A turbidity telemetry system for COVID-19 pandemic situations using nRF24L01+transceiver and SEN0189 water turbidity sensor-based microcontroller has been successfuly  developed.. The method used to characterize the sensor is by comparing sensor output voltages with the value of water turbidity. Turbid water used was created by adding distilled water with a concentration of sediment obtained from the filtered sediment with less than 60 μm in diameter. Data transmission performance for various transmit power was done by calculating the error percentages by comparing the number of messages sent by transmitter and received by receiver. The transmit power settings were 0, -6, -12, and 18 dBm and variations in the distance of data transmission from 10 to 80 m. The test results show that the water turbidity sensor has a good measurement range in measuring turbidity of water from 1.873 to 3500 NTU. Higher concentrations of sediment and turbidity of the water made the sensor output voltage decrease. There was a decrease in output voltage in the value, namely -0.0006 in turbidity sensor sensitivity. The results also show an increase in error percentages as the distance of data transmission increases, while the bigger the transmit power is used for data transmission, the smaller the percentage of errors occurs.

Turbidity has an indication that the liquid has been contaminated. In the testing process, turbidity in water can only be measured by sampling. To be able to maintain the quality of water, required a tool that can monitor and measure the level of turbidity of water in real time. water turbidity sensor SEN0189 is a sensor that works by measuring the amount of light from infrared led into the phototransistor that will produce the output voltage on the sensor. The study was conducted to be able to characterize the ability of sensors in detecting water turbidity. The method used is to test the sensors using sediment soil that has been filtered with a diameter of <60μm to be added into the pond containing 1 liter of water. The results show that the greater the concentration of sediment dissolved in the water pool the sensor output voltage will be smaller. The sensor has a sensitivity of -0.0008 and the output voltage when the sensor detects 0 NTU is 3.9994 volts with 5V operating voltage and the sensor can detect water turbidity linearly within the test range 1.873 NTU to 1011.93 NTU.

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ABSTRAKSTiga perempat wilayah Negara Kesatuan Republik Indonesia (NKRI) merupakan wilayah perairan.NKRI adalah negara kepulauan dengan jumlah pulau terbanyak di dunia yaitu 17.504 pulau serta mempunyai panjang garis pantai terpanjang kedua di dunia setelah Kanada. Kebiasaan nelayan Indonesia memasuki wilayah perairan negara lain membuat nelayan Indonesia ditangkap oleh penegak hukum negara lain. Kebiasaan nelayan Indonesia memasuki wilayah perikanan Australia kerap menimbulkan pasang surut hubungan kedua negara. Oleh karena itu, dalam penelitian ini dibuat prototipe perangkat yang dapat memberikan informasi kepada nelayan ketika berlayar bahwa posisi kapal melanggar batas perairan negara lain atau tidak. Sebagian besar kapal-kapal nelayan tradisional tersebut tidak dilengkapi dengan alat navigasi yang memadai. Sehingga perlu perangkat yang dapat memberikan informasi dini kepada jika telah mendekati batas zona perairan negara lain. Prototipe dibuat dengan menggunakan Arduino Mega 2560 / Arduino Uno dan GPS Neo-6M. Modul GPS Neo 6M digunakan sebagai penentuan lokasi posisi kapal kapal, posisi kapal latitude (x) dan longitude (y). Kemudian titik-titik pada garis perbatasan garis, data latitude (x i ) dan longitude (y i ) diinputkan terlebih dahulu dalam mikrokontroller. Mikrokontroller menghitung jarak posisi kapal dengan titik-titik pada garis perbatasan. Dari pengujian dan pengambilan data yang telah dilakukan, diketahui bahwa rata-rata error dengan Arduino Mega adalah 3,19 % dan dengan menggunakan Arduino Uno nilai error (rata-rata) adalah 5,32 %.

Thermistor is one of temperature sensor which works based on resistance changes and can be used as a temperature measuring instrument. In a previous study, an NTC thermistor of Fe2TiO5 was made in the form of raw pellet without doping, sintered at a temperature of 1200°C for 2 hours in oxygen. A thermistor constant value that obtained from the characterization process is 3821.65 K. This result showed that the thermistor has good quality because it has relatively large constant thermistor. Fe2TiO5 is one of semiconductors that used as basic material for main fabrication component of NTCs as temperature sensor. In this study, temperature measuring instrument using NTC thermistor of Fe2TiO5 sensor based on microcontroller ATMEGA 328. The NTC is assembled in parallel with a fixed resistor and then assembled on ICLM741 and microcontroller ATMEGA 328. The magnitude of the resistor varies at 1 MΩ, 2 MΩ, and 3 MΩ with each resistor having a tolerance value of 1%. From these variations we can get sensitivity value with the value of 0.00688 MΩ/°C; 0.0133 MΩ/°C, and 0.02195 MΩ/°C, respectively. As result, this temperature measuring instrument shows good sensitivity when assembled in parallel using 3 MΩ fixed resistor with a tolerance value of 1% and capable of measuring the temperature in the range 26°C – 103.2°C.

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Radiative properties and spectroscopic studies of several Nd 3+ doped borate glass system have been reported. Judd-Ofelt intensity parameter and other parameters like oscillator strength (f), effective bandwidth ( eff ), radiative transition probabilities (A R ), stimulated emission cross section (), branching ratio ( R ), radiative lifetime ( R ) and experimental lifetime ( exp ) for the hypersensitive Nd 3+ doped Borate Glass are listed and discussed. The variation of  2 values for the different host matrix are expressed their covalency among Nd 3+ ions in the glass matrix. In this study, reported that the hypersensitive transition achieved at 4 I 9/2  4 G 5/2 , 2 G 7/2 centered at 580 -585 nm range.Keywords: Borate glass, Judd-Ofelt, radiative INTRODUCTIONIn the several years and recently, laser gain medium based on Nd 3+ doped glasses have been attracted much attention from researchers in the field of photonic and laser. The above related to Nd 3+ laser application such as optical amplifier, laser pumping, optical communication, optical waveguide, storage data optically, radar and medical instrumentation [1][2][3][4][5]. Medium gain laser characteristics for commercial laser required were must satisfied sharpness fluorescent lines, strong absorption bands and sensible for high quantum efficiency in accordance with the needed transition photon [6].The above requirements have been obtained by a small amount of concentration Nd 3+ ions-doped glass material, since Nd 3+ ions were able to produce population inversion for result stimulated emission in the visible range (such as emission transition at 4 G 7/2  4 I 9/2 , 4 G 7/2  4 I 11/2 , 4 G 7/2  4 I 13/2 ) [7] and the NIR range (lasing transition 4 F 3/2  4 I 9/2 , 4 F 3/2  4 I 11/2 , 4 F 3/2  4 I 13/2 ) [1]. Improved laser performance is strongly influenced by the composition of the host glass matrix and the concentration of doped ions, since the stimulated emission quality depends on host matrix in which the ions are incorporated [7,8]. Several types of commercial glass are generally used as a laser host matrix, i.e silicate, phosphate, borate glasses and several heavy metal oxide glasses [1,2,7,9]. Some of the results showed that the silicate glasses has its advantages as well as high chemical stability, high transparency for UV, low thermal expansion coefficient leading to strong thermal resistance, a small nonlinear refractive index, high surface damage threshold,

The lasing transition 4 F 3/2  4 I 11/2 for Nd 3+ doped phosphate glass centered around 1.05 -1.07m is referred as hypersensitive transition. The radiative properties such as effective line width ( eff ), radiative transition probability (A R ), branching ratio ( R ), radiative lifetime ( R ), quantum efficiency () and stimulated emission cross section have been obtained for several phosphate and fluorophosphate glass contained Nd 3+ . The experimental and calculated oscillator strength were used to analysis Judd-Ofelt parameters ( 2 ,  4 and  6 ) also to predict the quality of factor . The phosphate glass material with the approximately 69P 2 O5-15Na 2 O-15K 2 O-1Nd 2 O 3 composition at 4 F 3/2  4 I 11/2 transition is suitable for laser medium. The enhanced radiative transition probability as well as branching ratio and stimulated emission cross section in this glass are 3694 s -1 , 52% and 8.67 x10 -20 cm 2 respectively. As in commercial laser, the magnitudes of the emission cross section in this study achieved in the range 4.0-5.0 x 10 -20 cm 2 .