8.33 spacing

[bearcatrp]

Lately, have been scanning civil air band. My 160DN came pre programmed with 8.33 spacing. I added a custom search for 25k spacing. Lately, scanning 25k doesn't pick up much and allot of static frequencies. When I switch over to 8.33, get plenty of hits without most of the static. Is the USA switching over to 8.33 spacing?

 

[K4EET]

25 kHz channel spacing was divided into thirds yielding 8.33 kHz channel spacing for air band.

 

[RichardKramer]

The aircraft comms here in the USA are still using the 25KHz spacing. There's a few test aircraft using the 8.33KHz freqs.
It's strange that you're hearing more with the 8.33 spacing. Maybe your scanner is out of alignment?

 

[K4EET]

The aircraft comms here in the USA are still using the 25KHz spacing. There's a few test aircraft using the 8.33KHz freqs.
It's strange that you're hearing more with the 8.33 spacing. Maybe your scanner is out of alignment?

I thought all aircraft with radios capable of 8.33 kHz splits were starting to use that split and aircraft with older radios that only do 25 kHz splits used the older split.

 

[RichardKramer]

I thought all aircraft with radios capable of 8.33 kHz splits were starting to use that split and aircraft with older radios that only do 25 kHz splits used the older split.

I'm not aware of any RCAG/ATC sites using 8.33KHz spacing; at least not here in the USA; except for a few test a/c talking to ground units.

 

[K4EET]

I'm not aware of any RCAG/ATC sites using 8.33KHz spacing; at least not here in the USA; except for a few test a/c talking to ground units.

Roger that.

 

[RichardKramer]

Roger that.

I did a search on Google and says the FCC has allowed some Flite svc and Enroute stations to use the new spacing here in the USA; but those freqs are mostly used by test aircraft.
But ATC stations must use the 25KHz freqs.

 

[nd5y]

There is no ATC use of 8.33 kHz channels in the US.
See this thread from 2016. It hasn't changed since then.

8.33 spacing questions

I was wondering if anyone here has an xls file with the 8.33 spacing from 108.000 to 137.000 that I can compare to what I did. I tried using something I found online but I am not sure its correct. It did say that with the 8.33 spacing I should get 2280 channels and I did get 2280 channels with...

forums.radioreference.com

 

[Ubbe]

It's aircrafts at 30.000ft levels that mainly use 8.33KKz as they cover half of Europe with their transmissions, so needed more channels to not interfere from one aircraft in southern Europe with one in the northern. Those channels are usually above 128.8MHz.

/Ubbe

 

[spanky15805]

ICAO standards for 8.33khz are in use in the EU for air to ground communications.

8.33khz channel spacing is NOT currently being used in the USA. The CM 300/350v2 radios are capable of 8.33khz channels.

Ultra high enroute and high enroute should see deployment first around 2035.

 

[JensLK]

Here in Germany/Europe pilots don’t get told frequencies any more. They get Channels to switch. For example:
ATC says: Scanner tune to:
118.005 118.0000
118.010 118.0083
118.015 118.0166
118.030 118.0250
118.035 118.0333
118.040 118.0416
118.055 118.0500
118.060 118.0583
118.065 118.0666
118.080 118.0750
118.085 118.0833
118.090 118.0916

 

[bearcatrp]

Just find it odd that in past few weeks, scanning with 25 khz wasn't getting much results and allot more static when locked in on a frequency. When I switched to 8.33 khz spacing, picked up plenty of hits and very little static. Just thought I would ask. Thanks for the replies.

 

[K4EET]

Just find it odd that in past few weeks, scanning with 25 khz wasn't getting much results and allot more static when locked in on a frequency. When I switched to 8.33 khz spacing, picked up plenty of hits and very little static. Just thought I would ask. Thanks for the replies.

While I am not a receiver design engineer, I wonder if this is possible:

When you do receive chatter that has very little static while you are set to 8.33 kHz spacing, are you receiving chatter only on frequencies in the 25 kHz band plan since you set a custom search for 25 kHz spacing? If that is the case, you probably would receive less static since the receiver's bandwidth is decreased for the closer spaced frequencies of the 8.33 kHz band plan. You may still be able to demodulate the AM/SSB 25 kHz spaced signals. Do the voices sound normal? Just trying to figure this out...

 

[dave3825]

Just find it odd that in past few weeks, scanning with 25 khz wasn't getting much results and allot more static when locked in on a frequency. When I switched to 8.33 khz spacing, picked up plenty of hits and very little static. Just thought I would ask. Thanks for the replies.

Do you have sdr? Did so, try that with 25khz spacing and see how that work. If more than the scanner, than the scanner may have issues.

 

[bearcatrp]

No SDR’s. Been using my 160DN. My R15 will be hear Tuesday so will test it out to see if I get the same issue.

 

[Ubbe]

you probably would receive less static since the receiver's bandwidth is decreased for the closer spaced frequencies of the 8.33 kHz band plan.

Scanners use only one bandwidth for AM. For older scanners like BC780XLT it uses a 25KHz wide filter but you can solder a diode to the easy to reach bottom side of its circuit board to change that to the more narrow 12KHz filter. Modern Uniden scanners with a DSP use something like a 9KHz bandwidth for AM.

As for the same reason that adjacent sites for radio systems doesn't use adjacent channels due to crosstalk I would assume the same rule applies to channels used in aircrafts, that they have at least one guard channel distance between channels in the same general area.

/Ubbe

 

[merlin]

I thought all aircraft with radios capable of 8.33 kHz splits were starting to use that split and aircraft with older radios that only do 25 kHz splits used the older split.

The aircraft radio itself is 25 KHz in the general aviation arena, Commercial is in a slow shift to digital except HF.

 

[merlin]

Just find it odd that in past few weeks, scanning with 25 khz wasn't getting much results and allot more static when locked in on a frequency. When I switched to 8.33 khz spacing, picked up plenty of hits and very little static. Just thought I would ask. Thanks for the replies.

The reason is as K4EET decribes. the narrower bandwidth has less noise but you still lock to a 25 KHz channel.

 

[xms3200]

Airlines are drifting away from antiquated HF to Satcom, they are using it for LRCS as well as datalink. As far as VHF, they have switched to VDL Mode 2, more bandwidth and faster data speeds for more information transfer, and voice is still VHF AM analog for reasons as discussed on these forums.

 

[dlwtrunked]

Here in Germany/Europe pilots don’t get told frequencies any more. They get Channels to switch. For example:
ATC says: Scanner tune to:
118.005 118.0000
118.010 118.0083
118.015 118.0166
118.030 118.0250
118.035 118.0333
118.040 118.0416
118.055 118.0500
118.060 118.0583
118.065 118.0666
118.080 118.0750
118.085 118.0833
118.090 118.0916

They ARE being told frequencies---just the nearest in 5 kHz steps as that is the best some of their transceivers can do.