Why voyager uses VLF? Any scientific reason?

[Willen]

Is VLF suitable for sea transmission? Water is good absorber of RF. May be they use AM or?

 

[cowboybob]

Is VLF suitable for sea transmission? Water is good absorber of RF. May be they use AM or?

Yes, it is. More along the line of CW in certain circumstances.

It has been used for world wide submarine comms for years but is limited to very low data rates.

Not sure about your Voyager reference.

 

[Mr RB]

Voyager generally uses subspace comms, based on the episodes I have seen.

 

[DerStrom8]

Lower frequencies tend to be able to travel around obstacles (and through media) more easily. If I am remembering correctly (and correct me if I'm wrong), "VLF" stands for "Very Low Frequency", "VHF" stands for "Very High Frequency", and "UHF" stands for "Ultra High frequency" (very imaginative names, right? ). This is (I would assume) why it's used underwater and over long distances. Audio frequency (20hz-20khz) waves actually travel faster through water than through air, and since VLF is between 3khz-30khz, it would actually travel faster through a medium such as water than through air.

When a lot of people think of "Radio Frequencies", they often picture signals in the MHz range, but VLF is much lower.

Hope this helps.
Regards,
Matt

 

[JoeJester]

VLF has been known to penetrate the ocean in excess of xx feet. VLF's groundwave follows the curvature of the earth.

Seawater has good conductivity.

ELF, Extremely Low Frequency, was the band used by the navigation system called Omega. It operated near 10.2 kHz.

 

[crutschow]

Lower frequencies tend to be able to travel around obstacles (and through media) more easily. If I am remembering correctly (and correct me if I'm wrong), "VLF" stands for "Very Low Frequency", "VHF" stands for "Very High Frequency", and "UHF" stands for "Ultra High frequency" (very imaginative names, right? ). This is (I would assume) why it's used underwater and over long distances. Audio frequency (20hz-20khz) waves actually travel faster through water than through air, and since VLF is between 3khz-30khz, it would actually travel faster through a medium such as water than through air.

................

You appear to be referring to sound waves. EM Radio waves are used for submarine communication although they are at audio frequencies. They travel slower in water than air but that's not a significant factor at terrestrial distances for light speed waves.

 

[DerStrom8]

You appear to be referring to sound waves. EM Radio waves are used for submarine communication although they are at audio frequencies. They travel slower in water than air but that's not a significant factor at terrestrial distances for light speed waves.

Woops, you're absolutely right.

 

[Nigel Goodwin]

As others have said, what's this got to do with Voyager?

Presumably it uses microwave frequencies?, or at least UHF - but I would expect it to be microwave (to allow high gain from a small dish).

 

[Ramussons]

Is VLF suitable for sea transmission? Water is good absorber of RF. May be they use AM or?

Are you referring to Voyager(s), The NASA space probes?

Ramesh

 

[dr pepper]

Some russian subs use ulf something around 70hz!

 

[mab2]

I don't really know the answer but I would make a few guesses (I'm sure someone will say if I'm wrong):-

1. low frequency requires less power to transmit for a given signal/noise ratio, and if you're sending from jupiter & beyond s/n is important.

2. if you are getting reflections (ghosting) off moons, asteroids, etc, it's easier to resolve the received signal.

3. the probe didn't generate data that fast so there's no need to go for higher datarates.

4. with 1970's technology, electronic reliability may have been better at low frequencies (it's not as if they can repair it if it breaks).

5. long wavelength electromagnetic waves are less prone to scatter/ dispersion over distance (that's why the sun is red at sunset, and the daytime sky is blue (and why infrared cameras can see through smoke)).

I suspect the last one may be the real reason.

 

[atferrari]

Last time I looked at, NASA had a good FAQ and if you ask at the right place, there is their people answering questions.

The two questions I asked were dutifully answered.

 

[Nigel Goodwin]

I don't really know the answer but I would make a few guesses (I'm sure someone will say if I'm wrong)

I think you're wrong on every count - and low frequencies won't even reach the earth, they are reflected by atmospheric layers, not to mention you couldn't put a large enough antenna array on a space craft.

There's no reason to imagine Voyager uses anything other than microwave, and the OP hasn't even confirmed he's referring to the space probe (and his reference to water rather suggests he isn't).

 

[mab2]

you're probably right nigel, I was a bit tired when I decided to post that reply (tired as a newt, in fact ).

a quick search confirms they use s band/x band uwaves.

As for which Voyager; well V1 is in the news just now, and whilst there have doubtless been many vessels named Voyager, that one seemed the logical assumtion.

 

[unclejed613]

looks like the US Navy had an experimental ELF system operating at 76hz for a few years but shut it down. as for vlf systems, it seems those are still operating. i was actually able to see the 76hz signal once on a spectrum analyzer.

most anything below a few hundred khz is reflected by the D layer of the ionosphere and would be impractical for space communication, so the OP must have some mysterious other Voyager in mind.... the OP used lower case voyager.... could be a translation anomaly.... original word in OP's native language may have meant something like "sailor" or "seafarer", and "voyager" was a "best guess" result

 

[JMW]

looks like the US Navy had an experimental ELF system operating at 76hz for a few years but shut it down. as for vlf systems, it seems those are still operating. i was actually able to see the 76hz signal once on a spectrum analyzer.

most anything below a few hundred khz is reflected by the D layer of the ionosphere and would be impractical for space communication, so the OP must have some mysterious other Voyager in mind.... the OP used lower case voyager.... could be a translation anomaly.... original word in OP's native language may have meant something like "sailor" or "seafarer", and "voyager" was a "best guess" result

IIRC that system supposedly killed cattle in Minnesota or Wisconsin. I was drinking then, so it could have been a fragment of my imagination.

 

[nsaspook]

looks like the US Navy had an experimental ELF system operating at 76hz for a few years but shut it down. as for vlf systems, it seems those are still operating. i was actually able to see the 76hz signal once on a spectrum analyzer.

The Russians still have a station.
https://g3xbm-qrp.blogspot.com/search/label/zevs
https://maps.google.com/maps?q=68+4...29908,33.701935&sspn=0.00143,0.00618&t=h&z=14

 

[DerStrom8]

This is the closest I can find to a "voyager" having to do with ocean rather than space: https://www.marinetraffic.com/ais/shipdetails.aspx?MMSI=375019000

EDIT: This looks more likely: **broken link removed**

 

[Willen]

Sorry If I used a word "voyager" badly. Then do not focus on a word 'Voyage'. I just heared that submarines and ships uses VLF to communicate. So I just wanted to know that why they use such extremely low frequency? Or what advantages they found on such VLF or EVLF? Does it has greater distance on transmission?

 

[Nigel Goodwin]

Sorry If I used a word "voyager" badly. Then do not focus on a word 'Voyage'. I just heared that submarines and ships uses VLF to communicate. So I just wanted to know that why they use such extremely low frequency? Or what advantages they found on such VLF or EVLF? Does it has greater distance on transmission?

Because (as already mentioned) VLF works under water, high frequencies don't.