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Radio Equipment => UHF Systems => Topic started by: jamiejig on May 04, 2012, 12:29:40 AM

Title: uhf
Post by: jamiejig on May 04, 2012, 12:29:40 AM
dose a uhf system have grate penetration with it having a low mhz. ie like a 900mhz video link
Title: uhf
Post by: papa_lazerous on May 04, 2012, 12:38:25 AM
More importantly does your computer have a spell check?
Title: Re: uhf
Post by: stebbo1986 on May 04, 2012, 01:02:43 AM
Wow!! im sure it does have good penetration being below 900mhz

the higher you go the less penetrtion you get
Title: Re: uhf
Post by: tdmodels on May 04, 2012, 01:26:11 AM
Quote from: papa_lazerous on May 04, 2012, 12:38:25 AM
More importantly does your computer have a spell check?

Papa, your posts are really 'great'ing on me  :P

Stebbo -  Yes, the lower the frequency, the better the penetration. Hence the reason submarines use extremely low frequencies (3 to 300Hz!!!)  Of course, other factors then come into play like transmission power and available transmission bit rates etc
Title: Re: uhf
Post by: Coyote on May 04, 2012, 01:37:53 AM
Yes Jamie it does, Dragonlink even worked inside an underground concrete car park
Title: uhf
Post by: glambert on August 16, 2012, 12:03:04 AM
Hello,

Your are right, great penetration.

In the following video, I turn around an 10 century abbey and both the Thomas Scherrer and the 900 MHz video downlink crossed these buildings made with old thick walls...  But distance was maybe only 100 meters.

https://vimeo.com/channels/multicopterpilot/36856866 (https://vimeo.com/channels/multicopterpilot/36856866)

Cheers

Gregory
Title: Re: uhf
Post by: electrotor on August 16, 2012, 01:09:15 AM
Quote from: tdmodels on May 04, 2012, 01:26:11 AM

Stebbo -  Yes, the lower the frequency, the better the penetration. Hence the reason submarines use extremely low frequencies (3 to 300Hz!!!)  Of course, other factors then come into play like transmission power and available transmission bit rates etc

Then there's antenna length.
Let's see, for 100Hz ... 300000/100 = 3000km wavelength.
Oh dear, that's a long trailing wire even if you use 1/4 wave.  :o