function Showcredit()



{





var credit

credit="Script programmed by Jens T.Saetre 25022007";

credit+="\n25022007 Converts dBmW to dBuV and dbuV to dBmW";
credit+="\n27022007 Corrected bug, W and mW was not calculated when uV or V was changed";
credit+="\n27022007 Corrected bug, dBm was not calculated correctly when uV or V was changed";

credit+="\nUpdated 27022007";





window.alert(credit);



}



function onchangemw(){
var p,u,dbm,dbuv,impedance,mw


mw=document.Power.mw.value;

dbm=10*log10(mw);

document.Power.dBm.value=formatnumber(dbm,3);

impedance=document.Power.Impedance.value;


p = exp10((dbm)/10)/1000;

document.Power.mw.value=formatnumber(p*1000,3);
document.Power.W.value=formatnumber(p,3);

u = Math.sqrt(impedance*p);
dbuv = 20*log10(u*1000000); 

document.Power.dBuV.value=formatnumber(dbuv,5);
document.Power.V.value=formatnumber(u,6);
document.Power.uV.value=formatnumber(u*1000000,3);


}


function onchangewatt(){
var p,u,dbm,dbuv,impedance,mw,w

w=document.Power.W.value;
mw=w*1000;
//alert(mw);
document.Power.mw.value=mw;


dbm=10*log10(mw);

document.Power.dBm.value=formatnumber(dbm,3);

impedance=document.Power.Impedance.value;


p = exp10((dbm)/10)/1000;

//document.Power.mw.value=formatnumber(p*1000,3);

u = Math.sqrt(impedance*p);
dbuv = 20*log10(u*1000000); 

document.Power.dBuV.value=formatnumber(dbuv,5);
document.Power.V.value=formatnumber(u,6);
document.Power.uV.value=formatnumber(u*1000000,3);


}


function onchangedbmw(){
var p,u,dbm,dbuv,impedance

dbm=document.Power.dBm.value;
impedance=document.Power.Impedance.value;


p = exp10((dbm)/10)/1000;

document.Power.mw.value=formatnumber(p*1000,3);
document.Power.W.value=formatnumber(p,3);

u = Math.sqrt(impedance*p);
dbuv = 20*log10(u*1000000); 

document.Power.dBuV.value=formatnumber(dbuv,5);
document.Power.V.value=formatnumber(u,6);
document.Power.uV.value=formatnumber(u*1000000,3);


}


function formatvalue(input, rsize) // Desimal avrunding
  {
   var invalid = "**************************";
   var nines = "999999999999999999999999";
   var strin = "" + input;
   var fltin = parseFloat(strin);
   if (strin.length <= rsize) return strin;
   if (strin.indexOf("e") != -1 ||
       fltin > parseFloat(nines.substring(0,rsize)+".4"))
      return invalid.substring(0, rsize);
   var rounded = "" + (fltin + (fltin - parseFloat(strin.substring(0, rsize))));
   return rounded.substring(0, rsize);
}


function onchangedbuv(){
var p,u,dbm,dbuv,impedance

impedance=document.Power.Impedance.value;
dbuv=document.Power.dBuV.value;


//p = exp10((dbm)/10)/1000;

//u = Math.sqrt(impedance*p);

//dbuv = 20*log10(u*1000000); 

//10^(dbuv/20)=u*1000000;


u=exp10(dbuv/20)/1000000; // V
document.Power.V.value=formatnumber(u,6);
document.Power.uV.value=formatnumber(u*1000,3);


p=u*u/impedance;

dbm=10*log10(p/0.001);

document.Power.dBm.value=formatnumber(dbm,3);//  



}


function onchangeuv(){
var p,u,dbm,dbuv,impedance,uv

uv=document.Power.uV.value;

impedance=document.Power.Impedance.value;



//p = exp10((dbm)/10)/1000;

//u = Math.sqrt(impedance*p);

//dbuv = 20*log10(u*1000000); 

//10^(dbuv/20)=u*1000000;


//u=exp10(dbuv/20)/1000000; // V
u=uv/1000000;
document.Power.V.value=formatnumber(u,6);

dbuv=20*log10(uv);
document.Power.dBuV.value=formatnumber(dbuv,5);

p=u*u/impedance;
document.Power.mw.value=formatnumber(p*1000,3);
document.Power.W.value=formatnumber(p,3);

//if ((p/0.001)=0) dbm=0

//alert(p/0.001);

dbm=10*log10(p/0.001);

if (Math.abs(dbm)<0.000001) document.Power.dBm.value=formatnumber(0,2) 
  else document.Power.dBm.value=formatnumber(dbm,2);//  = korrekt men i dbmW allerede





}






function onchangev(){  // ok
var p,u,dbm,dbuv,impedance,u

impedance=document.Power.Impedance.value;

u=document.Power.V.value;
uv=u*1000000;
document.Power.uV.value=formatnumber(uv,4);

//p = exp10((dbm)/10)/1000;

//u = Math.sqrt(impedance*p);

//dbuv = 20*log10(u*1000000); 

//10^(dbuv/20)=u*1000000;


dbuv=20*log10(uv);

document.Power.dBuV.value=formatnumber(dbuv,5);



p=u*u/impedance;
document.Power.mw.value=formatnumber(p*1000,3);
document.Power.W.value=formatnumber(p,3);

dbm=10*log10(p/0.001);

if (Math.abs(dbm)<0.000001) document.Power.dBm.value=formatnumber(0,2) 
  else document.Power.dBm.value=formatnumber(dbm,2);//  = korrekt men i dbmW allerede



}


function formatnumber(num,places)
{
var strOP,i,decimals,newdecimals,integer,newstring,numcopy
var ss=new Array()
numcopy=num;
    var a = Math.pow(10,Math.abs(places) == places ? places : 2);
     strOP=String(Math.round(num * a) / a).replace(/^(\d)/," $1");
     if (num<0) strOP=" "+strOP;     // put " " on negative numbers
      //num=parseFloat(strOP);  

    ss = strOP.split(".");//  split string by .   what about zero..?
  if ((num!==0)&&(ss.length>1)) 
  {
   
     decimals=ss[1];
     integer=ss[0];

     if (decimals.length<places) //  check str length after . and add zeroes if decimals shorter than places
      {   
      var addzeroes="0";
       
          for (i = 0; i < (places-decimals.length-1); i++)
          {
          addzeroes+="0";
          }
                           //01
       strOP=integer+"."+decimals+addzeroes;
      }              
  }
  else  // num= integer
  {
  decimals="0";
  for (i = 0; i < places-1; i++) 
   {
   decimals+="0";
  
   }  
  strOP=numcopy+"."+decimals;  
  
  }

if (numcopy>=0) strOP=" "+strOP;



return(strOP)
}


function exp10(x) {

   var y;

   y = Math.exp(x*Math.log(10));   // a^x = b^(x * log_b(a))

   return(y);

}


function log10(X)
{
return( Math.log(X)/Math.log(10)  );
// works OK !
}

function change_satellite_position()
{


if (document.Linkbudgett.Direction.selectedIndex==0) 
  {
   document.Linkbudgett.West_angle.value=360-1*document.Linkbudgett.Degrees.value;
  }
  else 
  {
   document.Linkbudgett.West_angle.value=1*document.Linkbudgett.Degrees.value;
  }




}