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Author: search.filters.author.Magkeethum, ApiwatSubject: search.filters.subject.SAGC

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    SAGC circuit design and implementation for FSK modem through radio channel
    (2021-05-19)
    Sutam, Apichat
    ;
    Magkeethum, Apiwat
    ;
    Wardkein, Paramote
    ;
    Koseeyaporn, Jeerasuda
    ;
    Sae-Chia, Sukkharak
    In this research, the sinusoidal automatic gain control circuit (SAGC) has been fabricated by using differentiator circuits, multiplier circuits, a summation circuit, a square root circuit and a division circuit. By using an Operational amplifier (Op amp) and 2 capacitors, the differentiator circuit has been constructed An Op amp and IC AD633 used as a multiplier are combined for fabricating the square root circuit [1]. Apart from evaluating the SAGC characteristics, the FSK recovery process for transmitting the (Global Positioning System) GPS coordinates through radio channel has been improved via the proposed SAGC circuit. The results show that the proposed circuits and its implementation operate perfectly and agree well with the conventional theory.
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    A Novel Chirp Demodulation Scheme Based on SAGC for Amateur Radio Data Transmission
    (2021-01-01)
    Sae-Chia, Sukkharak
    ;
    Magkeethum, Apiwat
    ;
    Wardkein, Paramote
    Based on the sinusoidal automatic gain control scheme (SAGC), an equalizer implementation and a chirp demodulator have been proposed. With the 1-unit constant of SAGe output amplitude, an application as an equalizer has been implemented in order to eradicate the unwanted cut- off frequency characteristic of an amateur radio. According to loss of radio reception caused by the multipath fading phenomenon, a chirp modulation has played an important role to attenuate strong interferences in wireless communication. Thus, chirp demodulation based on modified SAGC has also been proposed in this paper. The equalizer application's result shows that the chirp signal amplitude has been stabilized to 1 unit at any carrier frequencies. Furthermore, the sawtooth wave has been recovered by using SAGC chirp demodulation before comparator and sample hold block generate the information data. By the SNR range from 1 dB to 10 dB, the BER of the proposed SAGC chirp demodulation scheme is lower than the conventional one.