[Elecraft] odds and ends...

Sun Aug 19 23:36:35 EDT 2012

>From the manual

 Set the correct sampling rate. Use of 48 kHz
sampling will result in a display of almost 48
kHz: 24 kHz above and 24 kHz below the
frequency to which the KX3 is tuned. 96 kHz
sampling will yield approximately +/- 48 kHz
of spectrum, and 192 kHz sampling will yield a
display of about +/- 96 kHz

-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
Sent: Sunday, August 19, 2012 6:54 PM
To: WB4JFI
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] odds and ends...

I don't know the advertized numbers, but Mr. Nyquist aside, there is a reason that two independent experts with panadapter displays (Joe Subich W4TV and Larry Phipps K8LP of LP-Pan fame) state that a soundcard with a
48 kHz rate will produce a 96 kHz span on the pan display.

I do not doubt Nyquist, but I think the treatment of the numbers are a bit different (factor of 2)  Could it be due to the two channels? I really don't know the answers and do not have the energy to investigate such things anymore, I just choose to trust the experts who deal with this I/Q stuff on a daily basis.  I guess my scientific curiosity has declined with advancing years - it is no longer enjoyable to argue on the basis of observations vs. theory to sort out the differences - that was "fun mind games" many years ago. but today it is no longer a challenge.

73,
Don W3FPR

On 8/19/2012 5:45 PM, WB4JFI wrote:
> Mr Nyquist would be happily surprised at that.  With I&Q samples at 48kS/s each, you get a maximum of 48kHz, or one-half the total bandwidth.  Not 48k+48k.
>
> So, with a 48k sample rate, you will get plus and minus 24k from center.
>
> Sent from tfox iPad
>
> On Aug 19, 2012, at 4:33 PM, "Joe Subich, W4TV" <lists at subich.com> wrote:
>
>>> The sound card's maximum sampling rate will determine how wide your 
>>> panadapter display can be (in kHz); for example, a sound card 
>>> capable of sampling at 48 kHz can display slightly less than 48 kHz 
>>> of spectrum. If you want a wider display, you will have to ensure 
>>> that your sound card can sample at higher rates.
>> A sound card capable of 48 KHz sample rate can display slightly less 
>> than 96 KHz.  With I/Q inputs and 48 KHz sampling you get +/- 48 KHz.
>>
>> 73,
>>
>>     ... Joe, W4TV
>>
>> On 8/19/2012 4:20 PM, Richard Ferch wrote:
>>> Jeff,
>>>
>>> In addition to the cable, you will also need to be sure that your 
>>> laptop's sound card accepts stereo input. Panadapter software 
>>> requires stereo input (I and Q channels). Some laptop input jacks 
>>> will only accept mono signals, even though the laptop's sound card 
>>> itself is stereo. My newest laptop, for example, has a TRRS jack for 
>>> the sound card with a single input line, two stereo output lines, and ground.
>>> I have no way to get stereo input into this sound card. An older 
>>> laptop I have has separate input and output jacks, but while the 
>>> output jack is stereo, the input jack is mono. If your laptop is 
>>> like either of these, your only recourse may be to get an external 
>>> USB sound card with stereo inputs.
>>>
>>> The sound card's maximum sampling rate will determine how wide your 
>>> panadapter display can be (in kHz); for example, a sound card 
>>> capable of sampling at 48 kHz can display slightly less than 48 kHz 
>>> of spectrum. If you want a wider display, you will have to ensure 
>>> that your sound card can sample at higher rates.
>>>
>>> Note that if you need to use an external (e.g. USB) sound card, it 
>>> may or may not have 3.5mm inputs. For example, I have one with dual 
>>> RCA phono jacks for its line inputs. With one of these cards, you 
>>> would need to go from 2.5mm stereo for the KX3's RX I/Q jack to two 
>>> separate RCA phono plugs for the sound card's input.
>>>
>>> I don't know whether Radio Shack has the specific cable you would 
>>> need, but I am sure that they have cables and adapters that could be 
>>> combined to achieve the desired result.
>>>
>>> 73,
>>> Rich VE3KI
>>>
>>>
>>> WW6L wrote:
>>>
>>>> Per the manual Iit looks like I would need one of these
>>>>
>>>> A cable with a 2.5 mm (3/32") plug on one end and a plug that 
>>>> matches your sound card input on the other end (typically 3.5 mm 
>>>> [1/8"] stereo) is required.
>>>>
>>>> If I want to see a panadapter display on my laptop.
>>>>
>>>> Where do I get it?
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