[RTTY] Multipath, testing, soundcards

[Kok Chen]

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.

73
Chen, W7AY