Re: [Elecraft] K3: new feature idea / question
Brian Machesney wrote: > > I was just reading about the differing levels of success that people have > with "active noise cancelling" units. It occurred to me that one should be > able to achieve the same kinds of results using the second RX and separate > antenna in the K3 - with the addition of control over the phase (delay) of > the arriving signal. > FYI the Flex 5000 has this capability now and may be slightly ahead of the K3's implementation of diversity. They added the ability to adjust phase as well as amplitude differences between the two channels. This is exactly the capability Brian is asking for above. http://w9oy-sdr.blogspot.com/2009/07/more-diversity.html "Above is the latest "polar" control for the diversity project. The control allows you to adjust phase and gain between 2 antennas and 2 receivers in the F5K. Here is a shot of the F5K with diversity active" Hoping this friendly competition will eventually inspire Elecraft to do something similar! :-) I'm betting it will...maybe using the P3 display. 73, Bill -- View this message in context: http://n2.nabble.com/K3-new-feature-idea-question-tp3977080p3982322.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: new feature idea / question
Brian Machesney wrote: > > I was just reading about the differing levels of success that people have > with "active noise cancelling" units. It occurred to me that one should be > able to achieve the same kinds of results using the second RX and separate > antenna in the K3 - with the addition of control over the phase (delay) of > the arriving signal. > I believe it should be possible also since the K3 and KRX3 are virtually identical (as required for diversity). Any gain difference could be compensated using the separate RF Gain controls, but phase differences would require some sort of control knob, which is in short supply on the K3 front panel. It's simple to do this with an external unit like the MFJ-1025 which is the way I'm heading. DXE also has a much more expensive unit (NCC-1) but the 1025 can be modified to make it similar (except for strong signal performance). I've done all the W8JI modifications below (excluding the filter modifications) and I also added impedance converters for the two inputs. For some reason both inputs on my 1025 show input impedance on 160m of ~160 ohms, so I added 2:1 transformer inputs to get ~80 ohms on both parallel F-connector inputs (another mod). I'll be using two identical Beverages staggered ~1/4 wl and spaced ~1/8 wl apart, each matched to 75 ohms. I was concerned about possible reflection issues if the Beverages saw 150 ohms looking back into the 1025. http://www.w8ji.com/mfj-1025_1026.htm Once the crops are out of the field where I plan to install this I'll try to report back on how it's working. 73, Bill -- View this message in context: http://n2.nabble.com/K3-new-feature-idea-question-tp3977080p3980098.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: new feature idea / question
G4ILO said > you need at least two extra controls, preferably three, one to vary the >phasing of the two signals and the others to adjust the amplitude of the two >inputs so that the noise levels cancel exactly. Sounds like a description of the DX Engineering NCC-1 http://www.dxengineering.com/Parts.asp?ID=1227&PLID=215&SecID=114&DeptID=12&PartNo= DXE%2DNCC%2D1 Its expensive but if nothing else the manual is worth a read http://www.dxengineering.com/pdf/NCC-1%20Rev%203.pdf Trevor G0KTN __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: new feature idea / question
Smart thinking! Though using two receivers for this may be quite difficult to implement. They have to be *exactly* identical to obtain phase cancellation. That means AGC timing, roofing filter ripple, signal path gains, everything. I think this will be hard with the K3 and SubRX. The outboard noise-cancellation boxes have a much shorter/simpler and wider signal path, making cancellation easier. It may also be a better place to do this at the front-end and not at the back-end of a receiver. It would be a nice experiment though! How about just phase reverting the SubRX audio temporarily and give it a try? 73' Paul PD0PSB Brian Machesney wrote: > > I was just reading about the differing levels of success that people have > with "active noise cancelling" units. It occurred to me that one should be > able to achieve the same kinds of results using the second RX and separate > antenna in the K3 - with the addition of control over the phase (delay) of > the arriving signal. On its face, it would seem that one could achieve > destructive interference between "the noise only" coming from a "sense" > antenna and "the noise + signal" coming from a better receive antenna. > > Thoughts? > > -- > 73 -- Brian -- K1LI > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > -- View this message in context: http://n2.nabble.com/K3-new-feature-idea-question-tp3977080p3979212.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: new feature idea / question
A good thought Brian. My experience of two such noise cancelling devices is that, depending on the type and direction of the noise, they can be very effective in improving the signal/noise ratio although there is some insertion loss so weak signals are sometimes lost. I always have one connected to the K3 for use as needed. As I understand it the phase delay of the signal from the noise antenna and its mixing with the signal from the main antenna needs to take place before the signal gets to the receiver, so, with an external device at least, two receivers are not needed. However, I have been surprised for some years that no rig manufacturers build such a feature in. Perhaps it could somehow be done with firmware in the K3 using, say, the RX ANT or the AUX input for the noise antenna? 73 to all Geoff G3UCK - Original Message - From: "Brian Machesney" Subject: [Elecraft] K3: new feature idea / question >I was just reading about the differing levels of success that people have > with "active noise cancelling" units. It occurred to me that one should be > able to achieve the same kinds of results using the second RX and separate > antenna in the K3 - with the addition of control over the phase (delay) of > the arriving signal. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: new feature idea / question
Brian Machesney wrote: > > I was just reading about the differing levels of success that people have > with "active noise cancelling" units. It occurred to me that one should be > able to achieve the same kinds of results using the second RX and separate > antenna in the K3 - with the addition of control over the phase (delay) of > the arriving signal. On its face, it would seem that one could achieve > destructive interference between "the noise only" coming from a "sense" > antenna and "the noise + signal" coming from a better receive antenna. > > I own one of those units. One thought that immediately springs to mind is that you need at least two extra controls, preferably three, one to vary the phasing of the two signals and the others to adjust the amplitude of the two inputs so that the noise levels cancel exactly. The K3 has no provision for these controls. - Julian, G4ILO. K2 #392 K3 #222. * G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html -- View this message in context: http://n2.nabble.com/K3-new-feature-idea-question-tp3977080p3978631.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3: new feature idea / question
I was just reading about the differing levels of success that people have with "active noise cancelling" units. It occurred to me that one should be able to achieve the same kinds of results using the second RX and separate antenna in the K3 - with the addition of control over the phase (delay) of the arriving signal. On its face, it would seem that one could achieve destructive interference between "the noise only" coming from a "sense" antenna and "the noise + signal" coming from a better receive antenna. Thoughts? -- 73 -- Brian -- K1LI __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
