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[linrad] Re: MAP65 Beta Testing

Alex and all,

I apreciate if some body tell me how integrate Linrad and MAP65 via the network, I have no idea.

I am anything but an expert in networking; in fact, I have some network-related questions of my own, as you will see below.

Of course, the Linrad --> MAP65 network connection should(?) work without much effort on the user's part! I suppose my own setup is a more-or-less typical situation, so I will describe it first.

At K1JT, MAP65 runs on Computer "A" under Windows 2000. Linrad runs on Computer "B" under Linux (currently, Kubuntu 6.06). Both computers are connected to a network hub through RJ45-style CAT-5 cables, and from there to the outside world through a dedicated ADSL line. My XYL's computer is also connected to the hub, and occasionally a laptop is connected as well. The Linrad - MAP65 combination works OK without changing anything in this normal network setup (but more on this later).

Linrad 02.34 is set up to do its first forward FFT using "version 5" (SIMD /SSE instructions) and first backward FFT with version 1. This forces Linrad to multicast its TIMF2 in 16-bit format, the format expected by MAP65. To start the multicasting of TIMF2 data, hit "N" (Network setup) on Linrad's opening screen, and turn ON format 8. All other multicast options should be OFF. Then enter 0 to go back to the opening screen, hit "T" to toggle multicasting on, and then select mode "A" (weak-signal CW) for normal operation.

Now start MAP65 on Computer A. It should immediately begin receiving the multicast packets from Linrad; at the end of each minute its waterfall displays should update and the JT65 decoder will be invoked.

Now for the part where I am still scratching my head... MAP65 checks the serial block numbers of each incoming packet, so it can tell when any packet(s) have been missed. In my setup this happens all too often -- no doubt as a result of something I am doing wrong. MAP65 displays the percentage of dropped packets in the status bar at the bottom of its main window. In my present setup this number may be 3% or even larger for the first few minutes after starting MAP65; it then settles down to about 0.6% thereafter.

For reasons I have not yet identified, my system works better with the network speed set at 10 Mb/s. If I set it to 100 Mb/s things still work, but the percentage of dropped packets increases to about 2.6% in steady state. Moreover, these numbers stay essentially the same (0.6% lost data at 10 Mb/s, 2.6% lost data at 100 Mb/s) if I disconnect both computers from the network hub and simply connect the two through a "crossover" cable. Probably I am doing something stupid in the "recvpkt()" routine in MAP65; or perhaps I need to set some parameter differently in the Linux and/or Windows computers. If anyone can shed light on the situation, or suggest some suitable diagnostics, I would be grateful.

I use a completely different pair of computers for development work. One runs Debian Linux (installed from Knoppix) and the other runs Win XP/Pro. Between these machines the number of dropped packets is smaller but still not necessarily zero. With the network supposedly running at 100 Mb/s, I fairly often see a few (0-20, say) dropped packets (out of a total 33103) in a minute.

Loss of 1% of the data is arguably not very important. It does not degrade JT65 decoding noticeably. Nevertheless, i would like to understand what I am doing wrong.

	-- 73, Joe, K1JT

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