Abstract: Methods and devices provide a test signal to each of a plurality of antenna channels via a test signal line. Each antenna channel includes an amplitude adjustor and a phase adjustor associated with at least one antenna element. For each antenna channel, the test signal provided to the antenna channels is modulated to produce a modulated test signal. The modulated test signal is produced by: i) controlling the amplitude adjustor of the antenna channel to vary a current amplitude of the test signal between a plurality of amplitude states, and ii) controlling the phase adjustor of the antenna channel to vary a current phase of the test signal between a plurality of phase states. A received test signal received from the antenna channels is processed to determine amplitude and phase errors associated with the modulated test signals associated with the antenna channels.

Abstract: Apparatus for inserting transmit diversity into an RF signal for transmission, comprises: an RF splitter for splitting the RF signal to be transmitted into two signal parts, and a non-linear phase modulator which applies a non-linear phase modulation to one of the two signal parts, thereby to provide transmit diversity between the first signal part and the second signal part. One of the ways of inserting a non-linear phase modulation into the RF signal is to use a spinning disc with tracks of different dielectric strength. The apparatus is useful in cellular telephony for supplying repeaters and base station extensions with diversity capability.