FW: [Mep-dev] Device Selection

[Assi Friedman]

The DSP vs. processor trade is slowly fading away in the commercial world
due to the morphing of FPGAs into DSP machines.  That changes everything
since you can integrate the advantages of both into a single device.
So there is no reason why a moderate density Xilinx Virtex-IV won't be able
to handle FEC decoding and higher level signal processing in a single
device.
Assi


-----Original Message-----
From: mep-dev-admin@uppermeadow.com [mailto:mep-dev-admin@uppermeadow.com]
On Behalf Of Timothy J. Salo
Sent: Monday, November 03, 2008 10:41 AM
To: mep
Subject: [Mep-dev] Device Selection

One last set of comments for now (I hope).

I understand that embedded system design is often driven
by the device that is selected.  That is, the designer
examines lots of potential processors, DSPs or ADCs, and
finds that only a few fit the requirements of the task at
hand.  Given the (sort of) fast ADC sample rate required
by the MEP, there may not be all that many devices to
choose from.  _If_ this is the case, then it might be
useful to start thinking about the available devices
sooner, rather than later.

One choice, and I am by no means an expert in this area,
is whether to select a DSP or an ADC (and a processor to
drive it).  It seems to me, and again I am not the right
person to be making this assessment, that a DSP might
provide some advantages over an ADC/processor combination.
In particular, a DSP will be optimized for at least some
of the math necessary to demodulate and decode the received
signal.  In particular, I assume that a DSP will be pretty
good at extracting symbols from the received signal.

Do anyone know how well a DSP will do at decoding the FEC?

By the way, I think that there may be a wider range of
stand-alone ADCs available, than ADCs integrated into
DSPs.  But, some research ought to provide some answers.

How does the current conceptual design change if a DSP
is used in the outdoor unit, rather than an ADC?  Which
is better?

How fast a processor does the outdoor unit need, if an
ADC is used?

More random thoughts from,

	-tjs

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