Tuesday, July 23, 2019

As in previous years, some listeners have noticed an increase in the interference of WCSB’s signal this summer. Below is an article written in 2008 by Mark Manolio, WCSB’s chief engineer, on the cause of this interference.

Why do I sometimes get a poor signal from WCSB or hear another station from Canada on 89.3 mHz when I am trying to listen to WCSB over the air? 

Probably because of a weather phenomenon called "Tropospheric Ducting" over Lake Erie.

Tropospheric Ducting can affect the propagation of FM radio signals via bending and ducting along weather fronts in the lowest layer of the Earth's atmosphere, the troposphere. Signals don't bounce off of this layer and are not reflected. It's more like they are "bent."

Normally, in the first 5000 feet of the Earth's atmosphere, cold air (which is more dense) sinks and warmer air rises. The opposite of that is called a "temperature inversion" where the warm air is trapped below a layer of colder air. FM radio signals are guided through the boundary between the two layers like air through a "duct."

In our area, this usually happens over Lake Erie in the summer when it is warm and humid near the ground and a weather front approaches a high pressure area. This will affect FM signals that are on the same channel and are located near the lakeshore on opposite sides of the lake.

For WCSB there are 2 stations that can interfere with us: Primarily CKGW at 89.3 in Chatham/Kent, Ontario (went on the air in April of 2007 with a religious format and 16,700 watts) and at times when the "tropo" stretches further south, we can also receive increased interference from the WKSU "repeater" in Wooster, OH on 89.3.

WCSB is not alone! The other stations affected here in the Cleveland area by "tropo" are WJCU at 88.7, WZAK at 93.1 and WGAR at 99.5. Not to mention the small low-power station in Cleveland on 95.9, WOVU. The corresponding stations across the lake are CIMX at 88.7 in Windsor/Detroit with 100,000 watts, WDRQ at 93.1 in Detroit with 26,500 watts, WYCD in Detroit at 99.5 with 17,500 watts and CFPL in London, ON on 95.9 with 150,000 Watts.

Interestingly, the ducting is a bi-directional process so we are also interfering with them at the same time they are interfering with us. (although we may notice it closer-in to the station due to our lower power)

You will notice that when the weather changes, usually the ducting will stop as abruptly as it began. That said, if a stable inversion weather pattern establishes itself, the ducting can last a long time! (days or weeks).

Another way to know that the "Tropo" is "in" is to monitor FM channels that have only a Canadian or Detroit signal on them. Some examples are 93.9 FM "The River" from the Windsor/Detroit area and 101.1 WRIF from Detroit.

When the ducting is taking place, these stations will usually come in much more clearly than normal.

What can I do to minimize the interference?

If listening at home, you can use a directional antenna (such as a rooftop TV/FM antenna) pointed towards Downtown Cleveland. If the direction you need to point the antenna for WCSB is significantly different than the interfering signal coming from Chatham/Kent, Ontario, this should help. If mobile, there's not much you can do other than to drive closer to downtown to receive a stronger signal from WCSB or listen to our online (Internet) feed.

We have 2 full-time Internet streams available at www.wcsb.org so you can listen on the computer or on your smartphone.

Mark Manolio
WCSB Chief Engineer


								
														
							

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