Taxi company on aviation frequency band??

[intiractive]

Listening to my scanner this afternoon and instead of listening to my bank of programmed channels, i decided to free-scan on 108-137mhz aviation band, and i came across some chatter on 109.600mhz. after listening to them a while i found out it was a taxi company dispatch talking to their drivers. has the frequency chart changed lately? the newest chart i can find is from 2003. is it me, or isnt this illegal for them to use the aviation band?

Scott
Wilmington, NC

 

[nd5y]

The aircraft band has not changed. You are probably hearing an image.

 

[intiractive]

you might be right. i know my scanner picks up 102.7mhz radio station on 145.500mhz (though very rough and gargled)... but what i heard earlier from the taxi company was crystal clear.

 

[W2PMX]

From the numbers, I'd say your scanner was picking up a strong signal on 152.4. The reason FM broadcast doesn't come through clearly on 145.5 is that on 145.5 you're receiving a wide FM signal (200kHz wide) in a narrow FM receiver.

 

[K9WG]

deleted

 

[kb2vxa]

It's possible the taxi company is quite close to you and overloading your receiver. You won't notice anything strange listening to their frequency but overload can cause the front end of a receiver to generate spurious signals and one is appearing in the aviation band.

I'm not surprised they're crystal clear, assuming you're not listening in FM mode an FM signal can be properly demodulated by an AM detector, it's called slope detection. That's when the receiver is off tuned slightly and the signal appears on the slope of the IF passband. Quite likely since scanners shift the IF slightly in order to properly tune the bands, they're offset from one another to begin with.