Abstract: In order to verify the feasibility of digital pulse interval modulation（DPIM）used in ultraviolet(UV) communication, a DPIM modulation and demodulation system was designed based on field programmable gate array (FPGA). The deserialized data was input into the comparator under the control of latch during modulation process, and the DPIM modulation signal was output through comparing with the count value. In the demodulator, the number of free slot between neighbor pulses was detected by counter, and the original data was acquired through recovering under the control of latch. In the case of 16-DPIM, we input a set of serial binary data randomly and output 16-DPIM signal in modulation system. In the same way, we input a 16-DPIM modulation signal randomly and recovered the original data in demodulation system. On the basis of this analysis, a new dual-amplitude fixed-length DPIM modulation which could make up the lack of the DPIM symbol length change was proposed.