saxonia wrote:Yes I agree I am stuggling to get to grips with this .... 131.125 is Daventry Sector 32 which is what we can apparently hear on the youtube footage. This is also shown in various publications as 131.13.
Now the frequency shown on the Bearcat scanner is 131.1166 which is shown on your link below as 131.115. Now surely you would not hear 131.125 on 131.1166 as you would need to programme 131.125 into the Bearcat to hear this ???
Those publications are using the "frequency" published by NATS and spoken by Air Traffic Control.
Except it is not a precise "frequency", it is effectively a "channel".
If the frequency is 131.125 with a bandwidth of 8 ⅓ kHz, the convention is to call this channel "131.13".
The same frequency with a bandwidth of 25kHz is called "131.125".
Both are the SAME FREQUENCY, only the bandwidth is different.
Yes you WOULD hear it. The scanner has a 25kHz wide AM receiver. It does not have a 8 ⅓ kHz wide AM receiver. If you try and listen to a 8 ⅓ kHz AM transmission on a receiver that is designed for 25 kHz wide AM reception it is entirely likely that you will detect THREE 8 ⅓ kHz channels.
In this case 131.11666666666 131.125 131.13333333333
There are very few scanners that can properly handle 8 ⅓ kHz transmissions.
They may be able to select the frequency, but they do not implement an 8 ⅓ kHz bandwidth AM receiver.
I believe the new AOR DV1 has the facility, as you can select various bandwidths, but I doubt that even implements Eurocontrol's bizarre frequency/channel numbering and thus selects the appropriate filter bandwidth automatically depending on what frequency/channel you key in.
It you want that, you'd best speak to Airbus or Boeing.