I found out why when designing a receiver.
stations used to be 400khz apart now they are 200khz apart. but with FM stereo a serious amount of sidebands are beyond 200khz. Adjacent channel interference or slight treble distortion...
The internet has improved fixed point radio. Mobile is still not great
Not on FM, no.
stereo is about 5db worse on FM
Not on FM
They will all be brushless driven by HF switched mode controllers generating synthesised sine waves. Experience with model aircraft suggest that brushless motors are an order of magnitude easier to get RF suppressed on than sparky brushes.
At full strength (typically 1mV (60dBuV) or more presented to the aerial terminals) The s/n ratio difference diverges away from that figure as the received signal becomes weaker
Typically at 30 to 50 uV ( 30 to 34 dBuV) of signal at the terminals, there's an 18-20 dB difference.
I used to listen to Capital as a lad 45 miles from the Tx. Capital was
100 uV (40dBuV) at my tuner input, the noise in stereo mode was just about tolerable (thanks to the programme content) Mono was as clean as a whistle.
The defects of AM were susceptibility to interference - which was all AM
- and co-channel interference - particularly at night.
I haven't read anyone writing about the BBC early experiments with stereo.
IIRC these experimental transmissions were made on Saturday mornings, putting one channel out on the Third Programme FM and one on BBC television. Again, IIRC, they broadcast thing like games of table tennis!
IIRC!
PA
Yes, that doesn't help, the band is so overcrowded now (In many places). However before the audio signal even reaches the transmitter, it's subjected to no end of compression atrocities, that's the point I was making
208 refers to the wavelength in metres, which would normally use AM.
My Tandberg TR1010 FM Stereo Receiver needed at least 1 Microvolt at the aerial to overcome the squelch and decode the signal. Otherwise no sound at all.
I assume you mean millivolt. A microvolt would be in the noise.
Stereo car radios only really became practical when the interference rejecting chip arrived. And also by blending from mono to stereo seamlessly, depending on the signal level.
Something very wrong with it. I had an FmM1 fitted with the factory decoder at a later stage and it was OK. FM1 and FM2 were pretty well the same valve design.
Medium Wave! Didn't read the header.
I ;disagree this was around in the early days, but never really caught on very much, but maybe it has made a comeback more recently. It used to be annoying in the car though. The Philips implementation might have been less subtle than the current one is, it was a long time ago now. There used to be a mod for this for the little tiny Sinclair stereo decoder based around one chip, but you needed to have mega good eyesight to get it into the small space!
Brian
The Quad FM tuner from the 80s was quite good. I had a Revox in the 70s, which was excellent.
I remember my first FM (we definitely called it VHF) set was one of those Russian-mad Rigonda units, which I bought in 1970 (£65). It was the one with separate amp/tuner, turntable and speakers, not the more expensive console model.
I was prepared for the stereo reproduction from the turntable, but not for the sheer quality of the inbuilt FM receiver. Until then, we'd only ever had an early fifties radiogram (78 rpm plus MW and LW) and later, a small transistor radio (MW and LW) powered by a PP9.
The first thing I tuned to was the VHF-only and still relatively-new Radio Merseyside (which until then, I had not heard at all). Speech reproduction was so good that it sounded to me like someone in the same room. I just wasn't prepared for it.
Depending on where you were in the UK, there were others.
In the NW, there was Radio Eireann (Dublin) and Manx Radio, plus, of course, Radio Caroline off the coast of the IoM. Some professed to be able to get AFN, but I never heard that.
I am told that there were several off-shore stations available in the SE of England.
Pre the upgrade of national transmitter links to PCM, local radio (particularly that distance from London) would have sounded noticeably better than the national stations.
My grandparents had a mains-powered "wireless" (*) that probably dated from the late 50s or early 60s, judging by the design of the case. It used valves and it had a "magic eye" tuning indicator which allowed tuning to be adjusted for strongest signal / best SNR etc. I'm not sure whether the magic eye worked only on VHF or whether it also worked for LF/MF where accurate tuning was less critical. It used a dial, tuning knob and variable capacitor. I wonder how long after the BBC started VHF transmissions that radio was made. My grandparents weren't normally at the bleeding edge of technology: they continued to use a black-and white 405-line TV (with built in FM radio receiver) until 1979 when they moved house and bought a colour TV at the new house.
(*) It would probably have been offended to have been called a "radio". ;-)
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