[Aavso-sid-list] VLF/SID monitoring

[Siddhartha Jain]

Thanks Jean-Pierre. On the issue of sound cards, can you recommend a
good sound card?

I tested my antenna with three different sound cards. One is a
SoundMax (Analog devices card) built into my laptop, the other is a
built-in Soundmax card in a PC and the third is a USB sound card. Off
the three, the SoundMax card built into the laptop seems to be the
most sensitive to my antenna. Signals that appear in blue on the
waterfall in Speclab with other sound cards turn red/orange with the
laptop's built-in sound card.

Unfortunately, Speclab, both v2.70 and v21 b11, keep crashing with a
"Access Denied. Win32 Error" whenever the PC screen gets autolocked or
a RDP session into the PC is disconnected. So I have not been able to
monitor the signals for very long.

Thanks,

- Siddhartha WV6U


On Thu, Aug 7, 2008 at 7:49 AM, Jean-Pierre Godet <godetj at wanadoo.fr> wrote:
> On Thu, 7 Aug 2008, Siddhartha Jain wrote:
>
>> ...
>> ... Should I take the feed cable's capacitance into account when adding
>
> capacitance to the antenna's feedpoint?
>  - The answer is no if you have a circuit, in the loop, matching it to the
> characteristic impedance of the coaxial cable (50 ohms I guess) and, at the
> other end of the cable, another circuit to match it to the input impedance
> of the sound card input.
>  - If not, the answer is yes.
>
>>
>> And what should be the sound card's sampling rate? Speclab displays
>> capability up to 192,000 Hertz. Why not use the soundcard at the
>> maximum capacity?
>> ...
>
>  It depends of your sound card characteristics. If your sound card supports
> higher sample rate than 48,000, why not ? Only using the sound card as
> receiver, with a sample rate of 48,000 you should listen from near 0 to 24
> kHz. In other case (direct conversion receiver, etc...) "you should use the
> lowest possible sample rate allowed by Shannon's theorem... Don't use higher
> sample rate just because your sound card supports them ! " (Wofgang Buescher
> DL4YHF). Ex. : I use some sort of VLF receiver with an audio output 300-6000
> Hz, then I choose 12,000 as sampling rate.
>
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>
>



-- 
- Siddhartha
 WV6U