Jon Griver wrote: > Doug McKean wrote: > (Taken out of context) > >6dB would be comfortable. > >Unfortunately, I have been in a lab that passed at only 0.5dB. > There has been some confusion in this discussion between the test lab's > responsibilities and the manufacturer's responsibilities.
Jon, no confusion here. The statement was not intended to show an unfortunate situation due to the lab. The situation was with the chief design engineer back at my former company. Literally, "If you pass, you pass. Now be done with it!" And soon after, I was done with them. > The test lab tests the sample(s) the manufacturer submits. The lab's > responsibility is to test the product in a professional manner according to > the standards requested by the manufacturer. A margin of 0dB is a pass and > the manufacturer has the right to expect the test lab to issue a pass test > report. I would hasten to agree with this. As one lab explained to me, their obligation to the FCC is to be within a certain margin (1 or 2dB) of any random checking done by the FCC. This same lab would not pass anything within 1dB. There's just too many variables in manufacture that warrent confidence that the EUT represents the 'worst case' of anything the manufacturer will produce. > The manufacturer's responsibility is to comply with the EMC Directive (or > other regulations around the world). If the manufacturer does not realise > it, the lab should explain to him that a 0dB margin means that most likely a > large percentage of his production will be over the limit, and that he > should be aiming for a margin of xdB to give him a particular level of > confidence that his production complies. Yes. That they do. Most go with 6dB, and all would like 10dB. > Cynthia, when you do your statisitics, don't take the 0dB's into account, as > these do not refer to confidence margin, but to the test results of an > individual sample submitted to a test lab. > > Jon Griver > ITL (Product Testing) Ltd. > [email protected] Absolutley agree. ******************************************************* Doug McKean [email protected] ------------------------------------------------------- The comments and opinions stated herein are mine alone, and do not reflect those of my employer. ------------------------------------------------------- *******************************************************
