Hey!
So I have a raspberry pi that uses 5V/1.2A and a LCD monitor that uses 12v/0.2A. I would like to power both using a single wall power outlet. I found a power adapter that converts 100-240VAC/50-60Hz/1.2A to 12VDC/2A.
I was wondering if it is as easy as cutting off the connector on the...
Hey all, I was wondering if you can help me define the arguments for the dare() function of matlab. Here is the DARE form I have:
\begin{equation}
\begin{split}
\Phi(p_\infty) &= \Phi_\infty = \Phi_{33}-\Phi_{32}(\Phi_\infty+\Phi_{R})^{-1}\Phi_{23}\\...
Hey all,
I've had this point of confusion for a bit and I have thought that with time I may be able to clear it out myself. Nope, hasn't happened. I think I need help.
Let us say we have the following
\phi_{k+1}=\phi_{k}+v_k where, v_k\overset{iid}{\sim}\mathcal{N}(0,\sigma^2) and...
Hey all. Let me just get right to it! Assume you have a function f:\mathbb{R}^n\rightarrow\mathbb{R}^m and we know nothing else except the following equation:
\triangledown_x\triangledown_x^Tf(x)^TQy=0
where \triangledown_x is the gradient with respect to vector x (outer product of two gradient...
Hey all, I have been doing some math lately where I need to find the conditional expectation of a function of random variables. I also at some point need to find a derivative with respect to the variable that has been conditioned. I am not sure of my work and would appreciate it if you guys can...
Hey,
I have been trying to figure out how to solve \triangledown_x ||f(x)||^2_2.
I have used the chain rule (hopefully correctly) to get the following:
\triangledown_x ||f(x)||^2_2=2\triangledown_xf(x)^T \frac{f(x)^T}{||f(x)||_2}
Is this correct?
The reason I doubt my answer is because I know...
Hey all. So I think I've been trying to figure this out longer than I should, that is why I am here now. I was reading an ieee paper and have been pondering a missing proof (the paper deems this proof too easy to show, literally... I must be really stupid or something). It is a simple question...
Hey all. I know that A^TA is positive semidefinite. Is it possible to achieve a positive definite matrix from such a matrix multiplication (taking into account that A is NOT necessarily a square matrix)?
Hey all! Let me get right to it!
It is given that $$A \succeq 0$$
I need the following to hold for M: $$M^TAM\succeq 0$$
What are the constraints or conditions on M for M^TAM\succeq 0 to hold?
Anything would help at this point... I am open to discussion.
Note: It may be worth mentioning that...
Hey all. Let me get right to it!
I have the following objective function: \mathbf{minimize} \ \ trace((G^TG)^{-1})
I am trying to minimize it with CVX.
I used schur complement to do the following:
\begin{equation*}
\begin{aligned}
& \underset{G}{\text{minimize}}
& &...
Hey all. So I have been reading this article and have a question I would like to ask. I will be referring to this article extensively so it would be kind of you to open it: http://www.ee.ucr.edu/~yhua/MILCOM_2013_Reprint.pdf
I believe reading the article is not required to answer my questions...
Hey all. I am currently reading an article and there is a paragraph that I am having a hard time understand. This is what the paragraph says:
"Since Ar = Arτ and Ai = -Aiτ, we know that only the lower triangular (including the diagonal) elements of Ar are independent and only the strictly lower...
Hey all!
I am trying to figure out how one goes about to try and find the transfer function (impulse response) of a real life system. Assuming the system is LTI.
This "system" I speak of is a channel that is comprised of components such as linear amps, a mixer (can we even assume a mixer is...
Hey all! I have been trying this problem for a while and can't seem to get the same answer as the solution. If someone can tell me where I am going wrong, that would be much appreciated. I am very close to the solution, but I am missing a term in the denominator. Everything is shown below! Thank...
Hey all. I have been trying to calculate the input resistance of a common gate amplifier, but seem to have problems doing so.
I know I have to set a test voltage (or test current) at the input, and I've been told, to ground the output. So using the Hybrid pi model for a mosfet, I did the...
Hey all. I have a question regarding the solution to a question, both shown below (only part of the solution is shown). Specifically the line that states: H(Y|X) = H(Z|X). Why does this equality hold? Expanding and using the definition of entropy, I can see that for the above equality to hold...
Hello all,
I have been meditating on this for a while, but can't seem to understand how this simplification came to be. Any help will be greatly appreciated.
So, here is what we start with:
##\mathop{\sum_{k=0}^m\sum_{l=0}^n}_{m{\geq}n} x(k,l)##
We also know that: l (lower case L) = n-m+k
and...
Hey all. I have a question regarding an equation in a document I am reading about convex optimization of OP-AMPs. The document is attached, the equation is of section 3.4 and the equation number is (9). Can you please explain how it came to be? I understand that i3 = i4 = i5/2 but I don't...
Hey all. I am currently trying to brush up on my multithreading "skills" (I dare say) that I learned in my undergrad class. I have the following code that I am trying to run:
#include <pthread.h>
#include <iostream>
using namespace std;
void* func1(void*);
int main(int argc, char** argv){...
Homework Statement
Show if the set is convex or not!
S2 =
Homework Equations
I know that to show a set is convex you can either use the definition or show that the set can be obtained from known convex sets under operations that preserve convexity.
Convex definition: x1*Theta + (1 -...
Homework Statement
Find the derivative of f(X).
f(X) = transpose(a) * X * b
where:
X is nxn
a and b are n x 1
ai is the i'th element of a
Xnm is the element in row n and column m
let transpose(a) = aT
let transpose(b) = bT
Homework Equations
I tried using the product rule...
Homework Statement
Homework Equations
\check{T} = BTB^{-1} (eq1)
The Attempt at a Solution
Ok, so I have a couple of questions here if I may ask... First, I want to be sure I understand the wording of (a) and (b) correctly. Is the following true?:
(a)
Write the matrix T...
Hello all. So i have been trying to simulate a ndg transistor mixer in LTSpice. Here is what I have so far, but I am missing something and I can't figure what it is... Here is the schematic along with the waveforms.
For some reason the output will not go over 0.3V (do I have to bias it?)...
Hey all. So I am now trying to work on IF amps for a superhet AM receiver (medium wave) and found the following figure in the ARRL handbook:
I have a couple of questions regarding these schematics.
First and most importantly, do these work for IF signals (of 455KHz with BW of 18KHz)...
Hi all. I started a thread a while back about RF mixer design. I didn't know what to do or what design to choose. You guys laid some options for me and after some research and time I have finally decided that I will go for a double balanced, ring diode topology. Here is a schematic from google...
Hello all. I have been looking into RF amps. I have come across the following cascode amp (from ARRL handbook 2014, p 12.10, FIG. 12.11. Thanks to Baluncore for the great reference). Here is a simplified version made with Qucs:
My questions are regarding the capacitors, C1 and C2. Why are...
Hey all. I will get straight to the point. I am about to get into graduate school and I have the option to choose between Controls & Robotics OR Communication & Signal Processing. I am kind of not sure what to pursue, the reason is because I feel if I choose one I will unfortunately lose the...
Hello all. So I have been trying to build a mixer lately, I have done my research on google but I am still kind of lost. I know now many mixers exist; single diode, multiple diodes, single balanced, double balanced, unbalanced and so on. I don't want to build a circuit blindly, so I am trying to...
Hello all. I am trying to use a mosfet as a high power switch. I have an arduino nano pin controlling the gate of the fet. I am using an NTE2374 mosfet. I am using a typical circuit:
I also have the gate connected to the source (ground) so that when the gate is not HIGH, it isn't floating...
Homework Statement
For now I am trying to find the power spectral density only.
The Attempt at a Solution
From the given graph, I got g(t) = -1 + 2rect(t/2), with a perdiod of 4s
PSD = Sg(f) = lim(T \rightarrow\infty ) \frac{1}{2T} || G(f) || ^{2}
My fourier transform of g(t), G(f), I...