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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Choosing the right transformer
References: <3E2AEA6B.1A9BBDD1@webaccess.net> <3E2AF34D.4100ABAF@webaccess.net> <firstname.lastname@example.org>
Date: Tue, 21 Jan 2003 02:54:34 GMT
NNTP-Posting-Date: Mon, 20 Jan 2003 18:54:34 PST
> Nice explanation. I see what you mean but don't understand how it
> could possibly work.
> Let's say the dsp is working at 64 times oversampling (2.8Mhz). There
> is then one output bit every 0.35us that goes through the H-bridge. If
> it is a transition between a 0 to a 1, the bridge has to switch to say
> +20V. That 20V goes through the analog filter and then to the speaker.
> How come this signal could be digitized and analysed by the dsp fast
> enough to adjust its internal filter in time for the next bit? It
> looks to me the delay is too long, maybe I'm wrong.
What you have to look at is the desired bandwidth because that
determines the bandwidth of the input/output comparison which gives the
error signal for the DSP to use to correct the pulse width. Certainly
this will not be done on a pulse by pulse basis but rather on the
filtered output. Whatever filtering is done in the DSP must have its
bandwidth set to make the system stable.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com
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