fishfinder confusion

[96sidewinder]

I am looking at buying the lowrance 334 finder/gps or the eagle 642. I can get them for about the same price. The lowrance unit has 480 x 480 pixel w 2400watt & the eagle has 640v x 480 pixel but with 1500 watt. I primarily fish walleye, perch and occasionally get out on lake Michigan. I'm leaning to the eagle because of the vert pixels. Is this a good idea? Thanks, Bob

 

[JB]

Re: fishfinder confusion

That's how I would go, sidewinder. I doubt that you would be fishing waters where the extra power of the 334 would matter.<br /><br />Oh, and Welcome aboard.

 

[Boatist]

Re: fishfinder confusion

I say pick one with the best contrast. Vertical resolution is important in deep water but to see fish in deep water you need power. If you ever fish water over 100 feet go with the power. Also if you ever fish salt water go with the power.

 

[buckeye_sean]

Re: fishfinder confusion

Just a note, and something I learned at a recent fishfinder seminar;<br /><br />When deciding on fishfinders, and comparing power, make sure you are only looking at watts RMS and NOT Peak to Peak wattage. The true power of a fishfinder is found in the watts RMS and there is a difference. <br /><br />"Peak to peak" power is merely a marketing hype buzzword and is rated differently between manufacturers. It is not a reliable way to determine power.

 

[96sidewinder]

Re: fishfinder confusion

For some reason the lowrance literature only specifys peak power(2400), where the eagle lists both(1500 peak 100w rms). It sure would be nice to get a standard rating system like some other products.<br /><br />JB I appreciate the welcome! Bob

 

[96sidewinder]

Re: fishfinder confusion

Another footnote to add to the ratings confusion, Bass pro catalog lists the eagle at 100w rms, but the eagle website lists peak at the same except with 187w rms. Marketing people, sometimes ya gotta love em! Bob

 

[Boatist]

Re: fishfinder confusion

Peak envelope Power or peak to peak is 8 times RMS power. RMS (Root means Square)<br />RMS power times 8 = PeP power.<br />500 Watts RMS is 4000 Watts PeP.<br />100 Watts RMS is 800 Watts PeP.<br /><br />RMS is a way to compare an AC Circuit Power to a DC circuit Power.<br /><br />You can use either standard to compare just make sure to compare RMS TO RMS or PeP to Pep.<br /><br />To compare PeP to RMS devide PeP by 8.<br /><br />It should be the same for all manufactures.<br />It is just two ways to mesure power.<br />RMS is the power that would produce same heating as a DC Circuit of the same wattage.<br />This is a electrial stantard and will be the same in all electronics.

 

[--GQ--]

Re: fishfinder confusion

Boatist, you are correct that RMS is a way to compare AC to DC power of the same wattage. However, according Electrical Engineering Math (Physics) your multipling factor (8) is off. Perhaps you are correct pertaining to the electronic gadget in question above. My mind is limited. Would you elaborate further?

 

[buckeye_sean]

Re: fishfinder confusion

Perhaps I should have clarified a bit more on my post...<br /><br />As I was told, different manufacturers actually measure peak-to-peak power differently. Often, just to get the highest number (for marketing) possibl. This is why you can't trust the peak-to-peak rating. <br /><br />Watts RMS is a standardized measurement and more accurately tells the true power of the unit.

 

[96sidewinder]

Re: fishfinder confusion

Thanks for the info, every bit helps! Bob

 

[MrBigStuff]

Re: fishfinder confusion

RMS = ((Peak2Peak / 2) * 0.707)<br /><br />Peak2Peak = ((RMS * 1.414) * 2)

 

[Boatist]

Re: fishfinder confusion

Mr Big Stuff<br />Your formula is for Volts not Power or Watts.<br />Yes RMS Volts times 1.414 = peak Volts times 2 = peak to peak volts.<br /><br />If you won't belive me check these manufactures.<br /><br />Furuno<br />LS4100 2400 Watts Peak to Peak = 300 Watts RMS<br />Ls6100 2400 Watts Peak to Peak = 300 Watts RMS<br />GP1850WF 8000 Watts Peak to Peak =1000 Watts RMS<br /><br />Garmin<br />GPSMAP 178C 4000 Watts Peak to Peak = 500 Watts RMS<br />GpsMap 498C 4000 Watts Peak to Peak = 500 Watts RMS<br />FishFinder 160C 1200 Watts Peak to Peak = 150 Watts RMS<br />FishFinder 140 800 Watts Peak to Peak = 100 Watts RMS<br /><br />Lowrance<br />LCX26C-HD 8000 Watts Peak to Peak = 1000 Watts RMS<br />LCX111C-HD 8000 Watts Peak to Peak = 1000 Watts RMS<br /><br />Eagle<br />FishMark 640C 1500 Watts Peak to Peak = 187 Watts RMS<br />FishElite 640C 1500 watts Peak to Peak = 187 Watts RMS<br /><br />Check out these units or go find any others that list both Peak to Peak Watts and RMS Watts.<br />I am sure somewhere you will find a mistake but you will see the 8 to 1 Ratio holds true.<br /><br />Peak to Peak Watts devided by 8 = RMS Watts.<br />RMS Watts times 8 = Peak to Peak Watts.

 

[MrBigStuff]

Re: fishfinder confusion

That's because RMS is not useful as a true measure of power. You can apply a root mean square function to power but it has no real meaning. It's a marketing tool to play the numbers game.<br /><br /> http://en.wikipedia.org/wiki/Audio_power

 

[JohnRuff]

Re: fishfinder confusion

History note:<br /><br />All stereo's used to be rated in PeP (peak envelope power) and the federal govermnment put a stop to it because what it meant that on an occasional loud note it would actually reach that much power. But it was not the norm and RMS was then changed to be the actual output of an amplifers power. I remember that over night - stereo amplifiers seemed to get hit with a proverbial axe in their output ratings

 

[tangent]

Re: fishfinder confusion

I just ordered the Eagle 642. I got it for the screen size and because it is dual frequency. Pretty good deal with the NauticPath, I think.

 

[heycods]

Re: fishfinder confusion

Good Imfo gys thanks.

 

[--GQ--]

Re: fishfinder confusion

Although "Root Mean Square" is a general term used to measure power output of electronic devices, the two values (.707) and its reciprocal (1.414) apply to AC voltage only.<br /><br />All electronic devices operate on DC power. To compare RMS ratings between brands use this RMS = (Peak) (.125).

 

[tangent]

Re: fishfinder confusion

To calculate the RMS value you have to know what transducer waveform looks like. If it is a sine wave, then the .707 value works. If it is any other shape, you have to do the calculation (The square Root of the Mean of all the waveform values Squared). Also, if the signal is pulsed, then the true RMS value is much smaller since it is zero most of the time.

 

[--GQ--]

Re: fishfinder confusion

Professor Paristic, i think you're trying to pull a fast one. We're smarter that that.

 

[Paul Sullivan]

Re: fishfinder confusion

RMS is a useless parameter in fish finders concerning signal strength. There is no wave form per se' in a sonar signal. Although it is cyclical it is not ocsillating. Also the wave is a descete Dirac Delta function... not a square , triangle or sine wave form. It is a series of pulses very short in duration and very high in amplitude. It is a burst of energy which is reflected back as a attentuated form of the Dirac Delta function. To measure it as an RMS is not giving the true picture of how much energy is leaving your transducer. The function looks like a series of picket fence posts rather than a wave form with peaks and valleys...<br /><br />Looks something like this :<br />____I____I___I___I___I ... etc <br /><br />now you tell me how are you going to accurately determine the RMS of this function. Burst of energy <<< less than the period of the function. A more precise parameter would be the peak to peak power output.<br /><br />RMS is uselfull in determining how much energy your system consumes and how much it can handle before breaking down. As to signal strength the peak to peak parameter is much more useful in determing the strength of your systems ability to provide a detailed picture of what you are looking at.