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'[EE] 2.4 GHz over water???'
2006\01\24@171212 by Marcel Birthelmer

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Could you have some sort of antenna below the water level? I'm not sure what
the specifics would be, but given that sound travels so much better
underwater, it might be an option.
- Marcel

On 1/24/06, Enrico Schuerrer <spam_OUTenricoTakeThisOuTspamgmx.at> wrote:
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>

2006\01\25@034008 by VULCAN20

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Dumitru Stama wrote:

>I think 2.4 GHz is very high for underwater broadcasts.
>Under water you could get away with a low frequency transmission, even
>a sonar but i am quite sure 2.4GHz will not do the job.
>
>Dumitru Stama
>
>
>MB> Could you have some sort of antenna below the water level? I'm not sure what
>MB> the specifics would be, but given that sound travels so much better
>MB> underwater, it might be an option.
>MB> - Marcel
>  
>

I was planning on using radios because they are more energy efficient  
then sonar also there are other factors involved that would prohibit
signals through the water.

John

2006\01\25@090442 by Enrico Schuerrer

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----- Original Message -----
From: "Marcel Birthelmer" <.....marcelb.listsKILLspamspam.....gmail.com>
To: "Microcontroller discussion list - Public." <EraseMEpiclistspam_OUTspamTakeThisOuTmit.edu>
Sent: Tuesday, January 24, 2006 11:12 PM
Subject: Re: [EE] 2.4 GHz over water???


Could you have some sort of antenna below the water level? I'm not sure what
the specifics would be, but given that sound travels so much better
underwater, it might be an option.
- Marcel

I'm afraid that all frequencies higher than around 20 kHz have so high
attenuation in the medium water that is only useable for submarine boats and
transmitters with ultra high power. A transmission antenna with gain for 20
kHz for submarine transmission is in dimensions of Kilometers...

Enrico

2006\01\26@113418 by Gus Salavatore Calabrese

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Hello  Enrico    ( OE1EQW )    I would like to see your calculations  
please.

Since Maxstream ZigBee radios are attempting lower data rates than  
11Mbits,
wouldn't the effective range increase ?  Maxstream radios can accept  
bit rates
such as 38K.  I guess we would have to know more about the encoding  
scheme
for Zigbee.

AGSC

2006\01\26@115802 by Enrico Schuerrer

picon face
Yes, I can send the calculations to you - but I'm at home now and the calculations are in my office, so tomorrow I'll send it to you directly. If you have the data for output power and receiving sensitivity I can calculate more exactly.  

Reducing the transmission speed will enhance the receiver sensitivity if the bandwidth of the receiver front stage will be smaller too. Then the dynamic range of the connection will increase. The other way is to reduce the frequency of transmission - going to another band like 433 MHz will reduce free space path loss and the diameter of the fresnel zone, so the additional attenuation from fresnel effect will be smaller and the dynamic will rise.  

Regards

Enrico

-----Ursprüngliche Nachricht-----
Von: "Gus Salavatore Calabrese" <gscspamspam_OUTomegadogs.com>
An: <@spam@piclistKILLspamspammit.edu>
Gesendet: Donnerstag, 26. Jänner 2006 17:34
Betreff: [EE] 2.4 GHz over water???


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