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Long Wave radio era set to end with switch-off

economist.com

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Re: Long Wave radio era set to end with switch-off

#151

Post by a57721 »

jasonjayr wrote: post #22
RachelF wrote: post #17

Earlier quoted context omitted.

In some way it is short-sited, as radio is a good backup medium for global communications in case the entire Internet ever goes down. Vacuum tubes also aren't vulnerable to nuclear weapon electro-magnetic pulses. However, other than ham radio enthusiasts I guess no one listens to analogue radio anymore.

I got my RTL-SDR to see what I could listen to, and by the time I tuned in, nearly all the short wave stations I could tune to were just broadcasting evangelical religious stuff, or other crazy conspiracy stuff. It's remarkable that these powerful stations spend most of their broadcast day transmitting that content.

Most international broadcasters have left the shortwave band quite some time ago, unfortunately. I think it is still easy to find BBC, China Radio International, Romanian radio, Radio Havana Cuba, but the list is relatively short (compared to 20 years ago).

In the US, WRMI sells its air time to anyone at low prices. It's mostly religious stuff but there are some regular music shows too, I think.

Re: Long Wave radio era set to end with switch-off

#153

Post by dotwaffle »

cogman10 wrote: post #144
dotwaffle wrote: post #137

Earlier quoted context omitted.

I could be wrong, but I think DAB uses DQPSK (which can be thought of as a special version of QAM 4 if you squint a bit) and not anything like the higher QAM constellations because it's deliberately designed for mobile (road, train etc) where you don't have a steady signal, it can vary a lot with motion, so QAM 64 wouldn't really be possible. Though I did a quick check and apparently DRM+ uses QAM-16, so perhaps my k…

LTE and 5g both use QAM 256 and higher. Wifi 7 can use QAM 4096 (though not a lot of motion there).

That's a good point about LTE/5G. Thanks!

Re: Long Wave radio era set to end with switch-off

#154

Post by gorgoiler »

WarOnPrivacy wrote: post #150
gorgoiler wrote: post #42

Earlier quoted context omitted.

Some things in life happen for the very last time and we never realize it. Where were you when Jim Maxwell interrupted the test match coverage, for the final time, to declare that “listeners on long wave will now hear the shipp-ing four-cairst”? :) With apologies to Affabeck Lauder

> when Jim Maxwell interrupted the test match coverage for the final time... Jim Maxwell has thrown to the shipping forecast for the last time -- July 31, 2023 ref: https://xcancel.com/abcsport/status/1685999353712848896

You absolute bloody gem. Brilliant.

Thank you :)

Re: Long Wave radio era set to end with switch-off

#155

Post by hdgvhicv »

dotwaffle wrote: post #127
hdgvhicv wrote: post #96

Earlier quoted context omitted.

It’s a digital cliff. Analog fades away but is never a true replication digital remains stable for over but then vanishes. At the same quality dab is still perfectly long after fm becomes gabled. It then vanishes. The problem with dab in early days was the lower strength, the poor quality decoding, and the lower bitratr than should be been used for the codec.

Not entirely true. There's quite a bit of error correction applied: https://en.wikipedia.org/wiki/Digital_Audio_Broadcasting#Err...

Which either recovers or doesn’t. The gap between fully recovered and indecodavle is tiny.

Re: Long Wave radio era set to end with switch-off

#156

Post by HPsquared »

mpweiher wrote: post #97
alentred wrote: post #41

That's such a pity. Building a simple AM radio receiver was a simplest and coolest electronics project to do with kids. You need two transistors, a ferrite coil and a small set of simpler elements. And it is so simple you can actually explain what every part of the circuit does. And then the reward... Once built you could listen to BBC regardless of where you are in Europe. My kids just LOVED IT, no Netflix K-Drama r…

We did that in my physics high school class. Then we took away components until we had virtually nothing left, a diode I think(?), and still we had some signal. Turns out there was a transmitter on the top of the hill the school was also on. Fun times.

With enough power anything is possible... If you put random vegetation directly on the radio mast (NOT recommended!), it makes sound directly-

https://youtu.be/b9UO9tn4MpI

Re: Long Wave radio era set to end with switch-off

#157

Post by yakkers »

jhoechtl wrote: post #147
yakkers wrote: post #30

Earlier quoted context omitted.

HF propagates through skywave (most reliably from 5-30MHz), which is where the signal bounces off the ionosphere. In the MF (AM broadcast) band, you can observe this at night - in Australia I can pick up the 50kW Melbourne ABC station (public broadcaster) at 774kHz with a good radio, just about across the entire country. In the LF (longwave) band, the earth’s surface and the ionosphere start to behave more like a wav…

Everyone is talking about the massive power of Radio 4 - it wasn't. Radio poland or algeria have much stronger LW broadcast.

It’s still quite a lot of power for AM (amplitude modulation) broadcast on any band.

If Radio 4 was on shortwave with 500kW transmitters, I probably would have been able to listen in on my radio at home in Australia, no UK-located KiwiSDR required.

Japan used to have a 500kW transmitter on 774kHz (mediumwave/AM broadcast band) for NHK Radio 2, and when the local broadcaster on 774 kHz went off air at midnight for scheduled maintenance, I could pick it up on my car’s stereo quite easily.

Re: Long Wave radio era set to end with switch-off

#158

Post by WorldMaker »

ErroneousBosh wrote: post #138
xattt wrote: post #82

Earlier quoted context omitted.

LW-HFT all the wayyyyy! - some cryptobro /s

That'd be quite a challenge! From a quick Google I see that HFT carries out trades in an average of 700ns, which is close to the cycle time of a 150kHz carrier, so you'd have to come up with some really clever phase modulation scheme that could carry meaningful data in *one single cycle*. You're definitely going down the SDR route for that.

It's still technically "high frequency", just in terms of sound rather than trade volume. Also if it's some cryptobro's pet project it probably needs time to settle on some blockchain ledger, so extra reason to find a new meaning for "high frequency" like sound wave cycle to confuse the marketing on the project.

Re: Long Wave radio era set to end with switch-off

#159

Post by yakkers »

Peanuts99 wrote: post #37
jimnotgym wrote: post #33

I'm very sad to see this go. I was listening to DAB in the car, not so far from here last weekend, and it kept cutting out. Whereas you could get LW everywhere! I developed a love of cricket on Test Match Special from a very young age. A tiny inexpensive radio could get it anywhere. I actually never minded the interruptions from the Shipping Forecast, the real reason they kept this service up for so long. I know ther…

Digital radio was always going to be crap, it doesn't degrade gradually as signal gets worse They should have just put all the money into a better 4G network and ran radio through that.

At the very least, I wish Digital Radio Mondiale won out over DAB. It’s designed to use the existing long, medium and short-wave bands and can even co-exist with an AM broadcast. I imagine digital radio would work quite well with the propagation characteristics of the mediumwave (and longwave) broadcast band.

There’s also DRM+ for the VHF band, including the FM broadcast band.

https://en.wikipedia.org/wiki/Digital_Radio_Mondiale

Re: Long Wave radio era set to end with switch-off

#160

Post by 7402 »

toxik wrote: post #40
bilegeek wrote: post #29

IMO, when the last LW transmitter shuts down, the whole band needs to be reallocated to hams. Realistic small-ish antennas are shockingly doable with a capacitance hat, loading coil, and counterpoise.

I hate to rain on your parade, but a lot of interests want the low-frequency spectrum. It will absolutely never be allocated to amateur radio.

Already has been, although just small bits at present:

US 2200m band 135.7 - 137.8 kHz US 630m band 472 - 479 kHz

These became available in 2017 in US, following the agreement of the International Telecommunication Union's 2007 and 2012 conferences.

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