Some comments

Ethernet V. USB
The IP address (lack of) problem in a company network. You can use a
USB to Ethernet adaptor to turn the Ethernet port into USB;
www.amazon.co.uk/exec/obidos/ASIN/B0002AFKN0/026-1538281-3316427
No need to beg an IP address.

Ethernet is OS agnostic.

Ethernet cable can be 200m long, USB is good for 5m.

Lack of Ethernet power, could still use the USB port for power only
(as in the SoftRock).

Bandwidth for ATV, at home run Freeview TV over Ethernet and Wi-Fi
every day without any problem, so don't think it will be an issue.

Ethernet also supports remote operation.

GUI
The colour scheme can be changed, a good example is Ham Radio Deluxe
that supports high contrast colour schemes.

Using Ethernet and a mini Webserver a new GUI design could be 30
minutes with an HTML editor.

--- In ukmicrowaves@..., "Willis, MJ \(Michael\)"
<m.j.willis@...> wrote:

________________________________

From: ukmicrowaves@...

[mailto:ukmicrowaves@...]

On Behalf Of Jonathan Naylor
Sent: 15 May 2006 09:47
To: ukmicrowaves@...
Subject: [ukmicrowaves] Re: Microwave SDR Group


Hi Mike

I still think USB2 is a better interface for use in the field but

I

understand why you went for Ethernet.

I would disagree on this point. We want to be able to support the
software on multiple platforms and USB is painful to program to. The
socket interface is standard, has adequate bandwidth and allows for
stacking of multiple radios easily.

That is true, but the real problem is bandwidth. I guess for this
application, Ethernet is OK, for DATV I doubt it could keep up.

Hardware - modular is the way to go. I think you can do better

than

200mW and 3 dB NF but I suspect this is merely the back end to a

low

noise amplifier and a driver for the high power amplifier.

Correct. Most microwave operators are familiar with system design in
terms of components, and by keeping the output power low, and the
receiver average, we keep the price low, the design easily
reproducable, and enough to drive most amplifiers. We still want to
keep a market open for DB6NT don't we? :-)

Can you add 70cms to the front end list? I don't man as a rig for

the

band, just as a nice band to use for a transverter IF for those

of us

with transverters already.

It has been talked about. If someone were to come forward and

design a

front end, it might arrive even quicker. The constraints on design

are

not bad, the local oscillator must be clean BUT it does not need to
tune in 1Hz steps, the DSP can interpolate, and so on. Why not have

a

go Mike?

I don't have enough info, but is it not almost the same as 23cms?

Divide

the LO by 3?
I agree 1 Hz steps are not needed at all, if you have 100kHz of
bandwidth in I and Q 10kHz steps should do nicely.
More controversy, why does the LO need to be highly stable at all?

Why

can you not use a DDS to generate a "dirty" signal, multiply this

up to

act as an in band beacon and and have a cleaner LO frequency locked

to

it by the software every so often. All the LO filtering is then

done by

DSP and it does not matter that the DDS spurs are only 40 dB down.

As

long as the clean LO does not drift too much this should be OK. You
could reset it each second for example. A clean LO could be a

crystal

source like that from the IC202S multiplied up. That circuit manages
200kHz range at 144MHz with very low phase noise. Translating that

up

either by multiplication or by mixing should give an LO with good

short

term stability, reasonable and correctable drift.

Whatever Gui interface you design, it needs to be usable with a

laptop

on a hilltop when you can't see the screen very well. The current
picture on the web page looks great but would be almost

impossible to

use in a field.

What makes you say that? There is no easy design for GUIs that will
suit all people, so by keeping it simple and going with a design

that

echoes the IC-706 I have hopefully meant that the least number of
people will find annoying/unusable.

What I mean is that the screen needs a very high contrast colour

scheme

and relatively large figures.
You could make this configurable. For example, grey buttons on a

grey

background are not easy to see when there is sun on the screen.

This is

the windows default. It might be that you are using windows default
calls so that changes made in the settings would come thorough, but
realistically, a high contract colour scheme is not a bad idea. The
latest Anristu and Agilent test gear with LCD displays does this so
there must be a demand.

Mike





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