Subscribe to Blog via Email
Copyright Notice© Mark Biegert and Math Encounters, 2017. Publication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Mark Biegert and Math Encounters with appropriate and specific direction to the original content.
DisclaimerAll content provided on the mathscinotes.com blog is for informational purposes only. The owner of this blog makes no representations as to the accuracy or completeness of any information on this site or found by following any link on this site. The owner of mathscinotes.com will not be liable for any errors or omissions in this information nor for the availability of this information. The owner will not be liable for any losses, injuries, or damages from the display or use of this information.
Daily Archives: 2-April-2013
Engineering is a pretty conservative profession -- I have been accused of "abhorring change". Once something gets standardized it stays in place even when it does not make sense. This morning provided me a good example of this. Phone lines in the United States are usually characterized as having a characteristic impedance of 600 Ω or 900 Ω. These impedance levels go back to the early days of telephony (Figure 1). However, all the phone cables we work with are Category 3 and therefore have identical characteristic impedance (~725 Ω). So why the different impedance levels? I had a discussion with one of our telephony engineers about it this morning and all we could do is speculate. I thought I would document this speculation here. Continue reading