Radio reception of other pilots / blocking frequency

[Peter Strempel]

Hello, newbie question incoming:

On the ground, being somewhat far away from all other flights (U.S., so there is quite some big distance), I heard the controller loud and clear, but nothing from other pilots. I suppose this is mirroring the real world radio experience (but not sure on that, no real world pilot), and somewhat makes sense considering how radios work. However, that left me in the awkward position where I stepped on other pilots multiple times, because I did not hear them, blocking the frequency. Not a pleasant experience and certainly not my intention. At some point I used text message to say my thing, but that feels like cheating the system.

During climb, once I got a bit altitude, other pilots voices were coming in.

What is the proper way to deal with this situation? Trying to get your request in but avoid stepping on anyones toes, especially trying to not annoy the busy controller?

[Alex Ying]

Unfortunately, there's not a whole lot you as a pilot can do if you can't hear other pilots. The best solution is actually for the controller to enable single-frequency cross-coupling on their end in the AFV client. That would link (cross-couple) the multiple transmitters at different airports together so that transmission picked up by a transceiver at an airport are re-broadcast to every transceiver the controller is using.

Many ATC facilities have feedback forms, you can suggest that they add single-frequency cross-coupling to their SOPs by submitting feedback. While online, you can also suggest it to the controller, they may not be aware of that capability of AFV.

[Dustin Rider]

Yep, AFV was designed for exactly the purpose of making the radio sound and behave more like how it does in the real world, and it's one of my very favorite changes that was made on VATSIM. Of course that introduced the issue you just described. 

The technique I have usually found to be the most effective, from the pilot's perspective, is to try and time your transmission after your best estimate of another pilot's readback. That is, if a controller says, "AAL1022, descend and maintain FL360," silently read back the clearance, then chime in after you've finished. It's certainly not perfect, but it's a good place to start. 

[Peter Strempel]

Thank you for the explanation. I found the AFV user manual and read the section about the three cross-coupling methods. Interesting read to get some background information on the topic.

Anyways, this just adds to my respect for the controllers who not only deal with the traffic but also simulated radio technology limitations. 🙂

[Robert Shearman Jr]

Another tip is to jump in with just the ATC callsign followed by your callsign, and wait for the controller to respond.  That way, in case you did step on someone, at least it was for a 2-second transmission instead of a 10-second request for clearance.

[Lars Bergmann]

So much trouble CTR-controllers can avoid by just turning on XC... (Yes, I know it's not realistic, but guess what, IRL CTR controllers don't provide top-down service for major airfields or cover sectors the size of Texas by themselves.)

[William Teale]

Guess it depends where you are in the world - cross coupling is the norm in Australia, for example. Not having it would be unrealistic.

[Lars Bergmann]

16 minutes ago, William Teale said:

Guess it depends where you are in the world - cross coupling is the norm in Australia, for example. Not having it would be unrealistic.

The way VATSIM's single-frequency coupling (and by extension also the douplex coupling) works is (in most situations) physically impossible, and therefore unrealistic even for places that do couple frequencies together (which is most places during times of low traffic) 😉

Edited July 30, 2021 at 06:57 AM by Lars Bergmann

[William Teale]

what do you mean by "single frequency coupling"?

The cross coupling I've used on the network involves two or more frequencies, and seems to act much like the cross band repeaters I use for real. So which part do you think is physically impossible?

[Alex Ying]

3 hours ago, William Teale said:

what do you mean by "single frequency coupling"?

The cross coupling I've used on the network involves two or more frequencies, and seems to act much like the cross band repeaters I use for real. So which part do you think is physically impossible?

Single-Frequency (Cross-)Coupling refers to what's described in section 6.5.2.1 in the AFV User Guide. Suppose you have 3 transceivers A, B, and C. A receives a transmission from aircraft 1. With Single Frequency Cross-Coupling, B and C re-transmit what A is receiving on the same frequency as A (this is what makes it single frequency cross coupling). If aircraft 2 is not in range of 1 but in range of transceiver C, then they would hear aircraft 1 being rebroadcast by C.

In the world of AFV, this is not an issue because it's only a partial simulation of radio. In the real world, this would be an issue if an aircraft is in range of multiple transmitters because the transmitters will essentially be blocking each other because they're simultaneously transmitting on the same frequency. The effect is the same effect that causes blocking when multiple aircraft transmit at the same time.

Simplex Coupling (6.5.2.2) is regularly used in many real ATC facilties. Many FAA facilties are required to listen and transmit on all of their frequencies even when sectors are combined on a single nominal frequency. The frequencies are not cross-coupled to each other (re-broadcasting 1 frequency to another) which is what Duplex Coupling (6.5.2.3) does. I don't know if any real world facilities do it, but because it transmits on multiple frequencies, it doesn't run into the (real world) self-blocking issues of Single-Frequency Coupling.

On VATSIM, for NY Center and NY TRACON, single-frequency cross-coupling is essentially a must for us with 3 or 4 major airports regularly being controlled top-down by 1 controller but out-of-range from each other when aircraft are on the ground.

Edited July 31, 2021 at 04:11 AM by Alex Ying

[William Teale]

Surely the easy fix there is to prevent cross coupling of a single frequency in the software, because as you describe, you cant do this with real equipment for communication.

It does sound like a simple way to implement cross eye repeater jamming, though.

[Simon Kelsey]

2 hours ago, William Teale said:

Surely the easy fix there is to prevent cross coupling of a single frequency in the software, because as you describe, you cant do this with real equipment for communication.

We could have done, but this would have made operating in the VATSIM environment where we regularly have one guy with one main frequency operating multiple potentially very busy airfields dozens or hundreds of miles apart almost impossible, so it is there as a “VATSIMism” to make it practical to operate on the network without driving people mad.

There are actually some real world facilities which can and do cross-couple transceivers on a single frequency so it’s not quite as unrealistic as it might seem - I don’t know the technical details of how this is achieved but I am assured it is (probably with widely-spaced transceivers - I know in real life I have definitely heard aircraft speaking to London Information 250 miles away on the same frequency with both of us at low level so I assume there must be rebroadcasting going on).

[Alex Ying]

7 hours ago, William Teale said:

Surely the easy fix there is to prevent cross coupling of a single frequency in the software, because as you describe, you cant do this with real equipment for communication.

It does sound like a simple way to implement cross eye repeater jamming, though.

As Simon mentioned, sure there's an easy "fix" but that misses the point. We want single frequency cross-coupling because of how VATSIM is set up.

[Magnus Meese]

On 7/31/2021 at 10:00 AM, Simon Kelsey said:

There are actually some real world facilities which can and do cross-couple transceivers on a single frequency so it’s not quite as unrealistic as it might seem - I don’t know the technical details of how this is achieved but I am assured it is (probably with widely-spaced transceivers - I know in real life I have definitely heard aircraft speaking to London Information 250 miles away on the same frequency with both of us at low level so I assume there must be rebroadcasting going on).

Don't London Info have like three regional frequencies? Those must surely be bandboxed 99% of the time, and would provide an alternate explanation. I thought same freq multi-TX/repeating/bandbox usually were reserved for higher frequencies with more data capacity and thus more ability to do technomagic, though I don't really know much about anything ACC (or FIS) and you could well be right. I have heard of Best Signal Selection, but that's just selecting the best TX/RX aerial for any given transmission based on the recieved signal, not repeating it.

As for the US, I have no idea how those poor guys tolerate having multiple frequencies un-bandboxed. It's my understanding that a few Centres now have the capability, but most sectors and approach services don't. Why anyone would chose to "replicate" this on the VATSIM side of things I'm sure I don't know, but there are many who do.

[Brad Littlejohn]

1 hour ago, Magnus Meese said:

Don't London Info have like three regional frequencies? Those must surely be bandboxed 99% of the time, and would provide an alternate explanation. I thought same freq multi-TX/repeating/bandbox usually were reserved for higher frequencies with more data capacity and thus more ability to do technomagic, though I don't really know much about anything ACC (or FIS) and you could well be right. I have heard of Best Signal Selection, but that's just selecting the best TX/RX aerial for any given transmission based on the recieved signal, not repeating it.

As for the US, I have no idea how those poor guys tolerate having multiple frequencies un-bandboxed. It's my understanding that a few Centres now have the capability, but most sectors and approach services don't. Why anyone would chose to "replicate" this on the VATSIM side of things I'm sure I don't know, but there are many who do.

Here's a good example as to why, and I'll use a real world example for it.

When KVGT (North Las Vegas Airport) is closed, for clearances, their AWOS/ASOS advises you to contact LAS_APP on 124.0 on the ground or 125.9 if already airborne. However, at the time that VGT is closed, LAS_APP may be combined on 133.95 or 135.0 for the entire Director/TRACON sector. So a pilot on the ground won't be talking to ATC on the same frequency as the other pilots. So ATC will broadcast on both frequencies, while the pilots may not be, because of what the AWOS says at a given airport. There would be the occasional "Change to my frequency xxx.xx", but until that happens, you'd hear one side of the two-way communications between ATC and the pilot.

We'd have the same thing happen here when a sector combines while pilots are still on different frequencies. They can keep about on their flight without having to immediately worry about changing frequencies. once the pilots that are on the unused frequency either change frequencies (either by handoff or landing, etc.), ATC can simply stop transmitting on that frequency, and all is well.

BL.

 

Edited August 9, 2021 at 10:13 PM by Brad Littlejohn

[William Teale]

Hearing one side of the conversation is the issue, though. In that circumstance, you'd be better off bandboxing/crosscoupling the freqs - no downside.

[Aleksandar Stanisavljevic]

i dont know is it a correct topic to write this on ,but, is there any chance that future update of xPilot or such, have BLOCK feature,that you can transmit at the same time while someone else is talking on freq?
It would be great!

Thanks

[Magnus Meese]

On 8/9/2021 at 11:00 PM, Brad Littlejohn said:

Here's a good example as to why, and I'll use a real world example for it.

I do understand how it works, but I don't see why it HAS to be included on VATSIM. Real pilots (and controllers, to be fair) can have bad enough RT dicipline, why torture yourselves over a very very miniscule bit of "realism". The only reason most FAA facilities lacks cross-coupling is money, not technological limitations. I cannot fathom not being able to XC frequencies I'm using, in fact trying to not use XC for multiple frequencies at my facility causes the digital processing to throw a hissyfit and send every frequency to your headset with a mismatch of a few milliseconds. This is obviously bad functionality, but illustrates how our coms aren't even designed to do it that way.

Funnily enough, one of the two hosts of the podcast "Opposing Bases" (my main source for any FAA perspective on things, and highly recommended for anyone with interest in the US NAS real or simulated) has even described desperatly broadcasting "All stations, switch to my frequency xxx.xx. Do not reply, just switch" when getting overloaded with too many planes on too many frequencies. Sure you CAN replicate this on VATSIM, but why on earth would you if given the option of not to?

[Brad Littlejohn]

38 minutes ago, Magnus Meese said:

I do understand how it works, but I don't see why it HAS to be included on VATSIM. Real pilots (and controllers, to be fair) can have bad enough RT dicipline, why torture yourselves over a very very miniscule bit of "realism". The only reason most FAA facilities lacks cross-coupling is money, not technological limitations. I cannot fathom not being able to XC frequencies I'm using, in fact trying to not use XC for multiple frequencies at my facility causes the digital processing to throw a hissyfit and send every frequency to your headset with a mismatch of a few milliseconds. This is obviously bad functionality, but illustrates how our coms aren't even designed to do it that way.

Funnily enough, one of the two hosts of the podcast "Opposing Bases" (my main source for any FAA perspective on things, and highly recommended for anyone with interest in the US NAS real or simulated) has even described desperatly broadcasting "All stations, switch to my frequency xxx.xx. Do not reply, just switch" when getting overloaded with too many planes on too many frequencies. Sure you CAN replicate this on VATSIM, but why on earth would you if given the option of not to?

Hmm.. The easy way to do this would be that for all of the positions you would be relieving would be to:

1. set your primary frequency,
2. open up TX and RX for all of the frequencies you would be relieving,
3. then transmit the "change to my frequency xxx.xx" on all of those frequencies.

Leave that up for say, 3-4 minutes to catch any pilots that missed that call, then close them down. I know VRC has the ability to do that, plus that would help to eliminate the number of .contactme calls you'd have to give to each aircraft that aren't already tuned to you.

BL.

 

[Magnus Meese]

I think we're talking past each other here. I DO NOT want to replicate this. I absolutely hate being on a frequency where I am missing half the conversation. I think it's silly that it's necessary in the first place in real life (in the US). Please, for our sanity, could VATUSA just please start using the single-freq XC function, even though it's (heads up, filthy word incoming) unrealistic?

[Karl Mathias Moberg]

1 hour ago, Magnus Meese said:

could VATUSA just please start using the single-freq XC function, even though it's (heads up, filthy word incoming) unrealistic?

As far as I know, most of VATUSA already do this, there are very few situations where I've seen VATUSA controllers use multiple frequencies. The only places I have seen so have been in Canada, and Europe so far when I've been flying around the world.

[Alex Ying]

4 hours ago, Magnus Meese said:

I think we're talking past each other here. I DO NOT want to replicate this. I absolutely hate being on a frequency where I am missing half the conversation. I think it's silly that it's necessary in the first place in real life (in the US). Please, for our sanity, could VATUSA just please start using the single-freq XC function, even though it's (heads up, filthy word incoming) unrealistic?

I'll reiterate what Karl said above. I'm pretty sure it's strongly discouraged across VATUSA and everyone I know of uses single-frequency cross-coupling.

I think you might have mixed together two different conversations about real world and VATSIM into something that does not actually happen on VATSIM in the US.

Edited August 11, 2021 at 03:15 AM by Alex Ying

[Magnus Meese]

This is anecdotal of course, but what I'm talking about is what the OP is talking about, and I experience it almost every time I fly in the US. Maybe I'm just lucky. Just note that for all pilots to hear all other pilots, the XC needs to be manually switched on for that one frequency, if you just start AFV and do no more it will be off and therefore realistic VHF coverage (but not terrain masking) will be in force, which is a pain in large sector top-down situations.

Edit: I see that my earlier posts aren't extremely clear on separating the topics of real life and VATSIM. My two main points are: 1, please use AFV single-XC when on CTR positions; and 2, I feel bad for real FAA controllers who mostly cannot XC their frequencies but have to listen to double transmissions left right and center all day long. It is my impression that some C1+ controllers sort-of-kind-of replicate their misery by not using AFV-XC deliberately, and it seems to me that this is the reason for this entire thread when reading the OP. Maybe Peter and I have just been unlucky having controllers who forgot to turn it on.

Edited August 11, 2021 at 11:22 PM by Magnus Meese