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KNTH Distortion

T

ThatVoice22

Frequent Participant
Today at 415pm, I tuned in to KNTH to catch the Michael Medved show and heard odd distortion and signal breakup which got consistently worse; since I live on the north-side, I expected that the simulcast on FM 103.3 would be fine. No, the FM signal was equally conflicted.

By 430pm, both signals were completely unlistenable – I expected that it was a network snafu so the local news break would be fine – no, the Ron Samuels and local traffic updates were equally chopped and obliterated. I tuned in later about 545pm and all was OK. Perhaps someone can enlighten us on what this signal-in-a-blender sound was all about.
 
Probably only an equipment problem. But if it's fixed that's good.
 
That's because of the anomaly known as 'temperature inversion.' This happens occasionally when the STL becomes partially blocked by a fog bank that is invisible to the eye, but it's enough to block or degrade the signal to the transmitter. Sometimes a very heavy rain will do the same, which was experienced this afternoon at the tower site. The problem is alleviated by connecting the ISDN from our studio to the transmitter site ISDN. It is not done automatically; it has to be done manually. The broadcast signals were fine. The signal sent was not. KNTH has suffered with this problem since the days when it was KENR. One other thing about 'temperature inversion.' The 'fog' is created when the air is cold and the ground is warm and when the air is warm and the ground is cold. This generally happens in late fall or early spring.
 
ChuckTiller said:
That's because of the anomaly known as 'temperature inversion.' This happens occasionally when the STL becomes partially blocked by a fog bank that is invisible to the eye, but it's enough to block or degrade the signal to the transmitter. Sometimes a very heavy rain will do the same, which was experienced this afternoon at the tower site. The problem is alleviated by connecting the ISDN from our studio to the transmitter site ISDN. It is not done automatically; it has to be done manually. The broadcast signals were fine. The signal sent was not. KNTH has suffered with this problem since the days when it was KENR. One other thing about 'temperature inversion.' The 'fog' is created when the air is cold and the ground is warm and when the air is warm and the ground is cold. This generally happens in late fall or early spring.
Click to expand...

One of the most famous cases of ongoing inversion issues involved KBIG, a Los Angeles area AM whose transmitter was on Catalina Island, about 30 miles from the studio location.

The microwave path would be affected by differences in air and sea and land and sea temperatures to the extent that the receiving antenna could not capture the signal. So the owner mounted multiple microwave receiving antennas on one of the AM towers and worked with STL manufacturer Moseley for a diversity reception setup whereby the receiver would select the best signal.

The setup was written up in one of the radio engineering publications of the era.

Note: "Diversity Reception" is not a cocktail party for members of different ethnic or lifestyle groups.
 
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Tip-of-the-Hat to ChuckTiller for an excellent description of a temporary/exasperating meteorological condition which interferes with studio to transmitter link signals. Lone gone are the days of having a transmitting tower in the backyard of a program studio - - Great example of STL "unlinkage" provided by DavidEduardo - - thanx for the great info!
 
Listened to the translator yesterday...left channel hotter than right...audio was ok...maybe a little hot. stereo still on...
 
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