• FDM-FM COCHANNEL INTERFERENCE IDENTIFICATION SYSTEM

      Chang, Horen; Alvarez, Richard; Lee, Wilfred; Niwa, Kunihiko; Rieger, Frederic J.; Stanford Telecommunications, Inc.; International Telecommunications Satellite Organization; Comsat Laboratories (International Foundation for Telemetering, 1982-09)
      A prototype interference identification system has been developed to detect and identify interfering FDM-FM carriers originating within the INTELSAT* system. Interfering carriers are identified by distinctive code (signature) modulation of the energy-dispersal waveform of each FDM-FM carrier. Identification presently is accomplished within 10 minutes for ratios of interfering carrier power to noise power down to -2 dB, and for ratios of interfering carrier power to desired carrier power down to -17 dB. Possible improvements are discussed for more rapid identification.
    • PRESAMPLING FILTERING, SAMPLING AND QUANTIZATION EFFECTS ON THE DIGITAL MATCHED FILTER PERFORMANCE

      Chang, Horen; Stanford Telecommunications, Inc. (International Foundation for Telemetering, 1982-09)
      Due to the increased capability and reduced cost of digital devices, there has recently been a growing trend to digitize the matched-filtering data detector in the receiver. Comparing with an idealized integrate-and-dump analog matched filter, the digital matched filter (DMF) requires more Eb /No in order to achieve the same bit error rate performance because of the presampling filtering, sampling, and quantization effects. This paper analyzes the performance degradation resulting, separately and jointly, from these three effects. Quantitative results are provided for commonly chosen sets of design parameters. For a given performance degradation budget and complexity limitation, these results could be applied to choose the optimum DMF design parameters including the presampling filter bandwidth, the sampling rate, the number of quantization bits, and the spacing between adjacent quantization levels.