A longitudinal broadband damper system to control coupled bunch instabilities has been developed and installed in the 920 GeV proton accelerator HERA–p at DESY. The control path consists of a FPGA–based digital controller, a vector modulator, a 1 kW power amplifier, a kicker-cavity and the beam itself. The bunch phase signals are sampled by a digital FPGA board with 14 Bit ADCs and 10.4 MHz. Phase calculation for all bunches and offset correction is done by a digital filter realized in FPGA software. The filter has to deal with a slowly changing synchrotron frequency. Here we considered a filter design which treats each of maximum 220 bunches as an independent oscillator which has to be damped. With the FPGA–board output signals a 104 MHz sine wave is modulated. The resulting logitudinal correction kick signal is provided by the kickercavity to kick the proton bunches each with its correction kick voltage. Besides the technical details we present first operational experience and the actual system performance in a series of 3 papers (see also [1, 2]).