominated by noise of the above mentioned voltage controlled oscillator.

Abstract: A high frequency apparatus for receiving digitally modulated high frequency signals withstands vibration and has a simple tuning adjustment. The apparatus has an input terminal, a mixer which mixes the input signals and an output signal from a local oscillator, a voltage controlled oscillator which includes the local oscillator, an oscillating section, a movable conductive member and, a gluing agent for maintaining an adjusted state, and a control loop having a high loop band width which is large enough so that noise of the local oscillator is not dominated by noise of the voltage controlled oscillator.

Abstract: In a transceiver switchover arrangement for alternating connection of a first and a second receiver apparatus, and a first and a second transmitter apparatus, with a single antenna, the first receiver apparatus and the first transmitter apparatus are designed for a first frequency band f1, and the second receiver apparatus and the second transmitter apparatus are designed for a second frequency band f2. By means of on-off switches, in connection with two line sections, of which each represents a quarter-wave line for f2, and which serially represent a quarter-wave line for f1, one of the apparatuses is coupled to the antenna according to the mode of operation.