# Tag Info

18

I guess it depends on several factors, among others the order of the filter, but you have a few possibilities: Find a signal generator that gets there. These are rather inexpensive nowadays. Trust the math. This is a digital filter and as such it scales with sampling rate. If you can increase the sampling rate by two orders of magnitude you would have a ...

10

I would use my Agilent function generator, which goes down to 1$\mu$Hz, a fairly unremarkable (and obsolete) Model 33522A. My Rigol DG4102, I think, similarly has 1$\mu$Hz resolution and cost less. Unfortunately, you can't get that low with cheap DDS (eg. AD9850) modules because the tuning word is only 32 bits and the clock is typically 125MHz, so that'...

10

Feed forward refers to the direction of the signal flow. For feed forward, the direction is, well, forward :-) I think it is easier to show an example. I know that many "sigma-delta" ADCs (analog to digital converters) use a combination of feedback and feed forward. I found an example of a block diagram of such an ADC here in this article, about Higher-...

6

Option 1: Test on the PC. If your DSP code is written in C, then you can set up a test harness in GCC or Visual Studio. You know the sample rate for your DSP code, so use Excel to generate a test input CSV file, and have your test harness dump a CSV file output which you can check. Option 2: Test on the DSP with a PC interface. If your DSP code has to ...

5

If you have a D/A converter as well in your DSP system, you could generate this extremely low frequency signal in software an feed it back to your A/D input. Alternatively you could use a D/A Card or USB Adapter to generate the signal. One example of such devices would be LabJack but there are many more with varying price/capabilites out there. Another ...

3

Let me step back first...A control system needs an input and output, and some method to measure feedback. Open loop examples include magnetic stepper motors, while closed loop tend to be linearized for one or more variables. In between, there are signal conditioners or processors to feed an improved response in both time and frequency domain. This can be ...

3

The picture below represents a velocity controller that you can usually find in AC servo motor. It's just a fraction of the entire cascade loop. The low frequency signals (slow response) go through lower path, this is: velocity setpoint ($\Omega{set}$) , actual velocity ($\Omega{m}$) from encoder feedback, lowpass filter ($T_{f}$), PI controller (\\$...

3

Neither options seem very reasonable in 2019. the RLC is unnecessarily bad a filter, unless you do many stages, which becomes very complicated, tone detection is very sensitive to more than one tone being present, so not usually an option for audio / hydrophones. You'd want to do your localization in digital anyway, so do the filtering in digital, too. ...

2

If this was a frequency I could generate with a signal generator it'd be easy to check, but 0.05Hz is too low and I can't generate it. How do engineers check this kind of filters? There are three good ways to check for filter response, one is a dirac delta function (a impulse function or short pulse), the other is a step input, and the last one is a ...

2

This might sound silly, but it could work and result in a simple circuit with large margins for errors: demodulate the signal to a lower frequency. By multiplying the signal with a ~750 tone, you will have a ~30Hz and ~250Hz signals, that can easily be separated with a first order filter. You can easily achieve this by “chopping” the signal with the ...

2

You have defined your DC as varying at 0.000001Hz. Are you aware that this is 1000000s, or 1.9 years? If that's truly your intention, with a sampling rate of 64000Hz, you need to average 64,000,000,000 samples to get your 1 DC measurement! I imagine you don't really mean such a low DC rate, but assuming something in the low Hz region, I suggest instead that ...

1

The simple answer is that you are out of luck. With "tones of 784, 880 and 988" Hz, a second-order filter simply won't work. While, in theory, you could make the Q high enough to get the selectivity you need, component sensitivity will eat you alive. Instead, you'll need to take another approach. The early days of DTMF touch-tone detection used PLLs, with ...

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