Re: acoustic modems and cellular phones

On Tue, 3 May 2005 09:28:35 -0700, "Joel Kolstad"
<JKolstad71HatesSpam@xxxxxxxxx> wrote:

>"Jim Thompson" <thegreatone@xxxxxxxxxxx> wrote in message
>news:kh1f719p3tkm20rkr0micflsiovcvnndup@xxxxxxxxxx
>> You'd probably be better off to get a modem-ready cell phone driven
>> from a modem card in a laptop.
>
>I'll second that... but I admire your initiative in just getting something,
>_anything_ to work.
>
>There are still acoustic couplers out there that would probably work for low
>data speeds (newer ones had velcro straps that hold the speaker and microphone
>to the phone rather than the old 'cradle' style that only worked with the old
>generic Bell phones); this is probably the easiest solution. For a 'ready
>made' amplifier solution out in the middle of almost nowhere, I'd be tempted
>to tear apart some small amplified computer speakers, a boombox, etc.
>
>---Joel
>

I have a design (proven in production ~1977) for a "muff-cup"
acoustically-coupled 300-baud modem. But I found I got better
distortion by driving the EARPHONE magnetically (for outbound
signals), rather than acoustically thru the carbon mike.

But times have changed.

I'll see if I can find it in my archives. It used active-filter
"S-curves" for demodulation.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
.

Relevant Pages

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