Received a PM from Petermac as follows.

"Vinnie tried to explain ping to me but am still a bit confused what it is could you explain it to me and the other fish wrecked members I mean what does it really do sorry but I realy need things to be explained in basic thanks mate"

A Ping is basicaly a pulse or sound wave sent by your transducer downwards through the water, this pulse then hits and bounces back off any objects such as fish or the bottom (see pic).  The return pulse (echo) is then read by the transducer and displayed on the screen.  (hence the term Echo Sounder).

Your sounder knows when each pulse/ping was sent and how fast it travels through the water. 

It measures the time taken to travel down, bounce off an object and return.  From this can ascertain the distance/depth of the object from the transducer. 

It also reads the strength of the return and uses both the time taken and strength of the returning signal to work out what to display (usually a colour representing the strength of the return signal) on the sounder screen and how deep to display it

Ping speed is basically setting how many pulses per second your unit is sending out.  A higher pings speed is generally required to get a higher resolution picture (ie more information returning). 

Bear in mind you don't want to just crank up your ping sped to max and think this will give you a better picture as too high can also "confuse" the sounder with too much info to process and cause other problems. 

Ping speed of around half to 3/4 is pretty much around the mark you want to be (if settings are 1-20 then somewhere between 10-15).

Hope that helps Peter