Indonesian Journal of Electrical Engineering and Computer Science Vol. 31, No. 3, September 2023, pp. 1408~1419 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v31.i3.pp1408-1419  1408 Journal homepage: http://ijeecs.iaescore.com Implementing and developing secure low-cost long-range system using speech signal processing Samer Alabed 1 , Amer Alsaraira 1 , Nour Mostafa 2 , Mohammad Al-Rabayah 2 , Yehia Kotb 2 , Omar A. Saraereh 3 1 Department of Biomedical Engineering, School of Applied Medical Sciences, German Jordanian University, Amman, Jordan 2 College of Engineering and Technology, American University of the Middle East, Kuwait 3 Department of Electrical Engineering, Faculty of Engineering, The Hashemite University, Zarqa, Jordan Article Info ABSTRACT Article history: Received Apr 12, 2023 Revised May 6, 2023 Accepted May 9, 2023 In the proposed work, we present a secure low-cost speech communication system for long-distance communication. The system utilizes long range (LoRa) technology to transmit speech signals. LoRa technology uses spread- spectrum modulation to enable long-range communication with low power consumption. LoRa modulation allows for data transfer at a slow speed, typically below 22 kbps, which makes it infeasible for transmitting speech. To address this limitation, we suggest a speech coding technique that reduces the overall data rate of speech signals to below 7.5 kbps. This lower rate is more compatible with the LoRa module and ideal for transmitting speech. Moreover, this technique can improve the LoRa transmission range. Additionally, we have developed an encryption-decryption method to ensure the privacy of the messages and prevent unauthorized access by third parties. Keywords: Design implementation Encryption techniques Internet of things Long range networks Signal processing Speech processing This is an open access article under the CC BY-SA license. Corresponding Author: Samer Alabed Department of Biomedical Engineering, School of Applied Medical Sciences German Jordanian University Amman, 11180 Jordan Email: samer.alabed@gju.edu.jo 1. INTRODUCTION Low-cost long-range wireless communication systems are becoming increasingly popular due to their ability to transmit information over long distances without the need for physical cables or wires [1]-[5]. These systems are used in a wide range of applications, including military and defence, remote sensing, smart city applications, healthcare and medical applications, environmental monitoring, agriculture and telecommunications. There are several types of long-range wireless communication systems, including satellite communication systems, radio frequency communication systems, and microwave communication systems. These systems use different types of technologies and operate at different frequencies [6]-[8]. Long range (LoRa) is a wireless communication technology that provides a long-range, low-power solution for the internet of things (IoT) devices [9]-[11]. LoRa uses spread-spectrum modulation, which allows for long-range communication with low power consumption. It operates in the unlicensed radio frequency bands, which means that it is available for use without any licensing fees. LoRa devices can communicate over distances of several kilometres, making it an ideal solution for IoT devices that need to be deployed over a large area [11]-[13]. LoRa technology offers low power consumption, which is essential for battery-powered IoT devices. It also provides high network capacity and can support a large number of devices, making it suitable for large-scale IoT deployments. LoRa is a proprietary low-power, wide-area network (LPWAN) technology developed by Semtech Corporation [9]-[12]. Currently, LoRa technology is utilized in various domains, including but not