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Radio initialization code in cold start cause static noise (invalid SNR calculations?)


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Posted

Hi,

The radio initialization code is simply broken.

The static noise level on all radios depends if you do the hot or cold start.
You can easily check this on any Caucasus mission while tray to talk to ATC.

In cold start the static is far more noticeable than when you do the hot start.

Not mentioning the squelch does not work at all 😐 (already mentioned in other post in this subforum).

This actually cause the only AH-64D campaign to be unplayable as you need to modify it in order to play it.

 

Posted

Same with easy com. This is a bug report for a feature not actually looking for workaround.

Video record from simple mission with two slots. One hot one cold.
Can someone confirm?

 

Posted

Can‘t confirm this on my side….I‘m always doing cold starts in the AH-64D.

Squelching works for me. Note these are momentary switches. I switch all 5 on startup and communications works fine for me…..

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Posted
4 hours ago, Rosly said:

Hi,

The radio initialization code is simply broken.

The static noise level on all radios depends if you do the hot or cold start.
You can easily check this on any Caucasus mission while tray to talk to ATC.

In cold start the static is far more noticeable than when you do the hot start.

Not mentioning the squelch does not work at all 😐 (already mentioned in other post in this subforum).

This actually cause the only AH-64D campaign to be unplayable as you need to modify it in order to play it.

 

Check last post in that thread you have linked

Posted (edited)

The squelch function in radio is not "noise cancelling"! It suppress the RX path or specific radio receiver if the received signal strength is below certain level (there is even a knob for that - though non functional in DCS).

The squelch switch does not influence on the reception signal strength and the signal to noise ratio as common understanding of "noise canceling" might be. Those are two separate technologies quite far apart from each other. Squelch should just cut off the transmission if the signal is barely understandable or allow for a bypass. You can find a proper implementation of squelch in other aircrafts (beside some broken ones like A-10II, thinking the same guy had to implement this xD). Important is, squelches are separate for each radio. Those are separate analog radio paths which does not influence on one another. If UHF signal level gates (open up) the UHF squelch, it does not open nor influence on VHP, HF and any other squelch gates circuits. The point is each radio audio "opens up" if it detect usable radio signal for this specific radio.

The current implementation seems to have three problems:
- squelch in off state should normally produce static from given radio. This is not the case for AH-64D currently as opening the squelch sets the radio squelch in bypass mode (you hear all static that is currently in the air).
- invalid audio mixing implementation. Currently any radio transmission opens up all squelches which cause total garbage sound (for instance UHF transmission are mixed with static noise from VHF, FM1, FM2 and ADF if there are no VHF, FM1, FM2 or ADF audio transmissions at the same time). This is almost like developers think that squelch is implemented at post audio mixer, not in the intermediate frequency amplifier and detector circuits of each radio (therefore they are separate things).
- a initialization problem with squelch on/off. Those are off on cold start but no static noise is hearable, so user does not really know squelch is off. I know just in some recent patch squelch switches was changed from monostable to momentary. It might be true in real life but it is also true squelch in off should give radio static (which is missing as I already wrote). So the dev which done this was just lazy.

@corbu1 You probably switched all squelch switches to "on" after a cold start. I think you missed a point in how to reproduce this problem.

Edited by Rosly
clarification of what is the point
  • Like 1
Posted

One more remark: It seems that some payloads change the behaviour of the radio initialization code. Usually this means that we have uninitialized variables in the code and they get different values based on memory layout.

From time to time during the cold startup, I have the proper behaviour of the squelch. Means any squelch in off immediately produce radio noise sound.

This would mean the constructor for cold start for radio need to be fixed.

Posted (edited)

Another thing is that squelch off would only be used in circumstances where the circuit would suppress legitimate transmissions, such as being far away from a transmitter or having a broken antenna or something of the sort. From what I understand, the aircraft remembers the last state of each squelch circuit after shutdown. During cold start they are all off, which makes no sense. While not strictly wrong or a bug, it's inconvenient and unrealistic that the last person to fly the apache would've switched them all off.

I have also noticed that I get no background noise when they are off, only noise overlay when receiving a transmission, including intercom from ground crew. But just letting through the audio without a trigger point is the whole point of turning squelching off, so there should be static noise always. This is also why squelch should be on by default, no sane pilot would keep their sanity for long if they were listening to 5 radios blasting static into their ears all day long, so they likely didn't do that in their previous flight.

When I get a transmission, I do get static noise, but that's exactly when there should be no noise heard at all, since there is an active transmission in the air. What should happen is that when squelching is on and receiving a strong enough signal, the audio you get is exactly the same as squelch off and receiving that same signal since it's just a trigger point on when to let that signal through or not.

I also get noise on all 5 channels at once when receiving a radio transmission on one of them. This is wrong, addressing the other two bugs should automatically create the correct behavior for this as well, but it's probably worth looking into as well. The correct behavior would be 4 times static from 4 radios that don't receive and 1 normal transmission.

I have not yet noticed different volumes on the noise depending on hot or cold start, but I have not paid attention to that, since I usually just turn squelch on.

Edited by FalcoGer
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