  We present algorithms for initializing a convolutional network coding scheme
in networks that may contain cycles. An initialization process is needed if the
network is unknown or if local encoding kernels are chosen randomly. During the
initialization process every source node transmits basis vectors and every sink
node measures the impulse response of the network. The impulse response is then
used to find a relationship between the transmitted and the received symbols,
which is needed for a decoding algorithm and to find the set of all achievable
rates. Unlike acyclic networks, for which it is enough to transmit basis
vectors one after another, the initialization of cyclic networks is more
involved, as pilot symbols interfere with each other and the impulse response
is of infinite duration.
