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Re: [RTTY] Multipath, testing, soundcards

To: RTTY Reflector <RTTY@contesting.com>
Subject: Re: [RTTY] Multipath, testing, soundcards
From: Kok Chen <chen@mac.com>
Date: Thu, 22 Apr 2004 09:11:44 -0700
List-post: <mailto:rtty@contesting.com>

On Apr 22, 2004, at 7:57 AM, Tom McDermott wrote:

The CCIR put
together a standard for this, and describes the different path conditions to
be used for testing. A standalone DSP based path simulator was developed by
Johan Forrer, KC7WW, and I think a PC-soundcard based equivalent was also
produced (by I can't find by whom...).

I had mentioned this in private email with W7TI-Bill. There is a Linux GPL version of it, in fact, done by an OH ham. I have the folder of the source on my laptop's drive.

If you Google with "HF Channel Simulator KC7WW Linux" you should be able to find it. I sent Bill the URL for Johan's white paper that has a link to the Linux sources, so I should be able to dig it out again later (or perhaps Bill can post it). Johan also wrote about it in a QEX sometime in the late 1990s I think, he also presented a TAPR paper in 1999. I had communicated with Johan in the '80s or early '90s in conjunction with DSP modems, but I remember he was already working on channel simulators back then.

The real problem is that everybody should be able to click on a sound file to replay it (or, as I mentioned before, play it back from an MP3 player that you can swipe from your kid) but not everyone will be able to handle the intricacies of a channel simulator.

Chen, W7AY

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