| 摘要 |
<p>A test apparatus for transmitting a test signal to a device under test (15) a such as a mobile (cell) phone and for receiving from that device a return signal whereby to determine the ability of the device under test to deal with radio frequency signals the frequency of which are offset from a predetermined protocol, said apparatus comprising a transmit means (11) for producing a test signal the frequency of which varies in successive transmit periods and a receive means (12) for receiving from the device under test a signal the frequency of which varies in successive receive periods, the frequency determining components in the transmit means and the receive means comprising at least one phase locked loop (16, 23, 41, 52), the transmit means including first phase locked loop means to vary the radio frequency transmitted by said transmit means in accordance with the predetermined protocol and further phase locked loop means to offset the radio frequency transmitted by said transmit means to thereby produce said frequency offset.</p> |
