SmartSDR iOS Bluetooth audio disturbances.

Andy M5ZAP

Hi,

Apologies for yet another question to the forum.

When using SamrtSDR iOS and a  bluetooth headset every time audio is interrupted (for example enabling and disabling audio on a slice or after a PTT event) there is a large increase in audio level after the audio is reinstated. This event last for <1 sec.

The behaviour is only really apparent when just listening to predominantly noise like when listening to a weak signal if listening to a strong signal it is not as obvious if at all.

 Also the effect is different when using two different headsets, with  a BlueParrot VX540 it is very noticeable and you get large bursts of noise even when there are small almost imperceptible audio interruptions (probably a few missed packets of data). With a Logitech it is more just a increase in audio level after a PTT or enabling audio on a slice.

I have conducted a series of tests but have not been able to find the root cause of the problem. As the effect is different on different headsets the headsets seem to be part of the issue and wonder if it is some type of auto audio gain control and one headset is more aggressive than the other.

Not sure if the problem was there before the latest version as I have just acquired the Blue Parrot headset and it makes the headset almost unusable.

I have checked enabling and disabling audio in other apps does not have this effect and all works well it is only in SamrtSDR iOS I have the problem.

Tonight I will conduct a few more tests using the iPad with wired network connection so preventing any packet loss.

Any help would be appreciated.

Any comments Marcus?

Cal N3CAL

Hi Andy,

I've also noticed the audio levels changing as you described.  I'm using the Blue Parrot 450 headset.  It's only noticeable when I'm on SSB and there is no QSO going on.  When I'm on FM with the squelch enabled I do not notice the issue. 

I first suspected the Blue tooth headset was trying to scan for another device to connect with as the BlueParrot will connect to more than one device at a time.  I'm using SSDR iOS with a Ipad Mini4.

I turned my second bluetooth device (Samsung Phone )  off and it seemed to help. 

Cal/N3CAL

Andy M5ZAP

Hi Cal,

Interesting, if this was the case it must be dropping the BT connection. I did clear the paired list in the headset (Using PC app) so the only device was the iPad in question, so unless I put it into pairing mode it shouldn't be looking for another device.

Did you notice the problem on the previous release of SSDR iOS

Cal N3CAL

Hi Andy,

I've only recently started using the Blue Parrot at about the same time the latest iOS SSDR was released so I don't recall for sure if the issue was on a prior iOS release.  Sorry. 


Cal/N3CAL

Andy M5ZAP

Thanks, Does anybody have a Blue Parrot 450 who hasn't upgraded the app yet and could test?

ThisUserDoesNotExist

Hi everybody,

last night, I tried to reproduce this issue with the headsets I have available here but I can't. I don't have a Parrot 450 but only some Logitech and other brands.

Current thoughts:

• It could have to be with auto gain control of iOS or even the Headset
• It is unlikely that this issue started with the latest update as nothing has changed in this area
• It would be interesting to know if or if not the latest iOS 10.3 makes any difference
• It would be interesting to know if there is a difference when switching on or off the stereo setting in the Settings of SmartSDR for iOS
• I assume you have switched off AGC (and maybe NB and NR) during your tests. If not, maybe you want to disable these settings at least to find out if these are causing the issue in combination with the headset
• If the headset has it's own volume control, maybe you want to experiment with that to see if it makes any difference

My App has some code that indeed tries to re-connect the BT device if the connection gets lost. Maybe after a re-connect the volume may turn to a default value which might be the cause of the issue. However, there is no way to control this volume by software but if that's the cause of the issue then the question is, why does the BT headset disconnect.

73,
Marcus, DL8MRE

Andy M5ZAP

Hi Marcus,

Further observations - please read fully as the new information is spread across all comments. I think I have comprehensively tested most scenarios so if not immediately apparent please re-read.

I have conducted some more tests and it appears to be definitely a problem with how SSDR iOS interacts with the iOS. I have tested many other apps using mute and unmute etc on both headsets and none of them behave like SSDR iOS.

I even listened to the same white noise, same freq/band using web sdr in Safari on the same devices and performed a mute / unmute in case it was the type of audio producing a strange interaction with some auto audio gain and the problem was not present.

I updated to iOS Ver 10.3 and it had no affect on the problem. "Allow stereo" was disabled in app. It is not the blue tooth dropping out.

The problem appears whenever audio is interrupted but I used the Mute / unmute slider switch on a slice to easily reproduce the problem.

1 - The two Bluetooth headsets behave differently so might be two issues or a related issue that shows different symptoms.

A) Logitech H800 / Wired headphones / device speaker  - when a mute / umute is carried out, on the reinstatement of audio the audio is elevated for for a period of approx. 2 seconds before returning to the normal level.

This happens on both an ipad pro and a iPhone 6.  Also it is present using wired headphones on both devices. Interestingly it is present on the iPhone speaker but not the iPad speaker.

Blueparrot VXi 450 same as above but there is a very loud burst of audio for <500mS when the audio is reinstated. This is not heard on the Logitech or the wired speakers or iPhone speaker so is unique to VXi 450.

By changing the audio bias between the app and the iOS volume control it appears to impact the problem with issue slightly worse when volume level is biased towards iOS. But the audio tone also changes and this could be changing the visibility of the problem. Why does the audio tone change ?

2 - Another observation swapping between BT headsets is when listening in SSR iOS you cannot turn off the VXi 450 headset. You have to quit the app to allow the device to be turned off. Just an interesting observation.

3 - Another interesting observation is that this makes audio glitches due to Wifi dropouts more apparent as the audio is raised after each audio dropout.

Any other data / info please ask.

Cal N3CAL

Andy,

What version firmware does your Parrot 450 have?  I noticed mine had v1.05.  I downloaded v1.10 using the VXi updater but the issue is still there.  I've also tried turning the A2DP option (Streaming from BT devices) On and Off in the device config but didn't notice any difference. 

My iPAD Mini4 is currently on iOS 10.2.1  and I will try and update to 10.3. 

The way to reproduce the issue is to be in FM mode with the squelch off and toggle the TX button on the right side panel.  You will hear the rush of audio. 

Cal/N3CAL

Andy M5ZAP

Hi Cal, I had alrwady tried updating the headset to v10 software. It appears that anything that causes the audio out to be stopped causes the problem when the audio is re -enabled. Transmission in any mode does it .

ThisUserDoesNotExist

Thanks Andy and Cal,

thanks also Andy for your comprehensive tests. Looks as I have to buy me such a BT device to be able to reproduce that issue since all my devices work fine.

I just tried to get one via Amazon but can't. Seems there are only newer devices available.

Do you know where to buy and is the exact model number really "BlueParrot VX540" ?

73,
Marcus

Andy M5ZAP

Hi Marcus You should be able to reproduce the item 1 A) the elevated audio on audio reinstatement as that happens on wired headphones. And I have a feeling they are related. The blue parrot VXi 540 was from Lambda-ten https://www.lambda-tek.com/shop/?region=GB&prodID=B6128878 It's an expensive unit so if you want me to mail you mine for test purpose that would be fine.

ThisUserDoesNotExist

Hi Andy,

thanks. I was able to find the parrot. It's not that expensive here (probably due to the loss of the pound so brexit seem to work for us - hi) but I was indeed now (finally!) able to reproduce at least 1 A.

I always had "Allow Stereo" switched on and once it is on, you don't hear this 2 second long volume increase.

Can you try what happens with your Parrot when you switch "Allow Stereo" to on. Over all volume will decrease when switching this on so you will need to increase the physical volume sliders.

Also, please check if you are able to use the Microphone as one Headset I am using here works well with both settings (even without the 2 second volume increase) but it's Microphone stops working when "Allow Stereo" is switched on.

vy 73,
Marcus, DL8MRE

Andy M5ZAP

Hi Marcus

Switching to "Allow Stereo" does seem to stop the 2 second audio increase I agree, but unfortunately it has no effect on the parrot audio disturbances. In fact the action of switching the "allow stereo" on and off creates the audio disturbance (described well by Cal as a Crashing noise).

I think it happens when there is a large audio output step change. Like unmuting etc.

The microphone on the Parrot worked ok with the "allow Stereo" enabled.

ThisUserDoesNotExist

Ok, thanks. So I have now just purchased a Parrot and see if there is anything I can do.

vy 73,
Marcus, DL8MRE

ThisUserDoesNotExist

Andy,

as mentioned, I purchased the Parrott and started testing. I can confirm what you wrote. Even though I thought the effect is more noticeable, it is definitely there.

The bad news is, there is nothing I can do against it. I ran several tests (that's why I am answering so late) with all possible audio configurations (and there are quite a few configurations with their individual sub-options) but regardless what parameters I use, there is no change in this respect - only other side-effects.

My assumption is, that there is some kind of auto-gain-adjustment included in the Apple audio codec which is used for the BT communication to the parrot. Unfortunately, this can't be changed from my end. On a Mac you have more control over the codecs but apparently not on iOS.

The reason why you can't reproduce this with a WebSDR for instance also proves this to be right as in that case, indeed, a different audio path will be used. In my case, where I will have to use Audio IN and OUT, I am (or I should rather say iOS) uses the same Codec which is used for phone calls which seem to add this gain oddity.

I will have an eye on that and once there is a possibility for me to address this, I will do.

73,
Marcus 

Andy M5ZAP

Thanks Marcus for the update. As it affects the parrot deferantly to say the Logitech Bluetooth headset it must be the parrot implements the bt codec differently I will try contacting there customer support.