[Elecraft] P3 vs SDR-IQ

[Wayne Burdick]

John,

The P3 and PX3 use entirely different interfaces to the radio. The P3 taps into the K3/K3S 8.2 MHz I.F., while the PX3 uses a baseband I/Q signal from the KX3. While both methods provide the basic benefits of a panadapter, the P3's implementation provides higher performance, using more expensive hardware, and is priced accordingly.

The P3 is incredibly smooth in its tuning and presentation, and the unit is widely regarded as one of best panadapters available. Averaging, fixed-tune mode, noise blanking, peak detection and its many other features are all free of any sort of tuning noise or artifacts. 

If you're in "fixed-tune" mode, where the VFO/filter cursor moves across the screen, averaging information is preserved. There is no increase in the noise floor, no matter how fast you tune.

In "tracking" mode, where the VFO/filter cursor stays fixed at the center of the screen, averaging information is reset when you tune. This has always been the case, but I'll mention this to our panadapter design staff and see if it might be possible to preserve the averaging data in tracking mode.

In any case, I hope you can observe a P3 in action sometime.

73,
Wayne
N6KR


On Jul 31, 2015, at 1:13 AM, John Kramer <jkramer at iafrica.com> wrote:

> I think I know what Joe is getting at….and I agree with him, if I understand him correctly. When he refers to “noise floor” 
> he means that he loses averaging when he tunes, resulting in the crazy spectrum display (what Joe refers to as noise).
> 
> I haven’t seen or used a P3, but I bought my first Elecraft products 3 weeks ago - a KX3 and PX3. If the P3 behaves in the 
> same manner as the PX3 then I can see what Joe is complaining about. Right out the box my PX3 had this frustrating
> feature of losing averaging the moment you spun the VFO on the KX3. I pointed this out to a local KX3/PX3 owner, and
> he told me to download the latest firmware which allows you to select “fixed mode” or “fixed track”. I downloaded the 
> firmware. YES, it kinda fixes the problem….you can now tune the radio and KEEP the averaging….but the problem is
> that now your receive filter goes down the display as you tune. This is better than the previous method, however
> you now have your receive filter heavily offset from the centre of the display. You might tune down the band, with your
> RX filter at the bottom of the scale, and you are now unable to see much below, but you can see a huge chunk of 
> the band above you.
> 
> I bought the KX3 and PX3 for portable ops. My main rigs for the past 5 years are Flex rigs. I have the 5000/3000/1500
> and will be getting a 6500 soon as my shack rigs. With these rigs and PSDR, your RX filter REMAINS CENTRED and when 
> you tune around the band, you DON’T LOSE your averaging. This is how I like it to be, and if Elecraft can achieve this 
> in a firmware update, I would be very happy.
> 
> 73
> John, ZS5J
> 
> 
> 
> 
> 
> On 31 Jul 2015, at 2:56 AM, Eric Swartz - WA6HHQ, Elecraft <eric at elecraft.com> wrote:
> 
> Hi Joe - Do you have signal averaging turned on to reduce the noise floor? If you do, it has to stop averaging when the freq is being changed while tuning, temporarily raising the noise floor slightly. It then re-starts multi-pass averaging once you stop tuning. This is normal for signal averaging. I run with averaging set =2 or 3 passes. When I tune I barely notice a small increase in the noise floor.
> 
> If you have a lot of local pulse noise, you might want to turn on the P3s NB function to help.
> 
> If Averaging is turned off, I can't think of a normal scenario where the noise floor would go up when tuning the band. It certainly does not here.
> 
> Anyone else have any ideas?
> 
> 73,
> 
> Eric
> /elecraft.com/
> 
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