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Visitor kvasir
Visitor
3,974 Views
Registered: ‎10-16-2008

AMP-ADC on Spartan 3AN starter kit - noise

Hi, i know that problem's with adc and amp are common on this forum, but i didn't found solution to my problem ... I connected spartan3an startet kit AMP with ADC and DAC . Everything is working good, signal from guitar connected to amp header is heard on amplifier connected to DAC , signals observed on osciloscope are almost identical. Even delay based on ROM is working quite well. But the problem is that there is NOISE ... always NOISE ... When guitar is disconnected there is noise on dac-out , when guitar is connected, there is noise, when i play on it, there is noise too ... i thought that it is 50hz from electrical network, but not. When i put values on DAC by hand (into vhdl code) it works as expected. Any idea ? .. I know that on-board ADC \ DAC isn't audio-friendly , ideal would be audio codek , but i am trying with what i have. It is something like proof of concept, not actual hi-end audio application, but the noise is very anoying. The board is almost identical to spartan 3e (in amp,adc,dac part). As datasheet of amp says, input voltage range is always above 0 ... This is strange for me, as i am not an electronics engineer. But after whole path (amp,adc,dac) the signal is positive and negative so i think it doesn't matter i think...Oh and amp is set to -5 gain, in all other cases the signal is very distorted, clipped.

 

Thanks in advance for any info.

 

ps. Sorry for my writing style and language, english is my second language :)

Message Edited by kvasir on 01-25-2010 07:39 PM
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3 Replies
Visitor fanios
Visitor
3,293 Views
Registered: ‎05-24-2011

Re: AMP-ADC on Spartan 3AN starter kit - noise

Hi i am using the same spartan as u. I wonder if u could help because i can t set the gain on amplifier .Could u please tell which devices i should disable .

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Instructor
Instructor
3,290 Views
Registered: ‎07-21-2009

Re: AMP-ADC on Spartan 3AN starter kit - noise

@fanios

 

This thread has been sleeping for 18 months.  The original poster has not logged into the forums since January 2010.

 

There are many many threads which discuss troubleshooting the Spartan-3 series Starter Kits, specifically the programmable gain amplifier.  Please read through some of these threads for helpful ideas.

 

-- Bob Elkind

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Visitor fanios
Visitor
3,275 Views
Registered: ‎05-24-2011

Re: AMP-ADC on Spartan 3AN starter kit - noise

Ok.thanks. A simple question : I use impact 12.3 . Direct or indirect programming method ? 

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