LRV Contrast Calculator vs HamSmith

A good Luminance contrast can assist people with low vision in identifying important building elements such as Stairway Nosings, Doorways, Tactile Ground Surface Indicators and Signage in the built environment. With the introduction of the ADA (Americans with Disabilities Act) and DDA (Australian Disability Discrimination Act), it is useful for Architects, Interior Designers, Disability Access Consultants and even product manufacturers to quickly calculate the required LRV contrast of adjoining materials. Light / Luminance Reflectance Value, or LRV, is a measurement of light that is reflected from a surface. Some of the ways to find the LRV are by means of a colorimeter, spectrophotometer or directly by the manufacturer (for example, LRV noted on a fan deck provided by a paint manufacturer). LRV / Luminance Contrast is the light reflected from one surface as compared to the light reflected from another surface. This app calculates the percentage difference required when the LRV of any two samples are know. For example, if you have the LRV of the color of the door frame and the LRV of the color of the door, you can use this calculator to determine the contrast in % based on the formulas used in either USA or Australia. The Americans with Disability Act Accessibility Guidelines (ADAAG) recommends a 70% LRV or higher for those with impaired vision and Australian / New Zealand Standard AS/NZ 1428.4.1-2009 requires LRV contrast in a range of 30% to 60% based on the type of building elements.

HamSmith calculates component values for impedance matching circuits. All you need to do is trace a path on the Smith Chart with your finger from your load impedance to the centre of the chart. It's like walking a path through a maze, except that there are many different pathways you might choose! Each path will produce a different type of matching circuit: L-match, Pi-match, T-match. HamSmith also calculates the stub lengths for short-circuit and open-circuit transmission line matching circuits. A handy sweep view shows the VSWR results, which can illustrate the spectrum impact of different matching designs.