<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt"><div><span>I experimented with this and had no luck at all, I tried getting a forward view with no luck.  I must have done it wrong.  I also thought an echo sounder needs something to bounce off.  The surface has no density like the bottom to bounce off.  </span></div><div style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px; font-style: normal; background-color: transparent;"><span>Hank</span></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12pt;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande,
 sans-serif; font-size: 12pt;"> <div dir="ltr"> <font face="Arial" size="2"> On Saturday, June 21, 2014 7:37:45 AM, Alan James via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br> </font> </div>  <br><br> <div class="y_msg_container"><div id="yiv1093558526"><div><div style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 10pt; background-color: rgb(255, 255, 255);"><div><span>Lasse,</span></div><div style='color: rgb(0, 0, 0); font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 13.33px; font-style: normal; background-color: transparent;'><span>I've seen a "splitter"  or "junction box" you can buy for one of the echo sounders.</span></div><div style='color: rgb(0, 0, 0); font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 13.33px; font-style: normal;
 background-color: transparent;'><span>This enables input from 2 transducers to one screen. From memory the change</span></div><div style='color: rgb(0, 0, 0); font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 13.33px; font-style: normal; background-color: transparent;'><span>over from one view to another wasn't that straight forward.</span></div><div style='color: rgb(0, 0, 0); font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 13.33px; font-style: normal; background-color: transparent;'>I'm a bit vague about this, someone else may be able to give more information.</div><div style='color: rgb(0, 0, 0); font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 13.33px; font-style: normal; background-color: transparent;'>All the best with the testing.</div><div style='color: rgb(0, 0, 0); font-family:
 HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 13.33px; font-style: normal; background-color: transparent;'>Alan</div><div><br clear="none"></div>  <div class="yiv1093558526yqt4112971300" id="yiv1093558526yqt73276"><div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 10pt;'> <div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; font-size: 12pt;'> <div dir="ltr"> <div class="hr" style="margin: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); border-image: none; height: 0px; line-height: 0; font-size: 0px;" contenteditable="false" readonly="true"></div>  <font face="Arial" size="2"> <b><span style="font-weight: bold;">From:</span></b> Lasse Schmidt via Personal_Submersibles <personal_submersibles@psubs.org><br clear="none"> <b><span style="font-weight: bold;">To:</span></b> Personal
 Submersibles General Discussion <personal_submersibles@psubs.org> <br clear="none"> <b><span style="font-weight: bold;">Sent:</span></b> Saturday, June 21, 2014 8:13 PM<br clear="none"> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] Reversed echo sounder<br clear="none"> </font> </div> <div class="yiv1093558526y_msg_container"><br clear="none">wow, this is awesome thanks for the help. WeŽll have the chance to try this out next week. If it works, we will have both analogue and digital depth gauges.<br clear="none">IŽll make
 sure to  take some photos and upload them later.<br clear="none"><br clear="none">Lasse Schmidt<br clear="none">Upplevelsepresent.se<br clear="none">Skeppsbron 21, Tullhus 1<br clear="none">11130 Stockholm<br clear="none">070-28 32 660<br clear="none"><br clear="none">21 jun 2014 kl. 07:28 skrev Jens Laland via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>:<br clear="none"><br clear="none">> Lasse<br clear="none">> <br clear="none">> ** Is it possible to turn an echo sounder towards the surface to measure the<br clear="none">> ** distance to the surface?<br clear="none">> <br clear="none">> Because of the extreme (large) difference in characteristic acoustic<br clear="none">> impedance of seawater versus air, you will experience a sound power<br clear="none">>
 reflection coefficient of (typical)
 0.99893 between seawater (@ +15°C) and<br clear="none">> air at sea level (@ +20°C).<br clear="none">> <br clear="none">> Simply stated, you will receive (echo) 99.893% of the sound send upwards<br clear="none">> from a submarine towards the surface.<br clear="none">> <br clear="none">> -------------------------------------------------------------------------<br clear="none">> <br clear="none">> SEAWATER (15°C)<br clear="none">>   characteristic acoustic impedance    : 1.5443675<br clear="none">>   density                              : 1.025 SG<br clear="none">>   longitudinal velocity of sound waves : 1506.7 m/sec<br clear="none">>   wavelength @ 300 Hz                  : 5.02 m<br clear="none">>   wavelength @ 948.683 Hz (center)     : 1.59 m<br
 clear="none">>   wavelength @ 3000 Hz                 : 50.2 cm    (  19.773 inches )<br clear="none">> <br clear="none">> AIR, AT SEA LEVEL (+20°C)<br clear="none">>   characteristic acoustic impedance    : 0.0004132128<br clear="none">>   density                              : 0.001204 SG<br clear="none">>   longitudinal velocity of sound waves : 343.2 m/sec<br clear="none">>   wavelength @ 300 Hz                  : 1.14 m<br clear="none">>   wavelength @ 948.683 Hz (center)     : 36.2 cm    (  14.243 inches )<br clear="none">>   wavelength @ 3000 Hz                 : 11.4 cm    (   4.504 inches )<br clear="none">> <br
 clear="none">> sound power reflection coefficient      : 0.99893    (  99.893 percent )<br clear="none">> <br clear="none">> -------------------------------------------------------------------------<br clear="none">> <br clear="none">> Best regards,<br clear="none">> Jens Laland<br clear="none">> <br clear="none">> <a href="http://traktoria.org/" target="_blank" rel="nofollow" shape="rect">http://traktoria.org/</a><br clear="none">> -----------------------------<br clear="none">> My webpage works 100% with the Firefox Internet Browser, only<br clear="none">> <a href="http://www.mozilla.org/en-US/products/download.html?product=firefox" target="_blank" rel="nofollow" shape="rect">http://www.mozilla.org/en-US/products/download.html?product=firefox</a><br clear="none">> <br clear="none">> _______________________________________________<br clear="none">> Personal_Submersibles mailing
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