[Elecraft] PX3

[Walter Underwood]

I bet they digitize it as early as possible, then use an FIR filter to reshape it. Or scale the values after they FFT, since that is already in the frequency domain. The scale values would be a vector of constants, so it would be really fast and wouldn't even add delay (the bane of FIR filters).

wunder
K6WRU
 
On Apr 5, 2014, at 6:26 PM, Barry LaZar <k3ndm at comcast.net> wrote:

> Yep. That what I was questioning. I, too, remembered those words. I also know it will take more than just inserting an amplifier with inverse gain characteristics. I know it can be done. However, that doesn't sate my curiosity as to how they did it. I just hope the solution isn't proprietary.
> 
> 73,
> Barry
> K3NDM
> 
> On 4/5/2014 7:14 PM, Walter Underwood wrote:
>> Yes. I posted the text from the manual two days ago in the KX3 list.
>> 
>> "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."  (page 26)
>> 
>> I would not be surprised if they corrected for this in the PX3.
>> 
>> wunder
>> K6WRU
>> 
>> On Apr 5, 2014, at 1:55 PM, Barry LaZar <k3ndm at comcast.net> wrote:
>> 
>>> Good question. I have run at 192 KHz. with the sound card I have, a Steinberg UR22. The display I see using NaP3 shows a non-flat response. In fact, there are some words about this in the KX3 manual.
>>> 
>>> 73,
>>> Barry
>>> K3NDM
>>> 
>>> 
>>> 
>>> On 4/5/2014 1:07 PM, Uwe Hermanns wrote:
>>>> Hi,
>>>> 
>>>> is the frequency responce of the KX3-IQ really flat over 250 kHz?
>>>> 
>>>> 73 de Uwe, DL4AC
>>>> ---------- Weitergeleitete Nachricht ----------
>>>> Von: "Allen Patterson" <allenp at cryptosafe.com>
>>>> Datum: 05.04.2014 19:03
>>>> Betreff: [Elecraft] PX3
>>>> An: "Elecraft at mailman.qth.net" <Elecraft at mailman.qth.net>
>>>> Cc:
>>>> 
>>>> When is the PX3 going to be available for shipping?
>>>> 
>>>> You mentioned several software-firmware updates for the PX3 that are
>>>> planned.
>>>> What is the general schedule for each of these updates after initial
>>>> product shipment?
>>>> When is the manual for the PX3 going to be available?
>>>> 
>>>> 73
>>>> 
>>>> Allen Patterson, KC7SYR
>>>> Allenp at cryptosafe.com
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>> --
>> Walter Underwood
>> wunder at wunderwood.org
>> 
>> 
>> 
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> 
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--
Walter Underwood
wunder at wunderwood.org