IVC Full-duplex

[Shadow]

I was wondering when BMS will be able to afford full-duplex radios.?

I don’t mind if I have too pay more.

And why was half-duplex ever implemented in the first place. Anyone?

PS: Messed up the Title, what a dummy. Please Sir can you fix it, thanks.

[Dee-Jay]

why was half-duplex ever implemented in the first place. Anyone?

PS: Messed up the Title, what a dummy. Please Sir can you fix it, thanks.

Simply because radios are not working Full Duplex in the real life, only one can emit on the freq at a time.

[Arty]

I take it correct your saying Dee-Jay but I have heard real comms where 2-3 where talking at the same time and there was clutter in the comms. Maybe I have to re listen to it. As I recall it it was the civilian protection station - the military station and the F-16 on the same time all in the same freq UHF.
Not 100% cause it was long ago that I heard it but I remember that the pilot got angry cause they where messing up the comms and the situation was critical. For those that have it or know it was the incident with the HELIOS aircraft that crashed.

[Dee-Jay]

@Arty:

I take it correct your saying Dee-Jay but I have heard real comms where 2-3 where talking at the same time and there was clutter in the comms. Maybe I have to re listen to it. As I recall it it was the civilian protection station - the military station and the F-16 on the same time all in the same freq UHF.
Not 100% cause it was long ago that I heard it but I remember that the pilot got angry cause they where messing up the comms and the situation was critical. For those that have it or know it was the incident with the HELIOS aircraft that crashed.

It depends on distance and power of emitters … but basically … radios are half duplex. Implementing that kind of “glitches” when several person are emitting on the same freq is out of the scope of BMS and IVC.

[Eagle-Eye]

Friend of mine showed me an incident report just a few days ago about how he had a loss of separation (800ft, 4NM) because of comms. Two aircraft with almost identical callsigns were both looking for FL370. He told one to climb to 370, but they both replied.
Because the radio are half-duplex and transmissions started and ended at exactly the same time, there was no “stepped on” cue for anyone and the second transmission was just completely blocked out for ATC, so he didn’t hear one of the read backs. The only way he noticed the error was because of mode S information…

I also learnt that day that ATC has an override mode, with which they can have priority above all other comms, which is useful in a stuck mic situation or to interrupt someone. Would be nice if this could be implemented somewhere in BMS/F4AWACS.

[Kuhprah]

Never usesd the both Guard-Chanels? They can be heard by everyone at every time….

[Dee-Jay]

@Eagle-Eye:

they can have priority above all other comms, which is useful in a stuck mic situation or to interrupt someone.

… which will also depends on distance and power of emiter anyway.

EDIT:

I also learnt that day that ATC has an override mode

Are you sure he wasn’t talking about the “Distress” freq (121.5) ?

@Kuhprah:

Never usesd the both Guard-Chanels? They can be heard by everyone at every time….

Exactly.

[Eagle-Eye]

@Dee-Jay:

… which will also depends on distance and power of emiter anyway.

Are you sure he wasn’t talking about the “Distress” freq (121.5) ?

It was in a conversation between several ATCo’s, and one asked why he didn’t use the override. If it were GUARD, I assume he’d call it that as it’s how we have always called it during training.

[Dee-Jay]

@Eagle-Eye:

If it were GUARD

Not “Guard”.

Guard is 243.000 and is specifically military.
Distress is 121.500 and is civil use.

Question of semantic.

[Eagle-Eye]

Strange. During training we always used GUARD when speaking about both 121.5 and 243.0 MHz, and it was also indicated as such on the comm selection screen, but all ICAO DOCs and Annexes I just checked speak of “emergency frequency 121.5 MHz.”

There’s also hardly any word on 243.0 MHz, except for a few mentions in Annex 10 VOL V, while civil ATC uses UHF to communicate with military aircraft as well.

But as you say, semantics.

[Dee-Jay]

Military jargon essentially then to make a diff between the two freq.

[Kuhprah]

There are always a few confusing diffecences if you mix up Military comms with civil educations… not in all Points, but those are nearly 2 complete different worlds.

[Bravo]

Half duplex means basically you cant receive while sending,
and actually full duplex either uses two frq(like mobile networks) or time shared.
121.5Mhz is nicknamed VHF guard while 243 is UHF guard
121.5 is the international air emergency channel, but even ATC calls it Guard, Ive never heard them say testing distress, they always say testing guard.
156.8 Is Maritime distress channel and is just called CH 16

edit:
243 actually works in BMS on IVC as long as they have Comm 1 in Both/tuned to 243/or Guard
121.5 doesnt seem to work as far as I have tested it

[Dee-Jay]

243 actually works in BMS on IVC as long as they have Comm 1 in Both/tuned to 243/or Guard
121.5 doesnt seem to work as far as I have tested it

In BMS, 121.5 works as any other freq, but in military fighters, “there is no” (could depends on a/c) receiver only tuned on 121.5 like in civilian a/c but an UHF receiver tuned on 243

In BMS (just like in real F-16) you will hear anybody speaking on UHF guard (243) as long as you have set you UHF on “Both” mode.
You can also hear 121.5 of course, but only if you have manually set your VHF on 121.5

[Ahmed]

@Eagle-Eye:

I also learnt that day that ATC has an override mode, with which they can have priority above all other comms, which is useful in a stuck mic situation or to interrupt someone. Would be nice if this could be implemented somewhere in BMS/F4AWACS.

ATC have a more powerful transmitter, so many times they “win” the stepping battle, but not always, but I’ve never heard anything about a magic “overide” switch :D. The result totally depends on the power and position of everybody (the two transmitters stepping each other, and your own). So, in a given case, one guy in the North may understand the blocking guy, while another guy in the South may understand ATC, and everybody in between nobody.

So, the current IVC implementation is quite realistic, and definitely the best one in any civilian/military flightsim out there.

[Shadow]

Can we at least get rid of that stupid garbled sound ?

OK explain to me why US Equipped Air craft can only implement half duplex (or if you like simplex mode) VHF/UHV radio coms,

Civil
“Aircraft communications radio operations worldwide use amplitude modulation, predominantly A3E double sideband with full carrier on VHF and UHF, and J3E single sideband with suppressed carrier on HF. Besides being simple, power-efficient and compatible with legacy equipment, AM and SSB permit stronger stations to override weaker or interfering stations, and don’t suffer from the capture effect found in FM. Even if a pilot is transmitting, a control tower can “talk over” that transmission and other aircraft will hear a somewhat garbled mixture of both transmissions, rather than just one or the other. Even if both transmissions are received with identical signal strength, a heterodyne will be heard where no such indication of blockage would be evident in an FM system”

Or is it cause of the F-16 use of Mil-STD-1553 being a half-duplex command/response protocol. But does even that restrict duplex transmission as it also allows time division multiplexing.

If you cant explain that’s OK, at one time I knew this stuff reasonably well, but “if you don’t use it you lose it”

[Agave_Blue]

@Shadow:

Can we at least get rid of that stupid garbled sound ? ……

User/Client changeable.

Find the file “mic_block.wav” and replace it …. at your own risk … make backups.

[Blu3wolf]

@Agave_Blue:

User/Client changeable.

Find the file “mic_block.wav” and replace it …. at your own risk … make backups.

if you replace it with a 1 second blank audio file, the end result should be almost duplex Shad… at least for you. no one else will be able to hear you though XD