TamaraB
Question The Current Paradigm
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join:2000-11-08
Brooklyn NYC
 ·Verizon Online DSL
1 edit | reply to dishrich
Re: What about hospital equipment disrupting TV channels?
said by dishrich  :FALSE, because they ARE allowed, as cable ch 19 thru 21 are commonly used for over the air paging services, which is where they ARE legally assigned spectrum. Wait a Sec! As a former amateur radio operator, I know that the FCC regulates the frequency spectrum. If "ch 19 thru 21 are commonly used ... [for] paging services" then they must comply with FCC regs mandating they not interfere with licensed services on those same frequencies. Their use of that spectrum is limited to "in-house" use, and they may not radiate it outside their premises.
If the Hospital's paging system interferes with licensed spectrum outside the hospital itself, it violates FCC regulations.
Are you saying this is a "FALSE"statement?
Bob
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dishrich
join:2006-05-12
Springfield, IL
4 edits | said by TamaraB :Wait a Sec! As a former amateur radio operator, I know that the FCC regulates the frequency spectrum. If "ch 19 thru 21 are commonly used ... [for] paging services" then they must comply with FCC regs mandating they not interfere with licensed services on those same frequencies. Their use of that spectrum is limited to "in-house" use, and they may not radiate it outside their premises. If the Hospital's paging system interferes with licensed spectrum outside the hospital itself, it violates FCC regulations. Are you saying this is a "FALSE"statement? Yes, because "the FCC regulates the frequency spectrum" ONLY for OTA signal transmissions - NOT for what a CATV system "chooses" to use within their OWN closed system. 
It all depends - IF the hospital's particular paging system spectrum was ONLY for use WITHIN the hospital confines, & is exeeding their authorized power level, &/or it is NOT staying within it's assigned freqs, only then is it violating FCC regs. But, you DO realize there IS spectrum that is used for high-powered pocket pagers, police radios, airline traffic, etc. & unfortunately, those freqs ARE in the CATV midband. As I also told you, there are 3 CATV channels that share the FM band space - unfortunately, there are instances where strong FM transmitters can trash those freqs on a CATV system, making them unusable, that NO amount of shielding can fix.
And as far as the CATV system goes, they do NOT have to get a license to use those same freqs, since as I already mentioned, a CATV is considered a "closed-loop" system, & therefore is NOT "broadcasting" on those freqs. Because of this, there (in theory) is NO co-mingling of transmissions between the CATV system & those OTA devices. A CATV system does NOT have to get FCC permission on which freqs they use - only that they do NOT radiate their signal over a certain threshold. And this is one problem where CATV companies get into with customers who do their own wiring, & DON'T know what the hell they are doing! I run into this constantly with clients, who (incorrectly) blame the cable system for their crappy reception, which they actually brought onto themselves with their do-it-themselves TV hookups.  (ask fiberguy & cabletool & they'll tell you the same thing )
The bottom line - almost EVERY CATV system IS sharing many of the same freqs as many OTA devices & services. Again, the FCC gives the priority to the OTA devices, as long as they are within defined limits. It is up to the CATV system to ensure the proper shielding of their system/equipment. Again, it is NO different than a CATV system attempting to use ch 2-13 in markets WITH strong 2-13 OTA stations.
When I was going down to school@SIU-Carbondale a few decades ago,  the local VHF stations (3, 6, 8, 10 & 12) would sometimes have "co-channel" interfearance in them, since the cable system used all those same channels for TV service. In the case of ch 10, it was also an OTA translator for the local NBC station on 6, which you could see superimposed on top of WGN, which was on CATV ch 10. The rest of the stations were broadcast on the CATV system on the same channels, which sometimes caused multiple ghosting, sync bars drifting, etc. If you didn't have EVERY connector tight, it only got worse. Finally after they rebuilt the system, the reception improved drastically, but again, you had to have a TIGHT system to keep it like that. |
