Good point (after I erased the 2012 version from my machine). I did some Googling and found the 2008 version of the Blonder Tongue guide at: After a quick glance, it seems to have quite a bit on antenna systems, which are not used very much these days thanks to fiber and satellite backhauls.
Also, the 2009 version at:
The Motorola (now Arris) 2014 guide is what I like to use: (6MB) 302 pages.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Just like early electrical engineering books that explained the things that are just glossed over in current books. P Millet's website is a wealth of early electronics books.
-- Never piss off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-)
Yep. I downloaded a mess of those (mostly radio books) a few years ago and amd sloooowly going through them. What's interesting to me is that the origins or reasons behind various modern technical decisions and standards can be found in the old books.
However, I doubt any of this will help deal with the current OTA TV reception problem. I'm not getting any response from CaptainVideo so I guess I'll drop the project for now.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
captainvideo:
Your problem is two-fold: distance, and the all-digital broadcast requirement.
8 years ago, on NTSC(analog), distance would not have been been such an issue. You probably would have had snow on a lot of channels, but you still had picture and sound.Now, on ATSC(digital), you don't get certain stations at all, and frequent dropouts on others.
This is why I maintain that ATSC is 'less Green' than NTSC was: While with digital stations can piggy-back channels (4.2, 4.3, 4.4, etc.) they must BOOST THEIR SIGNAL for people with same OTA setup to receive them in the first place. And increasing signal strength meansUSING MORE ENERGY - something the folks over at Alt.Video.Digital.Tv fail to grasp.
You said you are using a 'parabolic' antenna currently - I'm assuming that is dish-shaped.
Have you looked into a variation on this form factor yet? It's all I'll ever use, even just 35 miles away from my market:
You may fail to grasp it, too. When you hear about TV stations (especially UHF stations) using millions of watts of power, they are referring to ERP - Effective Radiated Power. That means the actual power going into the antenna is much lower but the antenna has very high gain. Rarely do stations use more than a few thousand watts of actual power. The transmitter's actual power usage is a drop in the bucket compared to all the other energy a TV station uses for lights, cameras, HVAC, etc.
Pat wrote: "You may fail to grasp it, too. When you hear about TV stations (especially UHF stations) using millions of watts of power, they are referring to ERP - Effective Radiated Power. That means the actual power going into the antenna is much lower but the antenna has very high gain. Rarely do stations use more than a few thousand watts of actual power. The transmitter's actual power usage is a drop in the bucket compared to all the other energy a TV station uses for lights, cameras, HVAC, etc. "
________ Alright, say a typical medium market station has historically transmitted
2,000W as a NTSC. 2009 they go fully ATSC, still at 2,000W. Hundreds of letters from viewers flood their mailbox, and thousands of callers jam their phone boards about not being able to pick them up over the air with their new TVs. Most are from viewers in the outer one-third of the station's transmission radius.Station board deliberates, and after a couple months decides to increase transmitter wattage to 2,500W. Viewer complaints plummet, while greenhouse gas emmissions steadily rise to generate additional electricity as this scenario is mulitiplied across dozens of medium markets and many major markets.
Grasp that!
Yeah, I get that actual wattage is but a fraction of ERP, but it still adds up as many TV stations must increase their signal strength to cover the same audience area in digital as they did via analog.
On Sun, 6 Nov 2016 16:40:35 -0800 (PST), snipped-for-privacy@gmail.com wrote: (...)
This is too easy. WBZ has been running on reduced power for most of the last few weeks thanks to an antenna problem: No clue if it has been fixed, but judging by the lack of updates, probably not.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Don't forget the part where they have to modify their license at the FCC after hiring engineers to show that the increased power doesn't cause interference with any other licensed station in the area (or in Canada). That process can takes a long time and is expensive even before equipment is purchased. Most of the applications are on hold right now waiting for the auctions to be complete. ATSC has lots of issues, but creating a significant increase in greenhouse gases isn't one of them.
I was an engineer at an analog UHF station with a 5 MW EIRP, on a
1700' tower. The Comark transmitter used a pair of 65 KW EEV Klystons, for 130 KW of RF into the diplexer. A third 65 KW Klystron was used for the aural signal. That was in the late '80s, and our electric bill for the transmitter site was $45,00 a month.Solid state transmitters are modular, with around 1KW output, per tray. Look at the Harris Broadcast website for some actual data.
-- Never piss off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-)
I have a half-dozen such modules here, unfortunately with the water-cooled heatsink removed, if you want photos or to ask any questions. The modules are single or dual, using a BLF278 dual FET each. A 30W input is split into six to drive three duals, which are then combined to produce about 1KW from about 6KW input at
50V. The power supply rectifies three-phase 415V mains and chopped it to produce 50V at 60A, scary.A local ATV transmitter was using more than 50 of these to put 50KW up the spout. Pretty old-tech now though, the new lateral MOSFETs from NXP produce 1500W from a single device (two FETs), as Michael T has pointed out recently.
The really interesting bit to me is how simple the baluns are - just a couple of 8cm lengths of special hardline to match from about 12 ohms up to 50, at 225MHz. Transmission line transformers FTW! There's quite a few reference designs for this class of transmitter at
Clifford Heath.
Clifford, Michael:
So you're saying modern ATSC transmitters actually use less power then the old NTs?
I would try what the station engineer pointed out. You have a high gain antenna and a 28db amplifier, try it without the amp. I'm 51.9 miles* from a digital channel 36, I cut a folded dipole using
300 ohm twin lead, as I recall about 9.5" long. No Amp. It is no more than 10ft off the ground. I have zero dropouts and no audio problems.WTVY
Opps, just saw a glitch go by in the video.
Mikek
*According to TVfool.
Well that takes all the fun out of it! But do note my post of good reception at 51.9m miles with cut to length folded dipole, 10 ft off the ground. Channel 36, about 9.5" long. Mikek
Occam's Razor.
Sure, it can be done at 45 miles depending on tx power and frequency. However, Captain Video has an additional problem in the form of a mound of dirt in between his antenna and the station transmitter. or if you have Google Earth handy: The above path profile is NOT very accurate. I stopped working on the problem after Captain Video disappeared from the thread.
Incidentally, I sometimes can watch KMPH TV from Fresno, CA which is about 200 miles away from Ben Lomond. I live on the side of a hill which helps. The real culprit is atmosheric ducting and edge diffraction from two mountain ranges in between. It only happens a few days per year, usually in the summer, but the picture is 100% perfect.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
When I was a lot younger living in Kalamazoo Michigan, late one night I received a Wisconsin TV station across lake Michigan.
Mikek
The heaters in Klystons used a lot of power, that had to be removed as heat, in a water chiller. One 25 KW UHF transmitter that I rebuilt used a pair of 1.5V, 1000A heaters per tube. That was 3 KW, then the fan on the water chiller was a 480V, three phase, 5 hp motor. The circulating pump was anther two HP. None of this ended up at the output port.
-- Never piss off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-)
"The heaters in Klystons used a lot of power, that had to be removed as heat, in a water chiller. One 25 KW UHF transmitter that I rebuilt used a pair of 1.5V, 1000A heaters per tube. That was 3 KW, then the fan on the water chiller was a 480V, three phase, 5 hp motor. The circulating pump was anther two HP. None of this ended up at the output port. "
- show quoted text -
That doesn't answer my question of whether or not AT transmitters use less power than NT. Just a simple Yes or No would suffice.
The problem (defective transmission line to the upper master antenna on the CBS tower in Needham) was finally fully resolved this morning at
4:55AM. Lots more details atTony Matt
there is not a simple answer..
if the station stayed on the same frequency, then it can use lower power digital compared to analog. Digital fundamentally requires less power to close the link.
HOWEVER.
many stations also switched from a VHF frequency to a UHF frequency. The FCC allows more power to be used on UHF.
So in each case the answer is ...it depends.
I think it would be a gross exaggeration to say that digital TV is environmentally more friendly compared to analog because of power consumption.
m
There is another factor also. For the same bandwidth there can be several low resolution TV 'chanels' on the same ammount of bandwidth as one analog tv chanel.
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