[Elecraft] USB sound dongle

[Barry LaZar]

Joe,
      I agree with your comment on internal noise. However, 24 bits of 
quantization will get you a better dynamic range. But, It becomes an 
interesting point when the effects of receiver AGC gets into the 
discussion on this point. Someone in a much earlier post said that the 
receiver's AGC would keep things within bounds for a 16 bit card; he may 
be correct. But, if you run without AGC on the receiver and use AGC 
developed by the SDR software, having those extra bits will make a 
difference, particularly during noisy periods or contests.

     The issue is really when will all those bits go to a logic 1. With 
16 bits, it will be ~96 db where db=20log V2/V1. I know this is not what 
most perceive, but it's true the A/D convertor is a voltage sensitive 
and not a power sensitive device. There are some other interesting 
subtleties like how much dynamic range do you really need, etc. Since I 
haven't had my first cup of coffee yet, I think I would not like to get 
in to those at this time.

73,
Barry
K3NDM

On 8/21/2012 10:13 AM, Joe Subich, W4TV wrote:
>> However, this card is not current; I think the 0404 replaces it.
>> Someone can address this for you.
> The current version is eMU 0204 - approximately $125 at places
> like B&H Photo Video.
>
>> You really do want a 24 bit card and not 16 bit one.
> Unless you need the high sample frequency for wide panadapter service,
> any well designed 16 bit/48 KHz USB sound device will provide all the
> performance you need at less than 1/4 the price of something like the
> eMU 0204.
>
>   > The other thing is that that card should have low internal noise;
>
> This is *the most important* determinant of performance.  Internal
> noise dramatically reduces the effective dynamic range of the sound
> card.
>
> 73,
>
>      ... Joe, W4TV
>
>
> On 8/20/2012 4:40 PM, Barry LaZar wrote:
>> Howie,
>>        The dongles I have seen are not spectacular. They are about on par
>> with your average stereo laptop soundcard, OK but not great. I use a
>> E-MU0202 from Creative Labs. This card is a 24 bit card that can sample
>> beyond what Elecraft recommends. However, this card is not current; I
>> think the 0404 replaces it. Someone can address this for you. You really
>> do want a 24 bit card and not 16 bit one. The other thing is that that
>> card should have low internal noise; the high end Creative Labs card
>> meet this as does several others.
>>
>>        There are a number of software packages around that you can use. I
>> use NaP3 because it can control the KX3 and allows me to use VAC so that
>> I can pipe the output to FLDIGI for reading the digial modes. I have
>> essentially a full up computer controlled SDR that I can take out for
>> Field Day and operate portable with knobs and a battery. It's the craziest!.
>>
>>        I think, once you have it all lashed up, you will really have some
>> fun. Good luck and do use a good card with ASIO drivers for best
>> performance.
>>
>> 73,
>> Barry
>> K3NDM
>>
>>
>> On 8/20/2012 12:37 AM, Howard Hoyt wrote:
>>> Hi,
>>>
>>> I have been following the fun on this reflector while awaiting my KX3
>>> (next Friday!).  I am very interested in using the I&Q outs to interface
>>> with my laptop, and as many have noted, you need a good, compatible
>>> sound device to have a usable panadapter display. Does any one have
>>> experience with a 192k sampling USB sound dongle for their laptop?
>>>
>>> TIA!
>>>
>>> Howie
>>>
>>> Howard Hoyt - WA4PSC
>>> CE - WXYC-FM 89.3
>>> UNC Chapel Hill, NC
>>> www.wxyc.org
>>> 1st on the internet
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