My understanding is that MTBF is usually calculated by taking a certain sample size, then seeing how many fail over a certain amount of time. >From this number you can then use statistics to determine how many years the rest will last.
A simplified example would be if you take 100 devices, and 10 fail in the first year, then you assume that 5 would fail per year, and the mtbf would be 5 years. Remember 'M' is mean. Or average. Which roughly means that only half of the units will still be working in that amount of time. It doesn't mean your particular radio will last that long, just that half of the radios will last that long. Yours might fail in 10 days or a year or never.... Personally, I believe that this method is rather dubious since some electronic parts exhibit wear-out. Electrolytic capacitors as an example. Even if very few devices fail at 5 years, there is a good chance that most will fail at 20 years after the electrolytic caps have dried out. On Sat, Aug 26, 2017 at 9:29 AM, Kurt Fankhauser <[email protected]> wrote: > Where do these MTBF ratings come from by radio manufacturers? Are they > just made up numbers the manufacturer "hopes" that the product can achieve > or is actual testing done to get to these numbers? I thought i seen a radio > once with a 90 year MTBF rating. How they hell can they determine that? The > components in the radio didn't even exist 90 years ago. > > If a radio manufacture states in the spec sheets that the radio has a 40 > year MTBF rating but then also admits that after 4 years expect to have > problems due to a design flaw, what does that mean? Is the expected MTBF > rating only good in a "lab environment" under "ideal conditions"? > > Seems to me the MTBF is just marketing fluff and actually doesn't mean > crap.... > -- *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> <http://twitter.com/@packetflux>
