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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