Typically, losses are represented by positive dB values. A negative loss would indicate a gain in optical intensity. Thus, a loss of a negative value would indicate a problem in the test.
It is confusing that two optical test sets (OTS) from the same vendor would display loss differently. However, it is possible that one of the OTS' was designed by a company that Fluke purchased.
Here is the response from Fluke:
"Yes, the DTX format is to display a positive value for a loss and a negative value for a gainer. It the opposite for the Simplifiber.
The Simplifiber Pro displays in the new(DTX) format. "Good luck!
Tom
tjw Wrote:Hi all,
I am testing fibre with a fluke simplifibre, range +3db to -55 db. The fibre is multi mode and only about 500m in length with ST hot melts terminated at each end. I am testing at 1300 and the results are all around -0.80db. I believe this to be ok.
I am now confused as I am also going to test with Fluke DTX with the fibre modules installed. On reading the manual it states that if you get a negative reading the units require calibrating.
This as left me confused owing to the Simplifibre giving negative results.
Could someone kindly educate me and explain this.
Any help will be greatly appreciated.
