## Forums

## OT: An Engineering Program Manager Joke

inHi, Things have been pretty quiet hear for the last few days. Having nothing more useful to post, here's a joke about Program...

Hi, Things have been pretty quiet hear for the last few days. Having nothing more useful to post, here's a joke about Program Managers; A program manager has been working his team extra hard and as a small reward offers to take two of the engineers out to lunch. Walking to the restaurant they trip over a magic lamp and out pops a genie offering them each one wish...

## Multiple ADCs and aliasing

inI have two 1MHz ADCs and would like to interleave them by a half of the sampling cycle in order to get a single ADC with effective sampling...

I have two 1MHz ADCs and would like to interleave them by a half of the sampling cycle in order to get a single ADC with effective sampling frequency of 2MHz (I want to oversample the signal by as much as possible). But the aliasing properties of the data stream will be as if the signal was sampled at 1MHz because the ADCs are independent blocks and don't influence each other, right? Bes...

## Is 'Bessel' digital lowpass filter standard?

inHi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important...

Hi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important aspect is that the ringing (overshoot) shouldn't be higher than about 3%. When using a 3rd order Butterworth, I get about 9% overshoot, which is too much. Someone hinted my that a Bessel filter would be better suited. This program is a good start http:...

## Simple Integration

inI have an integral 1/(a^2-x^2) wrt x. If you use partial fractions we get (1/2a) * ln [ (x+a)/(x-a) ] +c and zero initial conditions...

I have an integral 1/(a^2-x^2) wrt x. If you use partial fractions we get (1/2a) * ln [ (x+a)/(x-a) ] +c and zero initial conditions gives c=0 however, this is a standard integral and should be (1/a)arctanh(x/a) How to get to that stage. I know of course arctanh(x)=(1+x)/(1-x) when I use this the sign is wrong.

## Real Square Waves

inHi Guys. Want to see some real square waves? Check this out: https://shareably.co/dangerous-square-waves/ [-Rick Lyons-]

Hi Guys. Want to see some real square waves? Check this out: https://shareably.co/dangerous-square-waves/ [-Rick Lyons-]

## How to synchronize ADC input to reference pattern?

inHi, I have some (quite old) network analyzer software source code which creates amazingly accurate results with PC sound devices. Basically...

Hi, I have some (quite old) network analyzer software source code which creates amazingly accurate results with PC sound devices. Basically it outputs some reference to line out while sampling its own output at the right channel and the two port response at the left channel. When using (cyclic) noise patterns as reference everything is fine because any latency is cancelled by the sam...

## Matched filter chiprate issue

inHi all, I have received a transmission which consists of a series of PN sequences. I recorded at 8*10^6 SPS (8 MSPS) and wish to perform a...

Hi all, I have received a transmission which consists of a series of PN sequences. I recorded at 8*10^6 SPS (8 MSPS) and wish to perform a matched filter on it. The transmission binary sequence is 1*10^6 bits long and I have just been informed that it was transmitted at a rate of 1,016,118.24682 bits/sec which seems like a very strange chip rate to pick but unfortunately this is beyond my ...

## Doppler correction, SatCom channel.

inHi, I am looking at a Goldcode transmitted from a LEO satellite and want to perform a matched filter on it. The problem is there is a...

Hi, I am looking at a Goldcode transmitted from a LEO satellite and want to perform a matched filter on it. The problem is there is a significant amount of doppler (20kHz) which degrades the performance of the matched filter significantly. If I have a chunk of this signal (quadrature sampled) what would be a good approach to negate the affects of the doppler? Any input will be much apprec...

## Hilbert transforms and sampling rate?

Hi all, My knowledge of biquad filter coefficients isn't great but from what I've experienced, they change based on sampling rate. but I've...

Hi all, My knowledge of biquad filter coefficients isn't great but from what I've experienced, they change based on sampling rate. but I've bumped into these two examples of hilbert transforms online and neither takes sampling rate into account. Are they okay to use or are they just based on 44.1kHz? Thanks, Matt // hilbert quadrature filter hilbertBiquad(x0) { x1 = biq

## OT: Those arithmetic questions

inOften you see questions on social media such as - find the answer to 9/3(1+2) (they usually use the divide symbol which nobody uses of course...

Often you see questions on social media such as - find the answer to 9/3(1+2) (they usually use the divide symbol which nobody uses of course so= I have replaced it with a slash) and they spout on about order of operations and so left to right the answer= is 3x 3 =3D9 and the catch is that people answer 9/9 =3D 1. Ha, they don't= know their order of operations which was agreed by conve...

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