I work in radio broadcasting. FM transmitters are inherently mono devices. The stereo encoding is often done by a separate device that’s not even part of the transmitter, sometimes the audio processor before the transmitter, sometimes the RF exciter or sometimes even the RDS encoder. In stereo FM broadcasting there is a 19Khz pilot tone which tells the radio it’s a stereo signal. This is what lights the FM stereo light and is why audio broadcast on FM had a strict and sharp audio filter which cuts any audio frequencies above 15Khz otherwise the audio high frequencies (up to 20Khz) can interfere with the 19Khz pilot tone (which you can’t hear but it’s there!) I wonder what it sounds like to dogs near FM radios! 😂if the pilot tone level is set too high at the transmitter some (young!) people on some radios can actually hear it! Also if the audio frequencies are not cut above 15Khz this causes the radio to drop in and out of stereo due to the audio frequencies encroaching onto the 19 Khz pilot tone. The audio input into most FM transmitters is actually a single multiplexed audio signal (not a separate left and right) so in effect the FM transmitter is actually mono but is blindly transmitting an encoded audio signal including 19 KHz pilot tone. Great little device in this video! Keep up the great work! Craig - Australia
@diracflux
Жыл бұрын
Fantastic explanation. Thanks Craig.
@RJDA.Dakota
Жыл бұрын
When I was much younger when we had the CRT screens , the above 15 kHz tone from the screen itself would drive me crazy.
@worldcomicsreview354
Жыл бұрын
Not entirely related, but ages ago I read a story from a collector of acoustic gramophones. He said a toddler he knew really liked one, but would cry when another was played. Maybe there was some sort of harsh screech coming from it that adults couldn't hear
@cooldudicus7668
Жыл бұрын
Is it possible to hear the 19 KHz tone if the radio is about out of range of the transmitter? I had heard a carrier tone on FM radio when driving in the past. It happens around the time when I start getting out of range of a radio station.
@StackOverflow80
Жыл бұрын
It's right, but I guess these days in pro area all the stereo mux is generated digitally and fed into FM modulator of the transmitter, or even entire high frequency FM signal can be generated digitally, amplified and fed directly into antenna. Pilot signal, besides making stereo light on, has another important role, and it is to enable to recreate suppresed 38kHz subcarrier (it is suppressed to save modulation power, also pilot signal is quite weak for the same reason). Pilot signal is exact half frequency of the subcarrier and it is in phase with it. Because early stereo decoders used simple diode demodulators, the subcarrier and both sidebands present was mandatory. Nowadays of course only one side band with no subcarrier would be sufficient, but back then, to be able to keep stereo decoders simple, such arrangement was necessary.
@guni82
Жыл бұрын
Here in Austria back in the 90s radio stations used to turn off the stereo carrier during traffic announcements so you could understand it better when having bad reception.
@Knaeckebrotsaege
Жыл бұрын
My Blaupunkt car radios from the 90s to mid 00s always force the traffic announcements (the ones that cut into whatever tape/cd/mp3 you were listening to) to be in mono. You can actually force this if you have one of those little FM transmitters and send out a "hinz triller" over it. The radio will respond by pausing tape/cd/mp3 playback, increasing the volume and switching to mono for as long as the traffic announcement lasts
@unclehogram
Жыл бұрын
@@Knaeckebrotsaege I remember Blaupunkt releasing radios that worked this way in Germany, think it was called ARI? Would switch to another station for traffic messages. Turned it off because keine deutsche sprechen but it WAS cool.
@PascalGienger
7 ай бұрын
@@unclehogramARI was the proprietary system to indicate a traffic information is broadcast. This feature has been included in RDS nowadays in Europe.
@Rich_123
Жыл бұрын
This is instantly one of my top Techmoan videos. What started as an obscure piece of AV history led us through a tunnel of how FM stereo came to be what it is today. Some great bonus tidbits in the comments too!
@EzeeLinux
Жыл бұрын
FM stereo radios in cars often have what is known as a "blend circuit." It reduces stereo separation and cuts noise as the signal gets weaker.
@InfiniteColorsMusic
Жыл бұрын
I was about to write exactly this. A tuner chip I worked with goes as far as giving the possibility to configure the response slope of the stereo blending circuit. On such tuners, the "stereo" indicator (if at all implemented) usually comes on if there is at least some stereo signal in the mix (that is, if the reception hasn't been switched to full mono)
@XMguy
Жыл бұрын
They try that Blend with HD Radio in the states as well. Annoying.
@derek20la
Жыл бұрын
@@XMguy You're confusing two different things. What Joe meant was as an FM signal gets weaker and noise level increases, radios in modern cars will "switch off" stereo in decreasing steps until it is completely in mono. What you described is when a station broadcasting in HD Radio fails to keep their analog and digital signals in sync (which happens far too often). If the digital signal fades, the radio is supposed to seamlessly switch back to analog FM, but when the sync drifts, switching causes a 1 or 2 second audio skip. Only the station can correct it.
@EzeeLinux
Жыл бұрын
@@XMguy HD only works IF you have a strong signal anyway. The US iBiquity system is garbage. :(
@XMguy
Жыл бұрын
@@EzeeLinux It should not be a license based system.
@fsphil
Жыл бұрын
If you capture that stereo output at a high enough sample rate, you may be able to see the 19khz pilot tone and the stereo difference signal at 38kHz in Audacity. It might even show the extra noise that lives up at 38kHz causing the stereo-only noise.
@SeanBZA
Жыл бұрын
Going to also need to sample at a much higher rate than the more common 44kHz, as those tend to start rolling off from 12kHz, and have a pretty steep attenuation at 19kHz, specifically to avoid birdies from beating with that pilot residue. You would need to sample at 96kHz or higher, to get enough bandwidth to accurately reconstruct the full stereo signal digitally, and would also need to get an output direct from the FM detector as well, as most of the audio chain would have low pass filtering that strips this. Pretty much excludes all common ADC units, you would need one that is designed for high sample rate and high bandwidth, definitely not an audio one.
@fsphil
Жыл бұрын
@@SeanBZA Yes, I should clarify I meant capture the special stereo output socket that is used for the dongle - it should be providing the entire baseband signal, stereo sub-carriers and all.
@y0uRF4t3
Жыл бұрын
@@SeanBZA High quality professional audio interfaces sample a 192kHz, 32bit, for example my Steinberg UR22C.
@SeanBZA
Жыл бұрын
@@y0uRF4t3 Yes, but a lot of them do low pass filtering to remove the ultrasonic signals out. 192kHz sampling just means that you can use low order filters, and not have too much phase noise in the signal, unlike the terrible high order Bessel filters you need with 44khz sampling, which gives some truly odd phase shifts in the audio passband, as a consequence of needing to get at least 30dB of attenuation at 22kHz so as to prevent aliasing. Higher sampling rate then a digital downconversion makes the analogue filtering much simpler, and more linear.
@PaulsOldVids
Жыл бұрын
Not all radios filtered out the pilot tone and this could interfere with the bias and noise reduction circuitry of cassette decks. Consequently, many were built with a 19Khz notch filter to remove the pilot tone when recording
@jooei2810
Жыл бұрын
Techmoan, the corner stone of KZitem!
@markmarkofkane8167
Жыл бұрын
The most interesting person on KZitem!
@pedrodaniellopesferreira2916
Жыл бұрын
@@markmarkofkane8167 in never miss one of his videos.
@eugeniughego2124
Жыл бұрын
this guy wakes up in the morning and asks himself: "what tech from decades ago can I make interesting and entertaining?"
@robertschnobert9090
Жыл бұрын
@@markmarkofkane8167 I love Mr Moan 🌈
@frstwhsprs
Жыл бұрын
@@markmarkofkane8167 All tech, no moan!
@jmulvey371
Жыл бұрын
My old college radio station in New Jersey was FM mono. That was simply the result of the college having been granted an early FM broadcast license (educational institutions were among the first licensees) and a pile of Cold War-era military broadcasting equipment, but no real budget. Our volunteer engineers worked miracles patching it together and we took full advantage by saturating a 3-mile radius with R.E.M., Meat Puppets and Robyn Hitchcock all day long.
@SenileOtaku
Жыл бұрын
WFDU perhaps?
@jmulvey371
Жыл бұрын
@@SenileOtaku Ha! No, although my sister went there. This was at Middlesex County College --though we usually referred to it as "The University of Edison."
@endymallorn
Жыл бұрын
@@SenileOtaku@J Mulvey Or WMSC?
@scottlarson1548
Жыл бұрын
One fun thing about the mono college station in my area (shut down a few years ago) is that they had no 15 kHz filter since there was no stereo signal to protect. That meant that sometimes cymbal crashes would fool stereo receivers into briefly turning the stereo light on since they sounded like a 19 kHz pilot tone.
@Allan_aka_RocKITEman
Жыл бұрын
TECHMOAN: _"It's deja vu all over again."_ To which I would add: _"The future DEFINITELY ISN'T what it used to be."_
@JWD1992
Жыл бұрын
I admit I had no idea that FM actually went out in mono and then got converted into stereo. But now I do remember over the years how the stereo indicator light would not light up if the station wasn't tuned in all the way, which I now know means that the 53kHz signal which allows for the conversion wasn't coming in. Fascinating.
@Devo_gx
Жыл бұрын
Also, you should grab a little SDR receiver and hook it up to a computer, as you'll actually be able to see a visualization of how the tuner is detecting the FM stereo information. Using an SDR is so much fun as you get to actually see the radio spectrum
@BingoLarsson
Жыл бұрын
Indeed! Also the difference between AM/FM modulation makes lot more sense when looking at the waterfall. Might also be a helpful tool to figure the RFI issue he has mentioned in quite a lot of videos.
@wrenchmonkey3920
Жыл бұрын
top tip. mite even spur viewers to get their amature radio ticket.
@namesurname4666
Жыл бұрын
@@jiriwichern i have an rtl sdr v3 and reception is worse than any radio i have (with the same antenna) but it's still interesting and fun to use
@fflynnful
Жыл бұрын
You can also see the HD (hybrid digital, not high definition) subcarriers on HD stations. There is HD decoder software for PC.
@Devo_gx
Жыл бұрын
@@fflynnful indeed. Techmoan won't see that as HD Radio isn't available there, but there is DAB decoder software too.
@markjamesmeli2520
Жыл бұрын
For decades I've wondered why hitting the mono switch on an old FM radio cleaned up the received signal. Now I know. I also know that there seemingly seems to be many FM radio stations broadcasting in mono. Your animated flag at 11:57 explains why I've always noticed that on the car radio, since that's mostly the only time I listen to radio anymore. As for back in the day, I guess Sanyo really needed that extra 12 bucks.
@uxwbill
Жыл бұрын
It's worth noting that your car radio is very likely to have a fairly aggressive stereo blending circuit. The goal is to try and strike a balance between having some degree of stereo separation while suppressing interference and noise.
@josephaltman460
Жыл бұрын
They should have advertised it as "Stereo Ready" with dongle. Like we did for satellite and HD radio in the 2010s.
@Zarkovision
Жыл бұрын
In the 1960s, when stereo FM came up, also the European brands like Grundig sold big box radios with valves and a "Stereo" logo, but the stereo demodulator was optional, and also made 50% of the price of the radio. But when you've paid 560 DM for example your Grundig 5295 here in Germany you really thought twice about spending another 250 DM for the stereo demodulator... Most people didn't until transistors made stereo FM much cheaper and a normal thing at least at the big box radios.
@professormicron6470
Жыл бұрын
5295 wasn't even compatible with Grundig stereo adapters because they haven't come out yet. Grundig was late to FM stereo party by around 1-2 years. Their first decoder for European market came out in 1963. Maybe they were more careful with market strategy than other brands and decided to wait. I have a 5299 which is exactly the same as 5295 but without speakers and it would be the only European tube receiver you need in your life if not for lack of FM stereo... It even has a phono preamp (not every example but some were outfitted with one). And then you've got radios from Saba and Philips that have FM stereo but guess what they didn't offer? Yeah the didn't offer phono preamps for their radios. I've actually spent some time researching if there ever was a mid-century styled (so 1962/1963 at newest- almost everything after that is just ugly) European (would be German anyway) tube device with FM stereo and phono input and I'm 99% sure that there wasn't even a single model like that:(. The earliest German devices with that kind of features are already in the modern minimalist style and usually hybrid designs with tube tuner and transistor amp. Grundigs also got quite ugly just as they introduced stereo decoders. There were some slightly earlier, less ugly stereo compatible tube radios from other brands that I have personal experience with and it that aligns exactly with what you say- the decoders for them mostly exist on paper. Interestingly Grundig decoders actually appear for sale from time to time, so maybe introducing them a year later helped sales. First tube radio I stumbled across that can equip a stereo decoder is a Körting Berlin (not a bad design despite zero brand recognition) and I've seen the original stereo decoder for it once but I wasn't able to buy it. I decided to get a first one that comes up but it's been 4 years of waiting so far. That's how rare these things are, at least anywhere in Europe. I found that the golden rule of 1960s high end tech also applies here- no matter where it was made, you'll still only find it in the US. Few years ago I accidentally stumbled across a Loewe Opta from 1962 that was made especially for US market and it came with FM stereo decoders as standard- almost the same exact decoder that nobody bought in Germany. And the most interesting thing is that it isn't even a high end tube radio, just an entry-level stereo model that someone decided to sell with stereo decoders as standard. It doesn't even have a stereo pilot indicator, only a magic eye. It's the most ironic thing ever, living just around the corner from Germany but if you want a German tube radio with FM stereo you'll have to transport it through half of the world. Alternatively you have to wait like 3-5 years for a chance that someone locally will sell you a good Japanese tube receiver that has everything built in. It's not a good life if you really want a tube stereo, especially on this continent
@SenileOtaku
Жыл бұрын
Yes, that was the case with our Telefunken Concertino 5384. It has the place on the back to plug in the stereo module, but we never had one. Still have it, which Dad bought new in the early 1960's, but having seen the videos on radio restoration on Mr Carlson's Lab, I'm hesitant to plug it in after i t sat unused for 20+ years (probably more like 30).
@AaronSmart.online
Жыл бұрын
I have a Bang & Olufsen Beomaster 900, a transistor receiver from the mid-late '60s, and the stereo demodulator was optional although installed in my example. If the demodulator is not installed, the "stereo" lamp is still illuminated if you select the tape or phono inputs and have the mono switch off.
@bobblum5973
Жыл бұрын
The same basic technique used to encode stereo sound into FM broadcasts was used to add stereo audio to NTSC television broadcast audio. A combined L+R monaural signal is mixed with a L-R (inverted R) signal subcarrier, canceling out the R to decode a 2L left channel signal, and likewise L+R mixed with an R-L (inverted L-R) to get a 2R right channel audio signal. [ _Much_ easier to diagram it than describing it in a short comment! 🙂 ]
@derek20la
Жыл бұрын
The FM band begins where NTSC channel 6 ends. Technically, the audio subcarrier of an analog broadcast on channel 6 is at 87.75 MHz. Even with the small frequency offset, it was "close enough" for most radios to easily tune. My memory of analog TV was listening to XETV channel 6 from Tijuana at 87.7 FM... and I lived in the San Fernando Valley of LA, 150 miles away to the north, due to tropospheric ducting most of the year.
@fflynnful
Жыл бұрын
And the L-R was run through a dbx compander for noise reduction and the pilot tone was 15,750, the horizontal sweep rate for NTSC.
@nfalister2732
Жыл бұрын
And the pilot tone was at 15.734kHz, so an FM stereo demodulator wouldn't lock on to it unless you modified it for the purpose. My parents had an early RCA "monitor" grade TV that had a multiplex output and line inputs (with stereo speakers even) but NO stereo demodulator. I found a schematic for a TV stereo demodulator in a magazine and retrofitted the RCA to have stereo audio back in 1982 or so. We had one "stereo" station in our market at that time. I thought we were so high tech!
@ntsecrets
Жыл бұрын
@@fflynnful which is why the encoders needed the video signal as well so it can use the horiz rate for encoding!
@bobblum5973
Жыл бұрын
For those questioning the 15750 KHz vs. 15734 KHz in the other comments, simply stated the 15750 was matched with 60 Hz for black and white, but tweaked to 15734 & 59.94 Hz for color to avoid artifacts in the picture. Similarly, the colorburst frequency isn't 3.58 MHz, it's 3.579545. Probably more than you wanted to know... 🙂
@organfairy
Жыл бұрын
In the 1960s it was quite common to sell 'stereo' radios without stereo - that is: They could amplify stereo sound from a stereo taperecorder or stereo grammophone, but they couldn't decode stereo radio. The reason was that many countries didn't broadcast stereo yet, and since it would make the radio more expensive to include a stereo decoder, they left it out but you could have it added later as there was a socket somewhere inside or in the back for the decoder module. In Denmark Program 1 - that played mostly classical music - got stereo in 1966, where Program 3 - that played pop music mostly for the casual listener - got stereo as late as 1972.
@MrDuncl
Жыл бұрын
I went down the rabbit hole of looking at the decoder modules for tube/valve radios. One article suggested they needed more critical factory adjustments than the radios themselves.
@mark314158
Жыл бұрын
Strangely in the UK Radio 1 played pop while Radio 3 was classical...
@UHF43
Жыл бұрын
And those that had the integrated stereo demodulator were marketed as Full Stereo (or Voll Stereo in German)
@organfairy
Жыл бұрын
@@mark314158 In Denmark the reason for our numbering was that DR - Radio Denmark (state owned and works much like BBC) didn't consider pop and rock to be worthy of broadcasting to the listeners. The controllers of DR came with a classical background and therefore wanted no such thing as music which only had the qualification that it was 'popular at the moment' (I imagine these controllers as people like Sir Humphrey from 'Yes, Minister') . DR had two programs, 1 and 2. But then came 'Radio Mercur' which was almost 1:1 like Radio Caroline in the UK. They transmitted from a boat outside Danish territory and they were really popular and often had more listeners than DR. In 1962 the Danish government made a controversial law that made it illegal for Danish people to appear in radio programmes not made for DR which effectively made it impossible for Radio Mercur to survive. But then program 3 was launched and it was meant as replacement for Radio Mercur - in fact many of the people who had worked for Mercur was now working for Program 3.
@MrDuncl
Жыл бұрын
@@mark314158 Radio 3 was previously the Third programme which was also Classical. It was the only one of the four main stations where there was any continuity in the name. The Home Service (news and talk) became Radio 4, while the Light Programme (which played the likes of The Andrews Sisters) became Radio 2. Nowadays, Radio 2 is the most popular station, playing the likes of Madonna who was deemed to now be far too old for Radio 1.
@ReluctantDruid
Жыл бұрын
Good to know that even after 40 odd years of listening to radio through headphones, that we can still be taught something. Thank you for your continuous teaching and entertaining. 😊
@helge.
Жыл бұрын
As someone who worked for Apple in the past your last comment on the adapters made me smirk a lot! Thanks for that!
@JaredConnell
Жыл бұрын
Today someone posted on LGRs video that every week techmoan and LGR are getting closer and closer to their childhood. And I thought to myself, have you seen techmoans videos lately? Shellac records and NSYNC cellphone toys don't seem like contemporaries to me lol. And this video proves my point even more, but that's why i like this and LGRs channel, you never really know what you're going to get!
@revidual
Жыл бұрын
My dad bought a big square chocolate brown mono radio in the late 70's, it came with brown headphones connected with a multipin plug. Its two channel output allowing me to enjoy The Hitchhikers Guide to the Galaxy in glorious stereo.
@tortysoft
Жыл бұрын
I had a cassette radio that I bought in 1976, I recorded HitchHicker in stereo on it back then. That radio wakes us every morning to this day :-) I'm reading the full 'HHGttG books on my podcast 'tortytalks' by the way !
@marcusdamberger
Жыл бұрын
I think the key takeaway here is BROWN! (it was the 70's after all)
@paulstubbs7678
Жыл бұрын
Brings back memories, Many years ago, Tandy electronics often sold oddball IC's, on one occasion it was a FM stereo demodulator IC, so I basically built one of these - well almost, as mine only output line level audio. In the early days of FM, you could buy an FM adapter for your AM car radio, these were a simple FM radio that fed an AM modulator, so you could listen via your car's AM radio. I had scored one of these and I had tapped into the audio before it hit the internal AM modulator, this I fed into the above mentioned decoder, and it worked first thing - way more success than what you just had with the Sony AM radio. Maybe my savveier was the fact that adapter was quite small, so they had skipped anything they could, like filters on the output to remove the FM stereo pilot tone, something the target AM radio could not reproduce anyway, so why bother filtering it out. On another oddball point, I am listening to KZitem audio in mono (99% is just single person dialogue) so your FM signal, demodulated into stereo, was then being made back into mono at my end, so interesting to hear the difference in the different samples, as everything I am hearing is mono. One could be forgiven for thinking, well if converting that signal into stereo added heaps of noise, well make it back into mono to get rid of the noise - does not work that way! Another oddball, feed that demodulated stereo into an X-Y scope, you'd think it would look like any other stereo signal - well it does not, it usually looks quite odd - strange that the human hearing does not notice. Add 1% distortion to an audio signal, often not noticeable on an oscilloscope, horrible to the ear. Turn stereo audio into FM multiplex, totally borked on a scope screen, but totally on to the ear. Go figure.
@ThisSteveGuy
Жыл бұрын
At least you can use one of those corded cassette tape adapters to get stereo out of the speakers.
@fredbear3915
Жыл бұрын
Oh yes please, Matt, go on... make that video!
@sgtsquank
Жыл бұрын
You nailed the reason why we still use our receivers 'mono' option. We live in a valley with terrible signal reception -- stereo will come in, but not very well. Mono generally will come in clear and with things like NPR, mono works fine.
@Bonedadyo
Жыл бұрын
When I was a kid (in the early 1970’s) we had an amp/receiver that had the FM stereo/mono switch. The stereo signal was so bad it was basically unlistenable. My father put a piece of tape over the switch to make sure it stayed on mono! Haha!
@Velodynamic
Жыл бұрын
In the 1980's when I was a kid we had a Grundig "boombox" stereo cassette player with tuner that had a dedicated slide just under the cassette player that went from "stereo" to "super stereo". Nobody really heard much difference but it stayed on "super stereo". lol
@5HlNOBI
Жыл бұрын
Theoretically, one could add a "dongle dongle" pre-amp after the dongle output then back to the speakers so that THEN you could have stereo FM on the speakers. Just because it would make a Frankenstein stereo radio that works.
@Hyxtryx
Жыл бұрын
That's a good idea. I'm surprised they didn't design it that way, with a line-in jack. Maybe they thought it would cause a consumer revolt. I can see consumers getting upset if they bought a stereo unit that was stereo except for the radio, and then they needed to buy something extra to get the radio in stereo. But if that extra thing is "just for headphones", then it sounds like an add-on device for extra functionality, as opposed to an add-on device just to get the features you thought you paid for. 😄
@blazingluke
Жыл бұрын
Loved the bit at the end, cracked me up!
@3rdmm
Жыл бұрын
Listening to FM in Europe, you'll often use the mono and noise muting switches if you're trying to get stations in other countries.
@adrienfourniercom
Жыл бұрын
in France during the 80's and 90's we had "free radios". You can create your own radio by paying your frequency in the FM. Nearly every one of them were mono. Nostalgia, I was listening to them constantly.
@richcolour
Жыл бұрын
Are free radios like the UK pirate stations?
@adrienfourniercom
Жыл бұрын
@@richcolour They used to be pirate in the 70's, but in 1981 the state opened the FM to avoid the overlap on the waves. Some still exist today, but they are very local. In the 2000, radios were supposed to go numeric, but the licence was too expensive for these little stations, so we still have the radio in analogical.
@gymnasiast90
Жыл бұрын
This reminds me of my Nokia 6230i. It has a radio app, but it requires a dongle to be connected. This dongle also houses a 3.5 mm headphone port - like with modern phones, they didn't fit one on the device itself. (I eventually bought that dongle in 2022, new old stock. I imagine the people running the webshop I bought it from must have blinked a few times.)
@tmofee
Жыл бұрын
The iPod nano was the same, it used the headphones as an antenna
@nb7466
Жыл бұрын
My new smart phone as an fm app that you need the headphones plugged in. The headphones are the antenna
@deathdeathrevolution3499
Жыл бұрын
Yeah that's how most portable ones work now, unless it's a bespoke radio it usually doesn't have a clunky antenna poking out, although I have seen a version of that for tv before so it was a thing, but it died out in the last decade
@GoldenCroc
Жыл бұрын
As others have said, there has to be very few phones around that got radio but doesnt need the headphones plugged in for antenna usage. I have never seen one, certainly not one without some kind of fold out antenna. Maybe there is one..?
@SeanBZA
Жыл бұрын
@@GoldenCroc most just need something plugged in, either the charger, headphones or a USB cable, to act as antenna, though there are some that managed to finagle a decent enough (in strong signal areas) antenna into the case itself. Funny thing is that if you buy a phone or device that has multiple world markets, like a mobile phone, media player or such, often the selection of the UI as being USA disables the radio function entirely. Bought a good number of small portable media players, where you can update the firmware on the device, and always select the firmware to be Australasia, as that not only gives you the FM radio, but also CCIR and OIRT bands as well, so many of them will have a FM receiver that will tune from 47MHz to 108MHz with no problem, and stereo is also built in. Pretty much every single Android phone, and every non smart phone, has a FM radio built in, just the US market, for some reason, does not actually enable them. Built into the baseband chipset, has 2 connections for the antenna input and a small local decoupling capacitor, and then all the rest is done internally in the baseband processing, with the audio being there for selection in the chipset. Some might even have RDS as well, but I have not seen that. Often you can also select it as a record input to the media player, even though google has gone on a pogrom of disabling audio recorders on Android, removing that function as part of updates, and removing most of them from the store as well.
@strongandco
Жыл бұрын
Good old Ken Bruce. Glad to hear he's taken at least one listener with him to Greatest Hits. Hopefully many more!
@malcolmhenderson3866
Жыл бұрын
I've followed Ken over too. Nice plug for Greatest Hits though.
@sonickrnd
Жыл бұрын
"It looks like you’re trying to listen to us from outside of the UK. Due to legal reasons, our streams are not available where you are."
@conwaytwt
Жыл бұрын
I have a story from just a few months ago. I was having trouble hearing my local public radio station. The sound was greatly reduced, and what I could hear was distorted. I could almost make things out if I turned the volume way up, but when the next program started, or when the hourly news break came on, the sound was MUCH louder and totally un-distorted. I put up with the bad sound for a few days, then I happened to have the radio on in my car and it sounded fine. I compared to the radio in the house, which was a little SONY ICF-38 portable MONO FM-AM radio. It turns out that the local programming at the station was going through an adapter that inverted the left and right signals, so the MONO signal from the station was canceled out, but folks using "modern" stereo FM receivers were not hearing the problem. When the signal came via satellite from NPR, the sound was fine for everyone. I contacted the station manager (who was unfortunately dealing with a lot of COVID illness) and the next time the station engineer was on site they got it fixed. Fortunately for recognizing the issue, I had just gone through the exact same situation with a church -- their KZitem video of a church service I wanted to hear was completely inaudible on my phone (single mono speaker) but the same audio worked fine on my wife's iPad (stereo speakers). I captured the audio into Audacity and inverted one channel to prove it. A few web searches confirmed that it's very common for a XLR to stereo adapter to get the phase wrong. SO the quick fix is to unplug one channel from the sound board and record the program to KZitem in mono.
@Adventurepil0t
Жыл бұрын
I would love a video on AM STEREO. Back in 1992 (in Australia) my dad had a mid tier Toyota celica (SX) and it had a button for AM stereo and it worked surprisingly well. The funny thing is I’ve never seen that option on any radio, car or not before or since. I wondered if it just split some random frequencies and just throw them on different sides, I don’t know. Have you ever seen such a system?
@VintageTechFan
Жыл бұрын
Most systems use quadrature amplitude modulation. How that works is hard to explain in a few simple words, but basically it is a normal AM radio signal modulated with the L+R sum signal to archive compatibility with mono receivers. Then they add a difference signal L-R modulated onto a supressed, but 90° phase shifted carrier, which cancels itself out in a classic AM demodulator, but can be detected by specialized circuitry and used to reconstruct the L and R channels. It just needs the bandwidth of a classic AM station. The transmitter side is much more complicated since you can't use high level modulation, but have to create the signal on low level and linearly amplify it, which is less efficient.
@dan_from_australia
Жыл бұрын
No, it is genuine stereo, and yes it is fascinating technically. Australia used the Motorola CQuam system based on a quadrature modulation as mentioned by Nitro. Unfortunately only one or two stations in Aus still use this system.
@Adventurepil0t
Жыл бұрын
@@dan_from_australia ah, that would explain why some of the AM radio promo stickers like 2WS had stereo written on them!
@AaronSmart.online
Жыл бұрын
VWestlife and Shango066 have done some videos on AM stereo. It was never really a thing in Europe so it's unlikely Mat will cover it
@Audiorevue
8 ай бұрын
I had a old receiver I can't remember the brand but it had an option for AM stereo, matter of fact that's why I bought it. Obviously I wouldn't be receiving am stereo but I just thought it was sort of a rare tech and kind of neat
@StackOverflow80
Жыл бұрын
I noticed that some portable radios used to have "MPX" output, which is the same like in this Sanyo Stereocast system, so that stereo enthusiasts could use some external stereo decoder. Using add-on stereo decoders, even DIY ones, was quite common in the beginnings of FM stereo. But standard earphone mono output of a mono radio receiver will never contain MPX stereo signal, because it always gets stripped by deemphasis (FM broadcast uses treble boost on transmitter side and opposite treble cut-off on receiver side, to further improve signal to noise ratio). This worked also on older FM mono radios unaware of FM stereo. On this you can see how clever were the designers of FM stereo system, in a matter of forward compatibility. They just didn't leave behind older devices, unlike they do nowadays. They say that stereo reception gives about 20dB worse signal to noise ratio vs. the mono reception of the same station. This is really huge difference. Many stations nowadays choose for mono only broadcasting, because they know, that many people listen radio as background on mono devices or small stereo devices, where speakers don't have good stereo separation. Mono broadcasting allows for lower transmitter output power while maintaining the same range, so that thay can save money (on us).
@hugeshows
Жыл бұрын
Hi Mat, I think this thing is what is known as an FM multiplex adapter. It decodes the stereo in the signal so the output of that jack isn't pure audio as you noted... They were common in the early days before FM stereo was popular. At first people weren't sure stereo FM would take off, and lots of regions didn't have any stereo stations. It was a way for consumers to hedge their bets and manufacturers to offer an upgrade.
@pedrodaniellopesferreira2916
Жыл бұрын
I believe you are right. I remember reading through an article years ago, stating that in the early 70's the standard for FM stereo was not well established. Yearly receivers came with a phase control to tunne in the pilot signal, just in case it would shift to another frequency in the future.
@irtbmtind89
Жыл бұрын
This also would have let Sanyo avoid paying royalties to GE and others for the FM stereo patents for every radio they made. Kind of like how the Xbox required a dongle to play DVDs for the same reason.
@tortysoft
Жыл бұрын
My father, a sound man at the BBC, built his own tuner and also bought a demultiplexer. We used to listen the the test broadcasts, BBC TV left channel, Radio 3 on the right. Many years later when I worked at the BBC I occasionally transmitted simulcasts, pics and mono sound on BBC2, stereo on Radio 3, all from my VT cubicle.
@S7EVE_P
Жыл бұрын
Actually a demultiplexer, as mentioned at 2:43
@sparky6086
Жыл бұрын
@irtbmtind89 That reminds me of RCA having the patent on superhetrodyne radio. For around 10 years, they didn't allow other manufacturers to use it back on the 1920's. When they finally began to license it to other manufacturers, some of them offered an add on superhetrodyne converter, so the consumer could retrofit their existing radio to superhetrodyne. Rather than getting into the weeds on what superhetrodyne is, in short as a practical matter, it allowed people to recieve many more stations. In early radios, the more powerful or closer stations would drown out the weaker or further away stations, so people were lucky if their receiver could discern 3 stations. With superhetrodyne, they might get a dozen or more.
@markmarkofkane8167
Жыл бұрын
That dual pin plug is similar to the plug at the end of a microphone for a portable tape recorder. Large pin microphone, smaller pin, remote switch. (To pause and resume recording and playback) This video is very interesting.
@UHF43
Жыл бұрын
The might have looked at their parts bin.
@dougbrowning82
Жыл бұрын
Those twin pin connectors can also be found on professional grade headsets. One pin for the mic, the other for the earpieces.
@rikprince8414
Жыл бұрын
Very nice!! Always interesting to see the workaround that manufacturers came up with. I was a bit surprised to find there are very few bluetooth speakers that were not mono output. :)
@smvwees
Жыл бұрын
I found out the hard way :( .
@deathdeathrevolution3499
Жыл бұрын
I mean most of the Bluetooth speakers aren't stereo because thats the standard for it, easier to source chips for the standard and buy them than make your own
@annother3350
Жыл бұрын
@@deathdeathrevolution3499 he's saying mono is the standard
@deathdeathrevolution3499
Жыл бұрын
@@annother3350 that's what I meant but it autod it I'll fix it thanks for making me aware though
@steviebboy69
Жыл бұрын
My bluetooth speaker does have 2 speakers in it but it outputs in mono, but it does give a more spacial type sound to it and it is only a cheap one anyway. But it has a JBL boot up sound to it though hehe.
@joekenorer
Жыл бұрын
I didn't know I could care so much about a Sanyo record player and the inconvenience of it's sub function FM radio being mono, and then bother buying a tertiary device to convert FM mono to stereo. How tf do you consistently get me involved in some ancient, garbage audio ephemera? This is why I'm subscribed.
@hattree
Жыл бұрын
In the US, channel 6 for television was at the bottom of the FM dial. It was always in mono. I can remember it was the only station that didn't make the stereo light come on.
@albinklein7680
Жыл бұрын
Thank you so much, Techmoan!! I have a Sanyo radio alarm clock since the early 80s (the good one with the flip clock mechanism and sliding pots) and since (literally!) 40 years I wonder, what that "Stereocast" jack on the back of the thing is! And tadaaa, now I know! You are the man!! Greetings from Germany!
@zanegandini5350
Жыл бұрын
Wow, that Sanyo Stereocast sounds VERY clean for FM radio! Much cleaner than the Sony stereo output later in the video. Goes to show newer isn't always better.
@ericpode6095
Жыл бұрын
I always assumed the mono switch just combined the left/right channels because I never really thought about it. The noise problem now makes much more sense.
@rog2224
Жыл бұрын
Some of the Mono DAB stations were in Stereo, but the spectrum was sold out from under them around 2010 for mobile comms expansion. Much like the deregulation of caustic and corrosive substances, it wasn't widely covered outside of specialist publications.
@GodmanchesterGoblin
Жыл бұрын
To be accurate, the spectrum that they were on is still used for DAB. In fact, the DAB frequency blocks used by the multiplexes have not changed or been reduced, more multiplexes have been added. It was the multiplex operators that decided they needed to sell the space a second time and so they added more stations to each multiplex. Since a single multiplex is always 1.536 Mbits/second, they can carve it up how they like. DAB actually allows the bit-rate usage for each station to be changed every s seconds, but most only change a couple of times a day if ever (mainly BBC R4, etc).
@maxx9137
10 ай бұрын
Dude, I love your outro so much. The chill music with all those cool clips you show is awesome.
@neilsradios
Жыл бұрын
4:20 I did the Alba version of that radio a few weeks back. Alba at the time were just rebadging imported radios but I got a Sanyo Stereocast as shown here and it works quite well. The radio without the adaptor has quite poor sound though.
@rEdf196
Жыл бұрын
Like that Sanyo proto-dongle radio twin plug, dual micro and 1/8 inch plug combo's were common place for tape recorder microphones in the 1960's to mid 70's the main 1/8" plug was for the mic itself the tiny 1/16" plug was for turning the tape player on or off. As a young 70's kid, I loved flicking the switch on and off while talking on the mic with cassette recording, then play it back with my voice pulsing squealing and pitching up and down.
@GaryKeepItSimple
Жыл бұрын
The Standards for Stereo Broadcasting world wide had only just started around then. The UK went Stereo in 73 so it was new technology. (And Expensive) and the public was not very interested like they were for other things. This is from the BBC history website:- Experiments in FM stereo began in the London area in 1958, with an FM Subcarrier system also evaluated. In the end the Zenith-GE system was chosen, helped by the fact that it had already been adopted by the US, and recommended by the European Broadcasting Union. Over the following years stereo became available to the rest of the country. Radios 1, 2 and 4 went stereo in 1973, with a celebratory Stereo Week.
@willyarma_uk
Жыл бұрын
If you sample the FM mono into your computer at 192KHz and then look at it with a spectrum analyser (I use GoldWave for this, I assume Audacity has this also?) then you can see the whole FM MPX with pilot tone, stereo difference and RDS data.
@dougbrowning82
Жыл бұрын
If you're tuned to the right station, you might also see the SCA carrier. SCA is a method of delivering environmental music to public areas, like shopping malls.
@dougbrowning82
Жыл бұрын
@thevinyldisguise7134 In some markets. I remember seeing a video of an SCA radio on KZitem about a year ago. Was a regular GE FM radio with an SCA board added.
@AdamG1
Жыл бұрын
Several local stations have added HD Radio streams and it's brought back the days of switching between mono and stereo to get a clearer signal if you're moving around. When you're driving in fringe areas it's pretty irritating when it keep switching between HD and standard radio. One reason I use XM most of the time
@jimb032
Жыл бұрын
I about spit my tea out when you popped the lid off of it. I was thinking "does it even have a circuit board, or it's a dead bug circuit squashed into the case?!" I like the whole thing pretty neat. I wouldn't want it as my only unit to listen to, but it's very 'flashy" and lets agree that there are things made that were 10,000 times worse. You made the video about Kenwood being the king of budget hifi, but Sanyo (or PanaFisheYo as I call them) made some seriously nice stuff in the day. Mono/Stereo switches were great in the day when the signal was not quite good enough for stereo but often times the mono switch made it very tolerable and listenable. (vs the stereo flipping in and out annoyingly) But I never knew that there was a type of NR that was available in mono that was not in stereo -very interesting! Thanks for the great video as usual!!
@rogerduerden373
Жыл бұрын
I can remember in the 70s and 80s when Radio 4 was normally broadcast in mono, but on rare occasions they switched to stereo for specific programmes.
@B3tanTyronne
Жыл бұрын
As much as I like the dongle (oh matron etc), the death star droid looking combi at 5:42 with the light show looks interesting.
@leamanc
Жыл бұрын
Fascinating stuff! I always thought the FM mono/stereo worked like that but I had it reversed. I assumed it was a stereo signal but that the receiver stripped out some signal to convert to mono. As an aside about one-speaker radios, my C Crane one-speaker radio has a switch for: speaker, mono out to headphones, and stereo out to headphones.
@dong6839
Жыл бұрын
I saw a briefcase device like this back in the 80's (made in the 70's) that had a built in FM transmitter! It was designed to allow you to broadcast your own little party, and all your guests would tune their car radios and portable radios to a particular frequency, and they would all hear whatever you were broadcasting (from the built in record player, or a plugged in mic, or line level input) it even had a simple mixer built in, so you could professionally "mix" your music with your voice or an external set of turn tables plugged into it etc. It was like an entire low power radio station in a briefcase. It was advertised for use at drive in theatres, beach parties, race tracks/drag strips etc, where you couldn't set up an entire public address system. There was even an external accessory sold for it to be completely powered off-grid. Not sure if it used a car battery and some sort of antiquated 12V inverter (not sure if they even had those back in the 70's) but it claimed to allow you to be able to use the transmitter in remote locations where you didn't have access to a power outlet! I can't remember who manufactured it, I want to say I remember seeing Realistic on it, but that could just be fabricated by my childhood memories of seeing shiny stainless steel switchgear and high end equipment and associating that logo to it.
@manoflego123
Жыл бұрын
I never realized FM was in stereo because I just listen to the news most of the time, but I do have a little '80s era GE alarm clock with a switch to enable and disable FM stereo. It also has a headphone jack, because there's only one speaker regardless of if the signal is in stereo, and the difference is remarkable. It almost sounds like the music is coming from "inside" your head instead of through your ears when you switch to mono.
@manoflego123
Жыл бұрын
This little alarm clock picks up really clean FM stereo compared to what you've got in this video, but I don't know if that's a result of American FM differing from UK FM at all.
@Stevedd33
Жыл бұрын
Wow! This really brought back memories. I'd forgotten that I used to have one of these. I bought it to go with my Sanyo clock radio as I was obessed with the idea of listening to things in stereo. Of course the station that I wanted to hear in stereo the most, BBC Radio 1, would continue to be AM only for many more years. Thanks for this. I really enjoy your channel and watch every video.
@Darxide23
Жыл бұрын
Quick nitpick about terminology. Whether the stereo switch is on or not, you're always demodulating the signal. The M in AM and FM stands for Modulation. You have to demodulate the signal to get any sound at all. What you're doing when you split the stereo signals out of a single mono broadcast is _demuxing_ the signal. Or it may be known as _demultiplexing_ instead. Muxing is just shorthand for Multiplexing. You'll see this rarely on a piece of old stereo equipment as an MUX or MPX switch setting. Anyhow, it doesn't change much. Everyone understood what was meant. Just thought I'd toss it out there.
@mikesbarn1858
Жыл бұрын
Here in the US we also used the 67 Hz and 92 KHz modulation signal for extra channels. It used the bottom and top 10% of the modulation wave.
@marcusdamberger
Жыл бұрын
Yup, they used to use the extra audio at those frequencies for services like a reading service for the blind, i.e. radio programs to read the newspaper and other sources of information, or I even think some audio books too. Usually offered on NPR stations. But you had to have a special radio that was modified for SCA service, or Subsidiary Audio. Some commercial stations would offer elevator music or services like Physicians Radio Network for doctors offices to have "commercial free" music, and I think sometimes grocery stores would also use similar services. But of course they had to pay a fee, and the special radio tuner was provided. Nothing stopped someone with a little knowledge to build a SCA decoder and hook it into the FM detector portion of the radio before all that got filtered out. Fran Blanche of Fran Lab did a video on the SCA receivers kzitem.info/news/bejne/2HiJsIiAnHOFlG0 In later years, they put paging services on those subcarriers and the radio station got paid for by the number of pages that went out. Then RDS was finally added in for Radio Data System for program information like Song and Artist to display along with other possibilities like telling the radio what other frequencies the station is available on if the current one gets weak to auto switch. But that is mostly popular in Europe where one network is on multiple FM transmitters filling in signal gaps in mountain ranges etc. Or using the RDS to tell the receiver to turn up the audio louder by a few dB for weather announcements, or news. I've heard that in Germany with the car radio turned down to background levels, then suddenly it pops up louder for 30sec while they tell you the forecast or news and then it dips back down in level to where you had set it at. In the U.S. they never seemed to use these options at all even though it's in the standard. But radio head units are not all equal.. They don't even to this day display all the information the same way even though screen real-estate has expanded while radio stations are all over the place with RDS data. Some seem to cram everything into one line and truncate text, or put their slogan only, or do some single line slow text scroll that's useless to read while driving.. RDS just seems badly implemented in U.S., while it seems way more consistent with what I've seen in Europe.
@fflynnful
Жыл бұрын
Those subcarriers are used for RDS. In the old days, before 1990 or so, muzac was at 67khz on a lot of FM stations.
@mikesbarn1858
Жыл бұрын
That was my point. I worked for Muzak tuning and repairing SCA receivers. I haven't seen one of those in 35 years.
@rodneyarnoldi
Жыл бұрын
I like the little sony XDR-S41D radio, could be useful when I'm on holiday, especially having the wake-up facility, although £60 seems quite expensive.
@Techmoan
Жыл бұрын
I bought mine when it was in the 'middle of Lidl' and while I can't remember the price I'm pretty sure it was £40-odd
@razeel2000
Жыл бұрын
I own this radio and I am quite happy with it. One thing I'd like to mention is that the wake-up alarm only works when it is connected to the power supply. When running on the batteries, it is disabled.
@Techmoan
Жыл бұрын
Did it come with a power adaptor, I can’t remember. If it did I could do with finding where I put it.
@razeel2000
Жыл бұрын
@@Techmoan Yes, it came with one. Model AC-P5005F
@NewCityMedia
Жыл бұрын
Great video. The Sanyo 'dongle' reminds me of the stand-alone stereo decoder boards you could buy in the electronics hobby shops in the 1970s. You could literally easily hook them up to virtually any mono FM radio, even the cheapest of portable budget sets, and produce a stereo output, as virtually all FM receivers pick up the stereo pilot tone as it is embedded in the mono signal anyway.
@klipkultur3680
Жыл бұрын
40 years ago I was wondering about that mysterious stereo thing and now I know. Thanks Techmoan!!!
@bslaws
Жыл бұрын
In 1958/59 my father was in England and purchased a Quad amp, preamp and single ESL-57 electrostatic speaker. When he moved back to the US in 1960, he bought another amp and another speaker so he could have stereo. I remember the original brochure showing a single ESL-57 sitting in the middle of the room as at that time, mono was the thing. He also had a Garrard 301 turntable. He had good taste.
@SeanBZA
Жыл бұрын
I would also say this was done to avoid paying royalties to the owners of the FM stereo rights holders, GE and Zenith, so instead developed the low cost stereo adaptor, so that only those who wanted stereo would buy it, and thus the royalties would be only based on the low cost module.
@boardsort
Жыл бұрын
Excellent ending! I like what you did with the Deja vu bit. Very creative.
@patrickalvino5544
Жыл бұрын
Great video as usual, Techmoan. Interesting topic of FM stereo. I have in my collection an AM/FM tuner from the 1950's labeled as "stereo" although this was well before the multiplex system of FM stereo broadcasting was adopted. It can output AM and FM simultaneously to different amplifiers and speakers. Although it was a bit before my time, I understand that some radio stations that had both AM and FM signals, would occasionally broadcast the right channel on say, the AM station and the left channel on the FM thus creating stereo broadcasting. Clearly this wasn't ideal as fidelity and reception would differ between AM and FM and of course, if you only have a normal radio, you are only getting half the signal, but it was rather ingenious nonetheless. Best wishes from across the pond.
@hormelinc
Жыл бұрын
I had one of these Stereocast adapters back in 1974 (they were becoming cheaper by then), but I did NOT use it on a Sanyo. I broke out the 2 plugs (via Radio Shack female plugs) and then figured out the power and the IF input. Yes, it took the IF output of the radio and then decoded the multiplex signal into the proper L/R audio. I think I used a G.E. portable radio to do that.I just basically touched the IF input wire around the inside of the radio until I got the MPX light and then got glorious stereo on my Koss headphones. It was pretty cool! FYI: You should look for an EICO MX99 multiplex adapter and make a video about that!
@jmulvey371
Жыл бұрын
Your last point about DAB radio stations choosing to degrade their signal in order to squeeze more content into the same bandwidth is an important one. Much like the transition to over-the-air digital tv in the US, what was touted as high-resolution signals becoming available for free has now become worse signal quality than what we had before. And the major cable and streaming services control the only valuable content anyway.
@tgheretford
Жыл бұрын
Quantity, not quality, sells radios. DAB only took off when the BBC created new digital radio stations and the choice of stations increased as bitrates decreased. An unfortunate and uncomfortable truth to us who want good quality audio but most people listen on a cheap single speaker radio in a kitchen or a workplace where high fidelity doesn't matter.
@jmulvey371
Жыл бұрын
@@tgheretford Over here I'm not even so sure it's about selling radios, per se. The real money is in content creation, and the way our corporate content creators have chosen to go about it is through market segmentation. Television broadcasting via a public license has become the home of home shopping network, christian broadcasters and old tv programs that cost little or, in the case of shows that are in the public domain, nothing. That is, it's low-end broadcasting for poor people. Anyone with a little money to spend is upsold into cable or streaming or something else, where the decent content lives. (Nowhere is this more repulsive than in the world of professional sports, where fan loyalty is converted to cash in the most aggressive and cynical way possible. Today in America, it's become impossible to be a fan of a pro sports team on a low-income budget. Revenues for the team owners, naturally, are higher than than they've ever been.) And, as I said, those net-based categories of broadcasters are almost entirely unregulated in the US, as opposed to over-the-air, which at least has to show some semblance of acting in the public interest. (Don't ask me how home shopping network qualifies.) I'd like to hope that the UK is incrementally better, but I'm probably kidding myself.
@10p6
Жыл бұрын
Here in the USA, we have FM, FM Stereo, then HD version of the same station, and then Sub channels in that same HD frequency, with the most I have found so far as 4 sub channels on one FM frequency. Hmmm.
@barrieshepherd7694
Жыл бұрын
A lot of US stations also had a sub carrier carrying low grade 'MUZAC' for use in lifts etc.
@derek20la
Жыл бұрын
@@barrieshepherd7694 That would be SCA services. Subcarriers at 67 and 92 kHZ.
@martin-uz1py
Жыл бұрын
That Sanyo RP7-1200 spherical record player looked interesting. Informative video as usual I had never thought about this myself.
@fearlessjoebanzai
Жыл бұрын
*RPT-1200 It says it is a lightshow in the globe! I'm sure Techmoan would go Techmad for that!!!
@JonFether
Жыл бұрын
I saw that thing listed and my attention was immediately drawn to it as well. I went fishing through the comments just to see if anyone else called it that RPT-1200. It may or may not be technologically interesting but for sure a great period piece. Hope Techmoan happens across one someday.
@martin-uz1py
Жыл бұрын
@@JonFether Etsy has one for £1,008.23 but that is quite steep for a novelty.
@cmjones01
Жыл бұрын
Most FM car radios these days gradually merge the stereo signal back to mono as the signal gets weaker, starting with the high frequencies where the hiss and interference is most audible. That's why you don't tend to hear the interference in a modern car, but will notice a change in the stereo separation and sound quality when the signal weakens. In our Ford this is most noticeable when driving under large bridges, for example. Back in the 1970s, some hi-fi tuners had a feature (Technics called it "hi-blend") which did the same thing.
@markelliot1248
Жыл бұрын
Hi Matt, Interesting stuff there. I would recommend for demonstrating FM one of the small FM transmtters intended for use in cars to take a MP3 player output and sending it to the car's FM radio. Only a few quid and would allow to to play some of your royalty free music through the receiver.
@SolitaryWolf
Жыл бұрын
Absolutely fascinating. I grew up in the 70's and never have come across a device that was so divided for its "parts" to separate FM stereo signals. This must have been when they were just beginning to split the FM signal ever so slightly to achieve the stereo sound and this unit didn't have the FM guts built into it yet. Thank you for sharing!
@AttilaSVK
Жыл бұрын
The difference between mono and stereo FM broadcast is due to the fact that the sound of a radio station has been processed heavily, including stereo image widening. That makes the mono reception sound worse than it should without such processing. Also, if you have a sound card capable of 192 kHz sampling rate (with a low-pass filter tuned high enough to let through about 60 kHz), you can use the multiplex audio output of the Sanyo to feed the signal into a computer, and for example, extract the RDS information from it using an application called RDS Spy. There's a video on my channel doing an FM band scan with my Revox B260 tuner with the MPX output (one of the scope outputs) hooked up to my sound card, and decoding RDS on the computer.
@vintagevideoau
Жыл бұрын
You used to be able to tell if the headphone jack on Sony products was stereo or mono by looking at the colour. Black was just for mono audio, and green for stereo. Same with the mic inputs too. Black for mono and red for stereo. Another great video. Keep it up!
@PascalGienger
Жыл бұрын
I always wondered why a recorded radio show at 19cm/s had a constant tone when played back at 9,5 cm/s. Sure enough that radio didn't have a low pass filter to remove the stereo pilot tone and the higher frequencies... The pilot tone by the way is not only there to indicate a stereo transmission but - as it's done with the same quartz in the emitter - it is always exactly 1/2 the frequency of the actual stereo difference signal - which is broadcast without carrier. So a small pilot tone is sufficient to create the 38kHz carrier in the audio signal. Later came RDS & Co at 3x yhe the pilot, 57kHz.
@hairydonuts6024
Жыл бұрын
Brilliant video. Totally forgot about the mono button, until you mentioned it here, & it's bought back a shed-load of memories from when I was a kid. Back in the summer of '73, Capital Radio opened in London as the first stereophonic commercial station in the UK. A few months after, my dad (who loved a gadget or two) acquired an ITT radio-gram, on HP, with a stereo FM radio built in. Up until then we'd only heard Capital in mono & marvelled at it's clarity but felt we were missing out because we hadn't heard it in stereo. As soon as we did, on the ITT, we were mortified. The signal was terrible & it sounded awful - so bad that we thought the radio-gram had a fault so my dad took it back to Radio Rentals (or was it DER?) & was told all about that mono button thingy. From that point on, we never listed to the radio in stereo until we moved closer to city in the late 70s. By that time we'd upgraded on to a Sanyo Music Centre which we actually owned! Still rented the telly, though, LOL!
@HannuPulli
Жыл бұрын
Fun fact, here in Finland they had DAB test broadcasts quite early on but decided it wasn't worth the effort to switch over and shut it down. Meanwhile in Norway they have shut down analogue FM broadcasts completely.
@thesteelrodent1796
Жыл бұрын
in Denmark they were going to shut down FM completely, but then it was decided to maintain the FM broadcast alongside the DAB, for traffic radio and emergency messages, but the FM frequencies are no longer posted on the motorway because they rely on RDS to interrupt what you're listening to for the emergency messages
@geirmyrvagnes8718
Жыл бұрын
...and good riddance! 😅
@nickvickers3486
Жыл бұрын
FM rules the roost in Spain and there are some pretty good stations both local and national. As far as I know DAB is only broadcast in Madrid and Barcelona, so I don't know what it's like. I don't think a digital switchover will happen any time soon. Also, there are very few stations on AM, this may help to explain why I can sometimes pick up British stations at night!
@filanfyretracker
Жыл бұрын
the USA has FM and AM still going. And there is no push to shut down the FM band at all. unless HD Radio as its marketed here is DAB than there has not been a drive for setting it up, Could also just be the sheer scale of the listening areas possible in the USA that analog radio is here to state because it carries better.
@keithposter5543
Жыл бұрын
@@nickvickers3486 DAB is terrible. See the bitrates in the vid
@jamesknightreading
Жыл бұрын
We had mono FM in the Channel Islands until 1984, much to my annoyance. You could only get a stereo signal from France, or if you went up to the North of Jersey. I think most of Guernsey could get a hissy FM stero signal from a roof aerial.
@neontime
Жыл бұрын
Professional receivers used in the broadcast industry usually have that output available on a BNC type connector. It will be labeled something like "multiplex", "mux" or composite. It is used in repeater setups to feed a transmitter directly without having to decode and re-encode the stereo signal. The composite output also carries the RDS data channel..
@leathere1
Жыл бұрын
Brilliant, thank you. I now feel very old. I had a Sanyo stereocast dongle with the smaller portable radio and matching headphones.
@ppotter
Жыл бұрын
When I used to record things from the radio in the 90s - albeit mainly comedy shows - I always used the mono as stereo round these parts was terribly whiny and hissy. Mono was crystal clear. And as soon as I typed that you mentioned it. Ha!
@fosterb247
Жыл бұрын
Super entertaining and informative as always Mr Techmoan - Thanks
@FranLab
Жыл бұрын
Yea, all FM stations are broadcast in mono which is done by design as the requirement in the 60's for all "new" stereo equipment be retroactively comparable with pre-stereo systems from the 50's, so they use a left-minus-right system where the right channel information is multiplexed on the main carrier signal in a secondary carrier which the stereo system detects, and subtracting that embedded audio signal from the mono reveals the left channel. Early stereo receivers typically had a control to allow you to determine how much separation you'd get, or allow you to listen in mono at much higher fidelity.
@skylined5534
Жыл бұрын
I remember the stereo/mono switches on 80s to early 90s car stereos very well! Them woz the days !
@marcusdamberger
Жыл бұрын
@@skylined5534 Yup, while on the freeway I remember you could eke out a little more range and listenability on a weaker station as you were driving away from it. Or if you were closer to the fringe or in a city with lots of tall buildings and got that annoying stereo picket fencing you hit the stereo/mono switch.
@kaitlyn__L
Жыл бұрын
Fran watches Techmoan? What a shock! :p
@marksweetman8765
Жыл бұрын
Very informative. I’d always assumed fm was stereo broadcast. You learn something new every day
@dansheppard2965
Жыл бұрын
The first truly legit use for irritatingly repetitive radio jingles, 😀. Something else that the dongles could help with is brand loyalty. If you get the dongle for your Sanyo suitcase thingy, you'd feel more like getting a Sanyo-branded portable radio thingy, it would be cheaper and you'd feel less stupid for having one kicking around.
@sjgoff
Жыл бұрын
I always learn things on this channel that I never thought I wanted to know...
@vapno92
Жыл бұрын
As soon as I realized, what this thing is, I came to the same conclusion, as You. I can imagine stereo decoder would be kinda expensive thing in early 1970’s with discrete components that need to be tuned properly etc. etc. so they made it an optional extra with premium price at the time. However, just a few years later, it basically shrank down to a single integrated circuit, something like MC1310, which was like few dollars, so this "Optional extra extension" became completely obsolete...
@VintageTechFan
Жыл бұрын
It's not that bad, FM Stereo was around in the days of vacuum tubes and the decoders for this radios usually used just one double-triode or 2-3 germanium transistors. They still sold them as addons, though.
@cocotoni1977
Жыл бұрын
My dad has produced a quite similar add on to listen to stereo output on what was originally a mono radio set for his bachelor thesis in ‘71. Having grown up in the ‘80s myself when the radios all has stereo built in I never understood the concept fully. Having seen it now as a product, well now it clicked. Thanks Matt!
@SidewaysCytlan
Жыл бұрын
What a strange device. How does it derive a stereo signal from a mono signal? Demodulation is pretty interesting stuff. Weekend rabbit hole!
@MrDuncl
Жыл бұрын
The stereo is there as ultrasonics along with the mono signal (as is RDS these days).
@DJNeiloSF
Жыл бұрын
Radio stations that broadcast in true stereo modulate their FM carrier signal with a stereo multiplex signal. It contains L+R and L-R information. A mono receiver will low pass filter the demodulated FM signal to get only the L+R mono signal. Stereo receivers extract both the L+R and L-R. They add these together to get the L left channel and subtract them to get the R right channel. This is why phasing of L and R signals is very important. If when creating the L +R with identical signals, reversing the phase on one will result in L+R =0 - no mono signal.
@tgheretford
Жыл бұрын
Forty years later, there are still mono digital radios being sold with an attachable speaker to get stereo sound, the modern day "Stereocast".
@engineer387
Жыл бұрын
I remember my mum and dad saying they had this or something very similar though I never saw it, fascinating to see it for real and explained so well!
@leefrohock
Жыл бұрын
Wow, you have a Hitachi TRK-8290E. I had one of those in 1981 and it cost me £179. I always regretted selling it but to buy one now with a working tape deck is near on impossible. very complex inside too as i recall. Love to see you do a Video on it in the future as i really miss it. Fantastic sound it had too :D
@lidbass
Жыл бұрын
I bought one in 1983 to take to university with me. Got it from Curry’s and I seem to remember it cost £120. The tape broke exactly one week after the guarantee ran out, but in those days there were strange things called ‘repair shops’ where it went for a holiday for a week or so. It then worked perfectly for years until, sadly, it was stolen. Would love to have another but a) it would just be to soothe the nostalgia and b) as you say they cost a small fortune and you can’t guarantee they will work properly. They were incredibly beautiful, though.
@unclehogram
Жыл бұрын
What's surprising to me is how much better the Stereocast sounds. I mean, I expected it to be a compromised experience but the reception sounded much much cleaner than directly out of the portable itself! Bet BBC Radio 3 sounds incredible through that.
@Hyxtryx
Жыл бұрын
That *could* be due to differences in impedance in the 2 outputs. Or maybe it is due to the base unit outputting not just a mono signal, but L-R signal above the range of human hearing, that might be interfering with the mono signal. ie: 14KHz in the mono, and 21KHz in the other signal causing a 7KHz beat frequency of a very low volume being perceived as distortion.
@Th0rnblade
Жыл бұрын
Trivia: The modern car radios DO have automatic mono/stereo switching, moreover, there's also a function called "stereo blending" implemented on virtually all of them. That means the switch from mono to stereo is done gradually, smoothly, in order to try eliminating the "hiss/no hiss" that you'd get in a car on the road with radio switching constantly between mono and stereo depending on the signal strength you get on the road. The function can be traced back, as far as I know (might be wrong) to the venerable stereo decoder IC "TCA 4500" invented by Telefunken somewhere in the mid 70s. Only one receiver from the 20 something I have from those times has this function implemented properly and that is the "monster" (for that era) "Telefunken HR 5000 digital". It has switches for: fm muting, mono/stereo, fast acting or slow acting high-blend and also delayed automatic frequency control (the delayed AFC works as to tune the station perfectly once you've captured it manually. This way you do not have the constant on AFC like in other models where you risk missing lower signal stations next to strong signal ones). Basically, everything you could desire.... But that receiver in itself is another story.
@furicle
Жыл бұрын
I had a Telefunken receiver where the mono/stereo was manually adjustable... A dial rather than a switch. On the road to fully automatic but not there yet.
@LenKusov
Жыл бұрын
What's funny to me is that since FM stereo is just multiplexing a mono channel at a strangely low frequency, you could actually - with the mux/demux circuitry on hand, anyway - record 2 tracks PER TRACK on a cassette deck with a good enough recorder. With a Teac or Technics tape deck (especially if you crank up the tape-to-head speed - higher tape speed means higher frequency response) you can get high frequencies up to 19 or 20 khz fairly easily. Granted, it'd still be at FM radio quality, but being able to turn a 2-track tape deck into a 4-track recorder sounds like a useful idea. Especially with the prevalence of boomboxes having double-speed copy, which bumps frequency response up to 24khz even on the cheap tape heads in a JVC ghetto blaster at the expense of chewing through tape really fast.
@stepheng8779
Жыл бұрын
I hope someone somewhere still has an RPT 1200 that works. I want to see that globe 'light show'. Loved Sanyo stuff back then 👍 For a portable radio back in the 70''s & 80's though I always went for Philips, 247m Radio 1 was useless on anything else 😂
@jeremyr62
Жыл бұрын
I remember encountering that Sanyo dongle in the early 70s. My first time listening to stereo. It was a big deal back then. Great video.
@Shineyongs.
Жыл бұрын
In the early days of FM broadcasting, there was no stereo broadcasting, so you had to connect an additional stereo module separately to hear it.
@xaenon
Жыл бұрын
There were (are) rules for radio and television that mandated backward compatibility for new technologies. The newfangled FM stereo stations had to broadcast a signal that could be heard on standard (mono) FM sets. The same rules applied to color television; you had to be able to receive it on a black and white TV. This was repeated when they began to push AM stereo in the 1980s, and there were two (possible three?) competing technologies that all had to be backward-compatible with older mono sets. Hence all this multiplexing stuff. Most other schemes for stereo involved a separate signal, but there are only so many frequencies that can be allocated.
@pcno2832
Жыл бұрын
I've seen some early 1960s console stereo systems (aka. "radiograms"), made in the USA, which had a similar arrangement, with the stereo decoder as an added-cost, dealer-installed option. This was probably to avoid having customers who lived in areas with no stereo broadcasts saddled with the cost of the decoder, which likely included royalties to the patent holders (Zenith, GE, and probably others). It might also have been used to allow manufacturers to ship "stereo compatible" systems before the standard for USA FM stereo broadcasts was finalized in April of 1961. This arrangement was used on some Canadian and (from the videos I've seen on them) English all-in-one systems into the early 1970s, probably for similar reasons. For Sanyo, which shipped its equipment all over the world, selling the decoder separately would have allowed them to accommodate whatever local standards were being approved at the time, especially considering the fact that 4-channel stereo systems, that were backward-compatible with 2-channel and mono equipment, were under consideration in various countries.
@PungieEC
Жыл бұрын
Most modern receivers in general and in cars will automatically switch between stereo and mono. The tuner will automatically if the signal strength is 35dBuv or lower switch to mono.
@TheSmcjose
Жыл бұрын
In USA there was radio stations that transmite Live Music in Quad SQ and some reciveres are ready for tuning and decod to Quadrafonic sound one of these equipements was Sony SQR AM FM Quadraphonic Receiver SQR-6650
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