this is bbc news. the headlines: a big fire has broken out at evin prison in the iranian capital, tehran, where hundreds of political prisoners, and dozens of dual nationals, are held. in videos posted online, gunfire and sirens can be heard. roads to the prison have been closed off. the chinese leader xi jinping is addressing the 20th communist party congress, which has opened in beijing. in a report on the five years since the last congress, he cited the many accomplishments of the communist party in achieving what he called socialism with chinese characteristics. britain's new chancellor of the exchequer, jeremy hunt, has admitted the government made mistakes when announcing unfunded tax cuts last month and that very difficult economic decisions would now have to be taken.

to public finances after weeks of turmoil. now on bbc news, click. this week, we are celebrating 100 years of the bbc in 23 minutes. we will look at the secrets behind the broadcasting technologies that changed the world. a radio legend talks about legendary radio. i used to set my watch by the pips. my favourite pip is always the last one. lara watches tv with friends. i guess the idea is we're not actually meant to be in the same place.

and in the quest for greener energy, 0mar discovers a tasteless fluid called water. it goes in your mouth and then disappears? today we are literally stepping into history. we are at alexandra palace and this place has seen it all. that's the studio in there. 2022 marks 100 years of the bbc. goodness me. what began with a single radio transmission has transformed into a global broadcaster. in that time, it has covered the biggest events of successive generations, working to inform, educate and entertain the nation. and throughout those hundred years, the bbc has been pushing the boundaries of broadcasting, embracing and sometimes even creating the latest technology. 100 years of broadcasting. it is amazing when you think of it. you don't look a day over 30. and this studio in alexandra palace has a very special place

in bbc history. in 1936 the bbc television service was launched right here on this spot. performers and orchestra would have been here. and a huge camera here! singing. and what viewers saw was this. this is adele dixon performing with the bbc television 0rchestra. she is singing a song called television which was written especially for the opening night of... television. it was broadcast to viewers across london and the home counties through the transmitter on alexandra palace, marking the beginning of what was then referred to as high definition television. yeah, don't laugh. before that, television was just an odd fuzzy experiment small, selected audiences. and behind—the—scenes there was a bit of a battle going on. see, the bbc had actually opened up two studios at alexandra palace.

this, studio b was a mechanical system which was made byjohn logie baird andit produced an image like this. meanwhile, in studio a, they were trailing an electrical system by emi and what they would do as they would alternate studios and systems on different days so they could compare the results and it turned out that emi's images at 25 frames per second were double the quality of the baird system. the baird camera was enormous. and if you are filming with the baird system you need quite a lot of make up too. gall... é�*zé jag very sexy. the emi system on the other hand could capture a well lit studio perfectly fine, so the winner really wasn't hard to choose.

under the lid of the emitron was this, a cathode—ray tube which is basically an old tv working in reverse, capturing the pictures instead of showing them. it stayed in use without much change for many, many years. the coronation of king george vi was the first time the cameras were used outside and the broadcast was watched by about 50,000 viewers. however, it was the coronation of his daughter that really brought television into our homes. 70 years later, many millions of us watched the queen's funeral on smart tvs, phones, laptops, or on huge screens around the country, demonstrating just how far technology has moved on. but now, let's go back before the time of television to the very beginnings of the bbc in 1922.

of course, way before television came radio and what do you need to broadcast a voice to the nation? you are going to need one of these. and one of the most iconic mics ever is the bbc—marconi type a and when i say iconic, it is an icon. literally. one of our colleagues, joe leates, really, really loves this microphone so we sent him to the archives to see what he could dig up. not many are around these days, especially ones that work, as it became tradition at the corporation to empty the insides and plate them with gold as leaving presents for announcers. but what a thing to have on your mantelpiece. the good news, though, is here at the bbc, we have plenty. you'll notice it looks pretty hefty and it's actually really big, so it tended to stay in studios and leave the world travel to its smaller counterparts. but what it missed in

adventure, it made up for in the circles it socialised in. it played host to filmmaker alfred hitchcock, poet ts eliot, legendary author hg wells and that's charlie chaplin. british singer and legend petula clark began her career aged nine in front of a taipei. now, lads, it's time to send along personal messages and greetings to you.... it was just to say hello, we are ok, don't worry about us, and give them a little bit of home news and that was it. during rehearsal there was the most enormous air raid and the producer asked if one of the kids could come up and sing a song or say a piece of poetry to calm things down. so i go up on stage and they put a box so that

i could reach the microphone, it was one of those big bbc microphones, you know. singing petunia clark there. so while setting off singing careers and directing the second world war the microphone was clearly doing something right operationally, too. eyes had been on the groundbreaking ribbon microphone invented by rca, the radio corporation of america but it was a little too expensive. so in true bbc form, they made their own for less than 10% of what rca were charging. nice going. the taipei stayed in use by the bbc from 1934— 1959, a whole 25 years. that is a long time when technology was developing so rapidly. so what about inside?

that taipei is called a ribbon microphone. that's because behind the perforated cover is exactly that, a ribbon of metal. with the help of one of the trusty bbc engineering manuals, we can see that soundwaves come in from either the front or the back and hit the ribbon in the middle. so thin that it flexes and wiggles when the noise vibrations in the air hit it, just like your eardrum. the flexing moves the ribbon through a magnetic field the microphone then connects to studio equipment that amplifies this up to a level that you can hear, and because the ribbon is a flat piece of metal, it can interpret vibrations from both sides. finally, of course, we want to hear a bit more of how the microphone sounds. well we can hear it in use by sirjohn snagge, the bbc voice who made the first annoucement of the d—day landings, and who went on to become one of the first

bbc television news readers. he specially recorded with the microphone for this demo tape. this speech is recorded from a bbc—marconi velocity ribbon microphone, type axbt. i will leave it to you then to make up your own mind for how that sounds. for lack of time, it was not l possible to- joe there. now, if you are a fan of radio, i mean, really a fan of radio, then you will know what this is. pips. they are called the pips and when you hear them, you will know it is something o'clock. i find them quite soothing. but have you ever wondered why they exist? ships. the pips tell ships what time it is and help them navigate. at the height of the british empire, britain had a lot more ships than anyone else anywhere in the world and their maps all needed to follow a strict

format so they could figure out where they were. the centre of all british nautical charts was the greenwich meridian, 0 degrees, and each vessel also kept a fancy clock on board that told them local time at the meridian and helped them to calculate their position really precisely. but over long journeys, how could the captains keep those clocks accurate to the second? well, to bring in the new year in 1923, the bbc ran an experiment to broadcast the midnight bongs of big ben on the radio. it was a bonging success and the following year the first fully accessible time signal, the greenwich time signal, started to be broadcast every hour and it hasn't stopped since. the pips, as they were known, were generated by a swinging pendulum fitted with electrical contacts.

so now you could have accurate greenwich mean time literally anywhere that you had a radio. the pips have become legendary, a symbol of bbc radio, and who better to tell us about them than another legend of bbc radio, tony blackburn. archive: welcome along - to the tony blackburn show this morning for this tuesday the ninth of december. my thanks, as always tojohn dunn for swinging us up until the seven o'clock hour. the pips have always been a favourite of mine since 1967 when ijoined the bbc and opened up radio 1. archive: good morning everyone, welcome to the exciting news - hour of radio one. everybody else finds it a bit weird that i like them but i do. i love them. on my programmes, i used to promote them, particularly as my favourite pip is always the last one because it is slightly extended. it is very bbc but they were very useful at one time because before all of these smart watches you would just have an ordinary watch which used to probably lose a minute a day or something like that. so i used to set my

watch by the pips. nowadays of course with the smart watches and things like that you don't need it quite so much but it is still very bbc and i still like it, i wouldn't want to see it disappear. archive: and off we go with | the next one and what a lovely sound this is as well. the original clock that kept the time still sits in the in the museum at the royal 0bservatory. in the 60s, though, an atomic clock started doing the job which stayed in use until the 1990s when it transmitted its last pips from the royal 0bservatory. ever since then, the bbc has generated its own pips from its atomic clock buried deep inside broadcasting house which uses gps signals to stay synchronised. so the next time you hear these, you know that they come from this. pips 0k, time for a look at this week's tech news now. first up mark zuckerberg has unveiled meta's new vr headset

at its annual event held for developers. with a pricetag ofjust under $1500, is almost four times the price of meta's current headset. the british artist damien hirst has begun burning hundreds of his own pictures as as part of an experiment to test the value of physical paintings versus digital works. buyers who bought pieces from his latest collection were asked to choose either the physical artwork or the nft representing it. those who chose the nfts were told their corresponding physical pieces would be destroyed. the nfts all cost e2000 and they all have the possibility of being traded in for a physical artwork and these ones are the ones that people decided not to trade in. could riding on rollercoasters cause phones to call emergency services? according to the wall street journal, six emergency calls were made at one us amusement park after rides caused new iphones to react as though

they had been in a crash. apple didn't deny the fault and says the tech will continue to improve over time. and a healthcare company has teamed up with microsoft to make health products more accessible for blind people. in new enhancements to the new microsoft seeing ai app will provide important label information for more than 1500 everyday products, including toothpaste and aspirin. birdsong and babbling water. listen to that. gorgeous, isn't it? we all love a bit of nature, don't we? and programmes like springwatch, an annual tv show that watches british wildlife during the changing seasons, offer us a unique insight into these animals' lives. for programmes like springwatch to run, it requires a lot of time, effort and equipment. with over 60 crew and 35 cameras, it is one of the biggest outside broadcasts the bbc offers.

so it needs a lot of power. but in an effort to be more green, and protect the wildlife they feature, springwatch has taken a number of measures to cut down their emissions. we turned up to one of their production bases to see what they are. this is the big one — the green hydrogen generator. why is it called green hydrogen? because the process of electrolysis used to separate the hydrogen from water is powered by solar energy. if it was powered by fossil fuels then it would be known as blue or black hydrogen. not so good, kind of defeats the purpose. but with solar, you are using clean energy to make clean energy. compared to diesel generators, it is a 3.5—tonne reduction based on what we normally do with a couple of weeks use. a couple of weeks, 3.5 tonnes? yeah. the only two things that this outputs is heat and brand—new water, the newest water in the universe. this is where it comes out. it is all there is, it is brand new. it's absolutely pure. tastes the weirdest thing, no taste at all.

it is all texture. nothing to it. no minerals, no nothing. not keen? no, it's fine, itjust goes in your mouth and disappears. massive operation. this is the site we are working on, 4,000 acres we have access to, which is a huge area to cover. so we have been putting fibre across the whole site and as a way of trying to keep things down, working on c02, we put fibre down once and leave it for the duration. we have nodes up and down the site where we can connect to as we come back and go live. you must have your favourite name here, right? i know what my favourite is. we'll go for that. they also have solar—powered cameras they have installed on sites such as in this beehive here.

so there is a sustained effort across the site to lower emissions, but also off—site a lot of producers are now utilising the work from home way of working so they don't spend unnecessary fuel going to sites. and for the really remote sites, they are using solar panels to power up the recording set—ups. there is also one more special thing about this system. it uses al to flag a clip when an animal appears, and tries to identify it. so this year we have 32 wildlife cameras across the site. all of those need to be monitored and logged for activity 2a hours a day. that is a fairly intensive process when it comes to labour, so bbc r&d have come up with al tools that will help identify different forms of wildlife. they are very accurate. species of birds are often quite distinct, so it's very good at identifying birds of different shapes and colours, so it performs very well. these changes aren't without cost. as mentioned earlier, the green hydrogen generator isn't normally as cheap

as a diesel powered one. and new ways of working always require some adjustment — but the team want to do what they can to set an example. it hasn't been seamless, but they were very determined to take advantage of that new carbon—friendly technology and we pioneered it. using new technologies that have been pioneered in science and bringing them to media is, from my point of view, really exciting. and the guys in the van here, our story developers, we asked them "was that the male, the female, "that one, that one"? ai and all that technology we have got is telling us instantaneously. but we are not going to save the world on our own, we won't save the reputation of the media when it comes to environment on our own. we need sport, we need light entertainment, we need drama, everyone has to buy into this. change is never convenient or easy, but the team here at springwatch are taking strides forward to help the bbc reach its goal of net zero greenhouse gas emissions by 2030. and here's hoping when it comes to powering our devices, this is a sign

of things to come. 0mar there in norfolk. meanwhile at manchester's science and industry museum, 100 years of the bbc is being celebrated with an exhibit featuring broadcast artefacts, plus a few more recent additions. this funky looking box was a prototype which was an early part of the bbc�*s research and development project for storing your data yourself, so the idea was that the device would keep track of what you are listening to and watching, but that data was just yours, unless you chose for it not to be. it was inspired by a new vision that sir tim berners—lee has for the web, to rethink the ownership of our data. back in 2018, he told us about what he calls a mid—course correction for the internet, an idea called solid. imagine a world where before

you use an app it says to you, where do you want to store this data? all across the data spectrum, you have complete control over your private and personal data, which is very exciting, an exciting vision, i think for those people who get an inkling of what it's going to be like. right now when we interact with companies over the internet, often without even thinking about it, we give them our data — lots of it. every website, app or streaming platform gathers information on us, our name and age, what we like to share, our files, photos, in fact all of our online browsing habits. platforms use this data to create recommendations, improve algorithms, or sometimes just for the purpose of selling it. but tim berners—lee's idea turns this on its head, giving power back to the individual. with solid, as users travel across the internet, all their data is stored in something called a pod.

this is an individual�*s databank in the cloud which only they, or those they give permission to, can see. so instead of the data freely flowing to companies when they want to access it, they have to ask for the user's permission. if this is approved they can look into the pod to view or add information. with pods, because you are in control, you can share what you have watched or listened to on one platform with the others, something the companies would never want you to be doing, but it means you could get more personalised recommendations. and if you want to stop using a service, you can cut off access to your data. or you could, even more dramatically, delete the pod, destroy all the data, and remove all trace of anything you have ever done on the internet. yes, it is a big endeavour, but it is not a ridiculously huge endeavour. what is exciting right now is just at the point when we should be broadcasting this, we now have also a start—up, inrupt.

for years on, it is a reality with bbc r&d working with inrupt to bring it to life. charlie, you have invited me to a party but it is no ordinary party. no, no it's not. it is bbc together, it's a watch party, but the particular difference here is your data is being protected in any way. watch parties allow friends to stream the same content at the same time, and they have exploded in the last few years. something like a third of under 30s actually had a watch party in the last 12 months, and it is really growing. so we have kind of built on the bbc�*s watch party and added the data pod element to it. as users log in, behind—the—scenes the software creates a pod for each person. here we go. and when you stop watching, this bbc trial shows you what data has been collected.

we couldn't do a watch party without storing some data about you. the difference here is we are storing that data away from us, in your pod that you control. it's notjust about entertainment — this is just one example of something you could do with this system. that's right, exactly. we have seen interest from healthcare providers, where your health data is incredibly personal to you, you don't want anybody getting access to that. no, people are more obviously sensitive about that. exactly. there is a project in flanders happening at the moment where some of your educational qualifications are being put into a pod. solid is just one of many ideas aiming to help us own our data. others, even allowing us to sell it, have failed to take off at scale — maybe the incentives haven't been right. but that could change. bbc r&d and tim berners—lee certainly think it might, and they have both been right before.

minutes. yeah, you're right. 0k! let's leave it there, shall we? thanks for watching and we will see you in another hundred years. 0r hopefully sooner, bye! hello. the weekend started with plenty of showers, some heavy and thundery in places, gusty winds. as one area of low pressure begins to pull away from the uk, there'll be fewer showers around for part two of the weekend. for much of the uk for much of the day, it'll stay dry. this is that area of low pressure pulling away. however, this is another one moving in towards the south—west later in the day, so there will be

some wetter weather pushing north again by sunday evening. let's look at how sunday begins. there's still some showers around, especially in scotland — some heavy ones in the west. temperatures a little lower than this in rural parts. a cooler night across southern areas of the uk. the showers in scotland will tend to fade away and will still be around the northern isles in the afternoon. as you can see, though, elsewhere in the afternoon, for most places, it'll be dry, there'll be some sunny spells. cloud increasing in northern ireland and, indeed, southern england, south wales, so you could see a few showery bursts of rain heading in later in the afternoon and by evening, it'll be turning much wetter in northern ireland as this moves north. temperatures pretty much where they're going to be over the next few days — around 12 degrees in glasgow, 18 in london. very wet on sunday evening in northern ireland. we'll see some wet and windy weather pushing north across the uk overnight and into monday morning. the winds picking up again through irish sea and adjacent coasts and into western scotland with gales in places. a much milder night, especially

across wales and england. closer to that area of low pressure on monday, it's northern ireland and northern england that could well see some showers but it'll be scotland bearing the brunt of some heavy downpours once again. for much in england and wales in the afternoon, actually, it'll be dry, broken cloud and sunny spells and not as windy as it still will be across the northern half of the uk. temperatures on monday may well be a degree or so higher in places. as we go into tuesday, this latest area of low pressure pulls away, then there's a ridge of high pressure settling things down. there is another area of low pressure, though, sitting to our south—west. and whilst on tuesday, most places are looking dry — just the odd shower here and there — cloud mayjust start to increase across eastern scotland, north east england. the breeze will pick up later towards the south—west, closer to that next area of low pressure, which will gradually, on wednesday, start to feed some outbreaks of rain in from the south—west, whereas many places will actually have another dry day but wetter weather becoming more widespread again towards the end of the week. that's your forecast. bye for now.

this is bbc news, i'm lucy grey. our top stories: gun shots are heard after a huge fire breaks out at a prison in iran's capital, tehran. state media reports at least eight people are injured. china's communist party congress gets underway with president xijinping expected to be given a third term in office. as the uk's prime minister fights for herjob, the new chancellor signals he'll make major changes to her economic policy. we have some very difficult decisions ahead, difficult decisions ahead, difficult decisions on spending, witchery is not going to rise as much as people hope. i will be asking all government departments to find additional efficiency savings. and, a chiller in chile.