System for testing a modem

Claim 1

System for the remote testing of a modem for two bit rates different from one another, particularly for viewdata traffic, the part for the higher bit rate being connected in the state of testing via a speed converter to the part for the lower bit rate, characterized by an error detector between the speed converter (14) and the transmission channel of the modem (12) to be tested, which error detector comprises some logic circuits, controlled by delayed clock pulses derived from a test signal, of which logic circuits a first circuit (21) is or remains conductive owing to a leading edge of the test signal, a second circuit (25) is or remains conductive owing to a trailing edge of the test signal, a third circuit (23) serves for resetting the first circuit and a fourth circuit (27) serves for resetting the second circuit, a fifth circuit (29) has an "AND"-function for the outputs of the first and the second circuit, and a sixth circuit (17) has an "EXCL-OR"-function for the output signal of the speed converter (14) and the clocked output (32) of the fifth logic circuit (29), and the clocked output (18) of the sixth logic circuit (17) is connected to the modem part for the lower bit rate.