RE: Modems


Subject: RE: Modems
From: James Gribbin (jgribbin@alaska.net)
Date: Wed Dec 04 2002 - 01:40:12 AKST


A hardware modem works fairly independantly of the computer. When it
gets down to it, it doesn't need a computer. It has crystal based
oscillators to generate the carrier frequencies and a hardware modulator
and de-modulator to add the outgoing data to the carrier and strip the
incomming data from its carrier. The only processor intervention is to
load commands and read back status. The data itself is sent and recieved
just like any other serial or parallel port. Even the command/status
ports are just regular i/o ports and need to be accessed only
occasionaly. On modems of this type you will usually see a couple of
oscillators (small silvery cans), an inductor or two (coils), a couple
of chips, and several discrete components (resistors, capacitors).

On a software modem, the carriers are generated and modulated with the
data by direct, time critical, processor interaction with a Digital
Signal Processor (DSP). The modems usually have 1 fairly large chip with
just a few discrete components.

On Tue, 2002-12-03 at 09:19, Matthew Dunaway wrote:
> So, what is a hardware modem, and how is it different from a software(??)
> modem or a "winmodem"?
>
> Inquiring minds want to know!! :-)
>
> -----Original Message-----
> From: Justin Dieters [mailto:enderak@gci.net]
> Sent: Monday, December 02, 2002 7:59 PM
> To: Matthew Dunaway; AkLUG
> Subject: Re: Modems
>
>
> It doesn't have to necessarily say Linux compatible on it (most
> compatile ones actually don't) it just needs to be a hardware modem. I
> am pretty sure you can find a good hardware modems for around $50,
> although you might need to go online to find one at that price.
>
> I think you said you only have PCI, but if you do have ISA, I know the
> Office Max on diamond has several ISA 56k modems on clearance for $25.
> (or maybe it was $15, i forget).
>
> You may want to take a look at these pages if you haven't already. They
> are a few years old, but it may still be relevent:
>
> http://www.idir.net/~gromitkc/rg/Comp_USA.txt
> http://www.idir.net/~gromitkc/rg/Office_Depot.txt
> http://www.idir.net/~gromitkc/rg/Office_Max.txt
> http://www.idir.net/~gromitkc/rg/Best_Buy.txt
>
> Justin
>
>
>
> Matthew Dunaway wrote:
> > I went to CompUSA and Best Buy today. Best Buy did not have any modems
> that
> > will work with Linux in stock. When they have them, they are $79.95. I
> don't
> > remember who made it.
> > CompUSA had a US Robotics for $99.99. It says it will work on any Linux
> with
> > kernel 2.3 or higher.
> > Does anyone know where I can get a modem for less than $99.99? I will get
> it
> > if I have to, but I would rather find someplace that might be cheaper.
>
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-- 
James Gribbin <jgribbin@alaska.net>

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