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Date: Sat, 16 Aug 2014 11:28:25 +0100
From: g4gvw <g4gvw@aol.com>
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References: <CAMFjj73P4GEnkpJjQ1LLHBsY3zpbRSCn+FQBXVKeDye2UerPbA@mail.gmail.com> <CAMFjj71p3xTzFoa_aYrYmYD-=jxAD=VKg2-VHYLovS2iyRPsRg@mail.gmail.com> <53EE5E74.4030405@tiscali.co.uk> <02fc01cfb8c5$542235f0$fc66a1d0$@comcast.net> <53EE894B.8050502@gmx.net> <6FC7B34C47134A0A86C1641F2A3F4489@AGB> <033401cfb8e9$89d608b0$9d821a10$@comcast.net>
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Subject: Re: LF: USB Sound Card?
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Status: O

Slightly OT but does anyone have experience with external Soundblaster 
'Extigy' and Linux.

73

On 16/08/14 01:32, hvanesce@comcast.net wrote:
> Graham and Tobias,
>
> Thanks for all of the information, I'm looking forward to implementing the options that you mentioned.
>
> 73, Jim AA5BW
>
> -----Original Message-----
> From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Graham
> Sent: Friday, August 15, 2014 7:49 PM
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: LF: USB Sound Card?
>
> Thanks  for the  run down  Tobias
>
> The  windows  re-sampling  caused  problems  with  wspr  in the  early  days on MF ,  as  its possible that  wspr  had  never  been  used  in a situation  where  100% of the  signal  arrived  at the  RX  .  qsb  was normally  part of the  process ..
>
> This  caused  a  strange  problem .  where  strong  signals  failed  decode , where as  low level  with  qsb  did
>
> It  eventually  transpired , that the  sampling  rates  where  not  quite the  same on all  systems  and  the  short  bursts masked  the  timing
> differences ,   tested  by  sample  audio  files  and a  stop-watch
>
> Later  , we  found  Opera / Ros  [ ros was  first]  that  decodes  failed with  other  software  running , additional  routines  where  added  to ensure the  sample  rate  was  held  at the correct  speed , since then , all  has been  ok
>
> I used  soundblaster 5.1  external  usb card , can be  picked  up  s/h now on ebay  for  very little
>
> 73-G,
> G0NBD
>
> --------------------------------------------------
> From: "Tobias DG3LV" <DG3LV@gmx.net>
> Sent: Friday, August 15, 2014 11:27 PM
> To: <rsgb_lf_group@blacksheep.org>
> Subject: Re: LF: USB Sound Card?
>
>> Hi Jim, Gary !
>>
>> Experiences with Software Defined Radios ("Softrock" type) over years
>> showed me the highs and lows of using a soundcard as an A/D-converter
>> for HamRadio use. The situation improved from using the
>> onboard-devices to professional external Firewire- or USB-2.0
>> soundcards as they became available at reasonable prices.
>>
>> to A) it's true, the windows type drivers support up to 16 Bit only.
>> There are some issues to sampling rate stability under windows, too.
>> That's why SDR-programs like Winrad, HDSDR etc. use the alternative
>> "ASIO" driver model, where 24 Bits are supported natively and where
>> the latency is smallest. ASIO drivers typically are bundled with
>> (professional) soundcards for studio-recording. I had the usual
>> "EMU-0202-USB" card, which was sampling at 192kHz/24 Bit. As this is
>> available no longer, today I use an "Icon Cube" and "Icon Cube pro"
>> (2/4
>> Channel,192kHz,24Bit,USB-2.0) for my softrock SDR. They are not too
>> expensive and do a good job!
>>
>> to B) Windows has different properties for the hardware sampling rate
>> and the offered (simulated) sampling rate. If these are not identical,
>> there is a software up/down-resampling done by windows. You have to
>> set the correct sampling rate at the hardware-settings (!) of the
>> chosen soundcard input/output. (sometimes Win7 resets this to 44.1
>> kHz/16Bit at another booting, so you have to check this first after
>> booting up the PC.) e.g. Even if the soundcard is just sampling at
>> 48kHz, the windows drivers offer 96 and 192 kHz as well, but actual
>> audio-data is still not more than 48kHz, the rest of the spectrum is filled with "blanks".
>>
>> to C) Typically the anti-aliasing filters of a soundcard are bound to
>> the current (hardware-) sampling rate (=Nyquist) and not be static.
>> Those filters are digital ones and part of the A/D converter chips.
>> But the datasheets of soundcards shows the filters of the 44.1/48 kHz
>> sampling rate only (0-20 kHz), as this is the standard where the
>> "dB-"measurements are done.
>>
>> 73 kHz Rx :
>> In Europe you can receive the DCF77 signals (77.5 kHz) very well by a
>> length of wire (or better a PA0RDT) and directly attaching it to an
>> input of a 192 kHz soundcard. (Here 55dB above noise at 600km
>> distance, software time-decoding by "SoDiRa" SDR-software). It is the
>> same setup as used for SAQ-listening at 17.2 kHz (using HDSDR).
>>
>> For decoding digimodes (WSPR,JT65,WSQ...) a simple USB-micro-soundcard
>> ($5) or onboard is ok, the programs just use "mono" and 48kHz at most,
>> even the cheapest (for headset use) do well.
>>
>> 73 de dg3lv Tobias
>>
>> Am 15.08.2014 22:12, schrieb hvanesce@comcast.net:
>>> Gary,
>>>
>>> I use a number of expensive and inexpensive external (USB) audio
>>> interfaces, and I like them all (good sensitivity, good dynamic
>>> range); but I experience the following limitations:
>>>
>>> A)
>>>
>>> I have not been able to persuade Windows and/or Speclab to process 24
>>> bits (I have been successful in applying 24-bit settings in
>>> Windows>ControlPanel>Sound  and Speclab, but have not acquired valid
>>> data after doing so; and accordingly have always used 16-bit settings
>>> with 24-bit external audio interfaces, even though I need at least 24
>>> bits for dynamic range considering VLF and LF environmental noise in
>>> some of my locations)
>>>
>>> B)
>>>
>>> Similarly to the above, I have been able to set up Windows and
>>> Speclab for 192kHz sample rates, but have not been able to view past
>>> 48kHz without aliasing (and accordingly I settle for 96kHz settings
>>> and interfaces in most cases)
>>>
>>> C)
>>>
>>> All of my external audio interfaces have steep low-pass filters at or
>>> near 22kHz pole frequency, so SNR is compromised for signals at 20kHz
>>> and above. I’ve disassembled some of these interfaces in attempts to
>>> modify the low-pass filter cutoff frequencies, but without a
>>> schematic could not be certain regarding changes.
>>>
>>> Have you seen any of the above issues with internal or external audio
>>> interfaces that you have used?
>>>
>>> 73,  Jim AA5BW
>>>
>>> *From:*owner-rsgb_lf_group@blacksheep.org
>>> [mailto:owner-rsgb_lf_group@blacksheep.org] *On Behalf Of *Gary -
>>> G4WGT
>>> *Sent:* Friday, August 15, 2014 3:25 PM
>>> *To:* rsgb_lf_group@blacksheep.org
>>> *Subject:* Re: LF: USB Sound Card?
>>>
>>> Hi Warren,
>>>
>>> Yes, I had an internal (on main board) & used it for a while for my
>>> grabber when 73kHz was first allocated to USA.
>>> It was good to about 94kHz.
>>>
>>> The SB0490 I suggested is only 96kHz :-((
>>>
>>> *73, de Gary - G4WGT*
>>>
>>> *                             *
>>>
>>> *MF-LF-VLF Grabber
>>> :http://myweb.tiscali.co.uk/wgtaylor/grabber2.html*
>>>
>>> *Web :http://myweb.tiscali.co.uk/wgtaylor/index.html*
>>>
>>>
>>>
>>> .
>>>
>>> On 15/08/2014 20:09, Warren Ziegler wrote:
>>>
>>>      I guess I should have been more specific .
>>>
>>>      What I am seeking is are some sound cards more stable with respect
>>>      to sampling rate and calibration? Also, any advantage to 24bit A/D
>>>        for LF data modes?
>>>
>>>        I wonder if anyone has tried 192kHz sample rate for direct
>>>      reception of 73kHz?
>>>
>>>      73 & Tnx Warren
>>>
>>>      On Fri, Aug 15, 2014 at 2:27 PM, Warren Ziegler <wd2xgj@gmail.com
>>>      <mailto:wd2xgj@gmail.com>> wrote:
>>>
>>>
>>>      I just acquired a Windows Vista tower computer - the price was right
>>>      it was free!
>>>
>>>      Seems that there is a problem with the internal sound card, but
>>>      everything else checks out FB.
>>>
>>>      I plan on using it with WSPR and other digital modes, am thinking of
>>>      an external USB sound card - will any old sound card do ? Or do I
>>>      need one with a calibrated sampling rate? I suspect that I will need
>>>      something really good for Spectrum Laboratory if I want to sample at
>>>      microHertz rates.
>>>
>>>      73 & Tnx Warren K2ORS
>>>
>>>
>>>
>>>      --
>>>      73 Warren K2ORS
>>>                       WD2XGJ
>>>                       WD2XSH/23
>>>                       WE2XEB/2
>>>                       WE2XGR/1
>>>
>

-- 
de Pat G4GVW
QTH Nr Felixstowe, Suffolk
East coast of UK