Abstract: A low-loss RF coupler for testing a cellular telephone through the antenna mount has a base with a hole large enough to fit over said antenna mount and a ground plane extending over a surface of the base. The hole has a contact portion which is electrically isolated from the ground plane by an airgap. A pair of transmission lines is provided, one having a signal portion electrically connected from the contact portion to the test equipment and the other having a ground portion electrically connected from the ground plane to the test equipment.

Abstract: A noise squelch circuit for a radio receiver (100) includes an adaptive filter (204) for shaping frequency characteristics of a demodulator out put (115) according to factors which effects squelch sensitivity. Such factors may include channel spacing of the receiver, received signal strength level, received signal deviation, and SINAD. The adaptive filter (204) comprises a switched capacitor filter, the response of which may be controlled by a control signal (212) according to one or more of such factors.

Abstract: A squelch tail circuit (20) is provided capable of incorporation within integrated circuit structures. A digital timer (26 and 27) provides a time delay based upon a feed-back comparison providing a long time delay to weak signals and a short time delay to strong signals. A comparator (22) is provided to activate the time delay upon signal loss.