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800 vs 600 MHz in radio's


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Hi all

 

  i still dont know this "block stuff"

  i do however found out that one sound guy from holland who does a lot off big movie's here in holland

  sold his audio ltd 2040's

 

  since i use those myself i wrote him why? did he not like them anymore?

 

  turns out he sold them because they where in the 800 Mhz  (our nabour  country germany uses the 800 for digital tv)range and he now has the  same radio's but in the 600 range.

  he also told me this 600 mhz range would also improve his distance because of how fysics works

 

  anybody feels like explaining why 600 mhz is more range then 800  in noob terms :)

 

 

  cheers

  martijn

 

  wonder why audio ltd did not sell me 600 range radio's 2 years ago :)

 

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Hi all

 

  i still dont know this "block stuff"

  i do however found out that one sound guy from holland who does a lot off big movie's here in holland

  sold his audio ltd 2040's

 

  since i use those myself i wrote him why? did he not like them anymore?

 

  turns out he sold them because they where in the 800 Mhz  (our nabour  country germany uses the 800 for digital tv)range and he now has the  same radio's but in the 600 range.

  he also told me this 600 mhz range would also improve his distance because of how fysics works

 

  anybody feels like explaining why 600 mhz is more range then 800  in noob terms :)

 

 

  cheers

  martijn

 

  wonder why audio ltd did not sell me 600 range radio's 2 years ago :)

Lower frequency/wavelength = longer distance, higher frequency/wavelength = shorter distance. Think of it like sound, a bass drum sound carrys further than the sound of a violin. Sound travels at 1120fps at sea level, a 60hz bass drum note will take 18.66 feet for a full wave length. An 8k note from a violin will reach full wave length in .14 of an inch. Basically long waves carry further than short waves.

Eric

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Wow thanks Eric

even i understand this :)

got to love this forum and it's inhabitants

cheers

martijn

p.s. this is a linear patern like 800 will give about 700 meters plain site

600 will give me 25% more?

p.s. 2 is there a downside to this regarding sound quality?

i mean why not use 50 MHz :)

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Wow thanks Eric

even i understand this :)

got to love this forum and it's inhabitants

cheers

martijn

p.s. this is a linear patern like 800 will give about 700 meters plain site

600 will give me 25% more?

p.s. 2 is there a downside to this regarding sound quality?

i mean why not use 50 MHz :)

There is no loss of audio quality. The 800 & 600 are carrier frequencys not audio frequencys. Yes 50 mhz will carry further but there are more transmitters of all kinds on lower frequencys so a clear path is more problematic. Basically there is no such thing as a free lunch. Good news: I have some VHF wireless units on the 170.00 band that sound very good.  Bad News: The VHF units pick up lots of random clicks & other RF hits due to a ton of garbage in the air today on the 170.00 band. I don't know if you'll get 25% more range with the 600 system as there is a point of no return but you'll get a stronger signal at a given distance that will help in rejecting any stray RF in the air.

Eric

Eric

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  • 1 year later...

Every country has its own frequency plan, from VLF (like 20 kHz) through VHF, UHF and microwave.

Europe more or less follows a common plan.

Canada and Mexico more or less follows the United States.

Other countries vary depending on who they chose to model.

In the United States 800 - 900 MHz was taken from broadcast about 30 years ago. It's now cell phones and land mobile communications.

Recently the 700-800 MHz band was taken from broadcast and is now various services including land mobile communications.

Bottom line is that wireless microphones are at the very bottom of the food chain.

Operating without a license could get you into trouble although in most cases whatever regulatory agency has its hands full without chasing down 50 mW transmitters.

On the other hand, operating a wireless microphone in a band with high power transmitters means you will have nothing but interference.

All wireless systems are NOT plug and play.

Bill Ruck

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" Basically long waves carry further than short waves."

Actually that is a bit of an oversimplification, and there is a lot more to it...

and I'd also have to add an "it depends" to that statement, as well...

as a practical matter, I have never been able to detect any consistent difference in RF mic range amongst several blocks, and suspect in our applications there is very little discernible difference in working range, if any

Edited by studiomprd
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" Basically long waves carry further than short waves."

Actually that is a bit of an oversimplification

Oversimplification?

Long waves travel long distances, short waves carry short distances.

Wave files can travel all over the planet it you have an Internet connection and a standing wave just stands there, waving.

Now THAT'S an oversimplification!

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To: Various posters here that have the facts right (most important) but not the reasons. Lower frequencies don't carry further because they are lower. The reason is that antennas for receiving low frequencies are larger and intercept more of the radiated signal. For instance, a one Watt signal radiated from an omni directional transmitter antenna spreads out in all directions. In a sphere, at say 10 feet away, a certain exact fraction (0.3 mW) of that initial one Watt will go through each square foot of that sphere and that fraction of the one Watt is independent of the frequency. (The sphere has 314 sq feet of area; one square foot is 0.003 of the sphere.) A large antenna (low frequency) will look like a big interception in that sphere and a small antenna (high frequency) will be a small interception. The larger antenna will intercept more energy and the smaller one less, not because of the frequency but because it is "covering" more of the sphere.

So, some of you are saying, couldn't we just make the high frequency antenna larger and intercept proportionally more energy (signal)? The answer is yes! and that is what a Yagi or LPDA does and that is one reason that they are gain antennas. In general, most of the time antennas for our use are just vertical whips cut to a quarter wavelength and therefore shorter at higher frequencies and hence they intercept less signal. That makes it seem that low frequencies go farther, at least at our powers and distances.

Regards,

Larry Fisher

Lectrosonics

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Well, im sure larry knows more about this than me, I always learned that it takes more energy to transmit a signal the higher the frequency the signal is traveling on.

EX. 1W at 600mhz will require less transmitting power than a 2.4khz signal going the same distance.

Also, lower frequencies travel better through surfaces.

This is what I learned in school.

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Hi Larry,

Following on from what you mention about gain antennas, why is that the whips we use are 1/4wave? On the receiver side, what would happen with a 1/2 wave whip? I've read about the different lobes and patterns but what makes the 1/4 wave whip optimal apart from size? Is it something to do with the ground plane design?

Thanks,

Yush

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" Why not 1/2 wave? "

Lectro RX's and TX's are mostly portable, as are Zaxcom, Audio Ltd, Wisycom, (and some others); portable users tend to prefer the small size of 1/4 wave aerials; other, better --more optimal if you will-- options are always available.

Shure TX's, portable RX's, and lower end RX's come with 1/4 wave aerials as well, though the higher end Shure RX's include 1/2 wave (coil loaded) versions, also called "rubber duckie".

Edited by studiomprd
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Half wave antennas have extremely high input impedances at either end, are near impossible to match, and really don't work very well. If fed in the center, they are just a standard dipole antenna. Quarter wave antennas are rugged, work well and are moderately broad band. Also they are SIMPLE (implied scream intended). Simple is beautiful in this complicated world.

Best,

Larry F

Lectro

Hi Senator,

i'm using optimal loosely, as in 'standard' - all portable Lectrosonic receivers come with 1/4 wave whips. Why not 1/2 wave? Do you know?

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