Impact of Finite Frequency Deviation on the Performance of Dual-Filter Heterodyne FSK Lightwave Systems
Abstract
A detailed theoretical analysis is given for the impact of finite frequency deviation on the sensitivity of dual-filter heterodyne Frequency Shift Keying (FSK) lightwave systems. Our analysis provides closed-form signal-to- noise ratio (SNR) results for estimating the bit-error-ratio (BER) performance of the system. These closed-form results provide an insight into the impact of finite frequency deviation 2 Delta fd, laser linewidth Delta v, bit rate Rb, and IF filter bandwidths on the system performance. It is shown that there is a well-defined relationship between the choice of frequency deviation and the tolerable amount of laser phase noise. When there is no phase noise, a frequency deviation of 2 Delta fd = 0.72Rb, is sufficient for 1 dB sensitivity penalty with respect to infinite frequency deviation case; whereas for a linewidth of Delta v = 0.5ORb the required frequency deviation increases to 2 Delta fd = 3. 42Rb for the same sensitivity penalty. The sensitivity degradation can be very severe for a fixed linewidth as the frequency deviation gets smaller: for a linewidth of 20% the sensitivity penalty is only 0.54 dB when the frequency deviation is infinite whereas it is 3.48 dB when the frequency deviation is 2 Delta fd = Rb. We also quantify the impact of finite frequency deviation on optimum IF filter bandwidths. For a fixed linewidth, the optimum IF filter bandwidth decreases as frequency deviation becomes smaller: for Delta v = 0.5Rb the optimum IF filter bandwidth reduces from 7Rb to 3Rb when 2 Delta fd reduces from very large values to 3Rb.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA247611
Entities
People
- Leonid G. Kazovsky
- M. O. Tanrikulu
- Ozan K. Tonguz
Organizations
- University at Buffalo