Investigation of non chirped NRZ, chirped NRZ and alternate-chirped NRZ modulation techniques for free space optic (FSO) systems

Rezki El Arif*, M. B. Othman, S. H. Pramono

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Free Space Optics (FSO) is the technology where transmission occurs through optical waveform that contains data transformed at the transmitter from electrical signal. Since the transmission medium of FSO is atmosphere, atmospheric scattering is the major cause for interruption of FSO link. Non return zero (NRZ) modulation is the dominant modulation scheme employed in commercial terrestrial Free Space Optic (FSO) communication systems. This research are required to investigate three viable modulation techniques; non-chirped NRZ, chirped NRZ, and alternate-chirped NRZ at 10 Gb/s and 40 Gb/s data rate. The 1550 nm of continuous wave (CW) laser is modulated with three different modulation formats over 1 km of FSO channel. The signal is propagated at different attenuation value based on Malaysia weather conditions. In this paper we have successfully compared the three modulation techniques in FSO system due to the Malaysia weather and the performance is accessed at bit error rate (BER) of 1x10-9. The presented simulation of these three modulation shows that alternate-chirped NRZ has slightly better performance compared to the non-chirped NRZ and chirped NRZ modulation format at clear weather, haze, light rain, medium rain and heavy rain. We believe that, this system is an alternative for the future optical wireless network that has a potential to be installed in the urban and sub-urban area.

Original languageEnglish
Pages (from-to)8731-8735
Number of pages5
JournalARPN Journal of Engineering and Applied Sciences
Issue number19
Publication statusPublished - 2015
Externally publishedYes


  • Chirping
  • Free space optic
  • Modulation
  • Non return zero


Dive into the research topics of 'Investigation of non chirped NRZ, chirped NRZ and alternate-chirped NRZ modulation techniques for free space optic (FSO) systems'. Together they form a unique fingerprint.

Cite this