[1000mp] Diversity reception using the FT-1000MP
Anders Granstrom
[email protected]
Sat, 03 Aug 2002 12:19:40 +0200
My dipoles for 21 MHz are only spaced vertically about 0.3 wavelength,
but there is still an diversity effect on the signals as you can hear
on my recordings.
http://w1.858.telia.com/~u85817669/ham_radio.htm
I was a bit surprised myself of the diversity effect, because the intention was to measure the
vertical angle of the radio waves coming into my dipoles using an oscilloscope in XY-mode (which actually works). Then after some thinking and listening I realised that there was more diversity effect
from multiple-hop stations, and the vertical radiation pattern for the
two dipoles are slightly different (the higher dipole works better for DX as you can hear on the UW0ZZ recording).
My conclusion is then that multiple-hop stations have radio waves coming from a broader vertical angle interval, and since the two dipoles receives not exactly the same vertical angle interval the sum of waves they receive are slightly different, therefore the fading pattern is also slightly different. This indicates that stacking yagis
at the same height and spacing that I have for my dipoles will not work
optimally for multiple-hop stations, since a large portion of time
the signals will not be added together in the correct phase and amplitude.
/Anders SM0IHR
>From: "Tom Rauch"
>Reply-To: [email protected]
>To: [email protected]
>Subject: Re: [1000mp] Diversity reception using the FT-1000MP
>Date: Fri, 2 Aug 2002 04:27:02 -0400
>
> > For the brain to do maximum processing for spatial filtering of dual
> > audio, reducing unrelated audio energy (noise) is very helpful. Yes,
> > you can use stereo speakers, let me re phrase that, yes you can use
> > dual speakers - one on the output of each receiver - for diversity
> > reception modes and to good effect ...
>
>Actually you have to be very careful using speakers, because
>isolation will not be near-perfect and the sound will mix.
>
>You can not mix the sound from two receivers on two antennas unless
>the receivers are phase locked, have exactly the same phase shift in
>filters, and have the proper phase of RF signals at the antenna.
>
>Headphones get rid of those problems, although it is still much
>better to have matched filters and phase locked (or common
>oscillator) receivers.
>
>I use heavily modified R4C's with carefully matched filters for
>diversity, with wide (1000-2500 foot) separation on 160 antennas.
>With antennas separated less than 2 WL diversity does almost no good
>at all, just as it does when one antenna has much poorer S/N than the
>better antenna.
>
>You have to actually hear good diversity to appreciate how bad less
>than optimum diversity sounds.
>
>73, Tom W8JI
>[email protected]
>
>_______________________________________________
>List Moderator: Richard Lubash N1VXW
>1000mp mailing list
>[email protected]
>To Change Options or Unsubscribe:
>http://mailman.qth.net/mailman/listinfo/1000mp
------------------------------------------
Join the world�s largest e-mail service with MSN Hotmail.
------------------------------------------
Click Here
------------------------------------------
--- StripMime Report -- processed MIME parts ---
text/html (html body -- converted)
The reason this message is shown is because the post was in HTML
or had an attachment. Attachments are not allowed.
Please post in Plain-Text only.---