Re: stereo and mono signals

["Eli Polonsky" <elipolo@earthlink.net>]

>Date: Thu, 24 Jan 2002 12:02:58 -0800 (PST) 
>From: Bob Nelson <bobonradio@yahoo.com> 
>Subject: stereo and mono signals 
>
>I've mentioned how I've been able to pick up 
>WNEF (91.7 Newburyport, // WUMB 91.9) in 
>Beverly when WMWM (also 91.7) is off. When 
>'NEF first signed on, I'd pick them up (again, 
>when WMWM was off) in stereo. Now their signal
>in Beverly seems to be in mono (on my car 
>stereo). 
>
>Now, I don't know if they're suddenly just 
>broadcasting in mono or whether stereo signals
>can only be picked up in mono after a certain 
>point-- which leads me to ask this question: 
>
>Can stations which normally broadcast in stereo
>be picked up in "mono" in their fringe area? In 
>other words, if you were in your car and at home,
>you'd pick them up but even though you have the 
>receiver set to "stereo", it defaults to "mono"... 
>You still pick up the signal, but in mono, not 
>stereo. 

This depends on the circuitry in your receiver. 
Most car receivers, either abruptly (more common 
in older receivers) or gradually, incrementally 
(more common in modern, digital receivers) 
default to mono reception when a signal 
becomes weak in order to avoid the increased 
static and noise inherent in reception of a weak 
stereo signal.

The older models are more subject to hearing the 
stereo effect "cut in and out" when you are driving 
into the outer reaches of the stations coverage 
area or other poor reception spots. The more 
modern car receivers generally "buffer" that effect 
incrementally.

However, even on receivers in which there is no 
circuitry to default to mono, it may become 
impossible for the receiver to demodulate the 
stereo multiplex effect of the signal when it 
becomes extremely weak.

It's possible that WUMB could be having technical 
problems with WNEF's transmitter regarding 
stereo. I know that their Worcester repeater WBPR 
has never been in stereo! It's something that 
they've vaguely said they'd deal with eventually, but 
haven't yet.

>-- some FM stations prefer to be in mono-- I think
>WBUR is usually, if not always, sending its 
>signal in mono due to its many talk and news 
>shows. 

WBUR goes stereo for "Con Salsa" Saturdays at 
midnight, "Only A Game" Saturday mornings, and 
the BU Marsh Chapel services on Sunday 
mornings. 

Whenever WBUR is left in stereo inadvertantly at 
other times during news/talk programming (due 
to an occasional automated control glitch, etc...) 
people immediately start calling to complain 
about static, etc... and it's usually not people 
listening in the fringes, but people listening right 
in the metro area on poor quality receivers such 
as analog boomboxes, etc..

I've tried to figure out the most polite way to say 
"you need a better radio"...
--