Arduino impedance measurement

Arduino impedance measurement. comCapacitance Meter with Arduino! Measure Impedance measurement range from 1 kΩ to 10 MΩ . Oct 2, 2019 · Using a half-wave rectifier circuit and Ohms Law to calculate Loudspeaker Impedance with Arduino. 7 ohms, slightly above the nominal value (8 ohms) of the loudspeaker used here. The EIS can 2 days ago · Arduino (ATmega) pins configured as INPUT with pinMode() are said to be in a high-impedance state. I have 2 questions: Can anyone help me with basic code to validate if the data bus is interfaced and writing and reading the data. There are three different modes currently, which are followings: 'A' : Temperature measurement. Pins configured as INPUT make extremely small demands on the circuit that they are sampling, equivalent to a series resistor of 100 Megohms in front of the pin. Record measurements: Accurately record the measurements. 15% for the phase. In this paper, we propose EIT-kit, an electrical impedance tomography toolkit for designing and fabricating health and motion sensing devices. An external precision resistor can be connected to the four-wire calibration port for the highest accuracy. I am facing issue with the interface. Mar 18, 2016 · I just started with this project, is there any way of monitoring the battery capacity of a battery with just the use of rtc, voltage sensor and current sensor? The Arduino microcontroller is provided with a successive approximation type Analog to Digital converter (ADC) which has the following specification. But Jun 13, 2011 · Looking to make a 2-contact Bioelectrical Impedance sensora body fat sensor with arduino. Inductive or Toroidal. Therefore, in this work, a low frequency impedance analyzer is designed by generating a low frequency AC signal that is sent to the sensor in order to measure the impedance of a cell. The raw values are passed on demand to a dual purpose python application via serial connection. The proposed system consists of a test strip that collects a blood sample from the finger and a hemoglobin meter that measures the impedance of the blood and converts it into the concentration of hemoglobin. 500 * 727 / 883 = 2. Step 2: Proceed by clicking on the ‘Quote Now’ button. Several 1 meg ohm high voltage resistors (each probably 2 feet long are in series from the meter to a common connection. A 5 volt current is sent through the electrode on one finger, then the second electrode connects back to the A0 port in order to read the current. Start measurement: Power on the instrument and start the measurement process as per the instructions specific to your equipment. 1. Output State (set with pinMode(pin, OUTPUT);) Low Impedance - Can provide 40 mA source (positive voltage), or sink (negative voltage) Good for lighting LED's, driving other circuits - useless for reading Sep 16, 2018 · A Python & Arduino gadget. If an accident occurs, the contacts go into a high impedance state. Now I'm going to match the impedances between uno and oscilloscope. Ability to do 4-wire measurements. I was going to use a wheatstone bridge to measure the impedance with the antenna as the unknown leg. How can I read high impedance condition with Arduino Uno? As I understand it, this is not a HIGH level. impedance measurements are made below 100 Hz, thus it is unnecessary to design embedded systems with Arduino-Based Biosensor Impedance Measurement Nurul Najwa Khamis, Nor F. Stable readings: Wait for the readings to stabilize. Measure temperature for 20 secs and plot in real-time. Then we’ll run a program that will calculate the resistance from Ohm’s Law. All you need is an Arduino, the resistor you want to measure, and another resistor with a known value. Then, in the PCB Prototype tab, enter the dimensions of your PCB, the number of layers, and the number of PCBs you require. This way the device can use electrodes with sizes in the range of 1 cm 2 to 40 cm 2. Once calibrated, the magnitude of the impedance and relative phase of the impedance at each frequency point along the sweep is easily calculated. Of course, since 328's ADCs are single polarity, I "cut " the negative part using a schotky diode (clamp to the ADC input), that means the ADC input DiVA Z = (0. First, the input impedance of the ADC. com, and sign up if this is your first time. frequency range of 10 Hz–100 kHz, with the upper frequency. (To clarify - this method does not directly measure the resistance, a different arrangement would be used for that. For these purposes, I use a measuring transformer ( RCMB121 ). Aug 10, 2016 · This simple example will show you how to measure the position. 4. point imposed by the AD5933 limitation. Bio Impedance Analysis (BIA) With the AD5933 : 9 Steps - Instructables. This method of measurement which avoids errors caused by wire resistance is called the Kelvin, or 4-wire method. Impedance measurement instruments are employed for development and characterization, and for sensors, electronic components, electrochemical cells, and materials tests. Regarding the experimental results, the errors in the impedance estimates of an electrical circuit that represents a Cole model were less than 1. So we use two switch to choose, making them function as a dip switch using them as pull down, to measure inductance is 0-0, 0-1 for capacitance Jun 21, 2020 · The circuit is really simple. I have been used two resistors, one of them is 1000 (ohm) and second is unknown resistor. This is done off chip using the real and imaginary register contents, which can be read from the serial I2C interface. 1 Impedance Impedance is an important parameter used to characterize electronic circuits, components, and the materials used to make components. 9mV per unit (5. 0 Impedance Measurement Basics 1. Mar 18, 2013 · As we can see in Figure 1 , the input impedance of an ADC is not purely resistive. the dds would send a signal through the bridge to the antenna Oct 29, 2019 · So, you can measure the impedance of a cable with fairly primitive tools and still get usable results. Jan 8, 2021 · The Arduino measures VOLTAGE relative to IT'S ground. This method consists of drawing a small current from the battery for 10 seconds and a high current for 3 seconds (IEC 61951-1: 2005 standards). In order to measure phase angle, 2 Analog input pins are required. e. As three functions measuring bone capacitance, inductance and resistance, we must choose we want to do, to choose the function and use 2 bits can count 0-0,0-1,1-0,1-1. 1) refer to sections of the AtMega 2560 data sheet. Dec 11, 2019 · Hello guys, I am starting a new project for my university using an arduino board. References shown in brackets thus (2: 26. 2. This makes them useful for reading a sensor. there is no ground at this point. To measure impedance over a wide range of sweep freqeuncy, multi-frequency gainfactors are saved at each point of frequency. Impedance (Z) is generally defined as the total opposition a device or circuit offers to the flow of an alternating current (AC) at a given frequency, and is repre- Sep 7, 2014 · Hi, I would like to seek guidance on the development of the Lightning Earthing Impedance Measurement Project. Jun 1, 2014 · Then, in order to develop portable devices for bioimpedance measurement, in [10] and [11] are presented works using Arduino, and in [12]- [14] the authors use the SoC Impedance Network Analizer Feb 8, 2022 · The patterns for current injection and voltage measurement are managed by an Arduino Mega 2560 board and four 74HC4067 Texas Instruments multiplexers. I based my circuit off of a website online Step 1: Introduction. Measure the cable impedance, then intentionally terminate it with a resistor that is slightly off. Internal temperature sensor (±2°C) Internal system clock option . The purpose of this study is to develop a low-cost arduino-based bioimpedance spectrometry device for the human body that can work accurately at frequency Mar 6, 2023 · Hi, I am trying to use AD5933 impedance measurement 16 pin IC with Arduino Uno. 5% . The meter will be near the high voltage source. The ATmega328P uses a Successive approximation ADC. And since the terminal voltage should not change MUCH in a second, you can use a resistor as the load. It consists of a biosensor which requires a low frequency AC input signal and the impedance data of the water and cell media is to be measured and displayed using an Arduino system. The op-amp also improve the input impedance. - gameinstance/speaker-impedance-measurement Arduino Battery Internal Resistance MeterIn this video we put together an internal resistance meter using an Arduino Nano, a couple of 10R power resisters, a Jul 26, 2016 · Currently, the cell-based biosensors have to be connected to an expensive impedance analyzer in order to obtain the measurement values. Another method of conductivity measurement uses an inductive probe (sometimes referred to as a toroidal sensor). May 29, 2020 · RESULTS: The impedance spectroscopy system was based on a built-in Arduino-Mega and AD5933 integrated circuit (Analog Devices) using open-source software. 7 V to 5. As such, the input is basically the input to a comparator, so the ADC has very high input impedance. Expand. Jun 11, 2014 · The problem of choosing the right method for performing measurements using an acquisition system based on the budget Arduino UNO solution is dealt with and the main assumption was to use the standard, widely available Arduino libraries. According Jun 21, 2017 · The Arduino could work as a controller/brain for an RF measurement system, but not for the "meat" of the system. When there is no leakage, the output contacts are low (GND). This paper describes an There are several factors here. System accuracy of 0. Powered by the Atmel ATMega328P microcontroller (so that it can be prototyped with Arduino) Low cost! Dec 11, 2019 · Hello guys, I am starting a new project for my university using an arduino board. Using AD5933 I can measure impedances from frequency range 1 Hz to 100kHz. Jun 16, 2016 · I am using IC AD5933 to measure impedance. Can I pull these contacts resistors (10k) to the power line? Arduino-based battery internal resistance meter. 0 Volts you get 5 / 250 = 20 mV / Amp. I communicate with the IC through Arduino Yun using I2C protocol. Arduino Battery Internal Resistance MeterIn this video we put together an internal resistance meter using an Arduino Nano, a couple of 10R power resisters, a Oct 19, 2019 · Bio-impedance measurement system design requires four major sub circuits for sending the signal, acquiring the signal using electrodes, Sensing the response and Measuring the response signal. Then, multiply the conductance by the subject's height squared. From this measurement the internal resistance is May 23, 2013 · Measuring voltage across a component in a circuit with a multimeter that has an input impedance of 10M ohms, is the same as connecting a 10M ohm resistor across the component. I already have the detector, its sending pulses about 50 mikroseconds long (picture 1) and has a peak voltage of max. Good for reading sensors but not lighting LED's. April 13, 2023 by Meng Li. Hello, I experience the following problem : I have an AC signal which I want to measure (volts) with Uno. Aug 12, 2017 · I built a circuit using an arduino uno that measures skin conductivity. Topics:1: Measuring voltages with an Arduino2: What is an "Op Amp"3: Basic circuits using Op Amps4: Example Feb 20, 2019 · In this tutorial, a loudspeaker will be analyzed by calculating the Thiele-Small parameters from impedance measurements using an inexpensive USB data acquisition system (minimum sampling rate of 44. Za'bah, Ahmad Mar 5, 2024 · Looking for guidance in frequency measurement. Jan 1, 2018 · This paper describes a possible solution that relies on Electrochemical Impedance Spectroscopy (EIS) measurements, and which is based on a simple portable instrument, and on some polymeric measuring probes, specifically designed and developed for non-invasive in situ measurements. An Arduino based speaker impedance measurement tool. I need to measure rpm with the Arduino. It consists of a current source Iz, connected between inputs one and two of the Impedance Measurement blocks, and a voltage measurement Vz, connected across the terminals of the current source. It operates by applying a known AC voltage or current to the device under test (DUT) and measuring the resulting current or voltage, respectively. Phase measurement capability . Jan 7, 2022 · Filter out noises that could cause inaccuracy on the impedance measurement result. Temperature range: −40°C to +125°C . As I said these are incompatible requirements, the op amp needing a positive supply rail Oct 19, 2019 · Bio-impedance measurement system design requires four major sub circuits for sending the signal, acquiring the signal using electrodes, Sensing the response and Measuring the response signal. It uses a potentiometer with its ends connected to +5V and 0V, and you read the analog voltage at the "wiper" connection which is the centre on most potentiomenters. 12 * 330) / (4. 46 ohms which is very close to the nominal value of 8 ohms. dI = VonLoad / Rload. Apr 1, 2022 · The patterns for current injection and voltage measurement are managed by an Arduino Mega 2560 board and four 74HC4067 Texas Instruments multiplexers. This is needed for the analog input and correct signal measurement. 058 volts. The results can later be visualized using To determine the fat free mass, first take the inverse of impedance to find conductance. Switching the signal between Z and \(R_{C}\). then if your unknown measures 724 the true value is 2. The instrument is able to perform impedance measurements in the range 1 kΩ to 1 GΩ, thanks to a specifically designed front end based on a logarithmic amplifier, and in the frequency range of 0. Piezoelectric materials can produce electricity under mechanical stresses, and often find uses in both sensing and transducing applications. Aug 15, 2015 · A hand-held device that contained AD5933 impedance analyzer chip and Arduino microcontroller was developed to detect AC impedance of the modified electrodes and deliver impedance data to smartphone through Bluetooth module. Signal generator circuit was simulated using 3 different means as using ICL8038 IC, the second method using IC741 and the third method using IC555 to Oct 13, 2012 · I believe the previous answers have oversimplified the problem. 88 mV resolution. Using a current transducer scaled so 0 to 250 Amps = 0 to 5. Mar 20, 2017 · Arduino Robotic Online Individual Classes (via skype) with Practical Explanations, Contact me on: nik261190@gmail. Jul 24, 2014 · Electrochemical Impedance Spectroscopy (EIS) has been recently proposed as a simple non-invasive technique to monitor the amount of fat and liquids contained inside the human body. if nX is the reading for Vx; nRef the reading for vRef then Vx (true) = Vref * nx / nRef. Im much more hesitant now, anyone have any experience outputting around the 0. The methods used in this project will educate the user on multiple engineering topics ranging Dec 1, 2021 · This study proposed a new anemia diagnostic system based on the impedance measurement of red blood cells. The cable impedance is only valid within a specified bandwidth i. Using the AD5933 impedance analyzer to measure impedance. The signals are supposed to be 8Mhz PWM by program. The second resistor is measured by using voltage divider rule. In addition, the impedance analyzer is bulky and not easily portable. In this blog post, we focus on the electrical impedance measurement of piezoelectric materials, using an MFIA Impedance Nov 2, 2021 · Using the ADC in an Arduino UNO for example you have a 10 bit ADC. I have been interested in making a Bio Impedance Analyser for body composition measurements and my random searches kept finding a design from the 2015 Biomedical Instrumentation class at Vanderbilt University. 05v that the scale-type units use? Im not fonding a whole lot online about these measuring devises The Arduino microcontroller is provided with a successive approximation type Analog to Digital converter (ADC) which has the following specification. The analog input pins will map input voltages between 0 and 5V into integer values between 0 and 1023 with resolution of 4. The total internal resistance Rint is given by: dV = Voc (the voltage you measure with the load disconnected) - V onLoad. By tfsoft81 in Circuits Arduino. Step 2: Circuit Diagram. But the measured waveform is weird, overshoot and undershoot. The circuit takes advantage of the ADC and DAC made available by the microcontroller of the Arduino boards and employs a logarithmic amplifier to extend the impedance measuring range to 6 decades without using complex programmable gain amplifiers. 4-5 volt (the absolute height Dec 28, 2019 · Arduino NANO has 8 pins while Arduino MEGA has 16 input pins. Impedance measurements can fluctuate initially, especially in reactive circuits. 0 volts / 1024 bits = 4. This article proposes a simple Arduino based tool that monitors the voltage drop and current through a speaker for the purpose of measuring its impedance. I connected my probe directly to the GND and pin 55 or GND and pin 11. The ADC is specified as having a 100 MΩ (that is MegaOhm) input impedance. However, my readings are off by over an ohm and I can't figure out why. - jessica-bo/arduino-impedance-measurements Jul 1, 2023 · Impedance Measurement and Analysis Solutions. Save PDF. So for example 0 to 5. 04+0. system June 27, 2011, 9:41pm 1. I have done a lot with arduino before, but its all fun and games till the project requires running current through your body. 00V / 1024 units). 6,260. Jul 13, 2015 · Especially the pin 11 and pin 5. You can then see just how horrible (or not) it is. This tutorial aims to provide an introduction to the use of Op Amps, and offer help in choosing the right one for your particular application. Checked device address - 0X0D Pull-up resistors are properly connected This paper describes an alternative low-cost solution, which is based on a logarithmic front-end and on an off-the-shelf microcontroller board, which remains below $100, while still having the capability of measuring over a frequency range of 0. I am not pro but followed some help guides and did perform below actions. EIT-kit contains (1) an extension to a 3D editor for personalizing the form factor of electrode arrays and electrode distribution, (2) a customized EIT sensing motherboard for performing the measurements, (3) a microcontroller library that automates Oct 8, 2021 · I'm attempting to calculate the resistance of unknown resistors using an Arduino Mega with simple voltage divider circuits. Favorite. One opamp input is at 320v, the other at 319v, the ouput needs to be something less than +5v. Ability to draw power either from the battery under test, or from a separate battery. 14% for the magnitude and 4. While the technique capabilities are still questioned, a simple and low cost device capable of performing this kind of measurements would help testing it on many patients with minimal effort. EIS is a safe perturbation technique used to examine processes occurring Jun 7, 2020 · Conclusion: The multi-frequency bioimpedance device developed in this research has the capability to safely measure the impedance of the human body due to its relatively stable electric current Feb 8, 2022 · This study proposes a low-cost, portable, eight-channel electrical impedance tomograph based on the AD5933 impedance converter. The frequency generator allows an external complex impedance to be excited with a known frequency. Rint = dV / dI. 3. This should tell you how much your body is resisting the initial 5v current. 12) This will give a value of 9. system June 27, 2017, 4:07pm 1. 1 kHz). 5 V power supply operation . Sep 11, 2014 · I know that swr is a ratio of forward and reflected power and I should be able to get this working. For more information on hardware and software setup, visit the CN-0510 User Guide for complete details. Posted on 2018-09-16. The circuit shown in Figure 1 is an electrochemical impedance spectroscopy (EIS) measurement system for characterizing lithium ion (Li-Ion) and other types of batteries. pcbway. Dec 22, 2004 · The AD5933 is a high precision impedance converter system solution that combines an on-board frequency generator with a 12-bit, 1 MSPS, analog-to-digital converter (ADC). I could not find any information in the data sheets about what the input impedance (s) of the analog input pins (A0-A5) were. They can extract complex impedance vectors at a single test condition, or while sweeping source parameters like frequency Step 2: Code and Performance. Oct 4, 2022 · After finalizing the design, you can proceed with ordering the PCB: Step 1: Go to www. Now using the 5V supply "DEFAULT" to measure both the reference and your unknown voltage (s) we apply a simple correction to get a precise value. The patterns for current injection and voltage measurement are managed by an Arduino Mega 2560 board and four 74HC4067 Texas Instruments multiplexers. But if the input impedance has a reactive component, then the 50% method will not give the correct result. Since the Arduino and FPGA are two different blocks, we Jun 27, 2017 · AC signal for ADC [solved] Using ArduinoProject Guidance. Oct 11, 2014 · This technique allows advanced meters to be able to measure both high and low conductivities as well as the ultra low conductivity of deionized water with one probe. Feb 22, 2022 · For measurements requiring high absolute impedance accuracy such as Bioimpedance Analysis/Spectroscopy (BIA/BIS) and Automated External Defibrillator (AED) body impedance, the MAX30009 offers several calibration options. Nov 14, 2022 · the op amp part is still undecided, but it should only measure the drop of the sense resistor, So sense resistor is 1 ohm, suppose current is 1A so it drops 1v. In other words, the AD5933 lets you measure the complex impedance of something. I want to know if they would work for a certain experiment I'm running that requires that the voltmeter has an input impedance in the order of megaohms. 01 Apr 20, 2021 · notable ones, we identify Arduino (DFT) impedance measurement method spanning a. Target precision: 2% ± 1 LSB. Special connecting clips called Kelvin clips are made to facilitate this kind of connection across a subject resistance: In regular, “alligator” style clips, both halves of the jaw are electrically common to each The Impedance Measurement block measures the impedance between two nodes of a linear circuit as a function of the frequency. Jul 24, 2011 · You usually need a high precision resistor (1% or better) in series with the inductor, a function generator to put a signal through the circuit, and an oscilloscope to measure the result. Feb 24, 2017 · The voltage measuring in a power generation plant or in a sub station is set up when the system is being built. The goal is to measure the energy of alpha particles (radioactive decay) using an alpha particle energy detector. This paper present a measurement system based on two System on Chip (SoC) solutions and Raspberry PI, implementing both a full 3-lead ECG recorder and an impedance cardiographer, for educational Dec 7, 2018 · The goal is to catch an AC leak. there is simple and fine method to to calculate the unknown resistor. Measure impedance and phase. The Jun 27, 2011 · Using Arduino General Electronics. The network impedance is calculated as the transfer function H (s) from the Among electro-chemical detection techniques, electrochemical impedance spectroscopy (EIS) has been one of the most widely used for impedance measurements due to its minor system interference, fast response, and accurate, reliable results [16]. If you are measuring the input impedance of a device for which the input impedance is a pure resistance, then the 50% method will work fine. The design is build with an input circuit for correct signal level for the Arduino. Using the same method the impedance is calculated for 200 Hz as 8. In this blog post, we focus on the electrical impedance measurement of piezoelectric materials, using an MFIA Impedance Resistance range: 1 to 1000 mOhm. If a voltmeter has a low input impedance, say 10kΩ and a voltage across a 10kΩ resistor is being measured, the multimeter is effectively changing the resistor value to Piezoelectric Impedance: Measurement and Modeling. You can also get a direct comparison of just how bad a mismatch is. With DC or audio, a 50-Ohm coax cable is like any other wire (with nearly zero series resistance/impedance and nearly infinite parallel resistance/impedance). Figure 2 shows the simplified sample and hold circuit. The best you will resolve is about 5. Signal generator circuit was simulated using 3 different means as using ICL8038 IC, the second method using IC741 and the third method using IC555 to Piezoelectric Impedance: Measurement and Modeling. I am doing a project to measure the state of batteries with different capacities and voltages using the method: Two-tier DC load. Not GROUND. Finally, substitute the value into the equation: y=3. I'm measuring the output voltage from the pins. Apr 25, 2024 · It consists of an Arduino microcontroller to control the necessary action for data performance and storage, a subminiature version-A (SMA) to alligator cable for electrode connections, an impedance analyzer circuit for impedance measurement, and thin film transistor (TFT) LCD to display the measured as results. It has two electrodes connected to two different fingers. The brief overview of the project is as follows, This overview outlines the concept of measuring the earthing impedance with the variable frequency AC source to predict the behaviour of power transmission earthing system under the influence of transient fault / switching transient In this tutorial we will learn about how to measure unknown resistance by using Arduino uno. This is designed by a virtual ground level of 2V5. The system works fine for frequencies greater than 1 KHz using the internal clock and for frequencies lower than that, I have to provide an external clock. A switched capacitor input is basically the sample and hold stage of the ADC. We’ll set up a voltage divider with the known and unknown resistors, and measure the voltage between them with the Arduino. 16-lead SSOP package Oct 26, 2023 · A vector impedance meter is an instrument designed to measure the complex impedance of electronic components and circuits. The Arduino chip analog input circuit has an impedance of about 100M//14pf. The capacitive part of the input impedance originates primarily by virtue of the sampling capacitor (C SAMPLE in Figure 2) from Jan 23, 2021 · Operational amplifiers ("Op Amps") offer an easy way to prepare these signals for measurement. 85x, where x is the value determined in the previous step, and y is the fat free mass in kg. my idea is the arduino automatically finds the lowest swr and shows the impedance. (Shown here Rp, Cp) Also the analog input pins can show a leakage current of 1uA (but typically 50nA). Contribute to fmeschia/esr-meter development by creating an account on GitHub. At 1000rpm, the signal is 200hz, at 2000rpm it is 400hz and so on. The voltage value is ~14v and I would like to use high . 2 – 0. Capable of measuring of 100 Ω to 1 kΩ with additional circuitry . 4-5 volt (the absolute height May 25, 2016 · We present a low-cost, portable electrochemical analysis system using impedimetric measurements rather than more commonly used potentiometric techniques. The presented impedance spectroscopy (impedimetric) technique uses a small perturbation to obtain a linearized response without affecting the composition of the sample as opposed to cyclic voltammetry (potentiometric) which repeatedly reduces Dec 4, 2022 · To simplify the circuit even further, omit phase 1. 01 Hz-100 kHz and for impedance values in the range of 100 Ω-10 GQ. 0 Amps. I have found a conditioned signal that feeds from one module to the next that I can use to measure (see descriptive image below). The system includes an internal per measurement calibration and constant current supply, and was able to stably iterate through excitation frequencies from 1 to 300 kHz. I posted about this project a few months ago: Analog Input Reads Incorrect Voltages - Using Arduino / General Electronics - Arduino Forum and thanks to everyone there, I was able to correctly measure This paper describes an extremely low cost realization of an EIS system that is based on a simple commercial Arduino Board whose cost is below 50$. . The overall gain is 0dB. By comparing the phase difference and magnitude between the applied signal Kelvin Method. The response signal from the impedance is sampled by the on-board ADC and a Oct 3, 2023 · High Impedance (resistance) - Makes very little demand on the circuit that it is sampling. With a known resistor between A0 and ground you can measure the voltage and calculate* the current through the resistor. 'B' : Impedance measurement. Disclaimer: If you use a Smartphone, you are doing so at you Apr 25, 2020 · The DFT algorithm produced real (R) and imaginary (I) data which was used to calculate the impedance and phase; however, it could only measure impedance values ranging from 0 to 100 kHz. by ue ib se rm vj ct ec zc pv