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KX3 I/Q out span

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gt-i

KX3 I/Q out span

The KX3 seems to have direct I/Q outputs to the sound card - which
sounds really attractive to me.
The manual says the span depends on the sound card sampling rate, like
48/96/192kHz. But it does not tell what kind of band width one can expect.
As I read further, there seems to be a 15kHz limitation imposed by a
default roofing filter, and this will go narrow automatically under
certain conditions.
Again, what kind of span can I expect, and will it depend on any filter
settings or not?
Thanks and 73
Gernot
DF5RF
K2 #2328
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Greg - AB7R

Re: KX3 I/Q out span

Gernot

The 15 kHz limit is only with regard to be dual watch function. The span
you will be able to see on the software is dependent upon the sample rate
of the sound card used. So if you use a 96 kHz sample rate sound card you
will see just slightly less than that on the display. Probably around 92
kHz.

73
Greg
On Jun 7, 2012 1:50 PM, "DF5RF" <[hidden email]> wrote:

> The KX3 seems to have direct I/Q outputs to the sound card - which
> sounds really attractive to me.
> The manual says the span depends on the sound card sampling rate, like
> 48/96/192kHz. But it does not tell what kind of band width one can expect.
> As I read further, there seems to be a 15kHz limitation imposed by a
> default roofing filter, and this will go narrow automatically under
> certain conditions.
> Again, what kind of span can I expect, and will it depend on any filter
> settings or not?
> Thanks and 73
> Gernot
> DF5RF
> K2 #2328
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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Matt Maguire

Re: KX3 I/Q out span

In reply to this post by gt-i

The I/Q bandwidth is discussed in the "SDR Applications" section of the manual. I quote:
The RX I/Q outputs from a receiver are not “flat” over an infinite frequency range; the signal-conversion process results in some slope (decrease in gain) as you move farther from the center frequency. In the case of the KX3, the signal will be reduced by about 2.5 dB at +/- 24 kHz, 4 dB at +/- 48 kHz, and 7 dB at +/- 96 kHz. The spectrum amplitude on the display, including the apparent noise floor of the receiver, will “roll off” by these amounts.

73, Matt VK2ACL

On 08/06/2012, at 6:49 AM, DF5RF wrote:

gt-i

Re: KX3 I/Q out span

Thanks Matt, that fully answers my question.

Anybody out there who used that feature already? I'm interested in
comparing this to solutions like K3+LP-PAN.

tnx es 73
Gernot
DF5RF

Am 07.06.2012 23:42, schrieb Matt Maguire:

> The I/Q bandwidth is discussed in the "SDR Applications" section of
> the manual. I quote:
>
> *
>
> The RX I/Q outputs from a receiver are not “flat” over an infinite
> frequency range; the signal-conversion process results in some
> slope (decrease in gain) as you move farther from the center
> frequency. In the case of the KX3, the signal will be reduced by
> about 2.5 dB at +/- 24 kHz, 4 dB at +/- 48 kHz, and 7 dB at +/- 96
> kHz. The spectrum amplitude on the display, including the apparent
> noise floor of the receiver, will “roll off” by these amounts.
>
> 73, Matt VK2ACL
>
> On 08/06/2012, at 6:49 AM, DF5RF wrote:
>
>> The KX3 seems to have direct I/Q outputs to the sound card - which
>> sounds really attractive to me.
>> The manual says the span depends on the sound card sampling rate, like
>> 48/96/192kHz. But it does not tell what kind of band width one can
>> expect.
>> As I read further, there seems to be a 15kHz limitation imposed by a
>> default roofing filter, and this will go narrow automatically under
>> certain conditions.
>> Again, what kind of span can I expect, and will it depend on any filter
>> settings or not?
>> Thanks and 73
>> Gernot
>> DF5RF
>> K2 #2328
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>

gt-i

Re: KX3 I/Q out span

Tom,
tnx for the info. Did you tried higher sampling rates already? Or is
48kHz the one you found to be best?
73
Gernot
DF5RF

Am 09.06.2012 23:53, schrieb Tom Azlin N4ZPT:

> With the KX3 and I/Q audio very nice display of spectrum at 48ks/s.
> but the resolution and niceness to me of the SDR on the computer
> displays are not very good compared to the P3 display. P3 with K3 is
> perfect display out to 200 KHz span. Spectrum analyzer quality
> exceeding that of the LP-PAN or other SDR programs in my opinion. But
> the P3 does not add extra demodulators.
>
> So pick what you want.
>
> 73, tom n4zpt
>
> On 6/8/2012 5:46 PM, DF5RF wrote:
>> Thanks Matt, that fully answers my question.
>>
>> Anybody out there who used that feature already? I'm interested in
>> comparing this to solutions like K3+LP-PAN.
>>
>> tnx es 73
>> Gernot
>> DF5RF
>>
>> Am 07.06.2012 23:42, schrieb Matt Maguire:
>>> The I/Q bandwidth is discussed in the "SDR Applications" section of
>>> the manual. I quote:
>>>
>>> *
>>>
>>> The RX I/Q outputs from a receiver are not “flat” over an infinite
>>> frequency range; the signal-conversion process results in some
>>> slope (decrease in gain) as you move farther from the center
>>> frequency. In the case of the KX3, the signal will be reduced by
>>> about 2.5 dB at +/- 24 kHz, 4 dB at +/- 48 kHz, and 7 dB at +/- 96
>>> kHz. The spectrum amplitude on the display, including the apparent
>>> noise floor of the receiver, will “roll off” by these amounts.
>>>
>>> 73, Matt VK2ACL
>>>
>>> On 08/06/2012, at 6:49 AM, DF5RF wrote:
>>>
>>>> The KX3 seems to have direct I/Q outputs to the sound card - which
>>>> sounds really attractive to me.
>>>> The manual says the span depends on the sound card sampling rate, like
>>>> 48/96/192kHz. But it does not tell what kind of band width one can
>>>> expect.
>>>> As I read further, there seems to be a 15kHz limitation imposed by a
>>>> default roofing filter, and this will go narrow automatically under
>>>> certain conditions.
>>>> Again, what kind of span can I expect, and will it depend on any
>>>> filter
>>>> settings or not?
>>>> Thanks and 73
>>>> Gernot
>>>> DF5RF
>>>> K2 #2328
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>
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