Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why Do FM Frequencies End in an Odd Decimal?

transition.fcc.gov

Post reply on HN
Print view View original

31–40 of 56 posts

Re: Why Do FM Frequencies End in an Odd Decimal?

#31

Post by stephencanon »

scott_karana wrote: post #27
stephencanon wrote: post #24

Earlier quoted context omitted.

0 is uncomfortably cold. 100 is uncomfortably hot. The temperatures that non-STEM people (“humans”) deal with on a day-to-day basis can be represented with satisfactory precision using two digits (OK, three in Australia), no negative numbers, no decimals. It’s a great system for casual temperatures. Whereas “reasonable” temperatures in C run from what, -18ish to 38ish? Where’s the sense in that? If you want to defend…

"Uncomfortably cold" is quite an understatement, when talking about allegedly "human" temperatures. Sure, at 100, healthy humans can survive as long as their increased water needs are met. (Sun is another matter, but I'm just talking temperature.) However, at 0F, permanent tissue damage onset is within 30 minutes, with almost any wind speed. ( http://www.nws.noaa.gov/os/windchill/images/windchillchart3.... )

Humans have developed clothing, which allows us to stay alive in cold weather. There’s very little we can do (short of going into a building with AC) to survive hot weather — 100 is tolerable (just), but heat gets deadly very quickly when you go above it. You don’t want to be outdoors for extended stretches in either condition (the analogy is imperfect; realistically my experience of 10F is subjectively similar to 100F, and 0F is more like 110F).

Re: Why Do FM Frequencies End in an Odd Decimal?

#32

Post by scott_karana »

stephencanon wrote: post #31
scott_karana wrote: post #27

Earlier quoted context omitted.

"Uncomfortably cold" is quite an understatement, when talking about allegedly "human" temperatures. Sure, at 100, healthy humans can survive as long as their increased water needs are met. (Sun is another matter, but I'm just talking temperature.) However, at 0F, permanent tissue damage onset is within 30 minutes, with almost any wind speed. ( http://www.nws.noaa.gov/os/windchill/images/windchillchart3.... )

Humans have developed clothing, which allows us to stay alive in cold weather. There’s very little we can do (short of going into a building with AC) to survive hot weather — 100 is tolerable (just), but heat gets deadly very quickly when you go above it. You don’t want to be outdoors for extended stretches in either condition (the analogy is imperfect; realistically my experience of 10F is subjectively similar to 10…

How does that change the fact that 0F is more than "uncomfortably cold" for most people?

I'm not disputing the 0F to 100F (or -18C to 40C) range in terms of being "regularly seen".

EDIT: I suppose the core of the misunderstanding is that I was addressing the "human centric" advantage and relation to brine, where you were just arguing (quite reasonably) the convenient representation of the range?

Re: Why Do FM Frequencies End in an Odd Decimal?

#33

Post by stephencanon »

scott_karana wrote: post #32
stephencanon wrote: post #31

Earlier quoted context omitted.

Humans have developed clothing, which allows us to stay alive in cold weather. There’s very little we can do (short of going into a building with AC) to survive hot weather — 100 is tolerable (just), but heat gets deadly very quickly when you go above it. You don’t want to be outdoors for extended stretches in either condition (the analogy is imperfect; realistically my experience of 10F is subjectively similar to 10…

How does that change the fact that 0F is more than "uncomfortably cold" for most people? I'm not disputing the 0F to 100F (or -18C to 40C) range in terms of being "regularly seen". EDIT: I suppose the core of the misunderstanding is that I was addressing the "human centric" advantage and relation to brine, where you were just arguing (quite reasonably) the convenient representation of the range?

It doesn’t, but I’m being slightly approximate. Keep in mind that perception of (and physical effects of) temperature is hugely nonlinear. 0F is more dangerous than 100F, but when you go outside of that range, heat becomes far more deadly very quickly. I shovel my driveway in -20F, but I would never consider doing that sort of outdoor labor at 120F. Many people live in regions where -40F occurs from time to time, but if its 140F, you will die (actually, I think the highest recorded surface temperature is 13xF).

To your edit: yes, I think that’s the real thing. I certainly don’t think the brine thing is reasonable, just that 0-100F is a nice range.

Re: Why Do FM Frequencies End in an Odd Decimal?

#36

Post by eigenvector »

amalag wrote: post #20
ds9 wrote: post #15

Earlier quoted context omitted.

Another example is the Fahrenheit scale. The eponymous originator calibrated his thermometer by the temperatures where he could obtain brine (0 F) and an inaccurate estimate of human body temperature (100 F). https://en.wikipedia.org/wiki/Fahrenheit

It is still nice because it is human centric, roughly 0 to 100 for temperatures is easily relatable to the human body. 90 is hot, 10 is cold. Celsius starting at the freezing point of water is not as human centric.

Fahrenheit is not intuitive, you just think so because you grew up with it. People who grew up with Celcius have no problem relating to how cold 30 C or 100 C or -20 C are.

Re: Why Do FM Frequencies End in an Odd Decimal?

#37

Post by GauntletWizard »

dfc wrote: post #30
pwg wrote: post #6

Earlier quoted context omitted.

It's the typical "write a lot, but don't really answer anything" style that so many politicians utilize, only substituting "talk" for "write". The entire section could have been summed up as: Because each broadcast band is identified by the frequency of the center of the band, the bands begin on an even number, and the bands are two "units" wide, making the center frequency an odd number. Edit: for clarification.

The text was most likely written by a civil service employee. Civil servants are not politicians.

You've clearly never worked in Civil Service.

Re: Why Do FM Frequencies End in an Odd Decimal?

#38

Post by twoodfin »

ef47d35620c1 wrote: post #10
kps wrote: post #7

Wikipedia¹ has a more interesting answer to "Why?" — After World War II, the FCC moved FM to the frequencies between 88 and 108 MHz on June 27, 1945. The change in frequency was said to be for avoiding possible interference problems between stations in nearby cities and to make "room" for more FM radio channels. However, the FCC was influenced by RCA chairman David Sarnoff, who had the covert goal of disrupting the s…

RCA went after Armstrong. They knew that by convincing the FCC to change the frequencies they could seriously disrupt FM and make existing equipment useless. Armstrong later committed suicide. His wife won all of the on-going lawsuits. Basically, RCA broke him financially and mentally with multiple lawsuits and years of "discovery". Armstrong is the father of frequency modulation (FM) and some argue the father of mod…

Ken Burns did a terrific documentary on the RCA/Armstrong fight and the birth of radio generally, Empire of the Air.

http://www.pbs.org/kenburns/empire/

Re: Why Do FM Frequencies End in an Odd Decimal?

#39

Post by dmur »

dfc wrote: post #30
pwg wrote: post #6

Earlier quoted context omitted.

It's the typical "write a lot, but don't really answer anything" style that so many politicians utilize, only substituting "talk" for "write". The entire section could have been summed up as: Because each broadcast band is identified by the frequency of the center of the band, the bands begin on an even number, and the bands are two "units" wide, making the center frequency an odd number. Edit: for clarification.

The text was most likely written by a civil service employee. Civil servants are not politicians.

I don't think pwg was implying civil servants are politicians, rather merely pointing out that the text reads like a political speech.

Re: Why Do FM Frequencies End in an Odd Decimal?

#40

Post by bcj »

stephencanon wrote: post #24
raverbashing wrote: post #22

Earlier quoted context omitted.

No, it's still a piece of crap "Human centric" is a false advantage. And it's not even human centric, the temperature of 100F is wrong, and what does brine have to do again with the human body?

0 is uncomfortably cold. 100 is uncomfortably hot. The temperatures that non-STEM people (“humans”) deal with on a day-to-day basis can be represented with satisfactory precision using two digits (OK, three in Australia), no negative numbers, no decimals. It’s a great system for casual temperatures. Whereas “reasonable” temperatures in C run from what, -18ish to 38ish? Where’s the sense in that? If you want to defend…

There are a lot of humans that live places where we regularly see negative temperatures. Where I live the temperature range is roughly -40–85ºF.

Choosing the freezing point of water isn't really mystic. It lets you know whether it will rain or snow. It also means that any negative temperature is capable of causing frostbite.

Post reply on HN