Radio London an offshore station is doing an rsl on medium wave, it is 1w, I don't think anyone has heard it, it is on 1206Khz if anyone wants to try https://www.biglradiolondon.co.uk

It's an abysmal signal. I was within a mile of their site yesterday, and it wasn't (quite) "entertainment quality" on my car radio. This is weird, because I can hear a couple of the Dutch LPAM stations on Felixstowe sea front, and they run about a Watt too. 1206 kHz is a reasonably quiet frequency, so they should go a bit further than they are!

Yeah, I used to hear York university on medium wave, it was an alright signal on a car radio parked away from a build up area, it was meant to 1w, it would go 20kms or more, mostly I would hear a lot of talking on it, York race day radio could hear even further away on 1602. I’m heard other universities in the past like the Hull one, I think it must of been skywave, don’t know the power of them, don’t know if the other universities have followed suit gone onto the low power fm trial, don't think I saw any on the list, if they broadcast at all, suppose it will be interesting to find out.

Albert H wrote: ↑Wed Aug 16, 2023 11:01 pm It's an abysmal signal. I was within a mile of their site yesterday, and it wasn't (quite) "entertainment quality" on my car radio. This is weird, because I can hear a couple of the Dutch LPAM stations on Felixstowe sea front, and they run about a Watt too. 1206 kHz is a reasonably quiet frequency, so they should go a bit further than they are!

Finished on the 14th, so whatever you heard wasn't that!

I know - I actually tried it on three separate visits to Felixstowe during their broadcast period, and it really was dreadful.

Recently, a friend of mine wanted to make a point about the muffled mod on Caroline 648 kHz, so put their 'net stream in to a little 4 Watt AM rig on 666 kHz from not too far away from their site. That 4 Watts into a fairly short vertical went for miles, and sounded much better than the 648 kHz!

Albert H wrote: ↑Sat Aug 26, 2023 11:17 pm I know - I actually tried it on three separate visits to Felixstowe during their broadcast period, and it really was dreadful.

Recently, a friend of mine wanted to make a point about the muffled mod on Caroline 648 kHz, so put their 'net stream in to a little 4 Watt AM rig on 666 kHz from not too far away from their site. That 4 Watts into a fairly short vertical went for miles, and sounded much better than the 648 kHz!

Yes, that's my experience too. They limit their bandwidth, while home-made rigs generally don't.
I remember listening on my car radio a playlist my PC was feeding to a 15W AM transmitter 10km away and one of my passengers (a musician!) asked my what CD I was playing! Of course the audio quality when listening to music in a moving car is somewhat affected by the noises the moving produces and the engine but still one could hardly notice the difference.

Apparently Caroline are installing an Optimod unit at their tx site tomorrow. It will be interesting to see what, if any improvement is brought to 648. I'm a bit far to get entertainment quality from Ordfordness so here it's a rebroadcast of their main stream via raspberry pi and one of those small sstran AM senders

That's interesting info and I will have a listen out. I do occasionally tune in to Caroline on 648kHz in the car, and at certain times of the evening the signal's strong enough with minimal fading, but it's a tough listen with its booming bass and lack of top end.

I tuned in "Radio 208 Copenhagen" on 1440kHz tonight around 6PM. It was a better listen than Caroline in my opinion, despite apparently running around a tenth of the power. I imagine Caroline would do much better on AM if they sorted their audio out.

Their mod isn't any better. They really are clueless.

It's tricky, you hear they've made changes and then your ears start deceiving you! I was listening yesterday and thought the bass sounded quite punchy, but there's so many variables, subjective and otherwise. Definitely no improvement in the top end. So I agree with you Albert, it could still sound a lot better. Good signal strength though, once the conditions start to play right.

People behind Caroline are probably all deaf at this point anyway

jvok wrote: ↑Sat Jan 13, 2024 6:55 pmPeople behind Caroline are probably all deaf at this point anyway

Ha ha, some of them are younger than I am!! And I'm not the oldest on this thread

Funnily enough the 558 services back in the day was often criticised for its lack of top end.

Oddly the 648 service is authorised more audio bandwidth than the 4.5 KHz a lot of AM stations are restricted to but the majority of radio's on the market are not designed to make full use of even this.

Persona Non Grata wrote: ↑Sat Jan 27, 2024 3:55 pmOddly the 648 service is authorised more audio bandwidth

I was a bit gobsmacked by this so rather than rely on my old ears I did some analysis with an SDR. It looks to be rolling off at about 4.6kHz.

That's odd. The Wireless waffle website quoted something like 6.5 KHz. Maybe the bandwidth was cut when they got the bigger transmitter?

https://www.wirelesswaffle.com/index.ph ... 122-083104

Not at all. It's always sounded like it's coming through a sock!

The BW DSPX they insist on using is capable of various output curves, and most of the 9 kHz channelling ones are within the UK legal specifications. However, they seem to have chosen the narrowest bandwidth setting. They really don't need to. Their rig is capable of audio to >12 kHz (which wouldn't be legal, of course), but there's no reason at all why they shouldn't go up to 7.5kHz. It would sound a whole lot better.

I offered them a Euro-specced Inovonics 222 - which sounds very much better than the silly DSPX (and is entirely analogue) - and that can be configured for really nice - but compliant - audio quality. I was told that they weren't interested, so as far as I'm concerned they can continue to sound muffled and have no real audience!

If one looks at the bandwidth of a lot of UK AM stations on an SDR it is clear a lot of them have up to 7KHz of audio at least during daylight hours.

It's generally allowed legally unless/until an adjacent channel station complains (then they have to switch down to 4.5 KHz)

ON most modern consumer level radio AM audio quality is treated as an afterthought though and they barely manage 3 KHz

Back in my pirating days I used to relay Atlantic 252 overnight on my FM station and folk were amazed at the quality. (Don't shoot me. There wasn't much else available to relay where I lived)

I've got a rig on in the Benelux with an audio bandwidth of bang on 7.4 kHz (it's ~90dB at 8.5 kHz), and it has a slight bass lift, and a slight mid range and treble lift to "brighten" the sound. On a good receiver, it sounds really good. It doesn't have the top end of FM of course, but it's perfectly listenable quality. Speech content is clear and undistorted, and music sounds really good.

I've used a slow-acting AGC to even out the basic levels of the various programme sources we use, and then there's roughly 3.5 : 1 of gentle compression to stop the quiet parts disappearing into the noise, and a fast limiter to prevent the rig running over mod. There's also a "phase rotator" to squeeze the last bit of level out of the set-up. The final stage (before the filtering) is a clipper to shave off any really fast peaks (like record scratches).

Just for the sake of amusement, we put the satellite feed of Caroline through it, and had a few friends of ours compare our audio with their 648 kHz audio. It was like night and day!

Getting it right isn't difficult.

Albert H wrote: ↑Sun Feb 11, 2024 11:29 pm Just for the sake of amusement, we put the satellite feed of Caroline through it, and had a few friends of ours compare our audio with their 648 kHz audio. It was like night and day!

Getting it right isn't difficult.

I thought the satellite feed of Caroline is long gone?
Wikipedia says it closed in 2013, a few years before 648 started. (https://en.wikipedia.org/wiki/Radio_Caroline)

Or is there presently a 'hidden' non-publicised satellite feed I do not know about?

We used the https://stream.radiocaroline.net/rc128/ stream. It used to be a satellite feed.