Our TIS station down the street was
installed several years ago, and I heard
a few things about it, which I think are odd.
The installer starts out with 10 watts and whatever
transmitting antenna they use. 10 or 20 feet long?
I don't know. But then the field strength has to
be brought down to meet FCC reguirements,
(I forgot the specs). And then the station isn't strong
enough in certain parts of our town (in my opinion.)
Also it's running an audio loop that hasn't been changed
since Novermber. But I happen to know that the
person who records it has to do about a zillion other
things, and this is just one more thing for him to do.
Bruce, DOGRADIO
Bruce, DOGRADIO, you go over to the licensees of your TIS station and tell them you will take over the business of updating the message and caring for the station and tell them you won't charge much.
I'd say, $5000 a year in one annual installment.
An interesting thing one can do with TIS is low frequency roll-off and still maintain the 3KHZ bandwidth requirement. For example, roll off the low at say 300 hZ. The 3kHz BW high end is now 3300 hz, thus improving the quality of sound.
Brilliant!
That's the way to do it!
Sec. 90.242 Travelers' information stations.
--
(8) Each transmitter in a Travelers Information Station shall be
equipped with an audio low-pass filter. Such filter shall be installed
between the modulation limiter and the modulated stage. At audio
frequencies between 3 kHz and 20 kHz this filter shall have an
attenuation greater than the attenuation at 1 kHz by at least:
60 log10 (f/3) decibels.
where ''f'' is the audio frequency in kHz. At audio frequencies above 20
kHz, the attenuation shall be at least 50 decibels greater than the
attenuation at 1 kHz.
Messengers who deliver bad news could have been undertakers but sometimes pursue radio as the place to ruin it for people in what little happiness they might accidentally have.
At least we get to be clever and smart until we get that message of gloom.
Musn't weep, or the text will start running off the page.
Quotes from the FCC rules can be discouraging but necessary to dispel misinformation.
Services for the burial of failed ideas are delayed because of terrible weather. Full coverage on your local Part 15 station.
I was just thinking out of the box based on a tech note from TenTec that reads as follows:
Description of Jupiter Transmit Roll-Off Control
The TX Roll-Off control was added to the user menu in version 1.17. This control allows the user to position the lower edge of the selected transit filter. The lower edge setting affects the
transmitted audio range. The control range is 0 to 1270 Hz with a default value of 200 Hz.
When adjusting this feature it important to remember transmit bandwidth and TX Roll-Off together determine the audio quality. The TX Roll-Off determines where audio starts on the lower side and transmit filter selection determines the passband. For example: if you have a 3 kHz filter selected and set a 400 Hz TX Roll-Off the transmitted audio would be 400 Hz to 3400 Hz.
The large control range will allow digital mode users to place narrow filters at any position they
choose. A large TX Roll-Off with a wide filter is not possible as other factors limit the usable
range. Likewise, the low frequency audio response is affected by hardware. So there is some inherent roll-off of frequencies below 150 Hz.
While trying to find a post where Rich recently displayed audio bandwidth figures for available AM receivers, I chanced upon this highly informative thread from earlier in the year,
Being reminded of the NRSC Preemphasis capability built into every SSTran transmitter, tests will begin immediately to employ this feature as per the opening post by PhilB.
For several years our transmitters have not employed this feature, but it's there, and I'll tell you what results.
Excuse me, I'm out here in the back adding Jumper S22 on the AMT5000.
EDITOR -- Correction... PhilB's comments appear later down the list, not Post # 1.
NCRS Jumper in place, the FCC approved AM pre-emphasis is turned on, and I'll tell you why I like it.
But first, some preliminaries.
My radio playlist is processed with Hans Van Zutphen's "Stereo Tools". a highly professional software that allows setting of just about every parameter of an audio path, including the ability to set the audio bandpass.
My encoding system feeds two different types of transmitters: AM radio transmitters and internet streaming encoder/server, a form of internet transmitter.
My previous bandpass setting favored the AM side of the operation, being set for 80 to 10,240 Hz, because that is a full seven-octaves of sound.
But with the NCRS PreEmphasis turned on, and according to remarks previously made by PhilB, there is no need for equalizers or audio bandpass filters, since the AM system filters its own audio, considering the loading coil, antenna and receiver as having their own bandwidth characteristics.
Given the freedom to do so, I've reset the "Stereotools" processor for a bandwidth favoring the outgoing stream server, which itself is fixed at 22,050 Hz sampling rate, stereo.
Thus the new "Stereotools" bandpass is 50% of that: 80 to 11,025 Hz.
Now I will tell why I like the sound of the NCRS PreEmphasis.
The "sharper" sound from radios, there is one in every room, "projects" farther into the room space and is much more listenable at distances away from the receivers.
The "flat" ordinary non-NRSC sound is fine while near the radio, but becomes "duller" with greater distance from the loudspeaker.
While this is, of course, a subjective evaluation, we will leave it to every future operator who tries NRSC PreEmphasis in his/her SSTran transmitter to arrive at their own conclusion.
In general, NCRS sound should improve highway listening in automobiles, where road noise often makes radio listening difficult. This same rule holds true in garden patio settings, where neighborhood powertools, barking dogs and aircraft above can compete with radio listening.