Center Relay or Repeater of A\C Transmissions.

[rr60]

It appears to me at times Sectors that have large areas of geographic coverage that I hear "patched" aircraft repeated on the frequency I am talking to Center on.

This is evident by the "processing" of the audio and the hang time after the aircraft makes it's transmission.

Not all aircraft are patched or repeated onto a given frequency.

Many times sectors simulcast over several transmit channels and one will not hear the aircraft reply.What I am curious about is relayed or patched aircraft onto a given frequency.

Anybody have an idea of how and why this is done?

 

[AirScan]

The process is called frequency "cross-coupling". As you observed it allows transmissions from one frequency to heard on another frequency. In a situation where the controller is working more than one frequency it allows the pilot to hear the transmissions on the other frequency and helps prevent pilots from talking over each other.

The system has been in use in Europe and Canada for a number of years now. I think I first noticed it in use in the US in the last 3 years where it has slowly started to become more common.

In Europe and Canada it's possilbe to cross-couple multiple frequencies together, there are some sectors in Canada where around 10 frequencies are cross-coupled together. My understanding is that the US system is not as advanced and they only have the capability to cross-couple two frequencies together at the same time. To date I have not heard a US Center cross-coupling more than two frequencies.

I'm curious what Center and frequencies (if you remember) you heard this on ? So far I've observed it being used in Indianapolis, Washington and Cleveland and the New York Oceanic sectors.

 

[ATCTech]

Just to add a little more detail to AirScan's very accurate post, the original Canadian coupling equipment was called RRTU - or Radio Re-Transmit Unit. This was a stand-alone in-line device were all frequencies that may be required to be coupled were fed through an internal matrix and what we called "scenarios" were preset using rows of DIP switches. The various combinations of coupled frequencies were then selected by a remote control head on the ATC Operations floor. This was because our original voice switch did not have cross-coupling capability internally. The RRTU did not allow for one-time or ad-hoc combinations to be created by ATC.

With the National replacement of the voice switch system, beginning in the late 1980s cross-coupling became software driven within the new voice switch and allows the controller to couple any or all frequencies assigned to the position. The first use of this new switch was Toronto (CYYZ) Tower in the late 1980s. I was part of the commissioning team of that first updated voice switch and of the installation of the RRTUs prior to that.

 

[rr60]

Txs Atc Tech and Air Scan thanks.

Jacksonville Center and Miami Center along the east coast between ILM OMD FL16 and FL270 patches were heard.

Also never knew Center had access to two types of winds aloft!

We were trying to avoid strong headwinds and asked to get a pirep from an AC climbing above us.

Center offered they had derived winds merged from computer forecast AND ACARS data from aircraft climbing through the altitude we were interested in.

Sure enough the PIREP and wind center said it would be we're exact! Learned something.

 

[joe1972]

Zny center controller

Hello was wondering if anyone knows why zny
Center controller can't be heard on 125.325 an on 127.175
Only hear aircraft use to be able to hear controller
Very clear is it possible that transmit power
On there end was lowered?

 

[alphazulu]

Joe I cannot say with any certainty, but I believe those (2) frequencies on occasion transmit from the Douglaston RCAG site.

 

[joe1972]

Thanks good to know where is douglaston?i use to hear them really clear
In my car in edison an from my home in cranford
So it sounds like they switch,I think the matawan
High freq is in Sayreville off route 9?the remote site tower
Is possibly in that area maybe there doing maintenance
To matawan?

 

[joe1972]

I'm hearing activity from zny controller on 118.975
Now have no idea where that site is?