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[aprssig] APRS SDR

Leonard Revelle n9ij at comcast.net
Sun Dec 12 17:18:55 UTC 2010


I suppose it depends upon the APRS client but those I am familiar with need little in resources to run. UI-View ran on almost nothing, for example, and has lots of features.
On Dec 12, 2010, at 10:59 AM, r gilson wrote:

> Has anyone used  a net book for APRS?  How much ram and what program did u use?  There are many netbooks out there and need some input before investing.  Thanks
> WA2WWK
> 
> --- On Sun, 12/12/10, Matti Aarnio <oh2mqk at sral.fi> wrote:
> 
> From: Matti Aarnio <oh2mqk at sral.fi>
> Subject: Re: [aprssig] APRS SDR
> To: "TAPR APRS Mailing List" <aprssig at tapr.org>
> Date: Sunday, December 12, 2010, 11:05 AM
> 
> On Sun, Dec 12, 2010 at 10:03:16AM +1000, Andrew Rich wrote:
> > Hello
> > 
> > I wonder if any work has been done in making a software defined APRS device ?
> > In that the hardware is common but the features and TX and RX are very much software derived ?
> > 
> > - Andrew VK4TEC - 
> 
> Lets see...
> 
> Old TAPR TNC2 did following in hardware:
> 
> 1)  (AX.25) HDLC processing
> 2)  Bell202 AFSK
> 3)  DCD
> 
> Radios were pretty much hardware too, even single frequency xtal rigs.
> 
> The AX.25 and above it (alike APRS) have always been entirely software.
> 
> 
> The HDLC processing hardware is rather rare in modern microprocessors,
> thus it is often done in software.  SDR you might say.
> 
> Bell-202 modems used to be "hardware", these days they are often software.
> If Bell-202 is software, then DCD is trivial addition on that software.
> 
> There are several "DSP TNCs" around.
> 
> Having a special SDR hardware that takes application bits in on one end,
> and puts IF/RF waveforms out on other is usually seriously more expensive
> approach.  A mid-scale Xilinx Virtex-IV, and 100 Msps ADCs/DACs does cost
> several kilo-dollars, or more commonly tens of kilo-dollars.
> 
> Long ago there were 56kbps modems with early Xilinx FPGAs for waveform
> generation and detection. One could say that WA4DSY was "software defined",
> as the used hardware is software reconfigurable.
> 
> 73 de Matti, OH2MQK
> 
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