KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Author: search.filters.author.Magkeethum, Apiwat

Search Results

Now showing 1 - 3 of 3
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    A Novel Multi-Slope Chirp Modulation and Demodulation with Instantaneous Chirp Rate Estimation
    (2026-05-01)
    Magkeethum, Apiwat
    ;
    Saechia, Sukkharak
    ;
    Wardkein, Paramote
    The growth of Internet of Things (IoT) applications is driving demand for Low-Power Wide-Area Networks (LPWANs) to support higher data rates with the same energy efficiency. While Long Range (LoRa) provides excellent noise immunity and receiver sensitivity, its data rate might be insufficient for some applications, including those real-time applications in which LoRa is required to have infrequent transmissions to maintain low power consumption. In this paper, a novel modulation is introduced to address these limitations by utilizing narrowband chirp to represent a data symbol with chirp slopes, called a multi-slope chirp signal. At the receiver, a new blind non-coherent detection technique is also presented to recover the proposed signal. The simulation results confirm that the proposed scheme can successfully transmit information at 2 to 4 bits per symbol, and when compared to LoRa SF 6, it reduces the Time-on-Air (ToA) by half and also achieves an improvement in spectral efficiency in the frequency domain.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    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.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    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.