There is one exception to the rule.
Pskmail arq works perfectly with vox. Just a matter of optimizing the
protocol to fit common hardware instead of the reverse...
The trick (thanks K9PS) is to send up to 512 bytes of data in a frame and
allow some more time for the switchovers.
73,
Rein PA0R
-Ursprüngliche Nachricht-
Von: Jose A. Amador [EMAIL PROTECTED]
Gesendet: 26.08.08 17:21:26
An: digitalradio@yahoogroups.com
Betreff: Re: [digitalradio] VOX not for ARQ modes
Seems we are reaching the age of the crippled PC. For a desktop there
should still be a chance of adding a serial port PCI card. I have never
used the parport for PTT so far, and it seems I never will...
USB is adequate for most common PC jobs, but not for interfacing radios
without some _special_ interface.
And of course, managing RTS seems to be the most adequate way of
applying PTT to a radio. All other ways (VOX, CAT, etc) seem to
introduce too much latency in an ARQ link.
VOX may be OK just for keyboarding, which may be the the solution for
most users, but hardly is a one size fits all solution.
73,
Jose, CO2JA
---
expeditionradio wrote:
Peter OZ1PIF/5Q2M wrote:
Either you have to add an external USB- RS232
[...] or resort to the VOX solution.
Hi Peter,
For ARQ or handshaking modes, VOX is simply
way too slow. Signalink will not work.
Not an option. Let's crunch the numbers:
1. Really fast VOX with 25milliSecond PTT delay.
2. Add 12mSec to 30mSec transmitter 90% power ramp-up.
3. Total delay = 37mSec to 55mSec!
Now, let's take a typical example of a slow ARQ
or handshaking mode running at 125 baud (symbols/second)
It transmits one symbol every 8 milliseconds.
In 37mSec, you have missed 4 symbols.
In 55mSec, you have missed 7 symbols.
Each time you miss some symbols, this creates
more errors that need to be corrected somehow.
So, each transmission with a VOX system, you
create errors... and each ARQ transmission is
trying to fix the previous transmission's error,
and the previous errors in the transmissions before
that... a vicious cycle :)
The other issue is VOX release delay. The longer
it is, the more the receive decoder will miss
symbols.
VOX is totally wrong for ARQ modes.
I'm surprised that Signalink doesn't offer
any RTS keying, it would be so easy to add
to their interface. They are really shooting
themselves in the foot with their design choice.
A lot of hams are buying these Signalink and
other VOX interfaces, and they don't realize
what they are missing by doing so. Of course,
Signalink doesn't tell them, (the truth would
be bad for business).
73 Bonnie VR2/KQ6XA
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