  We describe a new software package for simulating channelised, high-time
resolution data streams from radio telescopes. The software simulates data from
the telescope and observing system taking into account the observation
strategy, receiver system and digitisation. The signatures of pulsars, fast
radio bursts and flare stars are modelled, including frequency-dependent
effects such as scattering and scintillation. We also simulate more generic
signals using spline curves and images. Models of radio frequency interference
include signals from satellites, terrestrial transmitters and impulsive,
broadband signals. The simulated signals can also be injected into real data
sets. Uses of this software include the production of machine learning training
data sets, development and testing of new algorithms to search for anomalous
patterns and to characterise processing pipelines.
