A power amplifier used in a portable, radio frequency transmitter is switched between different modes of operation when transmitting differently modulated carriers. The first mode of operation corresponds to amplitude modulation (AM), while a second mode corresponds to angle modulation techniques such as frequency modulation (FM). A switching network alters the impedance of the power amplifier to match network for matching the impedance of the transmitter antenna in order to achieve maximum efficiency in each mode of operation. Various switching methods and impedance matching circuits are disclosed.

AM-FM transmitter power amplifier

A detachable element such as a headset ( 20 ) which stowable in a mobile electronic device (e.g., cellular phone ( 10 )) is described. In one embodiment, while in the phone ( 10 ) the headset ( 20 ) serves as the phone ( 20 ) speaker and microphone. Upon detachment from the phone ( 10 ) the headset ( 20 ) spontaneously changes its shape to facilitate user convenience. A wireless version of the handset ( 20 a ) automatically enters a stand-alone operational mode when detached from the phone ( 10 ). Separate and distinct embodiments of the headset ( 20 ) and ( 50 ) exist for a single piece phone ( 10 ) and a flip-type phone ( 40 ) respectfully.

Wireless apparatus with detachable element

A digital radar landmass simulator (DRLMS) used for stimulation testing pulse radars, wherein the DRLMS operates by synthesizing time-overlapping chirp waveforms using finite impulse response filters. The DRLMS, thus, effectively generates many overlapping complex pulse signals from many radar reflectors representing a semi-infinite continuum of closely spaced targets. The DRLMS also allows the insertion/injection of the effects of Doppler shift and jamming into the synthesized modulated signal.

Synthesis of overlapping chirp waveforms

In many systems now in use for sending digital data from a controlled station (e.g., a transmitting station), generally indicated at 10 in FIG. 1 , to a controlling station (e.g., a receiving station) generally indicated at 12 , a plurality of hopping frequencies are provided. In such systems, a first packet is transmitted from the controlled station 10 to the controlling station 12 at a first one of the hopping frequencies in the plurality. The data in a second one of the packets is then transmitted from the controlled station 10 to the controlling station 12 at a second one of the hopping frequencies. The data in a third one of the packets is subsequently transmitted from the controlled station 10 to the controlling station 12 at a third one of the hopping frequencies. The sequence of the different hopping frequencies for use as the carrier for the transmission of the successive data packets from the controlled station 10 to the controlling station 12 is known to the controlled station and the controlling station. By providing a sequence of different hopping frequencies for the transmission of successive data packets from the controlled station 10 to the controlling station, the controlling station 12 is able to differentiate the data packets, transmitted to it through a communication channel or by wireless, from a vast number of other data packets which are transmitted from other controlled stations to other controlling stations.

System for, and method of, providing frequency hopping

To harden transmissions, in both directions, between a master station (1) and a slave station (2), a table of communication parameter values is memorized in each station and the table values are then used in accordance with the master station's decision. Each message from one station to the other contains information to allow the receiving station to determine the parameter values to be selected in the table to eliminate values where there is a high risk of jamming.

Method of hardening transmissions, in particular between a control station and a transponder, and a device implementing the method

A frequency agile signal generator provided for emulating a communication signal of predetermined frequency and modulation characteristics including frequency hopping. The signal generator includes a digital controller such as a microprocessor or microcomputer for generating digital command signals specifying the desired characteristics of the output signal. In response to the digital command signals, a base digital frequency signal representing the desired base or center frequency of the output signal is generated by a number controlled oscillator in response to a digital frequency control signal. The digital command signals also control the generation of an analog modulation signal having desired modulation characteristics. For frequency modulation, the analog modulation signal is converted to a digital signal in the frequency domain and is algebraically summed with the frequency control signal to control the frequency of the number controlled oscillator output signal as a function of both the digital frequency control signal and the digital modulation signal. The number controlled oscillator output signal is converted to analog form to provide an analog output signal. The analog output signal can be amplitude modulated and/or attenuated as commanded by the digital command signals. For amplitude modulation, the analog modulation signal in the time domain is used directly under the control of the digital command signals as a mixer input to amplitude modulate the analog output signal or for on/off keying.

Charles W. True

Papers

Frequency agile signal generator for emulating communications environments