Why does MW reception deteriorate at night?

[Doseone]

Was going to ask this on the R4 LW thread but didn't want to hijack. There are clearly some knowledgeable radio buffs on here!!

I've noticed that MW reception (R5L & Talksport) deteriorates badly from early evening onwards. Strangely with Talksport, the deterioration is far worse during the adverts when it sounds as though 2 adverts are being played at once, then it improves slightly once the ads finish. Why does this happen?

 

[Noodley]

I thought MW reception was just crap all the time, it is for me. I have to stand on one leg with my arm out the window to get anything barely worth listening to with MW, which can cause problems when I want to listen to MW when driving.

 

[Night Train]

Mine is significantly worse at weekends. Weekdays I can get a strong radio 2 and 4 signal but weekends it can get fuzzy to the point of pointlessness.

I reckon it is a plot to get us to change to DAB.

 

[Noodley]

Are radios 2 and 4 not on FM tho? What is the point of using MW when the same programme is available elsewhere at a better reception?

 

[Night Train]

Are radios 2 and 4 not on FM tho? What is the point of using MW when the same programme is available elsewhere at a better reception?

Yeah, sorry, time warped there for a moment...

 

[Noodley]

What stations are still on MW? 5Live and Talksport as per OP, and Radio Scotland has MW option mostly for football. Gone are the days of twidling knobs under the bedsheets to get Luxenburg...

 

[Bman]

MW is good for places that don't have (or can't get) FM reception.

 

[marinyork]

Skywave

 

[Arch]

Durrrr! It's obvious why reception is worse at night.

The waves can't see where they're going in the dark.

 

[ColinJ]

From Wikipedai: Medium wave signals have the property of following the curvature of the earth (the groundwave) at all times, and also refracting off the ionosphere at night (skywave).

At night you will be picking up extra signals on the same frequency from further afield which can cause interference. My guess with the adverts is that the same programme is being broadcast on two transmitters, but the adverts are local to each area served? (So the music or speech might sound a bit fuzzy from your local signal having a delayed remote signal interfering with it, but the delayed remote ad could be completely different.)

 

[TheDoctor]

Marinyork has the answer, although just saying 'Skywave' isn't all that illuminating.
*Gross over-simplification alert*
The ionised layer in the atmosphere reflects MW, and at night it moves higher, so you get interference from distant transmitters. In the day it's lower, so far-away signals don't get here and cause interference.

Bugger, cross-posted

 

[Doseone]

From Wikipedai: Medium wave signals have the property of following the curvature of the earth (the groundwave) at all times, and also refracting off the ionosphere at night (skywave).

At night you will be picking up extra signals on the same frequency from further afield which can cause interference. My guess with the adverts is that the same programme is being broadcast on two transmitters, but the adverts are local to each area served? (So the music or speech might sound a bit fuzzy from your local signal having a delayed remote signal interfering with it, but the delayed remote ad could be completely different.)

Marinyork has the answer, although just saying 'Skywave' isn't all that illuminating.
*Gross over-simplification alert*
The ionised layer in the atmosphere reflects MW, and at night it moves higher, so you get interference from distant transmitters. In the day it's lower, so far-away signals don't get here and cause interference.

Thank you

 

[Glow worm]

I've noticed that MW reception (R5L & Talksport) deteriorates badly from early evening onwards. Strangely with Talksport, the deterioration is far worse during the adverts when it sounds as though 2 adverts are being played at once, then it improves slightly once the ads finish. Why does this happen?

Well I bored you all to tears with the long wave thread so I may as well do the same on medium wave.

The Doctor has it spot on above. This 'skip' effect allows signals on AM to travel much further at night which can cause interference from continental stations. The Geneva Frequency Plan of 1975 helped allocate frequencies among various countries to avoid the worst of this (each country is allocated a number of channels) and power etc is agreed through the good folks at ITU (Intenational Telecommunications Union). Their Christmas parties must be a right old knees up!

But Medium Wave (MW) is still a mess at night. I get Berlin under Radio 5 Live 693 here for example and Germany also knocks out Absolute on 1215 completely too. Broadcasters do themselves no favours too by woeful levels of maintenance of transmitters and many engineers have been let go. Absolute Radio sounds pitiful on AM. Shocking modulation and all the 'filler' channels (such as 1197 hereabouts) are badly maintaned. You are correct about Radio Cockney Tawk Spawt too . They suffer badly from having a number of transmitters on the same channel, which are all badly phased and interfere with eachother at night (so to speak). That's why in ad breaks you can hear several cockneys ads at once.

But MW does not always sound terrible. channels lower in the band are more stable at night and suffer less from the 'fading' some may remember Radio Luxembourg famously suffered on 1440. Spain's RNE 1 on 585 is fairly solid across the UK at night and France Bleu - Isle De France (they play some nice tracks if you can bear the constant traffic news) on 864 is a lovely steady signal (and Europe's only AM station broadcasting in stereo). Channels lower in the band travel further on the same power - that's why I can get BBC Hereford and Worcester (who?) here on 738 as well as Radio York on 666. If York were higher up the band, I doubt they'd get beyond Nottingham.

Before getting hijacked by the religious maniacs (they seem the only ones with more money than sense nowadays when it comes to renting air time) the Lopik facility in Holland used to broadcast Arrow Classic Rock on 675 (and before that the wonderful Radio 10 Gold - now on 828) and it was a superb, crisp signal- again rock solid and the bass really suited the rock tracks. The signal was so strong folks in Lowestoft could get it on their toasters. There was a time when Arrow seemed to be on everywhere hereabouts.

Radio signals also travel much further over sea - that's why Caroline and Laser 558 got out so well. It's why you can hear Radio Norfolk in Amsterdam on 855 and Aberdeen's Northside Sound on 1035 clearly on the North Norfolk Coast. It also allows some pretty spectacular trans Atlantic catches too. VOCM from St John's Newfoundland is commonly heard here on 590 in winter at night and last December I heard WEGP from Presque Isle in Maine USA on 1390.

There- if that doesn't win dullest post of the year I don't know what will.

 

[snorri]

There- if that doesn't win dullest post of the year I don't know what will.

You sound like the sort of person who would devise cycle tours to include as many names as possible from the dial of an old wireless set, Hilversum, Kalundborg, Motala, Morava, etc.

 

[Globalti]

Blimey Glow Worm - are you one of those bods with a big aerial sticking out of your roof?

You probably know a bit about those strange unexplained note sequences that used to be played continuously for hours late at night on wavelengths used by east-European stations. I can't remember what they are called now but I was interested in them briefly a few years ago, having spent hours listening to them as a kid and wondering what they were for. I did once succeed in staying awake for long enough to hear that one note sequence eventually ended with a burst of martial music then silence.