What modulator would you suggest? I would like the iPhone apps (SiriusXM, iHeart) to play as well
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FM Frequency of the week for Nov 12th: 87.75 and 87.9
- Thread starter ZantennaG1
- Start date
As posted previously, I'd suggest the Whole House Transmitter. It's a little pricey, but it really gets the job done. Google their website or do a search on Amazon. I think they're $119. But you can also go to their FB page and find discount codes. I think I saw them there for $89, I actually have purchased three of them, two of whcich are discontinued models with fewer features than the current model, but still going strong after more than ten years!
In fact, interestingly, the school's surveillance camera system also used the cable. Each camera had a small modulator and would backfeed the cable in the 50s and 60s blocks, effectively acting as miniature headends. There was no scrambling or "security" other than the surveillance personnel telling you "don't tune these channels or a black hole will open up and consume the campus", and each classroom (thanks to the "Cable in the Classroom" stuff that began in the late 90s) had a TV and a VCR hooked to the system. Anybody could play Big Brother and monitor the cameras if they wanted to, and we sometimes did!
One of us got an office referral for doing so from one of the surveillance personnel; they "just happened to notice" the classroom TV was on 63 (cafeteria, north wall) when they stopped in for unrelated business, which of course was dismissed and placed in the dustbin by the school secretary, alongside all the school bus, janitor and substitute teacher referrals they got. It was a busy day, Mr Ahmed was subbing in room 307 for Miss Grindells and he was notoriously referral-happy, so much so it actually cost him his job with the district. For real.
H
Harvey_Dogg
Guest
I remember when I was living in the UK that a DXer had received WTTV from Bloomington Indiana there.
The year was 1979. Thousands of miles Indiana!
THAT'S an impressive hop!
I seem to recall reading an article years ago about the coronation of Queen Elizabeth in 1953. The gist, again IIRC, was that CBS and NBC went to elaboriate lengths with chartered aircraft to get film to New York for what amounted to same day coverage. Meanwhile, ABC set up a massive antenna/amplifier system in far eastern Atlantic Canada to see if they could capture BBC signals....and they did get some useable, if grainy, footage on the air first. I could be wrong about the details, but what stands out in my memory was that ABC scored at least a small scoop versus their bigger and more well-heeled competitors.
Wow, I'd love to learn more about that.
From near Detroit in SE Michigan--
87.75 MHz: Completely empty now. However in the past audio from WLNS Channel 6 Lansing was easily receivable in the Detroit area from 50-60 miles. This disappeared in 2009 when they went digital. Later on, I'd receive WLFM-LP "La Mega" from Cleveland, Ohio about half the time with a noisy signal. This disappeared about four years ago, and nothing since. I've occasionally tried for WRME-LP, but no luck.
87.9 MHz: Filled with micro-FM transmitters. When I'm in traffic on a busy expressway I enjoy leaving my radio tuned to the frequency. Some of these have impressive range considering they're literally transmitting microwatts, using virtually nothing for an antenna, from inside a moving vehicle. I live approximately 1/4 mile from an interstate expressway, and I have no trouble hearing transmitters on 87.9 for 8-10 seconds as they whiz down the road when I swing my yagi in that direction.
During an E-skip event in mid-July this year, I received a dead stereo carrier on 87.9 MHz. I could tell by the characteristics of the signal that it wasn't local. No audio present, just a carrier. Never did ID it.
An interesting frequency to be sure.
87.75 MHz: Completely empty now. However in the past audio from WLNS Channel 6 Lansing was easily receivable in the Detroit area from 50-60 miles. This disappeared in 2009 when they went digital. Later on, I'd receive WLFM-LP "La Mega" from Cleveland, Ohio about half the time with a noisy signal. This disappeared about four years ago, and nothing since. I've occasionally tried for WRME-LP, but no luck.
87.9 MHz: Filled with micro-FM transmitters. When I'm in traffic on a busy expressway I enjoy leaving my radio tuned to the frequency. Some of these have impressive range considering they're literally transmitting microwatts, using virtually nothing for an antenna, from inside a moving vehicle. I live approximately 1/4 mile from an interstate expressway, and I have no trouble hearing transmitters on 87.9 for 8-10 seconds as they whiz down the road when I swing my yagi in that direction.
During an E-skip event in mid-July this year, I received a dead stereo carrier on 87.9 MHz. I could tell by the characteristics of the signal that it wasn't local. No audio present, just a carrier. Never did ID it.
An interesting frequency to be sure.
The story I've read – from 1953 – had NBC using RCA's Long Island facility, where BBC-TV had been received (and captured on film) previously, on the off-chance some E-Skip or F2 DX would bring in UK Channel 1 from Crystal Palace. The timing would give NBC live pictures for at least a few seconds during the early morning, instead of just the audio feed over wirephotos. It didn't work.
ABC, with pennies to work with, simply took the CBC feed of its kinescope of the BBC coverage once it landed in Montreal in the afternoon, and beat CBS (NBC wised up and paid for the feed from Montreal) to the punch.
It IS theoretically possible to see Very Low VHF (Channel 2 and long ago Channel 1) at great distances. Sporadic E and F2 Layer prediction is statistical. There are graphs in the NAB Engineering Handbook 1960 Edition. Basically, if you can get a dish big enough, and focused antenna gain, enough to drive the signal into the statistically possible areas of the graph for significant percentages of the time, it can be done. It would still be hit and miss, and grainy like a Sporadic E VHF-Low Analog signal tends to be. The founder of Radiosoft, Peter Moncure, designed and made a 16 foot dish from materials available at Home Depot and Farm Supply stores. It could be rotated for both azimuth and elevation angle. By orienting the dish, he was able to get some 35 Channel 2s under fairly normal conditions.
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Looks like there is cochannel interference without offset.
What frequency was this on? What kind of antenna and receiver were used?
What frequency was this on? What kind of antenna and receiver were used?
Somewhere in the 40 MHz range. Whoever set this up had to have a good receiver and a high gain antenna, even though the transmission was via the F2 layer of the ionosphere.
There could be no co-channel interference because there were no other stations on the air in that spectrum. The US had experimental TV in the late 1930s, but they were above 50 MHz, IIRC.
I don't believe the FCC assigned specific channel numbers to frequency bands or individual stations until 1939. The "generic" allocations were 42-56 and 60-86 MHz at the time, with the 5 Meter ham band between them. The 42-50 MHz band was reallocated to FM in 1939.
As far as I know, there is no way to have a signal that exceeds inverse field. So at 4000 miles plus the elevations on both transmitting and receiving end in the propagation path, you do need very high gain antennas. And if you notice, from the graphs I mentioned, it is still well below the free space value for the vast percentage of the time.
Solar Cycle 17 was close to its peak in 1938. F2 propagation works well above 50 MHz during the peak of a sunspot cycle, but not all the time, of course. That's the main reason why that BBC transmission was viewable, if noisy and distorted.
A whole lot of luck was also involved. It's also the main reason why 44-50 MHz was removed from broadcast use after the war.
I'm absolutely going to have to try this out sometime, I am also less than a mile from my nearest interstate. Thanks for sharing!
Happy Thanksgiving,
Z
I've seen that footage several times over the years. I even showed it to my grandmum once (born 1934) who just brushed it off as fake, because of course, "we (meaning: Fargo, ND) didn't have TV until after the war", therefore it couldn't possibly have happened and it was an hoax. Of course she also knows and can prove beyond a reasonable doubt the universe is only 2,021 years old because she watches Lindsay and Hagee. Seriously. 🤦
What system were they using for that transmission? I believe the Beeb had system-A (405-line/376I 50 Hz VSB, positive modulation) in place by 1938 but that would have required RCA have a compatible set, wouldn't it? Did RCA import a 405-line set specifically for monitoring transatlantic DX, or were their experimental 441/30 electronic sets able to process "weird" video formats like that? 441-line died out when it was replaced with 525/60 just before we got into WW2.
AFAIK CBS' mechanical colour system of the early 1950s was a variant of system A but it effectively went nowhere because of the Korean War and incompatibility with existing NTSC sets.
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The distances between Newfoundland and Labrador to London, England, are on the order of 2300 miles. Here is the link to the NAB Engineering Handbook with the Sporadic E and F2 Layer Propagation Statistics at VHF Low TV to FM BC frequencies. They only go as high as 60 MHz for F2 and 88 MHz for Sporadic E. They are on Pages 2-26 to 2-28 at this link from David's site.
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This seems more plausible than what I originally posted. Thanks for sharing.
The transmissions were on what later became Channel 1 in the UK, with a video carrier of 45.0 MHz, and the sound carrier at 41.5 MHz. Yes, the sound transmissions (which were AM, not FM) were 3.5 MHz below the video carrier, unlike most other TV systems, even in the early days. The channel width was 5 MHz.
I have no idea if RCA had a 405 line receiver imported from the UK, or they built it. I believe the transmissions were received and filmed in New York.
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