Ultrasonic Range Finder SRF05

[kamilhashmi]

Hello Guys,
I am working on this ultrasonic range finder. I am using a pic16f887. I am able to get the ultrasonic working and reading the values on the computer using rs232.
Although my values tend to be incorrect as i increase the range of the object. I believe its because i am using a 8 Mhz clock if i use a 20Mhz clock speed i can increase my efficiency. Please help me on this.
Thnx a lot

[temtronic]

In order to get any real help here, you'll have to show use the PIC type, compiler version as well as a short,compilable program that demonstrates the problem.
Before you do though,it's a very simple test, to swap out the xtal for a faster one and observe the result.