Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
RE: high frequency sonar pulses
Posted by:
Don Baker
()
Date: March 19, 2001 02:19AM
Hello Kurt
The “ping rate†of an active sonar is determined principally by the range to the target. One would like to maintain a high ping rate in order to have a high “information rate†for signal processing purposes. If we consider how the system operated, we see that the transducer is first connected to the transmitter and a burst of acoustic energy – the “ping†– put into the water. The transducer is then switched into a receiver and the system now “listens for returning echos. The “ping†travels out in the form of an acoustic pressure wave traveling at the velocity of sound in the water. A portion of the pressure wave is reflected back from the target. The time interval between transmission and reception of the echo is a measure of the range to the target as given by Target Range = (Velocity of Sound) x ½(Ping Roundtrip Time).
After a ping had been transmitted no further pings were transmitted until enough time had elapsed to allow the ping to travel out to the target and return. The greater the range the longer the listening period required and subsequently the lower the ping rate. As range decreased the ping rate could then be increased because the required listening interval becomes shorter – thus the shift to a higher “ping†rate as the ship closed the range to the target. There are other factors which had to be considered in the design of the sonar but it is basically the range to the target which determined the allowable ping rate. This explains the higher ping rate as the ship closed with the target.
The American sonars had an operator adjustable range setting to which the ping rate was tied in. I would think the British sonars also incorporated this feature.
Hope this is helpful,
Don B
The “ping rate†of an active sonar is determined principally by the range to the target. One would like to maintain a high ping rate in order to have a high “information rate†for signal processing purposes. If we consider how the system operated, we see that the transducer is first connected to the transmitter and a burst of acoustic energy – the “ping†– put into the water. The transducer is then switched into a receiver and the system now “listens for returning echos. The “ping†travels out in the form of an acoustic pressure wave traveling at the velocity of sound in the water. A portion of the pressure wave is reflected back from the target. The time interval between transmission and reception of the echo is a measure of the range to the target as given by Target Range = (Velocity of Sound) x ½(Ping Roundtrip Time).
After a ping had been transmitted no further pings were transmitted until enough time had elapsed to allow the ping to travel out to the target and return. The greater the range the longer the listening period required and subsequently the lower the ping rate. As range decreased the ping rate could then be increased because the required listening interval becomes shorter – thus the shift to a higher “ping†rate as the ship closed the range to the target. There are other factors which had to be considered in the design of the sonar but it is basically the range to the target which determined the allowable ping rate. This explains the higher ping rate as the ship closed with the target.
The American sonars had an operator adjustable range setting to which the ping rate was tied in. I would think the British sonars also incorporated this feature.
Hope this is helpful,
Don B
| Subject | Written By | Posted |
|---|---|---|
high frequency sonar pulses
|
kurt | 03/14/2001 05:59PM |
|
RE: high frequency sonar pulses
|
Don Baker | 03/19/2001 02:19AM |
|
RE: high frequency sonar pulses
|
Ron.C | 03/24/2001 02:13PM |