[NA] What kind of signal do motorhome TV's use?

[asicer]

A friend of mine rented an RV and drove it around Arizona/Utah for a week. I thought it was fascinating and sort of the opposite of the GA vacations I take

Anyway, that got me thinking. Say you pull into a campground that has cable TV hookup. Is that signal NTSC (yuck!), ATSC or QAM? How do they deal with encryption? If NTSC, I imagine they could use Macrovision but these days it's ridiculously easy to defeat. If QAM, I suppose they could give you a cablecard but I don't think they make TVs with that any more.

 

[SoonerAviator]

The nice ones use a satellite dish which auto-rotates to maintain signal and don't bother with campground cable.


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[Shawn]

Very few what you think of as cable signals are analog much more...so very few RV and travelers rely on that. You have two options these days, a portable satellite system that you either park and point the dish or an auto track system. Other option is to travel with a HD antenna. If you are in a populated area, there can be quite a few channels broadcast on HDTV over the air.

The days of plugging a co-ax cable into the back of the TV and getting signal are rapidly disappearing as the cable provides are now shooting digital signals down those lines that needs their decoder box.

 

[Timbeck2]

Holy crap, has it really become that complicated?

<---- hasn't motor homed in a few years.

 

[James331]

What's the point of taking a vacation, you can veg out infront of that screen at home?

 

[SkyHog]

What's the point of taking a vacation, you can veg out infront of that screen at home?

Well, for instance, I am full timing at the moment. Wife and kids are in a different state. Not all camping is vacation.

TV is very nice. In my case, I have a Winegard antenna and amplifier system with a hand cranked antenna adjuster kind of like the old Cherokee trim handle.

Works pretty good, provided I have an unobstructed view.

 

[kgruber]

Is this correct......If you have a 20 year old RV with the old style crank up antenna.......you will receive nothing?

 

[Palmpilot]

Is this correct......If you have a 20 year old RV with the old style crank up antenna.......you will receive nothing?

If it's an antenna that received both VHF and UHF analog terrestrial TV stations well, then it will receive digital terrestrial TV stations well. There is no such thing as an "HD antenna" or a "digital antenna." This is because all of the frequency bands being used now were previously used for analog TV. Vendors that call them "HD" or "digital" antennas are just engaging in marketing BS.

The only thing that needs to be different is that the TV either has to be capable of working with digital signals, or else you will need a digital-to-analog converter box.

 

[Shawn]

There is no such thing as an "HD antenna" or a "digital antenna." This is because all of the frequency bands being used now were previously used for analog TV

Not entirely true...new over air D-TV signals are moving up into the 500 to low 700 MHZ range which is higher than old VHF broadcast. They are reeking havock with wireless mics that use those frequencies in the entertainment industy since the FCC auctioned blocks to the networks and tech industry.

 

[denverpilot]

As someone else said, a regular ol VHF/UHF antenna on the roof is common for OTA HDTV or folks who like their sports or whatever get satellite dishes. They've made auto-tracking dishes for the roof and also portable ones for a while now.

At parks where there's been a cable hanging there I've hooked them up sometimes out of RF geek curiosity. They're usually just a cable system hooked to the park's bigger VHF/UHF antenna with an amplifier but sometimes you can tell they have a deal with the local cable company to toss unscrambled "basic cable" onto a park cable system.

Personally I just grab RedBox DVDs of stuff I haven't seen for nighttime viewing after the campfire is put to bed for the night.

 

[Palmpilot]

Not entirely true...new over air D-TV signals are moving up into the 500 to low 700 MHZ range which is higher than old VHF broadcast. They are reeking havock with wireless mics that use those frequencies in the entertainment industy since the FCC auctioned blocks to the networks and tech industry.

There were MANY analog TV stations broadcasting on UHF channels, and some of them were above 700 MHZ. Examples where I live included channels 54 and 60. (The latter covers from 740 to 746 MHz.)

 

[denverpilot]

Not entirely true...new over air D-TV signals are moving up into the 500 to low 700 MHZ range which is higher than old VHF broadcast. They are reeking havock with wireless mics that use those frequencies in the entertainment industy since the FCC auctioned blocks to the networks and tech industry.

There's also the Channel 51 move of TV stations off of that channel because it's in the new-ish (not that new really) 700 MHz cellular block. Mostly affects T-Mobile's buildout in that spectrum.

There's been some studies that stations that opted to covert to HD "in place" on VHF suffer more real world interference than was expected and their coverage dropped pretty significantly at the edge of their expected coverage areas, whereas those who popped up to UHF saw benefits from digital like you're supposed to at the fringes. (No ghosting or white noise, you get a slightly larger radius of usable signal and then it's gone... Because it fell below the recoverable bitrate needed to view it at all.)

Haven't seen any stations that stayed in VHF ask to move up though -- the transmitters were way too expensive to swap them out (yet). We'll see in a few years.

 

[Shawn]

Yeah...not so much as moving up but rather taking over those spectrums where they used to be just isolated channels in select markets, now it is more widespread use of those channels more nationwide.

We used to be able to use the white space in between channels for things like wireless microphones, now we have complete spectrums wiped off the map with a lot of new D-TV signals that have emerged.

 

[SkyHog]

Is this correct......If you have a 20 year old RV with the old style crank up antenna.......you will receive nothing?

Like this?


It receives digital signals pretty good. My understanding is that they're just normal analog signals but compressed digitally.

 

[denverpilot]

Like this?
View attachment 46363

It receives digital signals pretty good. My understanding is that they're just normal analog signals but compressed digitally.

The word you're looking for is "modulation". RF is analog, no way around it. It's how you modulate the RF and then how you re-create that at the far end that determines "analog" or "digital", to put it in layman' terms. Demodulation.

Or another way to think about it, the antenna doesn't care. Only the receiver itself does.

The latest and greatest tech in the radio world just dumps raw Analog to Digital conversion output raw into a computer and the computer runs Fast Fourier Transform math on the massive stream of incoming numbers coming in to "find" and demodulate the signal. Then you apply the rules for the data stream found inside. "Software defined radio" as they call it.

(This is how the Stratux thing is so cheap. Those receiver dongles are little more than RF A-D converters. All the "magic" of decoding the ADSB IN signal is done in the processor on the Raspberry Pi. The receivers were actually created to receive over the air digital TV signals and just happen to adequately cover the ADS-B 978 and transponder frequencies.)

The OTA signal in the US is 8VSB, or 8 bit Vestigal Sideband. It's insanity to try to explain that here, but wiki has info if you need some help with insomnia.

https://en.m.wikipedia.org/wiki/8VSB

Basically, US TV broadcast is a 32 Mb/s data transmitter with a large amount of that 32 Mb/s used for forward error correction, or "mathematically duplicating bits" for receivers that are in fringe areas or that are experiencing a weak signal.

Laid over the top of that "pipe" (you can think of the RF part as a data pipe, in a block diagram) is the ATSC standard for the data format contained in the "pipe".

Cable TV ended up using QAM (Quadrature Amplitude Modulation) of the RF sent down the cable, and variants.

Again, just think of it as a data pipe implemented in analog RF frequency ranges, just a different standard than ATSC. It's an ITU spec for the data riding the QAM RF signal.

https://en.m.wikipedia.org/wiki/QAM_(television)

Some HDTVs have a QAM receiver in them. It's usually useless because most cable systems scramble their signals, but back in the day, if you paid for a cable internet connection, you could often put a splitter inline and run a T to a QAM capable television and receive a few "basic cable" local channels.

Cable is their own little world since they can change pretty much anything they want to on a closed RF system as long as the set top boxes can receive it. OTA typically won't change much since it would orphan the TV itself.

 

[Palmpilot]

...My understanding is that they're just normal analog signals but compressed digitally.

The existence of digital compression is not the central issue; it's that the way the video and audio information are encoded onto the transmitted signal is fundamentally different.

The point about antennas is that a different encoding method has no effect on how well an antenna does its job. An antenna with good gain, good directivity, and flat frequency response over the width of each channel will work well regardless of whether the signal's modulation is digital or analog.