Re: News : ARM Trying to Buy AmperComputing

On 1/30/25 4:19 PM, The Natural Philosopher wrote:

On 30/01/2025 20:13, Charlie Gibbs wrote:

On 2025-01-30, The Natural Philosopher <tnp@invalid.invalid> wrote:
>

AM is of such crap quality it is unlistenable. 30-3kHz bandwidth

>
Isn't it 5 kHz?  I can't see wasting quality on a 2-kHz guard band.
>

Channel spacing is 9kHz. So since its double sideband you have to be WAY down at 4Khz.
By really careful tweaking I managed to get a radio design to 3.5Khz
 Total waste of time really - here in Europe there is too much RF clutter in the MW & LW bands
 

I've heard about AM stereo.  Is that for real?  If so, how?
>

No idea. Never heard off it. You cant make a silk purse...
 

and 40dB signal to noise? You have top be freakin' kidding me!
FM is way better,

>
As long as there isn't a hill between you and the transmitter.
And in a car you have constantly-shifting multipath interference.

 You get that on MW far far more.
 I've not had issues with FM reception - it either works pretty well or it just stops working till the next transmitter is in reasonable line of sight.
 UK has pretty good FM coverage overall - its a small place - and with RDS the tuner skips to the best transmitter and frequency  for the station you are tuned to. If its local, tough.
 

All in all, though, I consider FM a win - but it's nice to have
the AM option.
>

FM here has less stations but in practice a pretty good signal - the channel spacing in the UK is 200kHz so there's plenty of room, but in Germany they run 100kHz. The filters you need to reject a strong station 100KHz away do unpleasant things to the stereo at high audio frequencies.
 Germans have cloth ears anyway.

   The USA has a number of what they call "clear channels"
   on the AM band. Those stations install extremely powerful
   transmitters and become "regional radio". It is difficult
   to find a place where you can't at least receive some
   of those.
   https://en.wikipedia.org/wiki/Clear-channel_station
   Depending on exact atmospherics, you can often pick up
   clear channels from up to 1000 miles away at night.
   Few USA AM radio receivers have a 'sensitivity' or
   'bandwidth' adjustment. Those can be useful in rejecting
   strong close stations. You find them on 'desk-set'
   multiband radios, but not on consumer stuff.
   Sometimes that noisy mix of channels can be INTERESTING
   however ... drive half a  mile or go around the bend and
   you drift from one station to another to another  :-)
   When US automotive radios still had 'dials' there were
   two little 'triangle' symbols imprinted there. These
   were (are) the "when the bomb falls" emergency channels.
   A couple of megawatt+ stations are supposed to come on
   Just In Case.
   Hmmm - just for fun - there's been discussion of the
   upper+lower sideband width in AM radio. Now, what kind
   of music could be composed that would be adaptable
   to VLF/ULF/ELF frequencies ? With maybe 200 Hz or far
   less to play with ...  :-)