Negative amplitude means the signal is attenuated relative to a reference point, so if you see e.g. -20dB, it means the signal is 1/10th of the reference value. dB on it's own is unitless, so you will see things like dBm (relative to 1mW â 0dB = 1mW), or dBV (relative to 1V â 0dB = 1V).
In Colorado, the offer is valid at the Denver Zoo and the Denver Art Museum. However, the Denver Art Museum is Sunday only, because they already offer free admission to everyone on the first Saturday of the month. This list does change, so check the Museums on Us website, before you go.
2015 National Park Service Free Days. America's Best Idea â the national parks â gets even better with several fee-free days at more than 100 national parks that usually charge entrance fees.*.merica's Best Idea â the national parks â gets even better with several fee-free days at more than 100 national parks that usually charge entrance fees.*.