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W peak-to-peak and W RMS power

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Old 03-16-2004, 05:59 AM
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Default W peak-to-peak and W RMS power

What does one need to know about the maximun W peak-to-peak and W RMS power when sellecting a sounder? I'm sure more is better but at some point it must be an overkill depending on the depth you fish. Are there some general guide line's for minimum and maximun reguirements of W peak-to-peak and W RMS power for different depths? rcouret
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Old 03-16-2004, 08:04 AM
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Default RE: W peak-to-peak and W RMS power

I'm putting on a hat I have not worn in a long time and going by my ever fading memory here. RMS=.707 x Peak-to-Peak (if I recall)

Most manufacturers rate sonar power at RMS (root mean square). Some sonar manufacturers rate power at Peak-to-Peak. What you want to do is make sure you are comparing apples to apples as far as power. If a manufacturer states very high power just make sure it says RMS.

Typical power for inland and fresh water is 300W RMS. The higher the power the deeper and clearer the sonar will read (also a function of transducer construction). You can find recreational sonar power as high as 1000W RMS.

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Old 03-16-2004, 09:48 AM
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Default RE: W peak-to-peak and W RMS power

To get RMS, divide peak-to peak by 8, or conversely, multiply rms by 8 to get p2p. Mfg's or retailers who quote p2p ratings generally are trying to make you believe their sounders are more powerful than they are. 600 watts sounds a lot better than 75. It's like stereo mfg's who used to quote peak output for amps. Just make sure which rating they're using.

For freshwater and inshore saltwater, 300 watt rms is usually fine. Most offshore saltwater applications will be fine with 500-600 watts.
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Old 03-16-2004, 09:54 AM
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Default RE: W peak-to-peak and W RMS power

East Coast Trailers - 2004-03-16 7:04 AM

I'm putting on a hat I have not worn in a long time and going by my ever fading memory here. RMS=.707 x Peak-to-Peak (if I recall)

Most manufacturers rate sonar power at RMS (root mean square). Some sonar manufacturers rate power at Peak-to-Peak. What you want to do is make sure you are comparing apples to apples as far as power. If a manufacturer states very high power just make sure it says RMS.

Typical power for inland and fresh water is 300W RMS. The higher the power the deeper and clearer the sonar will read (also a function of transducer construction). You can find recreational sonar power as high as 1000W RMS.
I wear that hat full time, and actually it's .707 * peak.
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Old 03-16-2004, 10:37 AM
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Default RE: W peak-to-peak and W RMS power

So are you guys saying that you multiply p2p by .707 to get rms? If so, all of the sonar mfgs are confused.

http://www.si-tex.com/html/cvs-210.html

http://www.garmin.com/products/ff250/

http://www.charkbait.com/cs/csnavFuruno.htm
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Old 03-16-2004, 12:21 PM
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Default RE: W peak-to-peak and W RMS power

You divide peak to peak by two to get peak, then multiply peak by .707 to get RMS.

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Old 03-16-2004, 12:42 PM
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Default RE: W peak-to-peak and W RMS power

That still doesn't compute. Sitex says a 1000 rms unit is 8000 p2p. (8000/2)*.707= 2828, nearly 3x the actual rating.
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Old 03-16-2004, 01:06 PM
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Default RE: W peak-to-peak and W RMS power

The .707 times the peak value to obtain RMS only applies if the waveform is a pure sinewave, which the sonar pulse is probably not.

The methods that the Sonar guys use to determine RMS power are purely of their own making and certainly do not conform to TRUE RMS POWER formulas.
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