Re: News : ARM Trying to Buy AmperComputing

On 31/01/2025 04:49, Robert Riches wrote:

Regarding the (theoretical) audio bandwidth of US AM broadcast
radio:
      https://en.wikipedia.org/wiki/AM_broadcasting
 

Well, you live and learn
Absolutely not the case in Europe

In the section titled "Technical information" around 80% of the
way down the article, the audio bandwidth was reduced in 1989 to
10.2kHz.  Prior to that, it was 15kHz.
 The 15kHz matches my memories from earlier studies and the manual
that came with the Pioneer TX-7800 tuner I bought in 1980-81.
That tuner has a front-panel switch for AM IF bandwidth that
yields ~5kHz vs. ~15kHz audio bandwidth, based on some filters
(ceramic, IIRC) that were pretty high tech for the time.  Sadly,
it seems some dust has become lodged in the mechanical tuning
capacitor.  It still has partial function but like when it was
young.
 

Yup, You would need switchable IF strips or tuning parts for that

While the theoretical audio bandwidth was pretty decent at 15kHz,
now 10.2kHz, practical bandwidth depends on the receiver (as
stated in the article linked above) and on the RF S/N ratio.
Near to the transmitting antennas, the Pioneer tuner had rather
good listenable bandwidth.  Out in a rural county with a lot of
buzz-producing light dimmers and switching power supplies around
the house (and probably foil-backed fiberglass insulation in the
exterior walls), the audio S/N ratio is terrible.
 

Twas ever thus, and the change to FM convoluted such noise into merely increased hiss rather than recognisable interference.
--
"It was a lot more fun being 20 in the 70's that it is being 70 in the 20's"
Joew Walsh