Re: [Elecraft] [KX3] Noise blanker comments

2015-12-11 Thread David Anderson 
Still interested in any comments about how the KX3 noise blanker is 
implemented, and if it could be improved to make it as effective as the wide 
band RF blanker in HDSDR.

I now have the SDRPlay tracking the KX3 VFO so that in the event of static rain 
QRN I can switch to the SDRPlay for good copy when the KX3 is useless.

73 from David GM4JJJ

> On 9 Dec 2015, at 20:30,   wrote:
> 
> I use my KX3 on 144 MHz (with external transverter). 
> 
> Comments regarding the KX3 Noise blanker:
> 
> It is effective for some kinds of power line noise and ignition noise, I 
> normally leave it on at a setting of 6.
> 
> It is not effective at all with heavy rain or snow static. 
> 
> By way of comparison I have an SDRPlay dongle connected to the same 
> transverter and using the HDSDR software can enable the RF noise blanker in 
> that software and it can reduce an S9+20 rain static noise that masks all 
> signals to almost zero and allows me to decode a distant weak CW beacon that 
> is just above the noise floor. On the KX3, just S9+ noise no matter what 
> setting used on the NB.
> 
> I wonder if the DSP noise blanking could be improved in the KX3 to blank such 
> heavy static? Does the KX3 noise blanker work in the demodulated audio or the 
> RF domain?
> 
> Many thanks.
> 
> -- David GM4JJJ
> 
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Re: [Elecraft] [KX3] Noise blanker comments

2015-12-11 Thread Wayne Burdick 
David,

The KX3's noise blanker is implemented entirely within its DSP. Ahead of the 
DSP are the mixer and its duplexer, which have a finite bandwidth, and possibly 
the roofing filters, which have much narrower bandwidths. Because of this, 
there's no way for the DSP to gain access to wideband data for blanking 
purposes. 

While this does reduced effectiveness on some types of noise, the blanker still 
works well on most. I use it every day at my QTH on noise ranging from 
telephone-pole ESD to appliances and computer peripherals. And because the 
blanker is strictly operating within a narrow bandwidth, it cannot easily be 
"pumped" by signals well outside the IF passband.

The KX3's narrowband filtering also gives it a big advantage in blocking 
dynamic range compared to other SDRs that have nearly unlimited input 
bandwidth. For example, Sherwood measured the KX3's BDR at 138 dB, compared to 
something in the low to mid 120's for "pure" SDRs. The KX3 is also fifth on 
Sherwood's list for 2-kHz IMDDR3, again because of the narrow roofing filter.

Since the DSP controls blanking, it may be possible to implement additional 
noise blanking algorithms in the future. That is definitely on our list. If you 
send us a detailed description of the types of noise you encounter, we could 
try to duplicate them in the lab during this effort.

73,
Wayne
N6KR


On Dec 11, 2015, at 3:59 AM, David Anderson  wrote:

> Still interested in any comments about how the KX3 noise blanker is 
> implemented, and if it could be improved to make it as effective as the wide 
> band RF blanker in HDSDR.
> 
> I now have the SDRPlay tracking the KX3 VFO so that in the event of static 
> rain QRN I can switch to the SDRPlay for good copy when the KX3 is useless.
> 
> 73 from David GM4JJJ
> 
>> On 9 Dec 2015, at 20:30,   wrote:
>> 
>> I use my KX3 on 144 MHz (with external transverter). 
>> 
>> Comments regarding the KX3 Noise blanker:
>> 
>> It is effective for some kinds of power line noise and ignition noise, I 
>> normally leave it on at a setting of 6.
>> 
>> It is not effective at all with heavy rain or snow static. 
>> 
>> By way of comparison I have an SDRPlay dongle connected to the same 
>> transverter and using the HDSDR software can enable the RF noise blanker in 
>> that software and it can reduce an S9+20 rain static noise that masks all 
>> signals to almost zero and allows me to decode a distant weak CW beacon that 
>> is just above the noise floor. On the KX3, just S9+ noise no matter what 
>> setting used on the NB.
>> 
>> I wonder if the DSP noise blanking could be improved in the KX3 to blank 
>> such heavy static? Does the KX3 noise blanker work in the demodulated audio 
>> or the RF domain?
>> 
>> Many thanks.
>> 
>> -- David GM4JJJ
>> 
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Re: [Elecraft] [KX3] Noise blanker comments

2015-12-11 Thread Robert Vargas-KP4Y via Elecraft 
 Hi Wayne,
Thanks for the nice info on the KX3 NB operation. How does the much lower 
opposite sideband rejection limits the effectiveness of the KX3 in a 
competitive environment? I have always imagined that everything is good as long 
as a strong signal doesn't get closer than 1 khz. Am I understanding this 
right? What would be the IMDDR3 of something like the K3 or K3S at 1 khz 
spacing? I have never had any issues with the KX3 during contest with IMD, but 
then I have small antennas; therefore, signals are not very strong.
Thanks,Robert-KP4Y/W4

On Friday, December 11, 2015 10:49 AM, Wayne Burdick  
wrote:
 

 David,

The KX3's noise blanker is implemented entirely within its DSP. Ahead of the 
DSP are the mixer and its duplexer, which have a finite bandwidth, and possibly 
the roofing filters, which have much narrower bandwidths. Because of this, 
there's no way for the DSP to gain access to wideband data for blanking 
purposes. 

While this does reduced effectiveness on some types of noise, the blanker still 
works well on most. I use it every day at my QTH on noise ranging from 
telephone-pole ESD to appliances and computer peripherals. And because the 
blanker is strictly operating within a narrow bandwidth, it cannot easily be 
"pumped" by signals well outside the IF passband.

The KX3's narrowband filtering also gives it a big advantage in blocking 
dynamic range compared to other SDRs that have nearly unlimited input 
bandwidth. For example, Sherwood measured the KX3's BDR at 138 dB, compared to 
something in the low to mid 120's for "pure" SDRs. The KX3 is also fifth on 
Sherwood's list for 2-kHz IMDDR3, again because of the narrow roofing filter.

Since the DSP controls blanking, it may be possible to implement additional 
noise blanking algorithms in the future. That is definitely on our list. If you 
send us a detailed description of the types of noise you encounter, we could 
try to duplicate them in the lab during this effort.

73,
Wayne
N6KR


On Dec 11, 2015, at 3:59 AM, David Anderson  wrote:

> Still interested in any comments about how the KX3 noise blanker is 
> implemented, and if it could be improved to make it as effective as the wide 
> band RF blanker in HDSDR.
> 
> I now have the SDRPlay tracking the KX3 VFO so that in the event of static 
> rain QRN I can switch to the SDRPlay for good copy when the KX3 is useless.
> 
> 73 from David GM4JJJ
> 
>> On 9 Dec 2015, at 20:30,   wrote:
>> 
>> I use my KX3 on 144 MHz (with external transverter). 
>> 
>> Comments regarding the KX3 Noise blanker:
>> 
>> It is effective for some kinds of power line noise and ignition noise, I 
>> normally leave it on at a setting of 6.
>> 
>> It is not effective at all with heavy rain or snow static. 
>> 
>> By way of comparison I have an SDRPlay dongle connected to the same 
>> transverter and using the HDSDR software can enable the RF noise blanker in 
>> that software and it can reduce an S9+20 rain static noise that masks all 
>> signals to almost zero and allows me to decode a distant weak CW beacon that 
>> is just above the noise floor. On the KX3, just S9+ noise no matter what 
>> setting used on the NB.
>> 
>> I wonder if the DSP noise blanking could be improved in the KX3 to blank 
>> such heavy static? Does the KX3 noise blanker work in the demodulated audio 
>> or the RF domain?
>> 
>> Many thanks.
>> 
>> -- David GM4JJJ
>> 
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Re: [Elecraft] [KX3] Noise blanker comments

2015-12-11 Thread David Anderson 
Wayne,

Many thanks for the comprehensive reply.

Next time I encounter the static rain/snow that completely overwhelmed the KX3 
noise blanker, I will make a short wide band RF recording from the SDR and can 
send you a link to the file which may help with developing other DSP noise 
blanking algorithms.

I do agree the existing KX3 noise blanker does a great job on other types of 
pulse noises, and doesn't suffer much when used in the presence of other strong 
signals on the band. Much much better in that respect than my previous 
transceivers.

For now I am happy to use the KX3 in tandem with the wide band SDR when I need 
to blank out the rain static on 144 MHz which happens from time to time.

73 from David GM4JJJ

> On 11 Dec 2015, at 15:48, Wayne Burdick  wrote:
> 
> David,
> 
> The KX3's noise blanker is implemented entirely within its DSP. Ahead of the 
> DSP are the mixer and its duplexer, which have a finite bandwidth, and 
> possibly the roofing filters, which have much narrower bandwidths. Because of 
> this, there's no way for the DSP to gain access to wideband data for blanking 
> purposes. 
> 
> While this does reduced effectiveness on some types of noise, the blanker 
> still works well on most. I use it every day at my QTH on noise ranging from 
> telephone-pole ESD to appliances and computer peripherals. And because the 
> blanker is strictly operating within a narrow bandwidth, it cannot easily be 
> "pumped" by signals well outside the IF passband.
> 
> The KX3's narrowband filtering also gives it a big advantage in blocking 
> dynamic range compared to other SDRs that have nearly unlimited input 
> bandwidth. For example, Sherwood measured the KX3's BDR at 138 dB, compared 
> to something in the low to mid 120's for "pure" SDRs. The KX3 is also fifth 
> on Sherwood's list for 2-kHz IMDDR3, again because of the narrow roofing 
> filter.
> 
> Since the DSP controls blanking, it may be possible to implement additional 
> noise blanking algorithms in the future. That is definitely on our list. If 
> you send us a detailed description of the types of noise you encounter, we 
> could try to duplicate them in the lab during this effort.
> 
> 73,
> Wayne
> N6KR
> 
> 
>> On Dec 11, 2015, at 3:59 AM, David Anderson  wrote:
>> 
>> Still interested in any comments about how the KX3 noise blanker is 
>> implemented, and if it could be improved to make it as effective as the wide 
>> band RF blanker in HDSDR.
>> 
>> I now have the SDRPlay tracking the KX3 VFO so that in the event of static 
>> rain QRN I can switch to the SDRPlay for good copy when the KX3 is useless.
>> 
>> 73 from David GM4JJJ
> 
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[Elecraft] [KX3] Noise blanker comments

2015-12-09 Thread gm4jjj 
I use my KX3 on 144 MHz (with external transverter). 
Comments regarding the KX3 Noise blanker:
It is effective for some kinds of power line noise and ignition noise, I 
normally leave it on at a setting of 6.
It is not effective at all with heavy rain or snow static. 
By way of comparison I have an SDRPlay dongle connected to the same transverter 
and using the HDSDR software can enable the RF noise blanker in that software 
and it can reduce an S9+20 rain static noise that masks all signals to almost 
zero and allows me to decode a distant weak CW beacon that is just above the 
noise floor. On the KX3, just S9+ noise no matter what setting used on the NB.
I wonder if the DSP noise blanking could be improved in the KX3 to blank such 
heavy static? Does the KX3 noise blanker work in the demodulated audio or the 
RF domain?
Many thanks.
-- David GM4JJJ
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