NIStune Type 1 Diagnostics - Manual (Page 11)

5. USB Communications works but drop out frequently or various error messages appear
Things to check
1. Does your laptop have a part of its earth connected to the chassis of your car? This is highly recommended if
you are running the Pocket Romulator, to avoid damage to it and the Nistune board
2. Does the problem occur at a certain rev range, say when it hits 5000-6000 RPM that’s when the drop out
occurs. If so there is a frequency and noise issue. Refer to our ‘Diagnostics and communications’ document for
more solutions.
3. Do you get noise through your stereo system which sounds like a buzz that increases as the RPMs increase?
You may need to check your electrical system has sufficient noise suppressors on it.
Most dropouts occur because there is excessive USB noise going to the USB chip on the Nistune board. This
problem can be made worse when you are running other USB devices, such as USB-Serial converters or other
peripherals which can assist in creating more noise on the USB lines.
The problems could be associated with the type of USB A-B cable that you are using. Several users have indicated
that they had frequent dropouts with particular USB cables. These have been significantly improved swapping for
another higher quality USB cable. Higher quality cables tend to have better shielding characteristics which reduce
noise. It has also been noticed that shorter cables will assist in doing this also. During development and testing I
have used ~6 foot length USB A-B cables with minimal problems on my R31.
Poor shielding on any USB cable will cause problems, especially in an automotive environment where there is a
greater amount of electrical noise (from coil, spark plugs, distributor etc) that at a normal PC workstation for
instance would not experience this.