[time-nuts] wtd: WWVB info
kb8tq at n1k.org
Thu Aug 6 21:41:18 EDT 2015
Well, at least *some* of the chips out there do not make it to 96 KHz when sampling at 192 KHz. It’s
been a few years since I dug into them. Back then a chip that had an internal filter that went to 96K
was very much the exception rather than the rule. If the only point of 192K is getting to a 96K bandwidth,
a lot of the chip guys missed out on it ….
> On Aug 6, 2015, at 6:24 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:
>> 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
>> and antenna interface would likely be a custom card.
>> For the guys talking about the Tayloe receivers, the Tayloe front end is
>> 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
>> --- Graham / KE9H
>> On Wed, Aug 5, 2015 at 5:47 PM, Scott Newell <newell+timenuts at n5tnl.com>
>>> 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
>>>> 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
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