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[linrad] Re: MAP65

Hi Francesco,

When I receive an email from "root", I always know that it comes from a Linrad user!

I hope you do not mind if I copy this reply to the Linrad reflector. I think your question and my answer may be interesting to others.

root wrote:
Hello Joe, a simple question.
I use Linrad by long and long time, but with only "H" pol antenna. My question is
may i use MAP65?


And if the answer is positive, may i use it with results,
on my Notebook with the AC97 soundblaster and without wire (cross cable)
connection, right as i do today, where i have the main PC with Ubuntu
and Linrad and the notebook with the wsjt. They are only connected via
sound blaster.

As I understand it, you are connecting Linrad's audio output to audio input on the Notebook, using an audio cable. WSJT runs on the Notebook, and gives you a bandwidth of something like 2-4 kHz, right?

This procedure will not work for MAP65, because MAP65 wants to have access to the full 90 kHz bandwidth available inside Linrad. (I am assuming that your Linrad setup uses 96 kHz sampling, as I do.)

For your setup to work with MAP65 you can use one of these approaches:

1. Run both Linrad and MAP65 on the Linux computer. This may be an attractive possibility if this computer is fast (say, 2.4 GHz or faster CPU) and has plenty of memory (at least 1 GB). You will need two display screens -- and therefore either two video cards, a dual-monitor video card, or "remote display" of the MAP65 information to a second computer connected by ethernet. You might also need as many as three sound cards: for example, a Delta44 for Linrad input, the motherboard AC97 for Linrad sound output (required only for human monitoring), and a cheap add-on card for sending the Tx audio from MAP65 to your transmitter.

2. Run Linrad in your Ubuntu Linux machine and MAP65 in the Windows Notebook. This is probably simpler, and is certainly closer to what you have now. The Linrad setup stays as it is, but you enable its multicasting "network output" of 16-bit timf2 data . The two computers must be connected to the same local area network, either through an ethernet switch or on a private RJ45-style crossover cable. MAP65 receives its data input from the ethernet port, and sends Tx Audio to the transmitter. You will want to have at least 1024 x 768 screen resolution on the Notebook.

ciao and thank you in advance


One additional point. I solved the problem I was having, in which the Linrad --> MAP65 multicast data stream swamped my in-house LAN so that my wife could not read email on her computer. I changed the code in Linrad so that instead of using "multicasting," it sends the UDP packets explicitly ("unicast") to the IP address of my MAP65 computer. Then they do not pass through the cheap ethernet switch to which the computers are connected, and Marietta is happy again because her part of the network is not swamped.

I will be happy to help more, if I can -- but you should know that I will be away on vacation (at the beach, with grandchildren) for the next three weeks.

	-- 73, Joe, K1JT

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