Re: X-Band Fidelity (was Re: 1690 WMDM Lexington Park MD)

[Dan Strassberg <dan.strassberg@worldnet.att.net>]

Shel Swartz wrote:
>Years and years ago, when Boston's WMEX/1510 was a top 40 station, I noticed
>it seemed to have more fidelity than stations much lower on the band, like
>1150 or 590.  So I phoned WMEX's Chief Engineer, who explained that indeed,
>the higher teh AM wavelength, the better the sound....and the greater the
>skip.
>
>If indeed that is true, do any of you folks hear those new ex-band stations
>sounding a bit more crisp...with better high and low-end response?
>
As far as I know, from a technical standpoint, that's a total crock. Based
on his completely subjective observations (ALL observations of sound quality
are subjective), Shel noticed an effect that didn't exist. He called the
WMEX CE and got a satisfying explanation. The CE must have thought to
himself "what possible downside could there be from telling this guy what he
wants to hear?"

I daresay that until the carrier frequency approaches maybe three times the
audio bandwidth (that's the bandwidth of the audio chain in the receiver,
which, on AM, is usually less than the transmitted bandwidth), you would not
notice any effect of the carrier frequency on the audio quality.

I don't know if the Navy's multi-megawatt ultra-longwave TX in Cutler ME
still exists. Those transmissions, which were for communicating with
submarines around the world, were on something like 15.2 kHz. The modulation
was CW, as far as I know--no audio. Even at that carrier frequency, I
wouldn't be surprised if you could get telephone-quality audio--assuming the
transmitter and receiver were built for it. The Navy equipment was not. I
suspect, though, that with a carrier frequency of 60 kHz, which, as far as I
know, is a lower frequency than any used by the long-wave stations that may
or may not still exist in Europe, you probably could get audio quality that
sounded just as good as what you could pick up on 1510. (That's assuming
that both stations had equivalent audio chains and that you were able to use
the same radio to receive both stations.)