Posted: 4/30/2014 7:27:36 AM EDT
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The way I understand it, I can use a noise source and invert it, or put it 180deg out of phase, and this will negate the problem I have with a plasma tv when I visit my fiancee's family.
Does this look right? 
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Yeah, it needs to be 180 and have the same amplitude as the main antenna. And remember that
180 degree phase is dependent on the distances to the noise source, cable lengths and factors, etc, of both antennas, and this varies with the frequency used so both phase and amplitude will need adjustment. It will improve things, but won't eliminate it. I've got a hardware box that does the same thing that I'm no longer using, you have to dink with settings a lot in order to fine-tune the cancellation. |
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It's probably just a small matter of imprecise language, but to be clear one does not use a "noise source" to perform this function. The device is more commonly known as a "canceller".
The manual for the Timewave ANC-4 canceller has an excellent block diagram including the required T/R switch on Page 17, and a full schematic on Page 18: http://www.timewave.com/support/ANC-4/ANC_4TW8x11a.pdf Do you have a link to the Ham-It-Up device you are proposing to use? |
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I have the ham-it-up, and it doesn't do what he's thinking about. The Timewave does.
The Timewave is the hardware I was referring to. I've got one gathering dust at the moment, it works but has fairly high insertion loss and as I said is very sensitive to adjustments. The ham-it-up's noise source is for reciever performance measurements., so I think you're correct that he's confused as to the function. The configuration of the noise port on the ham-it-up is actually as an output as well, to feed equipment under test. |
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Quoted:
It's probably just a small matter of imprecise language, but to be clear one does not use a "noise source" to perform this function. The device is more commonly known as a "canceller". The manual for the Timewave ANC-4 canceller has an excellent block diagram including the required T/R switch on Page 17, and a full schematic on Page 18: http://www.timewave.com/support/ANC-4/ANC_4TW8x11a.pdf Do you have a link to the Ham-It-Up device you are proposing to use? Quoted:
It's probably just a small matter of imprecise language, but to be clear one does not use a "noise source" to perform this function. The device is more commonly known as a "canceller". The manual for the Timewave ANC-4 canceller has an excellent block diagram including the required T/R switch on Page 17, and a full schematic on Page 18: http://www.timewave.com/support/ANC-4/ANC_4TW8x11a.pdf Do you have a link to the Ham-It-Up device you are proposing to use? Quoted:
I have the ham-it-up, and it doesn't do what he's thinking about. The Timewave does. The Timewave is the hardware I was referring to. I've got one gathering dust at the moment, it works but has fairly high insertion loss and as I said is very sensitive to adjustments. The ham-it-up's noise source is for reciever performance measurements., so I think you're correct that he's confused as to the function. The configuration of the noise port on the ham-it-up is actually as an output as well, to feed equipment under test. Yep, you're right. It doesn't do what I thought it does... Oh well. I guess I just run more coax and get the antenna further away from the house. Using an SDR instead of a traditional radio does make it A LOT easier to work in that kind of RFI though. I think I'll have to use coax to feed the antenna too, instead of twin-lead. I'll have an SDR setup to leave at their house soon enough. |
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It's easier because I can see the signals through the noise generated by the plasma tv, and I can work around it more easily. Having more than one notch filter also makes it easier.
I suppose if I had a panadapter, I could do something similar, but I'm not sure it'd be the same. The sensitivity and signal selectivity is really what takes the cake though. |
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Quoted:
It's easier because I can see the signals through the noise generated by the plasma tv, and I can work around it more easily. Having more than one notch filter also makes it easier. I suppose if I had a panadapter, I could do something similar, but I'm not sure it'd be the same. The sensitivity and signal selectivity is really what takes the cake though. Wait until you use a good radio with good IF filtering You will learn what Selectivity and Sensitivity really mean 
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Quoted:
Wait until you use a good radio with good IF filtering You will learn what Selectivity and Sensitivity really mean Quoted:
Quoted:
It's easier because I can see the signals through the noise generated by the plasma tv, and I can work around it more easily. Having more than one notch filter also makes it easier. I suppose if I had a panadapter, I could do something similar, but I'm not sure it'd be the same. The sensitivity and signal selectivity is really what takes the cake though. Wait until you use a good radio with good IF filtering You will learn what Selectivity and Sensitivity really mean I doubt my IC7200 meets your 'good radio' criteria, but I think I understand what you mean. When I use the filtering on this thing it just amazes me. SSB band is ugly? I crank down to 1800 or even 1200Hz width to hear just the guy I am trying to work. Digi-modes? I am always amazed at the weak signals that suddenly are workable when I zoom in to barely their bandwidth. Scanning the band and some joker decides to be the voice of God? ANF...done. Oh now there's two of them? Crank on the Twin PBTs to fix it. I can't wait to get better at my code so I can see what it does for CW. Honestly I am seriously pondering taking the 7200 up on the mountain this year and having the 857D be the backup. |
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I doubt my IC7200 meets your 'good radio' criteria, but I think I understand what you mean. When I use the filtering on this thing it just amazes me. SSB band is ugly? I crank down to 1800 or even 1200Hz width to hear just the guy I am trying to work. Digi-modes? I am always amazed at the weak signals that suddenly are workable when I zoom in to barely their bandwidth. Scanning the band and some joker decides to be the voice of God? ANF...done. Oh now there's two of them? Crank on the Twin PBTs to fix it. I can't wait to get better at my code so I can see what it does for CW. Honestly I am seriously pondering taking the 7200 up on the mountain this year and having the 857D be the backup. Quoted:
Quoted:
Quoted:
It's easier because I can see the signals through the noise generated by the plasma tv, and I can work around it more easily. Having more than one notch filter also makes it easier. I suppose if I had a panadapter, I could do something similar, but I'm not sure it'd be the same. The sensitivity and signal selectivity is really what takes the cake though. Wait until you use a good radio with good IF filtering You will learn what Selectivity and Sensitivity really mean I doubt my IC7200 meets your 'good radio' criteria, but I think I understand what you mean. When I use the filtering on this thing it just amazes me. SSB band is ugly? I crank down to 1800 or even 1200Hz width to hear just the guy I am trying to work. Digi-modes? I am always amazed at the weak signals that suddenly are workable when I zoom in to barely their bandwidth. Scanning the band and some joker decides to be the voice of God? ANF...done. Oh now there's two of them? Crank on the Twin PBTs to fix it. I can't wait to get better at my code so I can see what it does for CW. Honestly I am seriously pondering taking the 7200 up on the mountain this year and having the 857D be the backup. I started off on HF with an Heathkit HW-101 over 25 years ago. I would love to have a pristine one just for nostalgia sake but I'm sure by today's standards it is awful. I am sure the 7200 is far better than many or the radios I have had over the years. |