What happened to Car Radio Antennas?

The France LW station at 162kHz did broadcast the programs of France Inter radio AND the current time encoded in its carrier for radio controlled cloc ks. I always tought that was an efficient use of resources. That was until

2016 when they stopped transmitting the radio but kept transmitting the tim e and still do.

Since they keep the transmitter operating I think they could broadcast a ra dio, now is just a wasted resource. I guess it probably comes down to the r adio not willing to pay for that transmission, still they could offer some public service.

I have a car radio with LW and autotunning and it stops at 162, but only b ackground noise comes out. It does a good job of autotunning LW and MW, har dly ever stops on useless noises.

Yes that was a clever system. But it also shows an unfortunate depedency...

However, the power was originally 2,000,000 Watts and it has since been reduced to 800,000 Watts and of course the mains power consumption has been reduced even more because of course the strong AM modulation is no longer present (the time is transmitted in PSK).

Presumably the new power level has been determined "experimentally" to have a reliable clock synchronization for existing clocks on the system, however the German time transmitter DCF-77 operates with only 50kW on 77.5 kHz so one would think that a comparable power level would be sufficient for 162 kHz as well. But of course the exising installs may have gotten accustomed to the earlier level and the operator may be forced to maintain a relatively high power.

The British LW transmitter Droitwich was originally on 200 kHz and its frequency was also very accurate and was sometimes used as a reference frequency e.g. to calibrate equipment or to stabilize oscillators. At the time of the shift to the 9 kHz raster it moved to 198 kHz which was of course inconvenient for those users. However it is still as stable as before. I have seen mod circuits at that time that e.g. used a PLL to lock a 200 kHz oscillator to the 198 kHz carrier using a divide-by-100 and a mixer to do 200-2 => 198 kHz and lock to that.

At this time they also transmit data in PSK, I don't think that was the case in those early days (I'm not sure). This is probably the reason it is still on air, normally such a station would have been shut down by now but such extra features may make systems dependent on it. (most other MW stations in the UK have been shut down by now)

I think it is still being done due to the older equipment as to using some very low frequencies ( below 500 kHz) to calibrate frequencys and clocks.

With the GPS systems I would think that they would be used by most everything now and probably more accurate. I use them to calibrate my radio service monitors for frequency. I can buy a $ 20 receiver board and hook it to my oscilloscope and service monitor and set it to better accurecy than the normal drift of the monitor after a week .

I don't know what the signal would be like in other parts of the world, but the US puts out standard frequency and time sgnals on 2.5, 5,10, 15, maybe 20 MHz. There are a couple of frequencies in Canada around 7.3 and 14 something MHz for time. Most cell phones are probably accurate to a second or so.

It wouldn't be just nearby or just shielding it would form a shorted turn.

With shielded loops the shield is not connected all round to form a shorted turn.

If you can't see that you're not qualified to discuss this at all.

--
Brian Gregory (in England).

Yes I had forgotten I had ventured out of the uk.* newsgroups in to international territory. :/

--
Brian Gregory (in England).

AM transmitters with over 50kW output are not used in the US at all. (There were a handful of experimental ones at one stage in the past)

Yes in Europe higher powers were not uncommon, a few were as high as 1MW.

--
Brian Gregory (in England).

But it's not called "high quality FM broadcasting", it's just called "FM".

What about all the other frequencies where narrow band FM is used for walkie-talkies, remote controls etc. etc.?

--
Brian Gregory (in England).

Well as you say, with GPS it is not really relevant anymore. The LW transmitters may be very stable but the propagation adds jitter and the interference from local equipment is troublesome as well.

It is easiest today to get a GPSDO that outputs 10 MHz as a reference for your service equipment, there are devices in different price and performance levels.

I do have a Leo Bodnar GPS locked oscillator that I can program to output any frequency and sometimes use to calibrate receivers etc. Very cheap. (it does not only use NAVSTAR but also GLONASS and GALILEO)

How insulting to people with ASD.

--
Brian Gregory (in England).

As I explained in another followup, it seems related to the situation that in Europe radio stations traditionally were a state thing, and you would have to cover an entire country with the same signal, so high output power is a reasonable move. In the USA, it looks like it always was a commercial thing and more focused on local operation, servicing a single town and surrounding area.

Still, with 50kW transmitter output AM a typical station would rather place 5 FM transmitters of 5kW and have the same coverage area but with much better quality. For a 5kW AM transmitter a single FM site would probably do it. (FM transmitters usually have antennas with ~ 10dB of gain so they effectively transmit 10 times more than their rated output power, which cannot reasonably done with MW (AM) transmitters due to physical limitations)

** It called " The FM band " and it IS reserved for "wide band" FM broadcasting.

The name refers to what exists.

** Yawnnnnnnnnn.....

.... Phil

** ROTFL !!!!!!

Obviously YOU are one of them.

Folk with ASD make all those around them suffer by shoving their bizarre thinking down their throats.

Plus totally misconstruing everyday words and their meanings.

..... Phil

Oh, I forgot.

In the US there are narrow band FM weather broadcasts.

NOAA weather I think it's called.

Definitely FM (albeit narrow band FM).

Definitely not in the 87.5-108 MHz band (somewhere around 162MHz IIRC).

--
Brian Gregory (in England).

Brian Gregory = Rabid ASD fueled Lunatic wrote: =====================================

** Like dog with a bone, this blithering IDIOT will just not let go of his bonkers notion.

Likely he believes the name "Steak Sauce" is false too.

Got no damn steak in it......

..... Phil

For some reason, Tesla's do not have an AM band. I can't imagine why that is...

-- A host is a host from coast to snipped-for-privacy@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433

cough, cough....

WLW. It ran 500KW+ in the past, but regulators cut them back to the ordinary 50KW level in ~1940.

The transmitter tubes had 3-phase filiments, if that gives you some idea of their size.

There were multiple stories of farmers getting bit by their hot barbed wire fences, metal roofs that played WLW, etc.

--
A host is a host from coast to coast.................wb8foz@nrk.com 
& no one will talk to a host that's close.......................... 
Unless the host (that isn't close).........................pob 1433 
is busy, hung or dead....................................20915-1433

You can't? Well I can!

- not useful in large parts of the world

- interference from motor control

Actually it makes no sense to make an AM (MW) transmitter using tubes today. Designs using semiconductors and some switching mode are

3+ times more efficient (mains->antenna) and that is a big difference at those powerlevels.

See e.g. Nautel NX

Probably the interference from the other electronics in the car. Easy to eliminate if you just leave the receiver out of the radio.

I just hope it is not like a friend that had a car about 40 years ago where he replaced the spark plug wires and spark plugs with the non resistor types. If you had an outside TV antenna which almost everyone did back then you could tell he was on the way from about 3 blocks away and when he got in the driveway you lost all of the TV station.