RadioBanter - View Single Post - Clear Channel and Public Service

Alan · January 29th 07, 07:23 AM posted to ba.broadcast,rec.radio.shortwave

In article lid writes:

I'm inclined to think the relative extra cost of adding NOAA to an
inexpensive AM/FM portable today would be considerably greater to that
of adding FM to a early-1970s AM set. You'd need an alphanumeric
display and enough buttons to handle programming. Either that, or you'd
put in a NOAA receiver that simply opens up whenever it detects modem
tones, without bothering to decode the data. I suspect most customers
wouldn't stand for that. The addition of FM to an AM set simply
involved adding an AM/FM switch and inscribing a few more numbers on the
existing dial.

Huh? The addition of FM involved a VHF front end, a different mixer
oscillator operating in the VHF range, different mixers, a different
detector, and in those days, AFC functions to deal with the problem
that the local oscillator drifted.

So, aside for the audio amp and the speaker, not much was common.

A NOAA receiver would need to find a NOAA signal to listen to ---
probably automatically, since most users would not bother to find one
locally, especially if they were traveling (think of the radio in a
car). It probably could be fixed on simple alert tones, but still,
would need the ability to find, tune, detect, and process the 162 MHz
narrow band FM signals. Not trivial, and of very limited value when
that radio is not in use.

If you live in tornado country, you probably want to keep a NOAA radio on
listening for alert tones all the time. When I was in Kansas last month,
my relatives there had one. A radio that is turned off most of the time
would not do the job.

Of course, in the San Francisco Bay area we are more likely to have
earthquakes than a tornado; earthquakes come with their own alerting system.

Alan