Abstract: A simulator generates a simulated broad-band signal that may include up to nd in excess of 150 harmonics for communication and signal processing applications. Clock signals are fed to a number of counters which cyclically address an EPROM storage that provides a digital waveform pre-programmed as to bandwidth and harmonic content. The digital pre-programmed waveform is fed to a digital to analog converter having a high bit resolution, in excess of 14 bits, so that a broad-band signal having 150 or more harmonics can be accurately generated. The EPROMs may be reprogrammed in accordance with a desired output signal to give a considerable flexibility with regard to bandwidth and harmonic content.

Abstract: A receiver test apparatus that injects a plurality of attenuated test sigs into a receiver under test is improved by contemporaneously injecting a test message to identify the level of the attenuation test signals so that an operator may easily identify the level at which receiver anomalies occur. The test signals and messages are programmed so that testing may be easily reproduced.

Abstract: A programmable time varying attenuator has a reprogrammable digital circuit or impressing an analog attenuation signal on a continuous wave noise signal. This signal is fed to the input of a receiver and since the digital circuitry can be reprogrammed with a known sequence to effect a desired analog attenuation, a receiver's performance can be monitored and evaluated when the attenuated signal or error signal is simultaneously received with information signals. A desired time relationship between the information signals and the time varying attenuating test signal or error signal is maintained since both are slaved to a common standard. The programmable time varying attenuator is programmable independent of the information signal source and, therefore, is adaptable with different sources while being a highly reliable and cost effect device for system testing.