The new F19 appears to be designed on the Fisher F5 process. The F75/T2 are default processes and the newer F5 process is what Fisher has moved to.
“F5 process” The Fisher F5 and “new” Gold Bug, and the Teknetics Delta, Gamma, and Omega use a process first developed for the F5. The “F5 process” is a variation on the “default” process which emphasizes quieter operation in heavy iron trash. -Dave Johnson Essays (Fisher site).
Also under Daves Essays, he explains:
Interactions between controls There are many types of discriminators, all of which have some effect on “air test sensitivity”. The most common pattern (nearly universal in older all-analog machines) is that “air test sensitivity” decreases slightly as discrimination is increased. Most of our recent designs do discrimination entirely in software, where control settings are actually data which don’t necessarily do the same things to signals that circuit components used to do. In the case of the T2 and F75, those differences were confusing to some users. In general if a T2 or F75 seems too noisy, the solution is to set the discrimination level to the iron range; and if that doesn’t do the job, also reduce the sensitivity setting. In the F70, F5, Omega and Gamma which are more recent designs, the interactions between control settings and signals are even more complex, but we did a better job of hiding the details thereby giving the user an improved sense of predictability.
Why the F19? The CPU is more advanced with firmware improvements and abilities.
The metal detecting world was first introduced to the word “processes” with the Fisher F75, which offers the user a selection of several different processes. For the convenience of the user we give processes names, but we say very little about how the process actually works in software because that’s a trade secret. In a few cases savvy users have made correct guesses as to what was going on in software, but we don’t confirm that the guess is correct.
We’re not a company who stands still. Over the last several years we have introduced a whole series of new products on several new hardware platforms, and have constantly advanced the science of target signal processing. In the future we plan to introduce new processes which, although they may “feel” like a member of the T2 process family, will operate on different principles and will produce results of a kind which are not attained by any metal detector presently available.
Dave Johnson
Chief Designer, FTP-Fisher
One only has to know that Fisher has improved the process that detects metal. And because of trade secrets, you may judge the outside as one thing, but will not recognize the inner improvements until it's compared with other previous units.
(Of course, recalls don't look good. But it does say the company listens and works quickly to improve the experience.)
