  We have compared simultaneous Ryle Telescope (RT) radio and Rossi X-Ray
Timing Explorer (RXTE) X-ray observations of the galactic microquasar GRS
1915+105. We find that radio emission, and therefore also the radio jet,
requires the presence of long (~100s), hard dips in the X-ray light curve which
seem to have a one-to-one relation with the radio events: each hard dip
produces a new radio "flare". We discuss the characteristic features of the
connection between the hard X-ray states and the radio emission.
