[RTTY] Sound Cards and Software

[Robert Chudek - K0RC]

Thanks Randy,

This article does contain the specific tests I recalled. Here's the gist of 
it from the third column on page 69:

"A Real-World Test

    "Signal processing for HF digital modes probably won't push PC sound 
cards to their limits. Signals arrive with plenty of noise of their own. 
Their bandwidth rarely exceeds a couple of kilohertz, and modes such as RTTY 
and PSK31 are interested only in the signals' frequency and phase 
characteristics, rather than amplitude. But to prove the point, we tested 
two sound cards at opposite ends of the performance spectrum to see how they 
would handle a real-world PSK31 signal. The two devices chosen for this test 
were the entry-level CompUSA PCI sound card and the high-end M-Audio Delta 
44 device.

    "For this test, we installed both devices in a Windows XP machine, and 
then fired up two instances of DigiPan PSK31 software, configuring one 
instance for each device. We then connected the (audio) output of an 
Elecraft K2 transceiver to both sound card LINE inputs using a Y-adapter, 
tuned to a noisy (and busy) PSK31 frequency, and noted the results.

    "Not surprisingly, the two DigiPan outputs were nearly identical. All 
signals that produced solid copy on one sound card also gave solid copy on 
the other, and those with a few "hits" due to fading and noise produced 
about the same number of missed characters on both. As we expected, the 
significantly weaker signal-to-noise and THD figures of the generic 16-bit 
sound card didn't affect DigiPan's ability to detect 180 degree phase shifts 
in the received signal or its ability to isolate the desired signal from the 
interference.

    "Software-defined radio applications are quite a different story..."

This was a thorough comparison of a dozen different sound cards. But now 2 
years later, like all computer technology, most of them are probably 
superseded by newer models.

73 de Bob - KØRC in MN


----- Original Message ----- 
From: "K9OR" <k9or at comcast.net>
To: <rtty at contesting.com>
Sent: Thursday, September 17, 2009 10:32 AM
Subject: Re: [RTTY] Sound Cards and Software


> FYI, there was a comparison article in May 2007 QST - "Computer Sound 
> Cards
> for Amateur Radio".
> Fourteen 16 bit, 24 bit, low end, high end boards compared.
>
> Quote from Bottom Line of article - "There are clear performance 
> differences
> between inexpensive 16-bit sound cards and the more expensive 24-bit 
> models.
> For most digital mode users, any of these cards will perform well. 
> Software
> defined radios and other high-performance applications will benefit from a
> high-end card."
>
>
> 73 Randy K9OR
>
>
>
> Date: Wed, 16 Sep 2009 14:23:25 -0500
> From: "Robert Chudek - K0RC" <k0rc at citlink.net>
>
> A few years ago "someone" (sorry I don't recall who it was) ran tests on a
> variety of soundcards, from cheap $20 cards to high-end $200+ cards.
>
>
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