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# Electronics and Communication Engineering - Science topic

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Questions related to Electronics and Communication Engineering
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One of my friend completed his bachelor degree in mechanical engineering. But now likes to join in computer science engineering related master degree program.
Is it possible to do masters in computer science related courses. If yes, please suggest the courses. Thanking you...
Dear, it's not possible to do master in computer science after mechanical graduate.
But heay try to robotics, automobile and other computer related course which is the available in Mechanical Engineering domain.
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I am studying microelectronics. I recently got confused about about the small signal models and large signal models. After reading an extensive list of sources, I have come up with some pointers which I want to verify that I have got right.
The term "small signal" can refer two things : small signal amplifier and small signal model/analysis. A small signal model is not the same thing as a small signal amplifier. The same thing can be said about the term "large signal". However both small and large signals are ac signals, and they are large or small with respect to the quiescent or operating point established by the dc bias circuit obtained using DC modeling in both large and small signal amplifier analysis.
Both large and small signal models can be used to model the non linear devices like diodes and transistors( which are operated as amplifiers in active region). The transistor amplifiers are used as voltage or current amplifiers when used as small signal amplifiers and the transistor amplifiers are used as power amplifiers when used as large signal amplifiers.
The small signal amplifier is an amplifier when the applied (AC) input is small with respect to the DC operating point on the DC load line. This type of amplifier uses small signal modeling for its ac analysis. Small signal modeling involved linearizing the non-linear circuit elements at the dc operating point.
There's exist two load lines: dc load line which gives operating point and then there's an ac load line.
The small signal amplifier analysis includes two steps:
1. DC analysis using DC modeling or Large Signal Modeling
2. AC analysis using Small Signal AC (or Incremental) Modeling
The large signal amplifier is used as a power amplifier. The large signal amplifier analysis includes two steps:
1. DC analysis using DC modeling or Large Signal Modeling
2. AC analysis is done using graphical analysis and no specific model is used here to model the AC operation of large signal.
The DC analysis is done using large signal modeling in both small and large signal amplifiers so it is also called large signal analysis. The AC analysis done in small signal amplifiers using small signal modeling is small signal analysis.
Please provide feedback if my points are accurate or need improvement.
(I tried searching large signal model of a transistor and also searching dc model of a transistor. The results obtained in images section of google search show the kinds of circuits for dc models and large signal models. That is also how I inferred large signal models and DC models are the same. Some references are also present to support this point).
References:
In my book about the semicondcutor devices I defined very precisely the small signal and the large signal concepts. Any nonlinear device can be modeled by a small signal model and a large signal model. Small and large is related to the ac signal amplitudes either current or voltage compared to the DC operating voltages and currents. In small signal, the signal is so small that one can linearize the device I-V characteristics. Otherwise the one has to use the large signal model.
In small signal amplifiers analysis one can use the small signal device models otherwise one has to use the large signal models.
Small signal models are either physically based or black box two port networks such as the h. model, the y-model and the s-model.
Best wishes
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We had a problem with "negative resistance" since it represented two different types of resistances - "true negative resistance"
and "differential negative resistance"
Now we have a similar problem with "negative impedance" since it represents different things in electronics and electrotechnics...
IN ELECTRONICS, we believe that all natural passive components (resistors, capacitors and inductors) absorbing energy from the input source have "positive impedance" (or simply "impedance"). So, from this viewpoint, the impedances of capacitors and inductors have the same positive signs. Conversely, the artificial electronic circuits - NICs (negative "resistors", negative "capacitors" and negative "inductors"), behaving in an opposite way (adding energy to the input source in the same manner as the according passive components do it), have a true "negative impedance". So, this classification regards to the way of processing energy - "positive impedance" means consuming while "negative impedance" means producing energy; "positive impedance" means "ordinary impedance" while "negative impedance" means something opposite as "inverse impedance", "opposite impedance" or "anti-impedance".
IN ELECTROTECHNICS, they classify the impedance of the reactive elements capacitor and inductor according to their behavior in time when a DC input voltage is applied - "negative impedance" symbolizes an "increasing voltage opposition" while "positive impedance" symbolizes a "decreasing voltage opposition". From this viewpoint, the impedances of capacitors and inductors have opposite signs.
IN ELECTRONICS, BOTH CAPACITORS AND INDUCTORS HAVE POSITIVE IMPEDANCE WHILE IN ELECTROTECHNICS, CAPACITORS HAVE NEGATIVE IMPEDANCE BUT INDUCTORS HAVE POSITIVE IMPEDANCE.
This concept is extremely simple, clear and intuitive if we think in terms of voltages when we apply a constant input voltage to the elementary RC and RL circuit. Then, voltage drops appear across capacitors and inductors; they change in a different (opposite) way through time but both they are voltage drops. Conversely, voltages appear across negative capacitors and inductors; they also change in a different (opposite) way through time but now both they are (electromotive) voltages, not voltage drops.
After these speculations, it is interesting to remember what a negative impedance converter did. What does it convert? Does it make a capacitor behave as an inductor and v.v., an inductor as a capacitor? No, it doesn't. A gyrator can do this magic. A negative impedance converter can make capacitors and inductors behave as sources (negative impedance elements) instead as passive elements having positive impedance:
I have presented these speculations in the archived Wikipedia talk page about negative resistance:
I have inspired to ask this question by the enthusiastic speculations of Tolga Soyata in the related questions about capacitor and inductor:
Dear Cyril Mechkov sir,
Capacitor is not considered as a current source because it can not provide current(energy) to the circuit for a long time. It will just momentarily provide(energise) the circuit, hence it is not classified as a current source.
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Please let me know if any book or website is available for reference
Can someone please provide me MATLAB code for calculating PAPR of OQAM/FBMC system
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Hi, How can we calculate the entropy of  chaotic signals? Is there a simple method or formula for doing this?
you can use :
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Hi, I have an assignment in my material science class that requires us to interview an electronics engineer that practices material science. I heard that those who are working in the Semiconductor industry do heavy material science at work. I don't have anyone to interview so I'm asking here for a favor if anyone of you is interested to share some of your knowledge and experience when it comes to this subject matter. Please comment or send me a message if you're interested. Your help is very much appreciated. thank you!
Try contacting Ph.D. students from EE at IITs or IISc.
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Suppose that X1, X2 are random variables with given probability distributions fx1(x), fx2(x).
Let fy(x) = fy( fx1(x) , fx2(x) ) be a known probability distribution of "unknown" random variable Y. Is it possible to determine how the variable Y is related to X1 and X2?
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Dear all
when I simulated VLC system, I used Rayleigh fading channel by calling the function "comm.MIMOChannel". However, I think the correct channel type should be Rician fading channel for VLC.
I would like to know, can i just replace ''Rayleigh'' in parameter "FadingDistribution" with Rician ? Or could someone tell me how to model the Rician channel, namely the main parameters in Rician ?
Thanks
I think it is not easy to determine the fading distribution of VLC channel as it totally depends on the scenario. For example the indoor scenario is totally different about vehicular ones. Also, other parameters might affect this like frequency, existing of blockage and shadowing, etc.
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Layout of VLSI circuits.
Electric VLSI Design System is an opensource IC Design tool. Good help/tutorials are available at cmosedu.com
In combination of another free tool LTSpice, you can have compete pre and post-layout simulation experience. Also, LTSpice supports BSIM4 models and you can use them by adjusting Lambda accordingly in the ELECTRIC.
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Requirements
1.we could adjust sound level acc to our req.
2.compensation circuit
I am working on a project where I am required to design and make a sound pressure level meter using ATMEGA 164P microcontroller and it is programmed using Atmel Studio. How would I go about doing this as I cannot find any help online.
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Good day everyone, I am modeling the IEEE 123 Node Test Feeder on Simulink.
After watching the webinar from Graham Dudgeon on Electrical distribution system modeling and analysis using Matlab and Simulink, I have been evaluating ways to build the model myself from a Matlab code. I have line placements working , load placement already running too. I have a problem on the interpretation of line configurations provided on the accompanying document.
If anyone can explain it to me or provide me with a reference to where I can learn how to use the provided configurations, and choose the right simulink model for the lines, this will help me adjust the lines parameters in accordance with the information provided.
The configuration data are provided in the following format.
IEEE 123 Node Test Feeder
Impedances
Configuration 1:
Z (R +jX) in ohms per mile
0.4576 1.0780 0.1560 0.5017 0.1535 0.3849
0.4666 1.0482 0.1580 0.4236
0.4615 1.0651
B in micro Siemens per mile
5.6765 -1.8319 -0.6982
5.9809 -1.1645
5.3971
Thanks for any Possible contribution
thanks
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At the receiving end of the NOMA system,whether we can use BP algrithm to dectect the signal or not.
Of course yes
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I am doing study of dimensional stones(marble/granite). I have
collected lot of signals using hammer and accelerometer setup from
NI. Now I am analyzing them. My target to find out out
frequency/energy concentration bands. I like to use wavelet packet
transforms and finally EMD on these decomposed signals.
I need to find out suitable mother wavelet for decomposition for
these type of signals. Does any body has already know about it?
I tried finding by max correlation of signal and constructed signal
using wavefun of matlab for all the wavelets and selecting highest
correlation. For every signal I get different mother wavelet. Does it
Ok?
Please suggest and comment to proceed further.
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I've got a bunch of antennas with varying VSWRs and dBi ratings, and a couple of standard SMA headers from various 2.4Ghz radios. I would like to learn how antenna selection will affect RF power and range.
Dear Mark,
welcome,
I would like to express the colleagues answer in an other way. In the link budget one defines also the effective isotropic radiated power EIRP which is the the transmit power Pt issued by the power amplifier at the input of the antenna times the antenna gain, that is the EIRP= Pt. At where At is the transmit antenna gain. Expressed in dBm= 10 log (Pt/1mw) + At ,
the EIRP is the quantity used to calculate the power reaching the receiver antenna. As the antenna gain increases the the received power will increase proportionally. This will increase the S/N ratio for the range and same receiver.
Best wishes
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Hi everyone,
I've just designed a wide band SIW slot antenna in CST using metamaterials and now I want to find out the effective permittivity of the structure. I've got the S parameters from CST and now looking for a method to plot the effective permittivity based on them or based on other parameters available in software. What is the equation? and Is there any Matlab code?
I extracted metamamaterial paramters using this technique but its not giving me results as NRW method is giving...WIll the result be different
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See above
May be a late answer but the attached file has some code and documentation is available in the pdf file at https://tetcos.com/pdf/v11.1/Primary-User-Emulation-PUE-Attack-Cognitive-Radio-v11.1.pdf
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The fifth generation of cellular network is expected to be able to provide wider bandwidth than the previous technology. In 5G era many services are predicted to occur and the 5G devices should be able to communicate with machines and humans alike in an intelligent manner. The fifth generation of cellular network (5G) also expected to provide multi gigabit per second (Gbps) data rate to produce high quality and reliable services also low latency for data, video and multimedia services.
Papers:
S. Kavanagh, "5G vs 4G: No Contest," 5g.co.uk , 27 September 2018. [Online]. Available: https://5g.co.uk/guides/4g-versus-5g-what-will-the-next-generation-bring/.
T. Wulandari, D. Perdana and R. M. Negara, "Node Density Performance Analysis on IEEE 802.11ah Standard for VoIP Service," International Journal of Communication Networks and Information Security (IJCNIS), vol. 10, no. 1, 2018.
M. Mezzavilla, M. Zhang, M. Polese, R. Ford, S. Dutta, S. Rangan and M. Zorzi, "End-to-End Simulation of 5G mmWave Networks," IEEE Communications Survey & Tutorials, vol. 20, no. 3, 2018.
Z. N. Azeemi, "Delivering 4G (LTE) To 5G Migration With Supply Chain Management," International Journal of Electronics and Communication Engineering (IJECE), vol. 6, no. 1, pp. 1-10, 2017.
متابع
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I want to obtain dispersion diagram of the periodic structure with CST. The structure is finite in transverse direction: "A row of pins which consists 7 pins laid under a metallic plate. The entire row is laid between two metallic sidewalls. the row of pins together with the sidewalls are repeated along the longitudinal direction periodically". But when I simulate the structure with CST Eigenmode Solver, I obtain two additional modes compared to a paper's result. Can anyone help me with this problem please?
Hi
Parinaz Sadri-Moshkenani : I have simulated the dispersion diagram with CST and i get results that is similar to the results in the paper i am simulating.
But i don't know the relation between beta(propagation constant) and phaseY. Can you tell me how these two parameters are related to each other?
I have attached the results for you.
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What is the practical operating frequency of FEMTOCELL. What kind of antenna (arrays) is used in the recent models and what is the range?
I have designed an microstrip multiband antenna...got the frequencies has 12GHz,13GHz 28 GHz and 38GHz... actually mmwave frequencies...can I use it for femtocells is my question??
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I am doing a project in power reduction of OFDM signals. Can anyone suggest ways to calculate power spectral density and the reason why the curve mostly starts at 0dB?
Just a conceptual answer which can be useful. The OFDM symbol is already composed from its frequency components which are the OFDM subcarriers having frequency k deltaf from k=1 to N where N is the total number of subcarriers. These sub carriers are amplitude shift keying by the modulating digital data.
Every subcarrier signal k can be expressed by Vk exp -j k 2 pi deltaf t + j phik,
Vk and phik can be represented in the constellation diagram with maximum amplitude Vkm. In fact in order to reduce the spectral power density one has to reduce the size of the constellation Vkm.
Best wishes
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IO cells are the Input and output controllers inside an integrated circuit.So they are basically used for the flow of data in and out of the chip.
Three types of circuits are there.. 1. analog 2. digital 3. mixed circuits
Dear Isen,
You asked your question 7 years ago and then i come accidentally and introduce an answer to your question. You may be need its answer but i assume another colleagues may need it.
So, there are only three types of pins: power supply pins, analog pins and digital pins. The two types can be further subclassified into in put and output pins.
-The input digital pins must be capable of ESD protection as well as logic level converter
- The output digital pins must be make the required level conversion plus driving the output load
- The analog input and output cells has only to convey the signal from the input to output and vice verse in addition to ESD protection.
So the differences stems from the functions assigned to the cells connected to the pads.
Best wishes
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This question is dual to the question below that I asked a few hours ago:
There, we began thinking what would happen when connecting the input voltage source in parallel to another voltage source (the output of a voltage follower) what was quite confusing for traditional thinking electrician and not so for electronics specialists. Here, we would like to know what happens if we connect the input current source in series to another current source (the dual situation). We would like to know it since we have the feeling that this is a powerful idea in electronics-:) Well, let's begin thinking...
It is obvious that we should apply the input current to the input of a current amplifier (e.g., a BJT) and to take the output current from its output. But we are curious enough to (try to) "blow" the input current into the output of the current amplifier (the BJT collector) and to take the collector voltage as an output. And we ask the same confusing questions:
Is this arrangement (two current sources connected in series) possible and correct from the basic electricity viewpoint? What would be the sense of this nonsensical connection? Can we use it somewhere in electronics? Can we see it in some existing circuit solutions? Can we see this idea in our life? Can we generalize it as a fundamental (particularly, circuit) principle?
BTW we have already managed to "blow" the input current into the collector of a BJT by applying a parallel-parallel negative feedback
but here we mustn't apply a negative feedback. Then?
As in the dual question, I have given a hint with the same attached picture. If this is not sufficient, look again at the link below:
I warn again: do not consider these speculations as an absolute truth; they show only my personal viewpoint at this phenomenon...
Cyril, You are right. This topic can be debated :-)
Josef
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Does any one know the PDF of sum of generalized gamma distribution?
If X is a generalized gamma, then X multiply a constant A, AX is also an generalized gamma? What is it parameters respectively?
How to find pdf when these gamma RV's are correlated.
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Camera gives live thermal streaming but I am unable to store image. I have tried the available options on internet.
This is what I have achieved so far.
Dear Umair,
Here is another one where you can save the frame you want (a small python script needed)
Best wishes,
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It has been recently claimed that D2D communication in LTE-A (Rel 12+) will establish direct communication with the device in its proximity (UE) and can have many potential advantages e.g., increased network spectral efficiency, energy efficiency, reduced transmission delay, offloaded traffic for BS and less congestion in cellular core network. In contrast, there are various anticipated challenges, for example Device discovery. D2D session setup, D2D resource allocation, D2D MIMO transmission and D2D-aided BS deployment in HetNets (Heterogeneous Networks).
Keeping this in view, can somebody shed light on possible differences between D2D communication and existing wireless transmission techniques such as WiFi Direct, Bluetooth, UWB? How is it different than these existing ones?
I think the main issue here for D2D communication is the interference management. It is correct that the devices in D2D can directly communicating in similar way as other Ad hoc wireless networks. But there is one major difference here, that in D2D the communication can be performed under the control of the network. The signalling of D2D communication is still controlled by the network, therefore, it is possible to select for example the subbands or time of transmission in order to manage the interference levels with the Up/Down links of the network. The network also observe the quality of communication and the packets could be redirected over the the network if needed. This could enhance the reliability of the system.
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I have a GNSS RF chip. I should connect the RF pin to an antenna connector with a 50 ohm microstrip transmission line.
I calculated the RF track width and printed the PCB
Now I want to measure the track impedance to verify calculation and design.
Is there any measurement device for that?
*The frequency of RF signal is about 1.5GHz.
Denis:
My understanding of the 'exam question' that Farid Hosseinzadeh has set us is:
Given the PCB with GNSS chip installed, what piece of test equipment should be connected to the input connector of the PCB in order to find the characteristic impedance of the track connecting the input connector to the chip?
The picture I have in my head is that the track is in the order of a few cm in length and I am additionally assuming that no modification of the PCB to facilitate the measurement would be welcome.
From the assumption about track length I was then thinking along the lines of section 9.2 in Keysight Technologies, 'Time Domain Analysis Using a Network Analyzer' http://literature.cdn.keysight.com/litweb/pdf/5989-5723EN.pdf, which is saying that the TDR NWA should be operated with wide frequency span to resolve down to disconuity separations in the cm region.
If you could provide details of the measurement you thinking of, which answers the requirement as stated in this post, without using a wideband test pulse or a wide frequency span NWA test signal, I will happily be educated.
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The extremely interesting and topical questions below were about the rift between digital and analog circuits
But the human aspects engendered by this "war" are even more important for us, human beings, living and working in this continously changing environment. This "digitalization" makes a tremendous impact on the electronics, particularly on electronics education. In addition to all the positive sides of this process, there are negative aspects as well...
First of all, this tendency has imposed the domination of the formal approach in technical education. Making circuits digital, miniaturizing and enclosing them in packages, and interacting with them by means of software (e.g., FPGA) has apparently eliminated the need of technical abilities, a natural aptitude to technics (simply, the vocation for mastering something material, e.g., real circuits, with his/her own hands). This gives a chance to students that are averse to technics to enter technical universities at the expense of those having a technical vocation. For example, students graduated mathematical, philological, trading and other non-technical schools can easily enter Technical university of Sofia by solving a few mathematical problems without any proof of their technical aptitudes). In the Computer systems department, where I teach basic, digital and microcomputer circuitry, our students become sooner a kind of "informatics" specialists than real engineers...
Of course, the same sorry truth can be said about teachers and university lecturers. The abstract digital ground gives an excellent opportunity for those of them having no technical sense, abilities and vocation, to work in technical departments where to build "brilliant" courses and to carry out "striking" lections analyzing circuits by applying sophisticated formal methods without understanding circuit phenomena. I have noted the sorry truth that I can talk with my colleagues about anything but only without circuits...
This topic is considered in the interesting materials below kindly given by Prof. Lutz von Wangenheim:
It is interesting to predict what will be the results of this process...
Have positive aspects and negative aspects
For example, negatively affect social skills
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How can I use cooperative spectrum sensing to eliminate primary user emulation attacks in cognitive radio networks using energy detection?
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My question regards the real necessity to have subframe (3GPP Rel. 12) or slot (3GPP Rel. 13) aligned transmissions in the unlicensed band.
According to TR 36.889: "Channel reservation refers to the transmission of signals, by an LAA node, after gaining channel access via a successful LBT operation, so that other nodes that receive the transmitted signal with energy above a certain threshold sense the channel to be occupied." This signal is transmitted until the next subframe or slot boundary is reached so that transmissions are aligned.
The channel reservation signal defined by the 3GPP standard adds an overhead to LTE-LAA transmissions that impact on its performance. If there were no necessity for any kind of time alignment to the PCell the SCell performance could be increased.
Therefore, my question is, what would be the possible implications to all LTE layers if the transmissions were not aligned at all?
I am still trying to understand if the time alignment to PCell's time frame structure is really necessary. It seems there could be non-time aligned transmissions by the SCell as long as it transmits the necessary signals (RS, PSS, SSS, BCH, etc.).
Does anyone know if there is some kind of limitation to non-aligned transmissions?
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I need materials in any form regarding antenna pattern in Opnet for learning purpose.Your help would be highly appreciated.
Yes Aparna Sathya Murthy .
I need useful tutorials and links,which might be useful in implementing it in Opnet simulator.
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As we know that larger the battery capacity, the longer your drone can function in one single charge of it. Small drones are normally best suited for 20 to 30 minutes flight.Our requirements are beyond this i.e longer flight on a single charge.
So what are the possible ways to overcome this issues and to prolong the flight of a small drone?
Dear Khan M. Asghar
"I am more interested in things like some constant charging device that dont let the battery down."
This can happen if:
- You have a battery that is charged by nuclear decay during a flight;
- You have a battery that is charged by a chemical reaction during a flight (burning hydrogen, fuel cells or some other);
and
- this battery can generate the output power you need to have a beneficial effect.
For all these suggestions there are solutions, the question is what finances can be allocated to your goal.
And another - You have a battery that is charged by electromagnetic energy (refer to N. Tesla's patents) that can be extracted from space. Which is also not to be ignored :-)
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What could be the maximum distance that one can control a UAV from?
I'd use commercial 3G-4G mobile phone networks in order to send and receive short communication lines that help upload discrete commands (eg. Speed, Altitude, Go to a preset waypoint, Cancel mission, Go back home....) and download basic status information. Wouldn't work for downloading real time imaging, but maybe acquiring some basic environmental information.
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Hi All,
Currently, I have designied a simple 2-way power divider based on Gap Waveguide technology (simply, it is quite similar to the conventional waveguide but without sidewalls) operates at 30 GHz (millimetre-wave band). The power divider is designed depending on coupling between resonators. Although changing the topology many times, the isolation between output ports a bad.
Please, in such power dividers what is the key of controlling the isolation.. And what do you suggest to increase the isolation between output ports?
Regards,
Bahaa
Then I suggest try absorbers, if your university has an anechoic chamber for antenna or EMC testing you will should find some absorbers there. These are replaced in routine and usually available, cut them to your required size and measure the results after placing them at places likely to be causing coupling. If it works you may order specific ones or for academic requirements this should suffice.
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I'm working on connecting the USRP N210 to my laptop.
When I connect my USRP N210 radio to the NIC on my host computer directly with an Ethernet Cable status is Network cale unplugged (Realtek PCle FE Family Controller). I do not understand from which reason it happens.
USRP Radio hava a default IP address od 192.168.10.2. Also, sebnet mask is set to default (255.255.255.0). When I check windows - radio connection by ping command with IP address of the radio everithing is OK. But when I chech Subnet Values on Host and Radio connection Is not good.
Hi,
during operation it is necessary to pay attention on Matlab version and accordingly to that have the corresponding OS.
With regards,
Ivana
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Can somebody reference me publications showing the design of ADC (pipeline or SAR) working in sub-sampling mode (IF subsampling in wireless receivers), whereas the ADCs has larger analog input bandwidth then its own sample-rate, this means, the ADC works in higher Nyquist bands (>10).
I found the IEEE SSC Publications of Ahmed Ali (ADI, NC) showing a 14b pipeline ADC with 125MS/s with up to 500MHz BW (8th Nyquist band) from JSSC 2006 and a 16b pipeline ADC with 250MS/s with 300MHz analog-BW (3rd Nyquist band).
And some 10b pipeline ADCs from China: Jian Li (JSSC 2008) with 30MS/s with BW=30MHz (2nd Nyquist Band) and Chen Lijie (2010) with 50MS/s with BW=50MHz (2nd Nyquist Band).
Subsampling operation SAR ADCs I found only two: Shuo-Wei Michael Chen (UC Berkeley) from JSSC 2006 with 6b 600MS/s SAR with BW=4GHz (13th Nyquist Band) and Michael Trakimas (Tufts Univ, MA) with 10b 10MS/s SAR with BW=25MHz (5th Nyquist band) from 2013 (IEEE CaS-I.).
Can somebody advice me some more subsampling-mode (IF sub-sampling) ADC from the literature?
Richard
Refer to some Application notes and the ADC parts mentioned therein from Analog Devices. They have very good collection of technical information which will help you precisely.
Thanks and best regards,
-Prasanna Waichal
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I am building a VLC system. A DMT signal (300MHz) from AWG directly modulates my LED. The LED is of SMD type mounted on a MC-PCB. I have transferred the DMT signal from AWG onto a 50 ohm trace on another PCB (via SMA jacks).
How can I connect the signal from trace with SMD LED terminals. The trace is locate don another PCB and LED is mounted on a separate MC-PCB. Can I use a simple copper wire to connect the trace and the LED terminals? For RF applications coaxial are preferable. Should I use a coaxial cable for connection between the LED and trace?
The maximum output voltage of the generator is 0.5 V peak to peak = +/-0.25 V (with DC component = 0 V) into 50 ohm = +/-5 mA.  The LEDs need a DC bias voltage in the range of 2.0 V to 4.5 V, with a current of a few 100 mA.  So you cannot drive the LEDs directly by the output signal of the generator.
The good news: If you place a suitable amplifier (transistor plus the necessary passive components) very near the two pads of one LED, you don't have to worry about reflections.  I would try a simple (not optimal) circuit like the one in the attached scan.  However, if this would be your first "homemade" PCB I would advise you to ask someone in the lab for support.
And, still being doubtful about the switching speed of these LEDs, I would start the tests using a very low frequency (e. g. 50 Hz). At frequencies below 100 Hz it might be necessary to use a greater capacitor at the input (e. g. 100 myF at 12.5 Hz).
I hope this is helpful. Good luck!
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i want to analyze the vibration modes (natural frequency) inside of a tapered rod of aluminum of one end 10mm diameter and other was 1mm diameter.please if you have a solution please let me know it.
Dear Atul Rananavare,
unfortunately tapered beams behave completely different than prismatic beams: the variation of the cross-section size induces non-trivial shear stresses that deeply influence also the constitutive relations as demonstrated in the attached papers.
In order to know the natural frequency of your beam, I suggest to use an highly refined 3D FE analysis.
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Also, does Open Vswitch OVS release that through VLan and bonding?
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While teaching op-amp circuits, which is the best way to explain the working of op-amp? I think the nullor model is useful.
For my opinion, these artificial constructs like nullor, norator etc. do not help at all.
According to my experience in teaching analog electronics (and that is the question!) , there are two basic areas which are necessary to (a) analyse and (b) design operational amplifier based circuits:
(1) Amplifier technics (bias point, small-signal begaviour);
So - finally, where is the need for an abstract model?
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As we all know - there is a variety of different types and working principles for chaotic oscillators. But I have only limited information on their practical use.
So - I am looking for a "list" of application examples (not only theoretical)..
Dear Lutz,
Wish you an enjoying journey to your son.
Chaotic signals have random nature much like noise and their applications stems from such unique characteristics.  So, they are used as an alternative to the pseudo noise code generators such as the maximum length PN codes. Their main applications are in spread spectrum systems where they are used to spectrally  spread a lnarrow band width signal to produce noise like wide band signal which becomes more imune against narrow band jamming.  Also, it can be used in orthogonalizing the different data signals to make them orthogonal and thereby do not interfere with each other  if they are transmitted in shared medium. This is is the code division multiple access CDMA. The last main application is to secure the data by encrypting them with cipher  keys generated by chaotic signals. One of the unique properties of the chaotic signals is that they are very sensitive to the  initial values and encounter large variations.
Best wishes and have a nice time
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Which one is more promising, network-assisted D2D or without network D2D communication? It's generally said that in D2D communication the two devices communicate directly using highly directional antennas keeping the out-of-band emission very low. Finally, is it related to cooperative diversity in any way?
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Hi,
I tried doing the CE BJT VI characteristics in the laboratory. However, I could not get the curves (both input and output chara). The following are the problems faced:
1) Input Chara - The base current keeps on increasing (even before the base emitter voltage reached 0.7V, base emitter current flows) - typical diode curve behaviour is not seen
2) Output Chara - The collector current is not flowing in the circuit (with increase in the collector voltage)
The BJT is working fine, so do the meters to measure current.
Please suggest a practical laboratory circuit to obtain the CE BJT VI chara.
Regards,
Raghu
Dear all,
Please find the attached circuit which I tried.
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i simulate a bow tie antenna but i cant see the same results as main paper. i think its excitation is wrong. would any one help me?
i attach the main paper with its simulation
thanks
attached are the simulations results S11, 3D radiation pattern, after removing the ground plane of substrate,.
Regards
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I am doing my research in RFID tag design.Now I want to know how to make  an
equivalent circuit model of the designed tag. Also I want to know, how to export equivalent circuit from CST simulation software
Thanks
Hello Aju,
you find attached a useful document on the equivalent circuit. you can export your design from CST as dxf file.
B.regards
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When discussing whether there is a connection between the transistor common-base stage and the op-amp inverting amplifier...
... Prof. Lutz von Wangenheim gave as an example the so-called "current feedback amplifier" (CFA). I have ever met this weird device, but I did not pay attention to it because I just did not understand what the hell all these absurd connections were (an output to output instead to input?) contradicting the simple engineering logic. Now it was enough to cast a glance at its internal circuit diagram (the attached picture below) to be amazed and admire this great circuit solution! This was a chain of ingenious ideas, a real "necklace of diamonds"! Just to see how beautiful, simple and symmetrical its circuit diagram is enough to admire it!
It was very interesting for me to see in this "cocktail" of famous circuit solutions some useful implementations of basic circuit ideas that have arisen for consideration in a number of previous questions:
http://www.circuit-fantasia.com/my_work/conferences/cs_2005/paper2.htm (the differential dynamic load idea and its implementations)
But what was my surprise when browsing through reputable sources? I noticed that instead of being made related to the classical tricks widely used in transistor circuits, the current feedback amplifier is presented as something completely new. I have not met even a hint of the existence of such famous circuit ideas like "common-base" and "common-collector" configurations, "dynamic load", "bootstrapping", instead, I read direct statements like "the inverting input is its low-impedance output terminal" (http://www.analog.com/library/analogdialogue/anniversary/22.html). But I would be very interested to see the look on the face of the ordinary (unenlightened in the intricacies of the circuit "handicraft") reader when he/she reads that the input of the circuit is... its output!
So, my suggestion is to try unveiling the clever secrets behind CFA as we go back in the past and try to recreate, step-by-step, the way its creators (David Nelson, Kenneth, Saller Bill Gross etc) were thinking when inventing it. If you allow me, I can start the discussion by exposing below my story about the possible reasons for originating this clever circuit solution.
I think the theory (right) is well written practice. And your statement is too hard.
I agree that the final verification gives us experiment.
Experiment really knows all the laws - even those which we do not know
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Recently I am trying to reverse engineering circuit of the torque sensor (attached pictures), that compromises of two TI op-amp, two regulators, AD685 for compatibility with HART protocol. But it's a sort of very time consuming and I have always been willing  to learn how to design these kinds of analog circuits. I really appreciate if anyone may show me a schematic circuit of this type of circuits. This will be a big help to me.
Thank you all
align your strain gauges as shown in the figure and make Wheatstone bridge of it, followed by Instrumentation amplifier, with required gain. you will be able to do torque measurement, be careful while selecting and Mounting Strain gauges. reproducibility and repeat-ability depends completely on the mounting methods....all the best!
attached is the signal conditioning schematic with 741 opamp. there are also ICs available in market which can reduce component density on board.
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I need to do network reconfiguration in distribution for that i need to form loops using tie switches. So how to for loops using Lp and Lq vectors?
Hoping this helps u.
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As shown in the attached file, the pins have been connected as follows:
PIN 1: +15V                         PIN 2: -15V
PIN 3: output to DAQ           PIN 4: Ground
PIN 5: Primary Input            PIN 6: Primary output
*correct me if any wrong connections
But for pin 3, do I have to put a resistor for the output?
Also, how do I calibrate the current sensor, that is, is there any equation so that I check the output and that I can implement it in my interface?
The HY 15-P is specified for a 10 kΩ load resistor (to ground).
Regarding calibration: execute at least 3 measurements: no current and ±IX. The no-load point is to check for linearity, the two other values defining a line.
You can do more measurements, calculate 'better' points to get the line equation, but the above should suffice regarding the accuracy of 1 % of this sensor.
Regards
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If i am measuring PWM signals from the micro-controller and for simulation process DC-link of the rectifier can be calculated by knowing the modulation index . is there anyway to calculate or to visualize the modulation index from the measure PWM signals ? If the supply voltage is given ?
Abdullah,
Welcome,
The modulation index of pulse width modulated waveform representing an output of a dc to ac inverter is purposely defined by the amplitude of fundamental frequency component contained in the output waveform divided by the  a reference inverter obtained by the fundamental frequency clocking FFC. The reference waveform which is a bipolar square wave gives an an amplitude of 2/pi Vidc, the input Dc voltage.
The the modulation index= Vof/ (2/pi) Vidc,
where Vof is the fundamental amplitude of the output pulse modulated wave form.
Then all what do need if to fiter the fundamental and measure its amplitude.
In fact you need to measure the amplitude of your output sine wave after the low pass filtering.
Best wishes
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I am doing research on antenna Design and I need some information about the materials used for antenna design...
The above lens is only in 2D.  The clever part is in designing and making the 3D meta-material that has the bandwidth and angular performance, is low enough loss, and can be made (and can be easily modifies to grade the dielectric constant.  Once you've done that the Luneburg lens is easy.  I don't think you will find any to buy.  Here is a 3D one.
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One reviewer required that"Proof that the results a OFDM signal are the chaotic signals. " But we cannot. We think the OFDM signal is not the chaotic signal. But we cannot gave some detailed illustration. Please help me.
OFDM is a multiplex scheme, if the transmitted data series is a chaotic one, than the corresponding OFDM signal may have some chaotic properties. Without any restrictions on the modulated data, we cannot say that an OFDM signal is a chaotic signal. For example, if the data is a periodic one, then the OFDM signal is also periodic, It is obviously not chaotic.
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I've seen papers for both, which makes me quite confused. I guess it might depend on its application or modulation mechanism? I wonder if there is any detailed derivation for velocity matching?
The group velocity of the microwave and light wave must match as the waves are wide band modulated. In case of a very narrow bandwidth the group velocity may approach the phase velocity in the limit of a single ferquency. So, in general, one has to match the group velocity.
This is equivalent to match the impedance of the two transmission media in a wide bandwidth by using the group index ng. That is zw= zo/ ng for the light waves and the ffective index for the microwave.
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While trying to run a parameter sweep in CST, I observed that for one particular value of the paramater I a getting some strange S21 characteristics. There are certain suden spikes in the curve at a particular frequency.
Could anyone clarify why this is happenning? Note that this happens here for one particular value of a parameter (gap = 0.13). For gap = 0.1 and 0.16 things seems okay. Is there any problem in my simulation procedure? Awaiting your valuable suggestions.
PS: I am trying to design a transition here from a planar patch structure to a Dielectric Waveguide.
S2(1),1(1) represents transmission to 1st mode in Waveguide port from Microstrip line port and S2(2),1(1) repesents that to the 2nd mode.
Hi!
I am quite sure, but the problem would have arisen because of improper selection of port, for that purpose first form the outer cylinder (vacuum) of radius slightly greater than your assigned radius and then select edge of outer cylinder for assigning ports. Second, what I saw, that your excitation is been given at some other line (microstrip line), not at your assigned port (may be, I am wrong), this can also create some problems. One more thing, gaps which you defined, have some physical significance in terms of electric field, magnetic field, fringing field effects and wavelength. So, it is also a problematic case, that's why you would be getting spikes. I will run your problem by own, then I will be able to discuss exact solution of your PS.
All The Best,
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i want brief details about reflection coefficient vs frequency in antennas. for a good antenna, if reflection coefficient is more or less
Dear Venkateswararao ,
The antenna is a load on the radio frequency feeding source. The feeding source, has normally a source impedance Zs. Assuming that the antenna input impedance is Za, then by definition the reflection coefficient rho can be expressed by
roh=( Za- Zs)/ (Za+Zs)
To feed the whole power to antenna, the roh must be equal to zero. Which means that Za= Zs. Normally Zs is pure resistive and equal 50 ohm then  Za must be matched to 50 ohm which means that the reactive part of the antenna impedance Xa must be made zero , which is the condition of resonant antenna, while the antenna equvalent resistance must be matched to 50 ohms.
From this discussion , the reflection coefficient will be minimum at the resonance frequency of the antenna. The reflection coefficient will be highest far from resonance frequency and drops to minimum at resonance frequency of the antenna. If there is equality of the resistive parts of the antenna and source  the reflection coefficient will fall theoretically to zero at the resonance frequency of the antenna.
Best wishes
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I have a task to Implement boundry scan and Verify IO Pads of My design using P1500 Bcell, But as we dont have dedicated state machine for P1500 protocol as we have for 1149.1 protocol. so I want to use 1149.1 state machine and p1500 Bcell at IO pad level so is it possible??
I am not getting exact signal mapping from 1149.1 to 1500 protocol.
yes i am getting at 1149.5 with slight variations in p1500B cell
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In few recorders we not use transducers and in few of them we use. So, i want to know that what are the advantages or disadvantages.
Please comment related to details of sensors also which is used in a hybrid recorders.
First the question is not complete and clear. Which type of recorder you are talking about? Mechanical, Electronic (Analog or Digital), or Magnetic etc.
Any recorder record a variable quantity. May be physical- temperature, pressure, humidity, weight, speed, acceleration, voltage, current, power etc. etc. Now these physical quantities need to be converted to another physical quantity say mechanical movement, or voltage or current depending upon the type of recorder. This conversion of one physical quantity to other takes place through a mechanism or a device called transducer. Simple microphone is a transducer. It converts air pressure into equivalent varying voltages. Speaker is a transducer that converts varying voltages at its input into equivalent  varying air pressure.
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In a basic pursuit problem comprising of a l-1 regularizer term, there can be more than 1 solution due to lack of uniqueness of solution. Will it mean that Basic pursuit denoising problem is not convex due to multiple global minimas
Dear Anomol
What you stated is true,The presence of more minima for the optimization problem assures that the surface of the error for your problem is concave, and that makes the solution is very hard and costly in that case you should compromise between the solution accuracy and the CPU time considerations.
Good Lick
Prof. S. EL-Rabaie
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(LASI - Layout System for Individuals)
As explicitly stated on the LASI homepage, LASI does not have circuit simulation capabilities. It is capable to create a Spice netlist, for the simulation you have to use some Spice implementation capable to import this netlist.
Regarding DRC: did you already check the materials (help, additional support packages)? And did you read the FAQ part on the LASI homepage?
Not sure whether this really helps...
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How to use non parabolic band approximation for the analysis of interband effects of electrons for plasmonic device application?
For a device application, you need the dielectric function. The experimental is the best. It includes all quantum effects.
You can calculate it in a model, or you can use a phenomenological  model, for example  describing interband transition with a Lorentz function.
To calculate the dielectric function from the band structure, you need in addition to the structure itself, the matrix elements of transitions between different states. Then calculate the appropriate sum. It is a lot of work to perform for the device application with little result.
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In the random acccess procedure of LTE, to mitigate the congestion in physical random access channel, the standard adopts the Uniform backoff scheme. The backoff window size is indicated by  Backoff Indicator, which is a system parameter broadcasted by eNodeB.
My question is: How does eNodeB select Backoff Indicator? Does the standard give any scheme to select Backoff inidcator?
Dear,
Back-Off indicator field indicates time delay between PRACH and next PRACH. Based on the value received in back-off indicator sub header field, UE performs random access procedure, at times where eNB suffers from lot of traffic,at that instance if a new UE sends a preamble but enb cant give any resources then eNB ask the UE to perform the RACHing after some time.this is informed to the UE in the form of Back off indicator.based on it UE has to wait for next RAChing procedure.
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Given a subframe, N Resource blocks are assigned to a particular D2D user (DUE). What is the best method of modeling? I am following the approach here as : (assumption)
NRB = 44; Timeslot = 64;
% RA = Resource Allocation (Real + Imag)
% RA_real shows the sub-carrier allocation (NRB)
% RA_imag shows the timeslot (note that 2-RB = 1 Resource for D2D device a.k.a DRB)
RA = randi([1,NRB], 1, N_D2D_devices) + randi([1,Timeslot/2], 1, N_D2D_devices).*i;
Any suggestions if it is right?
2. How to calculate the RSSI for it?
3. If DRB (0 + 0i to 0+1i) is dedicated for DRB 1for transmitting beacon of DUE-1, hence what will be interfering parameters for DUE-1. i.e. I think DUE-1 won't be able to hear any other member who occupies the same subcarrier because of full-duplex?
DEAR JAFFRY
HOPE THIS SLIDE PICTURES COULD HELP
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We have the circuit hooked up to an arduino uno. We are using the frequency counter function in the arduino uno. We are using a 10 MHz Gold AT-cut crystal (from Gamry).
When placing a small drop of buffer solution (30 uL) on the crystal, the resonant frequency increases to 15 MHz. How is this possible and why is it occurring?
"I understand that the frequency is supposed to decrease"
That's not always the case, especially when mass in particulate form comes in contact with the QCM surface [1,2].
The observed frequency increase could be attributed to the formation of a coupled resonator between the buffer solution droplet and the oscillating QCM surface [1].
1. Dybwad, G.L., "A sensitive new method for the determination of adhesive bonding   between a particle and a substrate", J. Appl. Phys. 58 (7) (1985) 2789-2790.
2. Vittorias, E., Kappl., M., Butt, H.-J., Johannsmann, D., "Studying mechanical microcontacts of fine particles with the quartz crystal microbalance", Powder Technol. 203 (2010)  489-502.
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any body please suggest in problem.
i choosen general formulae for optical communication
pr=pt*exp(-cr)/(r^2*(theta)^2). in this equation power values are too high comparing to transmitting power even in 10meters. but in papers mostly underwater communication this formula using.can any one help for this doubt .please if i try to plot it starting from 10^8watts orders even i am giving single oder powers10 Watts
dear ms somi
hope this info could help
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Hi, I am doing my research in supercapacitor. I have planned to use a pervoskite material as dielectric. So help me to deposit any pervoskite material on my substrate.
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The channels between BSs and users are generated with a normalized Rayleigh fading component and a distance-dependent path loss, modeled as PL(dB)=148.1+37.6log10(d) with 8dB log-normal shadowing. The transmit antenna power gain at each BS is 10dBi.
Say that the transmitter has M antennas, then you can generate the channel as
d = [Add distance here in km]
pathloss = 148.1+37.6*log10(d) + 8*randn(1) - 10; %pathloss + shadow fading - antenna gain
variance = 10^(-pathloss/10);
channel = sqrt(variance/2)*(randn(M,1)+1i*randn(M,1));
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The idea consist to create a switcher from a power divider using varactor diodes to adjust impedance adaptation. For a 6 ways power divider, four outputs works well but two output don't work despite the same condition used for worked outputs.
The structure is symmetric and has a cylinder shape.
Researchgate can be very useful sometimes
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the LEACH protocol is divided into rounds . Each round is divided into setup phase and steady  state phase. The power equations deal with steady state phase is known, but what about the power equations that's related to the setup phase .....
If you read the first paper of LEACH, you will find that they neglected power consumption in setup. The power consumption depends on distance and bits/ packet. If you know how many bits you need to send in setup you can calculate it.
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HI
I just found an bootstrapped sample/hold circuit from a text book. I have simulated the same. I need to calculate SNR, SNDR and ENOB for the same
Input at 5MHz, sampled at 100MHz
How can I do that on cadence?
Dear Anush,
I would like to add to  the Vladimir answer, that the error due to sampling is considered as a noise and distortion. To be more clear the sample and hold circuit outputs at a sampling time instant  nTs a value y(nTs) while the inpu is x(nTs) . As clear from you waveform the two values are different. They are only approximately equal.
So, the noise and distortion is the difference y(nTs) )=y(nTs) - x(nTs) ,
So building a difference time sequence extending a number of complete cycles of the input wave form can be used to evaluate the noise and distortion simply by by squaring and averaging the difference function along the observation time T=MTs.
That is N+D= sum y(nTs) ^2 over all Msamples /M,
The signal to noise and distortion can be determined by dividing the signal power to the noise and distortion power as defined by the above equation. That is,
SNAD RATIO=  sum x(nTs) ^2 over Msamples/M / N+D,
In order to separate the noise from distortion you need only to transform the output sampled sequence to frequency domain using the discrete fourier transform or the fast Fourier transform. The input tone and its harmonics will be apparent in this domain in addition to the noise floor. One can then determine the mean square value of the fundamental and the mean square value of the harmonies and the  mean square value of the noise floor. One can get also the spurious free difference
which represents the ENOB. However, the effective number of bits has only meaning for a complete A/D converter.
Wish you success
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