London Control 131.1166

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London Control 131.1166

Postby saxonia » Mon Feb 15, 2016 12:23 pm

Hi

The following youtube clip shows very clear 2 way comms in the Derbyshire area on the above frequency. My records do not show this as a past or present allocation ?

https://m.youtube.com/watch?v=DOXOXM5hi4w

Mike
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Re: London Control 131.1166

Postby Staffs Paul » Mon Feb 15, 2016 3:11 pm

The video is from M3TSY here on the forum so he may be of more help.

There is a comment under it saying.....

The transmitter is actually on 131.125 and is at Daventry, which is not 150 miles from Derbyshire :-)


I think the above comment is both right and wrong. It might be daventry atc but the frequency is correct at 131.1166 I have listened to that in staffs and got no traffic next to it on 131.100 or 131.125 so 131.1166 must be the spot frequency.

I still cant get my head around these 8.33kHz so called new steps? All airport for main tower/approach/atis etc seem to have stuck with the standard 25kHz spacing but some atc/nats/routes or whatever in between seem to be now using 8.33kHz instead of 25kHz spacing. Can anyone explain simply what the situation is? i thought 8.33kHz was supposed to be the new standard but apparently not?
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Re: London Control 131.1166

Postby saxonia » Mon Feb 15, 2016 3:21 pm

Do harmonics still exist in the ATC world .. ??? ;-)
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Re: London Control 131.1166

Postby saxonia » Mon Feb 15, 2016 3:47 pm

You will see 25khz every 3rd frequency ie 3 x 8.33 = 25khz. So 131.025 / 050 / 075 etc are valid

The closest I can get to 131.1166 is 131.1666 and 131.0833. I dont think 131.125 exists anymore ?

Still in complete confusion .. Unless ihe 15X is giving a false reading ?

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Re: London Control 131.1166

Postby Minus1 » Mon Feb 15, 2016 5:18 pm

The frequency is 131.125.

It is shown in NATS documents as "131.130" because that is the convention used to describe 8.33 kHz wide channels which are on 25k multiples.

e.g See this document http://www.ead.eurocontrol.int/eadbasic ... -02-04.pdf
Page 2.1 - 2

A 25 kHz wide channel on exactly the same 25kHz multiple would be described as "131.125"

25k channels are still used by most low level services because not all aircraft are not required to have 8.33 kHz spacing yet; only high level aircraft.

Don't tell me it is a bloody stupid and confusing system, I know.

Confusion is made worse by the fact that most scanners have 25kHz bandwidth AM receivers, so they will easily pick up 3 separate 8.33kHz wide transmissions.

Personally I'd take everyone who though 8.33 kHz spacing was a good idea out at dawn and shoot them, to preserve the sanity of the human race. :rolleyes:

If they were going to reduce the bandwidth, 10kHz would have been infinitely more sensible, easier to understand, and quicker to speak. :mrcool:
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Re: London Control 131.1166

Postby saxonia » Mon Feb 15, 2016 5:43 pm

We still dont have the answer to the original question tho ... !!!
131.1166 is not a valid frequency be it 8.33 or 25khz spacing :dizzy:
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Re: London Control 131.1166

Postby Minus1 » Mon Feb 15, 2016 5:52 pm

saxonia wrote:We still dont have the answer to the original question tho ... !!!
131.1166 is not a valid frequency be it 8.33 or 25khz spacing :dizzy:


You obviously have not understood the complexity of 8 ⅓ KHz spacing!

131.11666666666666666666666666666666666 is a multiple of 8 ⅓ kHz.
It is 8 ⅓ kHz below 131.125 MHz.

It is not relevant to the post because the frequency in question is 131.125 MHz

This guy has written out all the frequencies in full, for people who can't get a grip on Eurocontrols half-baked idea.
http://g3asr.co.uk/calculators/833kHz.htm

The heading "set on receiver" is misleading. He means actual frequency used, not what is set.
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Re: London Control 131.1166

Postby saxonia » Mon Feb 15, 2016 6:28 pm

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 ???

131.115 131.1166
131.130 131.1250
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Re: London Control 131.1166

Postby Minus1 » Wed Feb 17, 2016 1:00 pm

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 ???

131.115 131.1166
131.130 131.1250


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.
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Re: London Control 131.1166

Postby biggles » Tue Mar 01, 2016 12:57 pm

Hello to all, this is my first post here despite being an airband listener for 38 years! The frequency is indeed 131.125 but interestingly on my UBC125XLT I can't here a thing 8.33Khz below on 131.1166 but I do pick up the transmissions 8.33 above on 131.1333 albeit reduced signal strength. I guess it all depends on the sensitivity and selectivity of your radio. Ridiculous idea to have 8.33 channels as ATC units tend not to use channels either side if their within VHF range of another sectors frequency. Interestingly I heard an exec jet climbing out of Luton heading north last week to go transatlantic that caused slight problems for ATC as he wasn't 8.33 channel equipped.
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