1/2 f_s direct RF under sampling receiver for multi channel satellite systems

RF under sampling is more suitable for Satellite receiver systems in comparison to terrestrial systems. In conventional RF under sampling the minimum sampling frequency (f_s) should be atleast twice the system bandwidth; therefore for a system with a wide bandwidth, a relatively high f_s is necessary. In this paper we propose a direct RF under sampling reception method that halves f_s. The proposed f'_s is achieved by folding in band noise in half. A method of adapting f'_s for the reception of signals in different channels is also proposed; this ensures that the SNR is not degraded for any channel. To evaluate the proposed technique's performance and compare it to the conventional case a 3 channel, 1 GHz band test receiver and it's key device (i.e. S/H circuit) are developed. Using SNR and EVM as performance indexes, the performance of the proposed technique has been evaluated and compared to that of the conventional technique. The evaluation results show that the proposed technique can achieve the same performance as conventional RF under sampling for all 3 channels, using only half of the sampling frequency of the conventional technique.