[Mep-dev] Conceptual Block Diagram for review

[Assi Friedman]

The concept of using Ethernet between the outdoor and indoor units is an
intriguing one.  First, most made the associative but not correct assumption
that this implies using TCP/IP between the units.  An Ethernet device *may*
use TCP/IP but not necessarily so - unless this was specified somewhere in
the diagram that I have missed.  So as a baseline, we would have Ethernet
frames between the devices.  Since this is a point to point link, straight
Ethernet may be sufficient to transport the data in and out.

The bigger issue to dwell over is timing and synchronization. The ADC data
will operate in a synchronous manner.  Ethernet works in the frame domain
and therefore this synchronization is lost.  There are a number of
synchronous to packet conversion systems, all operate on the premises that
you have a much faster frame transfer rate than that of your bit rate, and
that you can sustain a longer propagation delay due to buffering. We would
need to consider that impact on our communications protocol.

Another point to consider is that many DSP detection schemes are based on
coherent sampling - i.e. that the sampling clock to the ADC is phase
controlled. This would be very difficult to achieve with the packet based
transfer mode between the indoor and outdoor units.  

Give that, I am not convinced that the advantages of Ethernet and POE versus
more traditional IF transmission is that clear.  If anything, decoding down
to the bit level in the outside unit and pushing that down a baseband feed
makes a bit more sense to me, unless the modulation techniques are highly
flexible, at which point I converge onto Paul's comment that we may end up
with everything outside...

Assi

 

-----Original Message-----
From: mep-dev-admin@uppermeadow.com [mailto:mep-dev-admin@uppermeadow.com]
On Behalf Of Roger Thompson
Sent: Sunday, November 02, 2008 6:49 PM
To: 'Paul Williamson'; mep-dev@uppermeadow.com
Subject: RE: [Mep-dev] Conceptual Block Diagram for review

Would adopting standard TCP/IP between the system components enhance the
flexibility of the design?