Error correction in the Gaussian beam telescope applicated to the new 40 m radiotelescope of Centro Astronómico de Yebes

✍ Scribed by E. García; C. O'Sullivan; E. Rajo; J. L. Vázquez

• Book ID: 102519393
• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 280 KB
• Volume: 48
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.21849

✦ Synopsis

2 ) should be the same as that (a 2 A 2 A 3 ) of lower injected-generation term (2 1 Ϫ 2 ). The phases between lower IMD3 and lower injected-generation term need to be out-of-phase. The phase of harmonic signal was adjusted and optimized by using RF phase shifter. The same logic was applied to reduce upper IMD3 (2 2 -1 : 1.3 GHz) with the magnitude/phase control of harmonic (2.4 GHz) in the feedback loop.

As shown in Figure 3(b), intermodulation distortion products were significantly reduced in 1 GHz bands. The experimental result showed that the CNR enhancement of 12 dB when compared with free-running operation was achieved by optimization of RF magnitude and phase. Figure 4 shows the received RF power of the fundamental signal (1.2 GHz) and IMD3 (1.3 GHz) with variation of input RF power for both free-running and the proposed schemes. As expected, the SFDR was improved from 72 to 81 dB Hz 2/3 by 9 dB with the proposed scheme.

4. CONCLUSION

A novel technique of intermodulation products reduction using the feedback harmonic injection in DFB LD for RoF link was proposed. The proposed scheme is mainly composed of a photodiode, two BPF, and RF phase shifter/amplifier. This scheme is capable of suppressing IMD up to 12 dB when compared with that of free-running DFB LD for RoF transmission link.