8.33 or 12.5

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Gemini4
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8.33 or 12.5

Post by Gemini4 » 10 Jan 2014, 13:57

which mode is best 8.33 or 12.5...?
mostly when i find frequencies and put em into a search on UK Aviation Frequency Database nothing turns up?
but i can clearly hear the freq..is it a miss match with the 8.33/12.5.

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Re: 8.33 or 12.5

Post by JGR » 10 Jan 2014, 14:19

You will need to search for both as a few airlines have adopted the new transceivers that use the 8.3KHz spacing and you will sometimes miss them out under a normal scan of 12.5KHz.

Mind you I have only heard a few in so much that I could count them on one hand but as time goes on more and more will move over so do not omit it too soon.
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RogerD
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Re: 8.33 or 12.5

Post by RogerD » 10 Jan 2014, 15:34

8.33 steps will pass through every possible channel, no need for 12.5 if the 8.33 mode is done properly.

The actual frequency 123.458333 won't appear anywhere online, it will be known by a 'name' as 123.460 i.e. rounded up or down to the nearest 5 kHz just to make things even more complicated :)

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Minus1
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Re: 8.33 or 12.5

Post by Minus1 » 11 Jan 2014, 13:41

Here is an example of the chaotic shambles they have created by the inane decision to use 8.333333333333333…etc kHz spacing:
This the first 0.1 MHz of the VHF airband.

The first freq is the actual freq transmitted, rounded here to 5 decimal places.
Second freq is what is spoken by air traffic control and set on the aircraft radio, the radio automatically adjusts to the correct actual frequency and bandwidth, your scanner won't do this.
In particular, note that 118.0 and 118.005 (for example) are in fact the same frequency (118.0), but use different bandwidths.
Most scanners don't have 8.33 kHz bandwidth so will just use 25 kHz.

VHF Air 118.00000 118.0 AM 25 kHz channelling example ".0"
VHF Air 118.00000 118.005 AMn 8.33 kHz channelling example ".005"
VHF Air 118.00833 118.01 AMn 8.33 kHz channelling example ".01"
VHF Air 118.01667 118.015 AMn 8.33 kHz channelling example ".015"
VHF Air 118.02500 118.025 AM 25 kHz channelling example ".025"
VHF Air 118.02500 118.03 AMn 8.33 kHz channelling example ".03"
VHF Air 118.03333 118.035 AMn 8.33 kHz channelling example ".035"
VHF Air 118.04167 118.040 AMn 8.33 kHz channelling example ".04"
VHF Air 118.05000 118.05 AM 25 kHz channelling example ".05"
VHF Air 118.05000 118.055 AMn 8.33 kHz channelling example ".055"
VHF Air 118.05833 118.06 AMn 8.33 kHz channelling example ".06"
VHF Air 118.06667 118.065 AMn 8.33 kHz channelling example ".065"
VHF Air 118.07500 118.75 AM 25 kHz channelling example ".075"
VHF Air 118.07500 118.78 AMn 8.33 kHz channelling example ".08"
VHF Air 118.08333 118.085 AMn 8.33 kHz channelling example ".085"
VHF Air 118.09167 118.09 AMn 8.33 kHz channelling example ".09"
KEY : = channel/stud | ~ = CTCSS/DCS | ^ = transmitter site | ¯ = overhead | * = trunked

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Re: 8.33 or 12.5

Post by Gemini4 » 12 Jan 2014, 11:37

funnily enough minus since you've mentioned the 25khz step..all my findings have matched
up with the UK aviation database can't put a link in as the website won't let me {bnghd}
except for one 131.525 which gives of a bleep noise for some reason.
1 131.525 Luton Airport London European A... Details
2 131.525 Luton Airport Monarch Airlines Details
3 131.525 Luton Airport Ryan Air 2 Details
4 131.525 Manchester Airport American Ops Details
thanks :D

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Re: 8.33 or 12.5

Post by Tigersaw » 12 Jan 2014, 11:52

Its going to be a while before airports operate 8.33, since all the 'customers' need to adopt it too.
The incentive for the airports is there, the licences are cheaper as its now based on spectrum occupancy, bandwidth x declared operational coverage.

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RogerD
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Re: 8.33 or 12.5

Post by RogerD » 12 Jan 2014, 12:07

131.525 is a data link channel (ACARS)

8.33 channels are indeed cheaper to licence, so they're becoming more popular for company ops channels.

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Re: 8.33 or 12.5

Post by Minus1 » 13 Jan 2014, 09:43

Heathrow already have an 8.33 kHz frequency, obviously it's only for large jets anyway
VHF Air 121.93333 "121.935" AM EGLL Heathrow Departure ATIS
KEY : = channel/stud | ~ = CTCSS/DCS | ^ = transmitter site | ¯ = overhead | * = trunked

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