[time-nuts] wtd: WWVB info

Graham / KE9H ke9h.graham at gmail.com
Thu Aug 6 19:03:59 EDT 2015


As long as there is no analog audio bandwidth Nyquist filter, or it is
digital and scales with the sampling frequency, then I agree.
--- Graham

==


On Thu, Aug 6, 2015 at 5:24 AM, David G. McGaw <david.g.mcgaw at dartmouth.edu>
wrote:

> That is not true.  If the converter is set to 192kHz sampling, the
> bandwidth will be nearly 96kHz, typically at least 80kHz, not limited to
> 20kHz.  That is the POINT of 192kHz sampling.
>
> David N1HAC
>
>
>
> On 8/5/15 10:03 PM, Graham / KE9H wrote:
>
>> Scott:
>>
>> You won't be able to use an off-the-shelf audio card, because they will
>> have
>> filters that cut off just above human hearing limits, somewhere in the
>> mid 20 kHz range.  I was referring to the data converter chips they use
>> on those high end cards.  The circuit for ~80 kHz (Nyquist) low pass
>> filters
>> and antenna interface would likely be a custom card.
>>
>> For the guys talking about the Tayloe receivers, the Tayloe front end is
>> just
>> a down converter to get the HF or VHF signals down into the range that
>> WWVB
>> is already in.  So to receive WWVB, you only need the backend of the
>> Tayloe
>> receiver, ie., no Tayloe mixer required.  Just the (audio) data converter
>> and the
>> DSP.
>>
>> --- Graham / KE9H
>>
>> ==
>>
>> On Wed, Aug 5, 2015 at 5:47 PM, Scott Newell <newell+timenuts at n5tnl.com>
>> wrote:
>>
>> At 12:40 PM 8/5/2015, Graham / KE9H wrote:
>>>
>>> Content-Transfer-Encoding: 8bit
>>>>
>>>> There are several high end audio Analog to Digital Data converters that
>>>> will clock at 192 kHz, ~23 bits ENOB, which puts a 60 kHz signal sweetly
>>>> in
>>>> the first Nyquist zone. Typical NF of the front end of the data
>>>> converter
>>>>
>>>> Any specific recommendations? I've seen the Asus Xonar U7 (USB) and Asus
>>> Xonar D1 (PCI) mentioned on some of the SDR sites. (I'm running XP and
>>> linux.)
>>>
>>>
>>> --
>>> newell
>>>
>>>
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