• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.7
• /
• pp.610-615
• /
• 2014

Filterbanks have been widely used in the field of multi-channel signal processing for their simple efficient implementation architectures. Especially, the polyphase DFT(Discrete Fourier Transform) filterbank is the most preferred filterbank for the uniform spaced multi-channel processing due to its simplicity. In frequency hopped communication systems, however, the use of the polyphase DFT filterbank is limited due to its undesirable transient response from hop-to-hop transitions. In this paper, the transient response of polyphase DFT filterbanks in the hop-to-hop transition was analyzed, and the efficient methods to overcome such a problem was proposed. Simulation results showed that the proposed schemes could resolve this issue efficiently.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.4
• /
• pp.789-796
• /
• 2013

It is known that the detection of hopping signals without any information about hopping duration and hopping frequency is rather difficult. This paper considers the blind detection of hopping signal's information such as hopping duration and hopping frequency from the sampled wideband signals. In order to find hopping information from the wideband signals, multiple narrow-band filters are required in general, which leads to huge implementation complexity. Instead, this paper employs the polyphase DFT(discrete Fourier transform) filterbank to reduce the implementation complexity. This paper propose hopping signal detection algorithm from the polyphase DFT filterbank output. Specifically, based on the binary image processing, the proposed algorithm is developed to decrease the memory size and H/W complexity. The performance of the proposed algorithm is evaluated through the computer simulation and FPGA (field programmable gate array) implementation.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.49 no.7
• /
• pp.39-47
• /
• 2012

The combination of the broadband property and the wide area coverage of satellite communications enables high speed transmission. Every user in the region under the satellite beam coverage can tranceiver and one can simultaneously communicate with multiple users. For these reasons, it is one of commendable telecommunication networks for information transfer. Since the satellite communications use open channels, it is likely to cause jamming with unwanted interference signals. In the thesis, APSK (Amplitude Phase Shift Keying) is employed, which is recommended for DVB-S2 due to high-speed transmission and excellent bandwidth efficiency. For obtaining reliable communication under the jamming environments, the communication satellite transponder rests on the polyphase filter bank structure, which enables switching among the subchannels and gain control on each subchannel, resulting in effectively eliminating jamming. Furthermore, the nulling scheme, one of the various anti-jamming approaches, is investigated, in which unwanted jamming signals are eliminated in the frequency domain after passing through the analysis part of the polyphase filter bank. The performance of the nulling scheme is evaluated for tone jamming and partial band jamming in terms of BER and EVM. The simulation results indicate that the nulling scheme improve the BER and EVM performance over the case without any anti-jamming approach.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.7
• /
• pp.641-647
• /
• 2015

In this paper, Analyzed the multi-channel signal processing algorithms for digital-transponder. To analyze suitable multi-channel signal processing algorithms, compare algorithms about four criteria. Four criteria are as follows, perfect reconstruction, interference rejection, resource usage and power consumption. Analysis for each algorithm in accordance with these four criteria. then propose the multi-channel signal processing algorithms for digital satellite communication system.