No argument. All we can say right now is neither factor (HF supply noise / enthalpy) appears to be significant based on the available data for the supplies and reasonable analysis on the chemical side. Neither the data nor the analysis is everything one could ask for.
Jeff On Thu, Dec 13, 2012 at 12:04 PM, Abd ul-Rahman Lomax <[email protected]>wrote: > At 03:07 AM 12/13/2012, Jeff Berkowitz wrote: > > I am looking at 1 minute averages. This is very solid. >> > > Okay. This would not detect "invisible" excess input power due to power > supply high-frequency variations. At all. > > This is what SRI did. They used a constant-current power supply, with > high-bandwidth control. The supply, then, faced with transients in > resistance, rapidly varies the voltage. So voltage is sampled at high > frequency, and is averaged and reported periodically. > > However, it's rather obvious, there must be some variation in current, or > the supply would not "know" to alter the voltage. Supplies actually produce > constant voltage naturally, if they are beefy enough, which they usually > are. Internal feedback rapidly changes the voltage to maintain constant > current, when the supply is in constant current mode. > > What Britz studied was the effect of current noise. It was very low. If > the current is tightly controlled, power remains the product of average > voltage times the constant current. Thus the challenged assumption was > "constant current." > > As McKubre has written, these supplies -- at least the one he used, which > was documented -- are very good. > > To be sure, workers in the field have examined the current with > high-bandwidth oscilloscopes. (They had not documented this in the papers, > one cannot possibly, in normally-published papers, document *everything*, > but we asked.) They don't see the high-frequency noise that would cause a > problem. > > The researchers should nail this down, and check for true solidity in the > power supply, otherwise, indeed, high-frequency noise could cause > misreporting of input power. >
