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Re: [Discuss-gnuradio] Improve FSK4 decodes in OP25
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From: |
Andy Walls |
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Subject: |
Re: [Discuss-gnuradio] Improve FSK4 decodes in OP25 |
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Date: |
Mon, 23 Jan 2017 08:05:03 -0500 |
On Sun, 2017-01-22 at 20:22 -0500, Luke Berndt wrote:
> Thanks again for all the help! It is great to be getting clear audio
> and having things look right on the charts.
> - Luke
You're welcome.
One thing I forgot to mention, that might also help reception:
Use antennas that are at least a quarter wavelength long with a good
ground plane and halfway decent antenna cable.
A 1/4 wavelength at 450 MHz is
(299.8e6 m/s / 450e6 Hz) * 1/4 ~= 0.167 m ~= 6.6 in
The stock RTL-SDR antennas are shorter than 6.6 in and are thus
"electrically small".
Amazon's stores have a few reasonable priced ones right off the first
page of the search for scanner antennas:
https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=scanner+antenna&rh=i%3Aaps%2Ck%3Ascanner+antenna
https://www.amazon.com/1094-BNC-Scanner-Antenna-BNC-Male-Connector/dp/B01DUSBHDM/ref=sr_1_1?s=electronics&ie=UTF8&qid=1485176439&sr=1-1&keywords=scanner+antenna
https://www.amazon.com/Scanner-Radio-Magnet-Mobile-Antenna/dp/B004C1T7PC/ref=sr_1_19?s=electronics&ie=UTF8&qid=1485176541&sr=1-19&keywords=scanner+antenna
with enough cable to move the antennas farther from indoor UHF noise sources.
-Andy