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Traveler information stations on AM 530, 1610, etc

The technical side of broadcasting. Think IBOC is a sham? Talk about it here! How about HDTV? Post DX reports here as well.
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Ben Zonia
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Re: Traveler information stations on AM 530, 1610, etc

Unread post by Ben Zonia »

bmw wrote: Sat Mar 25, 2023 3:31 pm I'm pretty sure it is limited to 5khz on the AM band so as to not interfere with adjacent commercial stations which take priority.
It's mainly the lower frequencies that are missing or attenuated. 30 Hz to 5 kHz would be great. WWJ and other stations had mobile studios in malls that had audio equalized to 5 kHz, and they sounded pretty good back in the day.

From flypaper.soundfly.com

"During a conversation, the fundamental frequency of a typical adult man ranges from 80 to 180 Hz and that of a typical adult woman from 165 to 255 Hz. Thus, if we look at these three images, the fundamental frequency of most speech falls below the lower edge of the “speech frequency band.”"

Thus, the fourth harmonic of a female voice is barely above 1 kHz. Since the highest note on the piano is 4186 Hz, you could still have voice that sounded good, if not music. Even most fundamental frequencies in music are much less. The only time I think they had that high a fundamental was "Noboby But Me" by the Human Beinz, where they pounded high C a probably a hundred times, and it had enough harmonic content to identify it as a piano note, even on AM radio, at least at the time.

The lowest key on the piano is A 27.5 Hz.

Frequency range of various musical instruments

https://www.zytrax.com/tech/audio/audio.html
Last edited by Ben Zonia on Sat Mar 25, 2023 4:27 pm, edited 1 time in total.
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Plate Cap
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Re: Traveler information stations on AM 530, 1610, etc

Unread post by Plate Cap »

Hi Ben,

Always a pleasure to have you in a discussion!

TIS stations are regulated by 47CFR§90.242 Here is a convenient reference as to your questions on frequency assignment, power, modulating audio rolloff, and more:https://www.ecfr.gov/current/title-47/c ... ion-90.242
The box that many broadcasters won’t look outside of was made in 1969 and hasn’t changed significantly since.
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Ben Zonia
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Re: Traveler information stations on AM 530, 1610, etc

Unread post by Ben Zonia »

Thanks Plate Cap.

Waveforms can be analyzed by Fourier Analysis. Fourier Analysis states that you can simulate any waveform by adding up harmonics with amplitude coefficients for each harmonic. Every musical instrument can be simulated that way, and that is how you could simulate it on a keyboard, though sometimes they use actual recordings of instruments, an early version of which is the Mellotron. Pipe Organs were the original "synthesizers", using pipe dimensions to simulate the harmonic distribution, but too expensive and too large for most people, though I have seen two in home basements. Most people attest that the electronic keyboards can do a remarkable job of simulation, though not enough probably for people like the late Dr. William D. Revelli, past head of the U of M Music Department. There is a asymptotic approach to the actual waveforms with the number of harmonics used, and diminishing returns.
"I had a job for a while as an announcer at WWV but I finally quit, because I couldn't stand the hours."

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paul8539
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Re: Traveler information stations on AM 530, 1610, etc

Unread post by paul8539 »

There has been one in Bay City during the winter. Some individual broadcasts the music that he has his yard Christmas light synchronized to. I tuned into it once, and it has a range of about a quarter mile or so.
radioandtventhusiast
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Location: Toledo, OH

Re: Traveler information stations on AM 530, 1610, etc

Unread post by radioandtventhusiast »

There used to be one in Toledo that was done by ODOT giving highway information with a robotic sounding female voice.
k8jd
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Joined: Fri Jun 28, 2013 3:35 pm
Location: Commerce, MI

Re: Traveler information stations on AM 530, 1610, etc

Unread post by k8jd »

I have seen signs on the roads to bridges etc "for info tune to 16xx "
The DTW info radio has moved from 920 to 1610. I heard the 920 signal all the way to my Commerce Twp. location.
Marysville had a TIS station 0n 1700 I think, antenna was behind the Public Safety building, always seemed to have distorted modulation. Not listed in the big list.
NO, now that I think back, it may have been on 1540, 1550 or 1560, because as I drove South,CBE really knocked it out.
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