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Hi, I don't know if I can help you with this. I guess that to calculate the energy of the signal, you need to do some sort of FFT to decompose the incoming signal into its fundamental frequencies. Then you can calculate the energy content of it. You can check about this in any signal processing book. There is a nice link to a free e-book about signal processing. You might get some info there : http://www.dspguide.com/ Regarding taking 230VAC to the AD, I suggest you to use a well designed resistive (and capacitive) voltage divider, then isolate with a differential isolator, such as Analog Devices AD210 or Agilent HPCL series or HCNR200/201. I suggest good filtering and EMI protection. Filter the input with a cut-off frequency less than half your sampling period. You can also use a signal transformer if you input signal is only AC. Just check the impedance, you don't want to use a low impedance with 230VAC. Always try to use isolation. It is a pain in the neck to design a circuit like this, but it is worse if you get 230VAC directly to the board. Do not use wall transformers to step down the voltage. Generally, their magnetics are really poor and they'll cause saturation. The output waveform will never resemble the input. Hope this helps, Mariano PS: By the way, I know my name is confusing. Mariano is a spanish male name. ----- Original Message ----- From: "noordspmot" <> To: "Mariano Filippa" <> Sent: Friday, February 27, 2004 1:04 AM Subject: Re: need u'r help hello Madam, i have been working on the dsp56805 board for a couple of weeks. i have seen u answer many queries.so that's the reason iam posting this query to u. i have been asked to take the input to the adc as 230 v ac.and calculate the energy content of the signal. this input shall have 6 harmonics with it. how do i calculate the energy consumed by each one (harmonics)of them. i have read that the adc can take only 3.3v max,so we shall have to scale it down to sample it. pls ,help out. thanks in advance, bye, Noor Khuteja --- In , "Mariano Filippa" <mfilippa@f...> wrote: > I have never found the electrical specifications of 5680x family. However, from what I've read, I assume that it also works with the core voltage: 0V ~ 3.3V. There is an application note that might help: DSP56800 ADC (AN1947/D). > > If needed to measure a sine wave, I would use either two methods: > 1) reduce amplitude and add offset. Play around with the VREF pin or do some sort of software calibration. > 2) reduce amplitude and rectify (using a precision rectifier with opamps) > > Check Motorola's application notes of Motor Control. They'll often have to take a sinusoidal current feedback, add offset and isolate from DSP. Take a look at page 29, application note MEMCOBUM/D. > > Hope this helps, and buena suerte > Mariano > > ----- Original Message ----- > From: Oscar Javier Tadeo Jaramillo G > To: > Sent: Sunday, January 25, 2004 8:53 PM > Subject: [motoroladsp] Electrical specifications for ADC > Greetings. > > I need work with the ADC module, sensing a senoidal wave, but i don't know what is the max in voltage amplitude of the input for ADC. > > The ADC can work with negative and positive value in the input? > Thanks > Cordialmente, > > Oscar Javier Tadeo Jaramillo Galeano > Nit: 98665185-4 > Telefono: 300-779-60-62 > > > -------------------------------- ------------ > Busc un auto? > Encontralo en Yahoo! Autos > M de 4000 clasificados todos los ds! > Usados - 0 km - Vendel tuyo > > _____________________________________ > Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. > > _____________________________________ > About this discussion group: > > To Join: > > To Post: > > To Leave: > > Archives: http://www.yahoogroups.com/group/motoroladsp > > More Groups: http://www.dsprelated.com/groups.php3 > > > -------------------------------- ------------ > Yahoo! Groups Links > > a.. To |
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Re: need u'r help
Started by ●February 27, 2004
Reply by ●February 27, 20042004-02-27
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If you want to measure the energy in an AC line you need to know the current at the same time. You can measure the voltage but that's all you will be measuring. If the current isn't in phase with the voltage you will not get what you want. Chris Pollard _________________________________________________________________ Find and compare great deals on Broadband access at the MSN High-Speed Marketplace. http://click.atdmt.com/AVE/go/onm00200360ave/direct/01/ |
Reply by ●February 28, 20042004-02-28
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Do you need to measure the current? He is talking about measuring the
energy content of the signal, up to 6 harmonics. Here's the original question: > i have been asked to take the input to the adc as 230 v ac.and > calculate the energy content of the signal. > this input shall have 6 harmonics with it. > how do i calculate the energy consumed by each one (harmonics)of them Don't you only need to measure the energy content of the voltage signal regardeless the current you are taking? If you measure voltage and current, then you are measuring power. Still, I'm not even 10% sure about this. Mariano ----- Original Message ----- From: "C POLLARD" <> To: <>; <>; <> Sent: Friday, February 27, 2004 5:42 PM Subject: RE: [motoroladsp] Re: need u'r help If you want to measure the energy in an AC line you need to know the current at the same time. You can measure the voltage but that's all you will be measuring. If the current isn't in phase with the voltage you will not get what you want. Chris Pollard _________________________________________________________________ Find and compare great deals on Broadband access at the MSN High-Speed Marketplace. http://click.atdmt.com/AVE/go/onm00200360ave/direct/01/ _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: To Post: To Leave: Archives: http://www.yahoogroups.com/group/motoroladsp More Groups: http://www.dsprelated.com/groups.php3 Yahoo! Groups Links |
Reply by ●February 28, 20042004-02-28
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If it's AC - YES. You can have the voltage vary all over the place -
but if there is no current there is no energy. Chris Pollard >From: "Mariano Filippa" <> >To: <>, <>,"C POLLARD" ><> >Subject: Re: [motoroladsp] Re: need u'r help >Date: Fri, 27 Feb 2004 18:48:53 -0500 > >Do you need to measure the current? He is talking about measuring the >energy >content of the signal, up to 6 harmonics. Here's the original question: > _________________________________________________________________ Get fast, reliable access with MSN 9 Dial-up. Click here for Special Offer! http://click.atdmt.com/AVE/go/onm00200361ave/direct/01/ |
