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HD in new cars

Kelly A said:
For transmitter sites located in downtown areas, lower gain and higher TPO may be best because you have listeners under-or in the vicinity of the antenna. For mountaintop sites or sites at least 10 miles from the metro, higher gain puts field where the population is. Using low gain in areas where there is nobody close in, is IMHO, a waste of energy.
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My experience building a number of facilities in Puerto Rico is in areas where there are mountaintop sites which are removed from the market, but from which multiple population centers can be reached is that 6 bays is optimum. Eight bays starts showing the null and peak effects of multiple bays, irrespective of bay spacing. And, for some reason, 6 seems to be best for issues like multipath in areas with significantly rugged terrain.

With electricity at over $0.30 cents per kWh in Puerto Rico, 6 bays allows maximum power for nearly any mountaintop and still keeps the transmitter to 10 kw.
 
In Central Florida, where the terrain is flat as a pancake, twelve-bay transmitting antennas are not unusual.
In the larger markets of Tampa and Orlando, many, if not most of the class C stations have six-bay transmitting antennas.
 
Agreed David. 99% of the mountaintop sites I've either built or have been involved with, use 6 bay antennas, or about 3:1 gain.
 
Kelly A said:
For transmitter sites located in downtown areas, lower gain and higher TPO may be best because you have listeners under-or in the vicinity of the antenna.
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That much is true, but some care should be taken to consider blanketing issues. I worked at a class-C station with a four-bay antenna about 1100 feet above ground, on a tower located in a fairly densely populated area. I had to deal with numerous complaints of "your station is the only thing I can pick up, it's all over the dial", etc.

An antenna with less than full-wave spacing may have helped in that situation, at the cost of higher TPO for the same bay count.
 
Forgive my lack of experience, but how bad can a downtown signal from a downtown transmitter site really be?
I suspect that the main problem is overpowering the reflections and overloading from other downtown stations that use smaller antennæ and/or are a few blocks away.
 
ai4i said:
Forgive my lack of experience, but how bad can a downtown signal from a downtown transmitter site really be?
I suspect that the main problem is overpowering the reflections and overloading from other downtown stations that use smaller antennæ and/or are a few blocks away.
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That depends on what's considered a bad signal. Many listeners consider multipath interference as being a lack of signal, when really it's a reflection that arrives at a receiver slightly later than the primary signal, cancelling each other out to the radio. Downtown areas with lots of traffic (moving reflectors) or office buildings (passive reflectors or shields) can also create the impression of a bad signal.
 
I scrod up, that comment I made referred to something else a couple pages back.

awsherrill said:
An antenna with less than full-wave spacing may have helped in that situation, at the cost of higher TPO for the same bay count.
Click to expand...
I believe that one of the issues with full-wave spacing is that they send a lot of signal
straight down, as all the elements are in phase both horizontally and vertically.
Not so with half-wave spacing where half the elements cancel the other half in the vertical plane.
 
frankberry said:
In Central Florida, where the terrain is flat as a pancake, twelve-bay transmitting antennas are not unusual.
In the larger markets of Tampa and Orlando, many, if not most of the class C stations have six-bay transmitting antennas.
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Virtually all Roswell stations broadcast on short towers west of town. The towers are relatively short, and have ten to twelve bays each, sometimes stretching the majority of the tower length! It is the most bizarre thing I have ever seen, and picket fencing is horrible as you get into the fringes. Here is one of them, but they seem to have scaled it back a bit:
https://www.google.com/maps/@33.394...4!1sU2FNmXNDgHs_HU9B9_rRtA!2e0!7i13312!8i6656 I count six but it gets out of focus and there may be nine. The top of the tower looks broken off.

I looked for some others, it appears that a lot of them are gone. It has been 15 years since I was out there, I can even see the tower base for some towers that have been removed. So I guess they got together and made an antenna farm somewhere.

Ah - here is a 12 bay in the distance:
https://www.google.com/maps/@33.385...4!1s_VuEtZoxMv6FcyNbfftTjw!2e0!7i13312!8i6656

There used to be more, maybe I'm just not finding them.
 
tomservo said:
Go back to the March 2013 imagery and you can see there's ten on that tower. And an AM skirt! Looks like you could jump up and touch that bottom bay, especially on that other image you linked.
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On the "populated tower" I see two 5-bay FM antennas and three microwave antennas and something that looks like an auxiliary service antenna. The other tower has fairly recently installed radials, and uses a folded unipole radiator system. There appears to be nothing else on the tower other than the AM.

Since the signage shows 4 FMs and one AM, we have several possibilities. One is that the two FM antennas (of 5 bays each) are diplexed with several stations. The other is that the FM antennas are backups, with the microwave antennas sending the programming to FM transmitter sites with taller towers of a better location.

Looking at the current licenses, it appears that two of the FMs are at the studio location in the link, and another two plus a translator are on taller towers at two separate locations, explaining the three microwave antennas (antennae?).
 
Kelly A said:
"Broken off" Bruce? Thanks David, I needed a good laugh this morning..
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Difficult to tell in that image whether it has a dissipator or not. I would think they would find a lot of use in Florida which has more lightning strikes than anywhere else in the world - not so sure about NM which looks more like a desert. Didn't somebody find a historical image that showed the tower taller?
 
rbrucecarter5 said:
Difficult to tell in that image whether it has a dissipator or not. I would think they would find a lot of use in Florida which has more lightning strikes than anywhere else in the world - not so sure about NM which looks more like a desert. Didn't somebody find a historical image that showed the tower taller?
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I believe they reduced the height of the tower to eliminate the need to light and paint it. They also kept the separate AM tower short via use of a Unipole(c) to get minimum efficiency with a short stick.

The Cortana assemblies are very easy to recognize by anyone who has worked a bit at transmitter or tower sites. I could tell what it was even without zooming in the "street view" pic.

Yes, the dissipators, as you call them, are widely used in Florida but they were, IIRC, invented in New Mexico by Ron Nott. Mr Nott, a pioneer inventor of solutions for static electricity problems on antenna structures, sadly passed away last Friday at his home in Farmington, NM.

A tribute and history of Mr Nott's career are found at http://www.radioworld.com/news-and-business/0002/ron-nott-consultant-and-supplier-dies/339441
 
Kelly A said:
Thanks David, I needed a good laugh this morning..
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I'm always looking to brighten your day... but without static discharges!
 
We checked out a friend's late model used Toyota Corolla, like maybe 2015?
We were surprised to find that the system had excellent audio,
a really nice touch-screen, bluetooth, USB ports in the dashboard,
a rearward facing camera that takes over when the transmission is shifted into R,
We are not sure if it had RDS, BUT....no HD radio and no SiriusXM.
Adding those, plus navigation must just take swapping or adding a chip.
We did notice spaces on the screen where soft buttons seemed to be missing.
 
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ai4i said:
We checked out a friend's late model used Toyota Corolla, like maybe 2015?
We were surprised to find that the system had excellent audio,
a really nice touch-screen, bluetooth, USB ports in the dashboard,
a rearward facing camera that takes over when the transmission is shifted into R,
We are not sure if it had RDS, BUT....no HD radio and no SiriusXM.
Adding those, plus navigation must just take swapping or adding a chip.
We did notice spaces on the screen where soft buttons seemed to be missing.
Click to expand...

Same thing with a friend's 2012 Chevy Cruse - obviously HD radio and satellite had been in some models, but not this one. Fully functional navigation and everything else, AM FM is good, but no HD. Blank spaces where soft keys had been active.

Are we already seeing the automakers remove HD and satellite as economy measures - concentrating instead on bluetooth?
 
rbrucecarter5 said:
Same thing with a friend's 2012 Chevy Cruse - obviously HD radio and satellite had been in some models, but not this one. Fully functional navigation and everything else, AM FM is good, but no HD. Blank spaces where soft keys had been active.

Are we already seeing the automakers remove HD and satellite as economy measures - concentrating instead on bluetooth?
Click to expand...

Automakers do not remove satellite. It makes them a lot of money, as they are incentivized and share part of the ongoing revenue stream.
 
DavidEduardo said:


Automakers do not remove satellite. It makes them a lot of money, as they are incentivized and share part of the ongoing revenue stream.
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Meaning that these no-SXM, no-HD units are non-OEM? Or are there stripped-down units put in cars at the factory in anticipation of potential car buyers who have no desire for either satellite or HD? If the latter, satellite has been selling its investors (and the SEC) on SXM's availability as standard equipment on make after make for years. Shading the truth, are they? How easy is it for a car buyer to get a no-frills (or at least no-satellite, no-HD) in-dash entertainment unit?
 
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