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VHF vs. UHF what's the difference ?

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  • VHF vs. UHF what's the difference ?

    which is better ? and why is it better ?

  • #2
    Originally posted by twostone
    which is better ? and why is it better ?


    It depends(TM). I'm guessing wireless mic? I think UHF is better, but have patience for one of the more knoledgable guys. But, you can help by telling us more about the situation. Nothing is ever just plain better than something, everything has its pluses and minuses when used differently.
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    • #3
      This is something I was pondering last night too. From experience - i.e. the main products in the market - VHF tends to be fixed frequency, more often non-diversity than not. And UHF tends to be diversity, with some (=higher) models offering frequency agility.

      But coming down to the basics - UHF is a higher frequency. I'm guessing there's also more channels available at higher frequencies (kinda like the difference between 20Hz and 200 Hz, versus the difference between 2k and 20k...?)

      But even so - why is VHF drop-out a more common occurence than UHF?

      AS
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      • #4
        Telex wireless I do know that their instrument wireless work good but I just wanted to know more about their wireless mics and what difference does VHF or UHF makes.

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        • #5
          Thanks for the info.

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          • #6
            It's a good question... and there is no correct answer of course!

            First of all, both VHF and UHF share the domestic TV spectrum. TV channels alternate alloted frequency groups gorgraphically, so adjacent areas alternate channels.

            In general, UHF offers more available spectrum bandwidth so more channel possibilities exist IF running mulitple mics is an important part of your sound plans. Also, in crowded RF environments, UHF increases the chances of finding a clear channel.

            High quality VHF is also available in frequency agile models, though less common than fixed frequency. Due to the lower frequency (longer wavelength) antennas will be considerably longer, but there's no reason why performance can't be very good as well. Provided you have an available channel, one benefit of VHF is (possible) improved performance where range is concerned, and also in buildings with a lot of multipath issues. VHF tends to be a bit more tolerant of these issues, though some serious advances in the past year with UHF technology has really closed the gap here. There is a definate limitation with available frequency spectrum though, limiting the number of available simultaneous mics to maybe 8 or 10 channels in most parts of the country. Some cities have less available channels.

            Some examples of high quality VHF units are the Shure UC series, the AT-1200 series and I'm sure Lectrosonics and Sennheiser had one as well.

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            • #7
              UHF = "Ultra" High Freq.
              VHF = "Very" High Freq.

              Higher Freqs = Better Quality, Less Range
              Lower Freqs = Lower Quality, More Range
              (Based on the same TX power etc)

              As has been said, both spectrums are shared with TV... A problem that has been resolved in Australia by the government giving the TV stations priority and making a lot of VHF mics un-usable due to interference!

              Or so I've heard.... Probably not a problem in your area.

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              • #8
                VHF vs. UHF what's the difference ?


                VHF is cheaper, but increasingly becoming obsolete in the new catalogs.

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                • #9
                  Originally posted by fukawi2
                  UHF = "Ultra" High Freq.
                  VHF = "Very" High Freq.

                  Higher Freqs = Better Quality, Less Range
                  Lower Freqs = Lower Quality, More Range
                  (Based on the same TX power etc)



                  Generalization... but there are some really excellent quality VHF units available, though VHF is begining to fade from existence. It's just a data link for all practical purposes.

                  UHF can have similar range also, but what is happening is receiver sensitivities are increasing so TX power can decrease yielding superior battery life. High VHF receiver gain is not as good a solution to more noise in the available VHF spectrum.

                  Marketing has a lot to do with the disappearance of VHF, and UHF is now cheaper to manufacture given similar performance.

                  Karl from Lectrosonics could probably give more interesting and in depth info about where the industry is and where it is likely to progress to...

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                  • #10
                    Wow great info. guys, thanks so much.

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                    • #11
                      Originally posted by agedhorse


                      Generalization... but there are some really excellent quality VHF units available, though VHF is begining to fade from existence.


                      Right. There's nothing inherent to VHF that sacrifices quality vs. UHF. FM radio is in the VHF spectrum. The modualtion types can be used in both frequency ranges.

                      UHF just has more alotted frequencies and that is where the manufacturers are finding more flexibility.
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                      • #12
                        Lots of good info already here, and to sum up: VHF and UHF are simply two different parts of the same spectrum. UHF was originally exploited because it was less congested, and more channels were available. However, lately, this is not the advatange it once was, since DTV is encroaching on the UHF spectrum. I've heard from quite a few people saying that they have an easier time in some cities setting up VHF systems because of this.

                        One reason we don't see the wide variety and high technology in the VHF systems is simply because all the development efforts went into UHF some years ago. So whatever IS available in VHF is generally older designs. Not to say that they are necessarily bad. In fact, some of the old VHF Vega equipment is still some of the best-sounding analog wireless you might find.

                        One thing that IS a technical advantage for UHF is that the FCC Part 47 (governing wireless mics for our industry) allows only 50mW for VHF transmitters but allows for up to 250mW for UHF transmitters. And transmitter power is key to getting better range and more resistance to dropouts.

                        So where is it going? As more DTV channels get turned on, and more wireless mics are being put into use, the spectrum will definitely get more crowded. I see advances in digital transmission as being right around the corner. Spread spectrum stuff, automatic networking systems like what is seen today in WiFi etc but with decent audio quality and low latency.

                        -Karl
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                        • #13
                          Originally posted by karlw
                          One thing that IS a technical advantage for UHF is that the FCC Part 47 (governing wireless mics for our industry) allows only 50mW for VHF transmitters but allows for up to 250mW for UHF transmitters. And transmitter power is key to getting better range and more resistance to dropouts.

                          -Karl


                          At the expense of battery life of course!!!

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