A novel optical single-sideband (OSSB) signal generation with simultaneous IF signal up conversion technique is proposed to overcome the fiber dispersion problem. With this up-conversion technique, a high frequency OSSB signal is generated by using two low bandwidth intensity modulators in combination with fiber gratings. The low frequency local oscillator (LO) signal is modulated by employing frequency doubling technique or frequency quadrupling technique respectively. The OSSB radio frequency (RF) signal generated by mixing the intermediate frequency (IF) signal and low frequency local oscillator (LO) signal, is transmitted over standard single-mode fiber successfully. The received signal error vector magnitude (EVM) is 5.8% rms and 13% rms.
A novel method is proposed for optical up-converted single-sideband (OSSB) signal generation in radio over fiber links, which can realize optical carrier reuse synchronously. The OSSB signal is generated in order to overcome the fiber dispersion problem by using two intensity modulators in combination with fiber gratings. With this up-conversion technique, a 25 GHz OSSB radio frequency signal is generated by mixing an intermediate frequency signal (5 GHz) and low frequency local oscillator signal (10 GHz). The signal is transmitted over 25 km standard single-mode fiber successfully. And the received signal error vector magnitude is 5.8% root mean square, with eye diagram widely open.
Instantaneous frequency measurement (IFM) of input unknown microwave signals is critical importance for modern radar warning receivers in the field of electronic warfare. The photonic techniques have attracted more and more attentions for IFM due to the advantages of wide bandwidth, low loss, light weight, and immunity to electromagnetic interference. In this paper, a photonic approach to IFM with extended range based on phase modulation is presented. In the proposed measurement system, two optical wavelengths and two segment dispersion fibers are used to construct the frequency-dependent amplitude comparison functions (ACFs). Several ACFs can be jointly utilized to determine the microwave frequency without ambiguities beyond a monotonic region of the conventional one ACF. Then the measurable range of microwave frequency can be extended and the accuracy can be improved by selection of ACF with large slope. The operation principle of the photonic approach is illustrated and the experiment results show that the errors are limited within ±0.15 GHz from 8 to 20GHz frequency measurement range.
A novel technique for instantaneous frequency measurement of unknown microwave signal based on both phase
modulation and intensity modulation is theoretically and experimentally demonstrated. Based on the output microwave
power through dispersive fiber links, three amplitude comparison functions (ACFs) are established, which are combined
to measure the frequency of input microwave signal with improved measurable range and accuracy. In the frequency
estimation process, the measured calibration ACFs are utilized as the look-up table. The experiment results show that
measurement error smaller than 200 MHz can be obtained for the frequency from 0.5 GHz to 20 GHz.