Re: Microwave SDR Group


David Lewis <g8jxa.radio@...>
 

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 &#92;(Michael&#92;)"
<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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