I should’ve been clearer Dave. It’s a way of synching the signals up to the absolute millisecond so that if you pick up both tx’s at once, you won’t hear an echo or distortion . It’s a way of keeping 2 sites on the same frequency, as spectrum is a finite commodity
@@RingwayManchester I was wondering how they could sych the transmitters via a land line. To do that surely they would have to send the carrier frequency over the line which since it is in the 800kHz region would have to be coax cable. They would have to be synchronized in phase as well as frequency to prevent mutual interference.
@porridgeandprunes Precise frequency control and transmitter synchronization has been practiced for many years, even back to the war. (WW 2, The Big One, Edith!). It is not necessary to transmit the baseband signal between stations, a pilot signal which can be transmitted by relatively low frequency means, even wireline is used with proper gear which can monitor the two signals and make correction as needed. IIRC, KOLN and KGIN TV in Nebraska used such a scheme to keep two VHF transmitters synced to avoid interference.
Carrier synchronization has to be a lot more precise than milliseconds. It's done to share a channel, and minimize both low frequency intermodulation products (eg, 20-50 Hz), and the "whoosh" effects of carriers adding and cancelling at subaudible rates. Using specially conditioned phone circuits, thy might produce a hundred kiloHertz clock, and multiply that same base to broadcast carrier frequency at each transmit site.
The former KTRH 50 KW AM site in Houston, Texas is now a residence. The site was installed with a monster 50KW RCA transmitter as well as a lower power backup, 4 towers, IIRC, and a residence for the Chief Operator plus dorms for others was part of the main transmitter building. In addition, the TV transmitter site for KTRK-TV was also the home of Bob Sutton, his wife and family. It was used thus from its inception in the 50s until the new Super Whizbang tall tower went into operation and remote control was instituted. Downstairs were a pair of RCA TT-25 CH transmiters, upstairs a proper residence. There was a swimming pool, which was used to cool the dummy load. Rumor had it that Bob and the family would swim in the winter, the pool being heated by running the alternate transmitter into the dummy load. Ahh the good old days, we don't do things like that any more. Oh yes, both Bob and his wife were licensed operators, so she would watch the transmitter if he had to be off site. She would also man the controls while he was maintaining inside or behind the transmiiters. I was an Engineer at the studio while I was in High School, the start of a 62 year career as a Broadcast Engineer and Consulting Engineer.
I wish I was rich enough to have purchased the vacant Radio Australia site at Shepparton in Victoria when it was (sadly) closed down. Ready to go Shortwave Broadcasting station!
BT are going to be selling a lot of sites off in the near future. Just registered your interest with BT property. Just remember most sites have some form of asbestos contamination which will have to be remediated.
I don't understand a word of the technical stuff but love the storytelling, the in depth research and your obvious affinity for the subject matter. All power to your transmitter!😁
We lived out at Penmon Point from 2012 until 2015. We drove by the Penmon transmitter daily. I often wondered about the history, and had no idea it was still active while we lived nearby.
2:03 ... Look at that 1930s art deco... Low but big windows (with hoods and big ledges), rounded building corners, tall rectangle entrance (with simple cement hood), rounded driveway... JUST BEAUTIFUL!
A great offering as always, Lewis. Thanks so much. What a good idea to wrap the phone in tinfoil to stop RFI. I wish I'd thought of that way back in 1980 when the neighbour reported me to the police for ruining Coronation Street with my CB. Instead of sorting them a trap I'd have wrapped the bloody thing in Bacofoil for them! Nasty bugger, be was. Only had to ask, and id have sorted it for him, but he had to get the flying squad out to me. At least I got my own back when he reversed over the new lawn mower he'd just got from Argos. Must have forgotten he'd left the box behind his car when he went back out again. I was cleaning our windows. Really funny, that was. Almost fell off the steps laughing! Happy days!
I worked as a lineman for BT, and in the Downend area of East Bristol, subscribers often had a problem of hearing BBC Radio Bristol on their telephones, from the BBC transmitter on 1548 kHz in that area.
What kind of bandwidth did BT offer, as to bridge tap or loading free conditioned 4 wire "pairs", that might be used for sync signals in the 100 kHz plus range? (Thinking T- and E- carrier with special interfaces...)
We got antenna in Tywyn. Radio 5 live.We got a terrace called Marconi bungalows as he had a transmitter there and even visited once moring his motor yacht nearby. That would be some content for you in the future please
I enjoy your videos, I'm a radio geek too. I always love to hear and see presentations about old radio installations, like this one about Penmon. Thanks!
Shame to see the continuing sunsetting of AM radio stations. Also, I wonder if, should the site ever become completely disused, Arqiva would want to sell off the current transmitter building? I'm sure someone else would take it on and convert it to residency, like the original. These quirky buildings should be saved.
The mention of TX synchronisation took me back to the '80s and the effective end of analogue AM/FM mobile radio. Back then large organisations had wide area coverage schemes which were made up of multiple sites connected by landlines to a control room. So that they could have 'all informed' communications, rather than select base stations individually, trials were completed where the transmitters were operated in Quasi-Synchronous mode. Each TX had a high stability crystal frequency standard (around 5 Mhz I think) which was divided/multiplied to hold the transmitter to a very accurate frequency near to the nominal frequency. Each site TX would have a different offset in the few Hertz range. 10/15/20 Hz I seem to remember When the transmissions from multiple TXs were received in the mobile receiver the beat frequency between the differing frequencies was outside the pass band of the receivers audio circuits so did not interfere with speech or cause an annoying hum/whistle. The difficulty was that for the system to work well a lot of line conditioning was needed to compensate for the line frequency response, propagation delay and phase distortion as audio had to leave each transmitter at the same time and phase (much as in the video description) This was relatively easy- even then - as bucket brigade delay lines could be used but the system only worked well when lines were copper throughout. If a circuit was routed via an telephony carrier system then group delay and frequency shift, in the carrier system, then conspired to make make the system somewhat unstable. In the organisation I worked for a colleague designed a Vestigial Sideband interface to the lines/carrier system operating with a 3.7 kHz carrier taking the lower sideband modulation to pass down the 300-3900 Khz carrier channel . This was able to stabilise the frequency / phase shift and delay in the carrier system to around 1 degree of phase shift for 1 degree of frequency shift. Unfortunately this was never used in anger as MPT 1327 came along and our nationwide network was developed using that instead of CCIR SelCall and DTMF dialling.
A little pronunciation thing: Llanddona is pronounced with the DD sounding like the TH in "the" or "thou". So LlanTHonna. I hope you enjoyed your stay. I once as a kid got a 50p out of the coin return of the cigarette machine in the entrance of the pub at Red Wharf Bay. We were staying in a caravan in Benllech and found we could pick up Winter Hill UHF on a black and white portable TV.
i saw two sachets of brown sauce on the road and went to stamp on them, i was disappointed when they didn't go 'splurt' but i remember my dad wishing he'd found it then saying: you'll share half of that with your sister [a preemptory clip around the ear] and don't complain about your pocket money next week. was a tenner. we were rich, me and sis, all summer long! 😊
My Dear Lewis, your videos are brilliantly presented with well thought out material. Your narration is sincere and very pleasant to listen to. If only the rest of RU-vid presenters would follow your lead.
I would love to live in this. Webbs Garden Centre opposite the Droitwich transmitter was receiving BBC Radio 4 through their phones and needed filters. I know this as I had a tour of the place.
I live in Sélestat, France, near the German border. In the early days of ADSL internet, we still used filters on the plugs of our landline phones. One day around 2009, my filter broke : I could hear loud and clear the signal of Radio France (France Bleu Elsass 1278 kHz) whose transmitter is located just in the southern suburbs of the town. It was 200 kW power at that time I believe. I bought another filter, but still used the defect one from time to time for the fun of listening to landline radio. Since that time, I don't use phone on landline anymore, only via IP/ADSL, and the transmitter has been shut down.
Interesting video, I went to uni in Aberystwyth and I'm not surprised it was a bit of a radio dead zone given how enclosed it is by the mountains; it's such an underrated part of the country though! I wonder who the last broadcaster on medium wave will be in the UK? I reckon Caroline will keep going as long as Ofcom are willing to let them, and there'll probably be the odd pirate as long as public webSDRs are a thing.
That picking up the audio on a landline handset used to happen in Lincoln too when BBC Radio Lincolnshire was on 1368 KHZ AM with emissions also hitting the top of the Long Wave Dial.
Another excellent video, Lewis! Many thanks! Maybe an interesting future topic would be the move to VHF/FM transmissions in the UK following the end of the second major world disagreement. There was a lot of interesting technical R&D involved.
I was living in a home that my brother owned 14 years ago and I heard voices from the vents of HVAC system especially at night and I had no radio on and I searched high and low for a radio that may have been left on and I do know that it had a pond/lake shore and I did see radio towers from near the town I lived by but I was at least 5 to 7 miles from the town and maybe further from the towers and I'm not sure if they were an am tower or what cause I know am towers can transmit signals through the ground from the ground radials I've seen videos of it.
Thanks for that - it’s very interesting how the BBC radio network developed quickly and ambitiously during the 1930s ( and again in the 1950s with FM).
Interesting video, Lewis. It's story reminds me of the huge radio tower atop the Westward Ho hotel in downtown Phoenix. It has a long history starting in the 1920's, from radio to tv to finally cell phone service. When I was a kid, the FCC would come to town twice a year to give radio exams and in the banquet room of the Westward Ho is where i upgraded my ham licence.
Have you considered doing a video on the first (1927) trans-Atlantic telephone links between the UK and USA? Absolutely massive sites. In the USA the transmitter was at Rocky Point, Long Island, New York (the Radio Central complex)¹ and the receiver was at Houlton, Maine. In the UK the receiver was at Cupar, Scotland (not sure where the transmitter was). ¹ Just a kilometer away from Tesla's Wardenclyffe Tower.
I used to live very near there, always wondered what it was for. Also I never figured out how the transmitters coped with the issues of time dilation in Wales resulting in frequency drift.
I used to live near Cheltenham in the 1960s; Birdlip radio station and the associated Winstone station were two Civil Aviation Authority airway stations, a few miles apart on top of the Cotswolds; I think Birdlip was transmitting and Winstone was the receiving field; Birdlip had a substantial building with consoles, but Winstone was just a wartime single brick structure, dilapidated when I first found it, but evidence of past antennae fields at both sites. I’d be interested to see a history of these 1950s era airway stations, built for air traffic control and traffic lane management.
So very interesting..Thank you.. For anyone interested in radio history, recommended reading is “The story of broadcasting”, published by A. Burrows in 1924. There is a freely available e-version on the internet. It tells the story of the start of broadcasting by the BBC.
I'm upset now, how the hell did I miss it when it was first published! Damn RU-vid notifications not working again... I live not 2 miles from here, all I knew about the mast was that it was the BBC mast, in my naivety I thought it was BBC TV, didn't think of radio! I know people who've live in Beaumaris/Llangoed/Penmon for upwards of 80 years, I am going to make it my mission to find out as much as I can to fill some of the gaps... Really interesting video, more interesting facts with which to bore visitors, thanks Lewis! Little upset you didn't say hi as you passed lol And yes, I for one am waiting for the Llanddona video!
Penmon is nowhere near Portmeirion! Penmon is eastern Anglesey, Portmeirion is Cardigan Bay... But yes, The Prisoner was filmed at Portmeirion. And my god do they milk it! lol
I know it as the BBC transmitter, always thought it was where BBC TV was transmitted from, with ITV up at Llanddona, little did I know until today it was BBC radio only!
Would be great if you could give a bit more details about the antennas itself. It seems like the whole mast carries the signal, but isn't there something like a big ground plane necessary? Like with old monopole antennas on cars? I'm fascinated how antennas work. That they give electrical power to the air. It's still mind blowing to me. Thank you for the cool videos. I would love to see someone covering german transmitter sites, like you do in GB.
Fascinating.. Guess we'll never know if the owners of the old build really know it's origins. I suspect yes as the deeds would have made interesting reading. I'm surprised the tower has not been commandeered for mobile and Tetra (Or whatever it's called now). Perhaps the single point of connection at the base puts tenants off it on the premise of reduced physical stability, especially where microwave links might be needed....?
No, thats perfectly stable and normal with even big towers. A cellular user would need to get the base insulator bridged though so the tower would then be earthed. I'm also surprised it hasn't been let out to someone else. Thing is though, ideal sites for MF broadcast are often not ideal for cellular use. Arqiva probably have an engineer not far away from there with keys. A look inside would be interesting. I wonder if the tx etc is still in there.
Once in a while, I pass this site to visit the south side of Red Wharf Bay. Passing the chain link fence doesn't give much away as you say, the older building is now a domestic dwelling. I did wonder whether it was a 'Home Office' facility for communication. I had no idea it was for BBC Radio 4. Sadly Radio 4 on Medium Wave is now completely closed as of 2024. Similarly because of the terrain, local Radio Cumbria further up the coast is valiantly continuing on 756 and 837 kHz.
Why did the BBC use such short antennas? 250' is a quarter wavelength around 1 MHz. At the low end of the present AM band, one might choose a 400+ foot tower for base impedance and reasonable radiation efficiency, though larger stations favor half wavelength to reduce sky wave at night, and up radiation efficiency a touch more.
In the end, did BT determine and remedy the cause of interference to landline phone services? It is very sad that AM radio stations are being switched off in so many areas around the world, digital radio has its place, but for some situations, analogue radio is preferable, especially for long distance listeners and listening to sports events while attending said event live.
I see from your and from other channels that there are many derelict transmitter sites, but vandalism appears to be quite out of the ordinary. Two questions - are the sites till under active surveillance and security? If not, why are they allowed to stand and decay? Most governing bodies would demand they be either kept up or demolished as a hazard. Your thoughts?
Buy a site where they need improved cellular srevice, then rent the tower to the telephone company.. i knew a guy who owned a lot with a cellular tower.. they pay him big bucks to put their tower on it...
Here in the UK they're in the process turning off all the AM / MW transmitters. So radio will only be on FM / VHF and DAB (Digital Audio Broadcast), as well as online.
@@michaelturner4457Stupid, stupid move. AM MW and Shortwave broadcasts are still viable and much more durable in time of accident or disaster. Nowadays there are no AM radio in many automobiles. You can bet I keep a portable in mine, with good batteries.
Dear Ringway, some great historical research here. I wonder if L. Hotine was related to Brigadier Martin Hotine who was reponsible for the 1936 Ordnance Survey of the retriangulation of the UK and devised the triangulation pillars that we know today. (Sorry you know I am a sad b******d interetsed in such matters. :-)) . As for the warning signs about pacemakers and implants, I think if you have made it to reception without keeling over you should be okay. Great video and drone flying. And Manucnians complaining about anything? Even Welsh language programmes? A pure fabrication. Best wishes Phil Sharp,
