Devantech SRF08 Sonar problems..

I have it all connected properly, plenty of power available to the SRF08. I2c BUS. I can program it to send data back in inches, cm, us. The first
echo works to about 3 feet. I can stick my hand in front of it from 0 to 3 ft and the reading I get from it is correct. Beyond 3ft ECHO1 registers 3ft and wont change. I can get ECHO 2-16 also. It seems there is a dead spot between 3ft and 4 1/2 feet. Echo1 only registers to 3ft, and echo 2 only registers echos between 4 1/2 and farther.
I see there is a gain setting for the SRF08. Can I change this and solve my problem? I am not polling the sensor at high speeds.
I have Polaroid Sonar out of a hacked camera that was nice. I had to keep track of timing with the CPU, but it was accurate to about 1/32" and I didn't get these problems with the echo bouncing back too quick (or at least the sensor is reporting this. I don't know how the SRF08 is reporting an echo at 3 feet when I hold my hand 4 feet away, and there is nothing between my hand and the sensor.
It seems this sensor has a very wide 'fan out'. point it straight and it will detect an object 2 1/2 feet away, even if the object is 15 degrees from the direction the sensor is facing.
is there something I am doing wrong with this sensor?
Rich aiiadict AT hotmail DOT com http://rich12345.tripod.com
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Hi Rich. I don't know if you are doing something wrong, but I did have a period where I thought I wasn't getting the range I should from an SRF04 unit (similar, but not I2C) and eventually found it was getting an echo at some fixed distance from a side lobe. So when I rotated the sensor to point at the ceiling, my "false echo" went away, and I got the long range response I expected. HTH's.
--
Randy M. Dumse
www.newmicros.com
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