  Radial velocity curves for 15 bright subdwarf B binary systems have been
measured using high precision radial velocity measurements from high S/N
optical high-resolution spectra. In addition, two bright sdB stars are
discovered to be radial velocity variable but the period could not yet be
determined. The companions for all systems are unseen. The periods range from
about 0.18 days up to more than ten days. The radial velocity semi amplitudes
are found to lie between 15 and 130 km/s. Using the mass functions, the masses
of the unseen companions have been constrained to lower limits of 0.03 up to
0.55 M_sun, and most probable values of 0.03 up to 0.81 M_sun. The invisible
companions for three of our program stars are undoubtedly white dwarfs. In the
other cases they could be either white dwarfs or main sequence stars. For two
stars the secondaries could possibly be brown dwarfs. As expected, the orbits
are circular for most of the systems. However, for one third of the program
stars we find slightly eccentric orbits with small eccentricities of
e~0.02-0.06. This is the first time that non-circular orbits have been found in
sdB binaries. No correlation with the orbital period can be found.
