  An internal shock model is proposed to interpret the radio to infrared (IR)
emission of the compact jets observed in the hard spectral state of X-ray
binaries. Assuming that the specific bulk Lorentz factor of the jet at its base
varies with a flicker noise power spectrum (i.e. P(f)~1/f), I estimate the
energy dissipation profile along the jet and the resulting partially
self-absorbed synchrotron emission. For this type of velocity fluctuations, and
a conical jet geometry, the shock dissipation at large distance from the black
hole balances exactly the adiabatic losses. This leads to a flat radio to IR
spectral energy distribution similar to that observed in compact jets.
