Abstract: An oscillator circuit (200) is provided having a crystal oscillator (202) operating in a first oscillator mode to produce an oscillator output signal (201). The oscillator output signal (201) has a desired frequency of operation. The oscillator circuit (200) also includes switches (206A and 206B) for selectively forcing the crystal oscillator (202) to operate in a second oscillator mode in order to shift the frequency of the oscillator output signal (201).

Abstract: A four port antenna switch (300) for switching a receive port (320) and a transmit port (310) between a remote antenna port (330) and a standard antenna port (340) is provided. The switching actions of the receive port (320) between the remote antenna port (330) and the standard antenna port (340) is provided by a relay (350) under the control of a relay controller (352, 354, 400). The switching of the transmit port (310) between the standard antenna port (340) and the remote antenna port (330) is provided by diode switches (360, 370) under the control of diode switch controllers (332, 324, 312, 314, 400). The switching actions of the relay (350) and the diode switches (370, and 360) is complementary to each other, wherein sufficient isolation between the receive port and the transmit port is provided. In this arrangement, a low power relay may be used because the relay only switches low level received signals, and the high power transmit signals are switched by the pins.

Abstract: Eliminating self quieting in a receiver by operating the crystal oscillator in a parallel mode of operation until a harmonic falls within the passband of the receiver and then switching the oscillator to a series mode of operation, which is separated sufficiently from the parallel mode of operation so that no harmonics fall within the passband.