Distant reception of HD FM Radio question?

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This topic contains 50 replies, has 9 voices, and was last updated by  Alfredo_T 3 years, 11 months ago.

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  • #8829

    mwdxer1
    Participant

    Then 98.7 moved to the West Hills. Back in the 70s, KUPL ran 100KW on 98.5 from Mt. Scott. It was my best FM in signal from NW Portland.

    #8833

    Andy Brown
    Participant

    The consolidation of ownership starting in ’96 resulted in the consolidation of transmitter sites for two main reasons.

    In many cases, moving stations to the “best location” was not possible without creating interference problems. Competing owners were not about to move a channel up or down, lower class or lower power just to allow someone else to move their transmitter site. However, when these stations fell into the hands of the same owner, a lot of juggling began. Class A’s like 94.7 and 107.5 ended up as C2’s in the West Hills, for example. Totally not possible when these stations were incepted. Dropins move overs and upgrades/downgrades allowed stations like 98.5 and 106.7 to move to the West Hills as well, moves that were not possible before the Reform Act decimated the sanctity of the landscape. Surely, these factors effected the Seattle transmitter locations, I’m just not familiar with the nuts and bolts of what happened up there. When your Clear Channel, Entercom or any group that has a cluster in a big market and have bought all the stations in the suburbs as well, you can do a lot of this kind of grid deconstructing to max out the population centers although it comes with a cost to the outlying areas. So to be clear, the two reasons are the consolidation of ownership and the waiving of any limits on the number of stations you can own.

    Radio is not better. The biggest owner has more debt than it can ever pay off due to paying way too much to buy all those licenses, and the smaller group owners somehow haven’t gotten the message that wanting to be like Clear Channel is not the way to go. In the duration we’ve also seen larger group owners ignore the internet totally in the late 90’s when getting a jump was so crucial. So not only were they late to the internet, they ignored the media change that was happening in consumers lives like iPods and streaming. Sure, now they have jumped into that, but they are still woefully behind. Other problems like dumping a lot of talented people in favor of automation and group programming has so alienated the young listener that it now doesn’t matter a whole lot as to how well coverage is from any particular transmitter site. Chances are the programming is available somewhere on the dial if you are so inclined to listen to the corporate swill they now vend.

    One additional minor reason for relocation to optimum sites is that the technology of combiners and master antennae has advance a lot in the last twenty years. It used to be that they just didn’t build antennae that could handle the combined ERP’s of a dozen or more full power stations all across the dial. In fact, more narrow banded antenna for single UHF TV licensees operating in the upper regions of the UHF TV band where ERP’s of megawatts were needed to reach “A” coverage contour distances were so expensive very few stations could afford being that high on the band.

    #8924

    mwdxer1
    Participant

    Thanks Andy for the explanation. I find it interesting with digital UHF that two full power stations, KOMO 38 & KIRO 39 Seattle can be side by side. I guess with digital OTA, the channels can be crammed right together and not suffer interference. That could never be done with analog. With more and more of the TV band going to cel service, TV stations in metro areas may be forced to have all of their channels right in a row. There is a lp translator on ch 8 in Seattle, right next to 9.I wonder if there is any interference between the two, with 8 being lp?

    #9029

    Alfredo_T
    Participant

    Not that long ago, I read on a cable TV technology Website that the reason that analog cable systems can successfully use adjacent channels without interference is that the amplitude of the sound carrier is reduced, compared to what was used over the air (in my recollection, OTA broadcasters ran the sound carrier -7dB with respect to the visual carrier). Before some clever engineer figured out this trick, cable systems couldn’t use adjacent channels. In fact, a very common channel lineup on early cable systems was 2, 4, and 6 (or possibly 2, 4, and 5 if there was a strong over-the-air channel 6 or educational FMs in the area).

    With digital OTA, there is only one carrier, and the adjacent channel’s carrier is always at least 6 MHz away.

    #9041

    Andy Brown
    Participant

    Four and five are not adjacent. Four is 66 – 72 MHz and five is 76 – 82 MHz. Between 72 and 76 MHz are 68 channels with a bandwidth of 20 kHz and a maximum power of 1 watt.

    http://www.ecfr.gov/cgi-bin/text-idx?SID=adf9eb7e204a9766b8f9d6d4c26c169c&node=se47.5.90_1257&rgn=div8

    There is all kinds of stuff being used in that band, the most recent being language translation devices which I don’t know bupkis about, but read this:

    http://www.commlawblog.com/2013/06/articles/unlicensed-operations-and-emer/effective-date-of-revised-auditory-assistance-device-rules-set/

    #9055

    Alfredo_T
    Participant

    I should have been a bit clearer in my wording, since consecutive channel numbers aren’t always adjacent. The 72-76 MHz area has long been popular for radio controlled models, but the language translation stuff is new to me. Other NTSC countries have had their own interesting uses for that 4 MHz sliver; some time ago, I read that this area, along with 42-48 MHz, are used in parts of Chile to broadcast subscription-based background music services.

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