[linrad] Testing MAP65 v0.8

[Joe Taylor <Princeton.EDU; joe@xxxxxxxxxxxxxxxx>]

To:      Users of MAP65
From:    Joe Taylor, K1JT
Subject: MAP65 update

On-the-air testing of MAP65 continues.  Last week with my 
modest station I made 60 EME QSOs with 48 different stations 
in about 16 hours of operating, including WAC on 144 MHz. 
Most of the QSOs were made by responding to CQs that 
appeared on MAP65's "Messages" screen while I was monitoring 
the EME portion of the 144 MHz band.  The Linrad-MAP65 
combination works very well, and I am finding it a pleasure 
to use.  I continue to make program enhancements, many of 
which are now falling into the  "operational convenience" 
category.

A number of messages already received reflect the obvious 
fact that many stations do not have xpol antennas.  These 
operators are nevertheless interested in the other 
capabilities of MAP65, besides polarization matching.  In 
particular, a number of inquiries have been received about 
using the SDR-IQ hardware with MAP65.  There may also be 
interest in connecting the SDR-1000 (or later models from 
FlexRadio) to MAP65.

In principle, any hardware that can be made to work with 
Linrad should also be usable with the Linrad-MAP65 
combination.  At present this is true only if the sampling 
rate can be set to 96.000 kHz (four channels, two I-Q pairs) 
or 192.000 kHz (two channels).  If you want to try MAP65 and 
don't have xpol, a simple way to get started would be to put 
nothing into the Y channel (or perhaps put the X signal into 
both X and Y inputs).  I have tried this in my station and 
it works -- although of course no polarization information 
is produced for the received signals.

The SDR-IQ can provide effective I-Q sampling rates of 
55.555, 111.111, 158.730, and 196.078 kHz for a single 
polarization.  MAP65 will need some modifications to be able 
to work with one or more of these rates.  I will put this on 
the "To Do" list.  When I get to it, I will probably provide 
an option for more efficient single-polarization use, as well.

Over the past weekend I confirmed that running Linrad and 
MAP65 on a single computer is possible -- and indeed may be 
the best arrangement of all.  You still need two display 
screens, however.  This can be done with two video cards in 
the single computer running Linrad and MAP65.  Another 
option is to use a second computer for display only.  Both 
Linrad and MAP65 would run on a fast computer with at least 
1 (or maybe 1.25) GB of memory.  The Linrad display would be 
done on this computer.  A second computer (can be old, slow, 
small memory) would be used to display MAP65.  Any 
combination of Windows and/or Linux should be usable.

In my tests I ran both Linrad and MAP65 in a 2.4 GHz Linux 
machine.  I displayed MAP65 on Windows, after installing the 
the free Cygwin/X11 package.  In this configuration the 
Linrad-MAP65 combination is stable and responsive.  Linrad 
reports that it is using about 12% of the CPU.  At the end 
of each minute, MAP65 decodes the previous minute's 
transmissions noticeably faster than when it is actually 
running (rather than just being displayed) on the older 1.5 
GHz P4 Windows machine (which also has 1.25 GB memory).


My earlier problem with dropped multicast packets seems to 
be fixed in MAP65 v0.8.  However, when running the 
Linrad-MAP65 combination on two separate computers I still 
have some network-related problems.  Perhaps someone on this 
list who knows much more than I about networking can help.

My computer network looks like this:


        ADSL      10 Mb/s  --> Computer_A
DSL --> Modem --> Ethernet --> Computer_B
                  Hub            |
                           --> Computer_C

Three computers are connected to a 10 Mb/s Ethernet Hub. 
Computer_A is my XYL's machine.  Computer_B runs Windows 
2000 Pro, and Computer_C runs Linux (presently the Kubuntu 
6.06 distribution).  In addition to the connections of all 
three machines to the hub, a crossover cable makes a direct 
100 Mb/s connection between computers B and C.

The ethernet interfaces on B and C appear to be configured 
correctly.  On Linux they appear as eth0 and eth1 
(occasionally they boot up as eth0 and eth2, I don't know 
why???).  Connections to the Hub are assigned dynamic IP 
addresses; I assigned hard-coded addresses 192.168.10.12 and 
192.168.10.13 for the direct inter-machine connection
between B and C.

I can use the 100 Mb/s direct line for many purposes.  I can 
ping over it in either direction; I can ssh into Linux from 
 Windows; I can use Cygwin/X (as described above) to 
display Linux X programs on the Windows screen.

However, I cannot seem to persuade Windows 2000 Pro to 
accept multicast packets over the direct line.  When I run 
Linrad on computer C and MAP65 on B, the multicast traffic 
is always received over the slow line, through the Hub. 
This uses most of the 10 Mb/s link's bandwidth, and my wife 
can't read her email when I'm on the air.  This is NOT GOOD.

By default the multicast traffic generated by Computer_C 
goes to eth0.  I can use the Linux "route" command to 
explicitly tell the system to use eth0:

# route add -net 224.0.0.0 netmask 224.0.0.0 dev eth0

This works fine (but of course, still sends the heavy 
multicast traffic through the hub).  If I remove this 
routing instruction and instead enter

# route add -net 224.0.0.0 netmask 224.0.0.0 dev eth1

the multicast data are not received by MAP65 running on the 
other machine.

If I unplug the crossover cable from the Windows machine and 
instead plug it into a laptop running Win/XP, the laptop 
receives the multicast packets without a problem.

Thus, it would seem that the problem must be in my setup of 
the Win2k machine -- the one with two ethernet interfaces. 
Can anyone shed any light on this situation for me?

I would be very happy to receive more feedback from others 
who have been using the Linrad-MAP65 combination.  Are there 
problems that I may have overlooked, perhaps because MAP65 
has been designed with the peculiarities of my own station 
in mind?  Please share your experiences on this list.

	-- 73, Joe, K1JT


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