Re: Generate DTMF
- From: Tim Wescott <tim@xxxxxxxxxxxxxxxx>
- Date: Mon, 28 Apr 2008 23:54:00 -0500
On Mon, 28 Apr 2008 19:23:12 -0700, cell wrote:
I used a 8052 MCU (24MHz crystal) and a 8 bits R-2R DAC to generate DTMF
tones.The sampling frequency is 5kHz. The output is then input to a 2nd
order LP filter. The telephone line seems to not recognize my tone. Is
the order of filter enough or not?
Thanks!
I'm going to paint my house a greeny-blue color. How much paint do I
need to buy?
Or in other words, tell us enough to answer your question, and maybe
someone will be able to help.
I would expect that nice sine waves fed to an 8-bit DAC with a sufficient
sampling rate is more than good enough. Have you looked at your
telephone line on an oscilloscope and compared your DTMF tones to what
comes out of a regular telephone?
--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com
Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
.
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