Re: TNC-PI TXdeley - was Re: Routing issue?


jiejun.kong@...
 

Hi John,

What I saw about TNC TXDelay's time unit is different from what you described here.   Tadd Torborg, who has also participated in the discussion here, has a webpage about this topic  http://tarpn.net/t/faq/faq_txdelay.html
 
"Usually TxDelay is measured in n milliseconds (1/1000ths of a second) or in 10s of milliseconds (1/100ths of a second)" and TNC-Pi is also mentioned at the end of the page.

It seems that you are saying TNC-Pi must send (or pretend to send) some dummy bytes to its audio output to emulate a timing latency.  Though this is possible, it is kind of weird to implement timing parameter in this manner, as we already know that TNC-Pi does have two built-in timing crystals X1 at 3.57MHz and X2 at 20MHz.

We'd better let John Hansen, W2FS confirm on this point.  Last time I contacted him to ask for the pitnc_getparms and _setparms utilities as the weblinks he offered in TNC-Pi manual have expired.  He didn't reply to me, I didn't know what happened to him, so finally I had to download the utitilies from somewhere else.  Anybody here knows him personally and can forward the message to him? Hope this message will find him in good health and spirit.

As to the DCD problem, I am attaching a drawing here to explain it one more last time.  Here the DCD problem is never about the collision, but about the extra latency introduced.   If DCD is fast, then everything is okay.

 
Best Regards,
James Kong, KM6JNN

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