Hi John, nice video presentation. What I find odd is that there seems to be little comments and interest in the matter. I have owned the AFE822x and still use the RSPduo when they came available. I used a Timewave ANC-4 in the past and did experience the power of Diversity years ago and never stop using it. Now all hams have their mouth full talking about local QRM, but almost all do not use Diversity, even with a cheap and simple QRM eliminator. Seems they like to keep suffering and complaining ;-). Good luck with your channel end educating good practice. Cheers, ON2RON
KD6CFE was here. Thank you for your contribution of great videos on RF communications. Of course most of it is above my intelligence and schooling , but I still like to attempt to keep up on electronics and technology.
одна из побочных задач необходимых в решении проблемы "массива антенных решеток" на основе множества одноканальных недорогих sdr приемников-это синхронизация тактовой частоты, поправки ppm, которую можно сделать с помощью python на основе опорного сигнала (например мобильные сети) в интернете есть лабораторная работа по захвату gsm fcb (freq corr burst)
9:32 You mention improving SNR, or pointing a null at the interference. How do you decide which to do? Depends on conditions? 14:10 Should the noise-collector be the same type of antenna as the primary antenna? 14:55 Shift 180 deg? Or just invert? 15:40 Isn't Diversity Gain the same as beamforming a lobe with Array Gain? 16:22 Isn't 3 db a DOUBLING of strength? And therefor quite a lot? 17:25 "Baseband" simply means the raw RF signal, correct? 18:22 Are the source transmissions in your examples analog or digital?
Hi John, Thanks for your note. Everything is about improving SNR. Typically, you can achieve more by reducing noise/interference. Noise probe should do a good job of collecting noise, while the other antenna should be your primary antenna. Shifting 180 degrees = invert. Diversity gain is primarily compensating for different paths of reception, which fade at statistically different times, i.e. compensating for complex fading. Beamforming is just getting the best lobe or null regardless of multipath.
@@VE6EY Thx! "you can achieve more by reducing noise" -- So, a noise collector is generally more useful than beamforming? "Shifting 180 degrees = invert" - But then the signal is delayed by 1/2 a wavelength. So your cancellation assumes the first half of the waveform is a mirror of the second half, which it might not necessarily be. It seems that, for most accurate cancellation, you'd want inversion without any delay. I believe an analog inverter (eg inverting op amp) inverts without delay. "Diversity gain is primarily compensating for different paths of reception" -- You mean, simply having multiple antennas, without any processing, will improve reception?
@@johnaweiss When you simultaneously capture two coherent channels at baseband, and then phase shift one of the channels and combine both, there is NO delay
Yes. As long as you record both channels in their coherent form and play them back as such. I have written some software to do this for my own use and it works fine. Unfortunately, there are no SDR software packages that do this for us. Hopefully, something like SDRConnect with add this in the future.
Hi John, nice video presentation. What I find odd is that there seems to be little comments and interest in the matter. I have owned the AFE822x and still use the RSPduo when they came available. I used a Timewave ANC-4 in the past and did experience the power of Diversity years ago and never stop using it. Now all hams have their mouth full talking about local QRM, but almost all do not use Diversity, even with a cheap and simple QRM eliminator. Seems they like to keep suffering and complaining ;-). Good luck with your channel end educating good practice. Cheers, ON2RON
Thanks, Ron. I agree. New ideas can take time to take hold, if ever. Of course, this is really quite an "old" idea.
KD6CFE was here. Thank you for your contribution of great videos on RF communications. Of course most of it is above my intelligence and schooling , but I still like to attempt to keep up on electronics and technology.
Hi Al, thanks for your kind words. Just get an RSPduo and do some hands on learning about modern diversity reception if you have two antennas!
Great stuff 👍🏽Thanks for sharing. 73 🎙 Ira
Thank you!
одна из побочных задач необходимых в решении проблемы "массива антенных решеток" на основе множества одноканальных недорогих sdr приемников-это синхронизация тактовой частоты, поправки ppm, которую можно сделать с помощью python на основе опорного сигнала (например мобильные сети) в интернете есть лабораторная работа по захвату gsm fcb (freq corr burst)
9:32 You mention improving SNR, or pointing a null at the interference. How do you decide which to do? Depends on conditions?
14:10 Should the noise-collector be the same type of antenna as the primary antenna?
14:55 Shift 180 deg? Or just invert?
15:40 Isn't Diversity Gain the same as beamforming a lobe with Array Gain?
16:22 Isn't 3 db a DOUBLING of strength? And therefor quite a lot?
17:25 "Baseband" simply means the raw RF signal, correct?
18:22 Are the source transmissions in your examples analog or digital?
Hi John, Thanks for your note. Everything is about improving SNR. Typically, you can achieve more by reducing noise/interference. Noise probe should do a good job of collecting noise, while the other antenna should be your primary antenna. Shifting 180 degrees = invert. Diversity gain is primarily compensating for different paths of reception, which fade at statistically different times, i.e. compensating for complex fading. Beamforming is just getting the best lobe or null regardless of multipath.
@@VE6EY Thx! "you can achieve more by reducing noise" -- So, a noise collector is generally more useful than beamforming?
"Shifting 180 degrees = invert" - But then the signal is delayed by 1/2 a wavelength. So your cancellation assumes the first half of the waveform is a mirror of the second half, which it might not necessarily be. It seems that, for most accurate cancellation, you'd want inversion without any delay. I believe an analog inverter (eg inverting op amp) inverts without delay.
"Diversity gain is primarily compensating for different paths of reception" -- You mean, simply having multiple antennas, without any processing, will improve reception?
@@johnaweiss When you simultaneously capture two coherent channels at baseband, and then phase shift one of the channels and combine both, there is NO delay
@@VE6EY You mean, phase shift just enough so the signals line up, right?
@@johnaweiss Yes. When the copy of the signal on Channel A is -180 degrees with the copy of channel B, and amplitudes are equal, they should cancel.
I found your presentation very informative and clear. Many thanks ! Any suggestion of technical literature with some more math ?
Hi. Thanks for feedback. You might do some searching on "beamforming" or "spatial signal processing". Tons of math!
Can the diversity function be performed on an IQ-recorded portion of the spectrum?
Yes. As long as you record both channels in their coherent form and play them back as such. I have written some software to do this for my own use and it works fine. Unfortunately, there are no SDR software packages that do this for us. Hopefully, something like SDRConnect with add this in the future.
@VE6EY - is the state of diversity reception still at the same place?
As far as I know. Thanks