Author Topic: Clicking Sound in Headset  (Read 2800 times)

Sparky67

Clicking Sound in Headset
« on: August 15, 2021, 06:03:43 pm »
Hi all,

We have a PilotAware Classic fitted in the aircraft which, except for the odd USB plug losing its connection, has been working fine for a few years. Recently a very intermittent clicking has started in the headsets which, by process of elimination and substitution, appears to be generated by the PAW box.

Once the clicks start, which can be 2 minutes into a flight, an hour into a flight, or not at all, they are only stopped by rebooting the PAW box. The clicks are very brief, sometimes regularly spaced every four or five seconds, or can be more or less frequent.

We have an audio amp fitted between PAW and the Trig radio and can switch the power to that off, so PAW audio can be muted if required without turning the whole box off. Switching that off seems to make no difference.

Has anyone experienced similar headset clicks and can offer us advice on fixing this please?

Thanks,

Martin


Sparky67

Re: Clicking Sound in Headset
« Reply #2 on: August 16, 2021, 07:38:22 pm »
Thanks. The click is still present with the transponder switched off, so it's not RF breakthrough from that. I have a small audio transformer so that can be fitted between the PAW output and the amplifier / Trig radio input. There is also some very low level data noise audible from the Pi which the transformer might help with as well? It’s going to be a few weeks until I can get to the aircraft to work on it again but I will try to remember to report back…!

Martin

steveu

Re: Clicking Sound in Headset
« Reply #3 on: August 18, 2021, 11:23:33 am »
Which engine does the aircraft have, and is there an effing big capacitor across the rectifier/regulator output?

To alleviate the symptoms, have you tried a ferrite bead on the power input to the PAW and the Trig?

Appreciate all suggestions are not the answer, just symptoms alleviation.

exfirepro

Re: Clicking Sound in Headset
« Reply #4 on: August 20, 2021, 09:45:11 am »
Hi Martin,

I have heard of a few previous reports of low-level interference from the PAW processor, which is usually induced by proximity between the PAW and aircraft audio wiring, though this is very rare and doesn’t usually present as ‘clicks’. PAW P3i transmissions are very short duration and occur approximately once every 2 seconds - so if they were causing the ‘clicks’ they would be regular, not intermittent.  It is of course possible that something in the PAW is starting to break down and generate unexpected interference - early Classic unit’s are starting to get a bit long in the tooth now, so this could be the case. It would be worth carefully opening the box (after removing the microSD card to avoid breaking it) and making sure everything is correctly located - i.e. the ‘Bridge’ board is fully home on its pins on the motherboard and all other connectors are tight - you mention ‘loose USB connections’ in your OP, but also need to check the antenna, power socket and audio plugs.

Further areas you need to investigate should include proximity of wiring (especially any recent changes) to the PAW unit or its P3i antenna. As already advised, improvements can be achieved by adding ferrite chokes to power and/or audio cables or by installing a ground loop isolator between the PAW audio out and your intercom, or simply by re-routing your wiring. Unfortunately there is no ‘quick-fix’ recipe - it’s just a case of trying all the options.

Please keep us posted on developments.

Best Regards
Peter

JCurtis

Re: Clicking Sound in Headset
« Reply #5 on: August 20, 2021, 10:16:17 am »
If powered from the aircraft, check the ground connection of the power supply. If you can measure it how many ohms between  ground at the power supply and the battery?
Designer and maker of charge4.harkwood.co.uk, smart universal USB chargers designed for aviation.  USB Type-A and USB-C power without the RF interference. Approved for EASA installs under CS-STAN too.

Sparky67

Re: Clicking Sound in Headset
« Reply #6 on: September 03, 2021, 03:58:48 pm »
Thanks all, some useful suggestions there. It’s going to be a couple of weeks now until I can get over to the hangar but will take those with me.

It’s easy enough to wire in an audio transformer (recovered from an old ADSL router) so will look at that first. There is some very low-level data noise present too, not too noticeable when the engine (O-200) is running, which that might help with.

We have an electronic reg, switching the dynamo field off makes no difference and the clicks don’t coincide with it stopping and re-starting charging. I did think about RF getting into the audio wiring so fitted bypass caps in the PAW audio amp. The P3i data bursts do sound about the right timing, but why so intermittent?!

I now have the parts to build a (5A max) analogue 12-5V converter and a heavier-duty USB power cable, so that will be trying that too - after soak-testing it on the bench. And I will certainly have a closer look at the Pi out of the aircraft.

Thanks again.

Martin

exfirepro

Re: Clicking Sound in Headset
« Reply #7 on: September 06, 2021, 11:44:00 am »
Hi Martin,

Thanks for the feedback. I can’t at the moment think why the clicks (if PAW generated) should be intermittent. As you are obviously aware, electrical interference is usually specific to the individual vehicle/installation, but I will give it some further thought.

You obviously have a good handle on the issues involved and potential ‘fixes’. Please keep us ‘in the loop’ so we can all learn from whatever you may find.

Best Regards

Peter

Paul_Sengupta

Re: Clicking Sound in Headset
« Reply #8 on: September 18, 2021, 09:23:37 am »
Sometimes the clicking caused by RF breakthrough from the PAW antenna into the audio system, can be intermittent depending on head position, etc, especially with ANR headsets which can be particularly susceptible to RF.

Sparky67

Re: Clicking Sound in Headset
« Reply #9 on: November 20, 2021, 07:25:36 pm »
It’s certainly a possibility Paul. If I knew when it was going to happen, and it lasted longer when it did, I could remove the P3i antenna connector and see if that stopped it. The connector is just accessible under the panel.

The dedicated supply for the PAW box has now been fitted (a deconstructed and hard-wired Anker unit as described on this forum) and the audio isolation transformer has been added between the PAW box and the audio amplifier. The intermittent regularly-spaced clicking hasn’t been reported since, although to be fair, the aircraft hasn’t flown many hours since the work was completed. So I’m keeping an open mind on a working result at the moment!

I’m also now wondering whether this could possibly be interference from electric fences. The airfield is surrounded by farm land and the clicks seem to be heard the most just after taking off, or on approach. Does anyone know how often electric fences pulse their volts into the wire? If it’s around two seconds I will go and look for one in the same area with an am radio!

Thanks.

Martin
« Last Edit: February 02, 2022, 08:55:57 am by Sparky67 »

GeoffreyC

Re: Clicking Sound in Headset
« Reply #10 on: November 26, 2021, 06:36:01 pm »
I’m also now wondering whether this could possibly be interference from electric fences. The airfield is surrounded by farm land and the clicks seem to be heard the most just after taking off, or on approach. Does anyone know how often electric fences pulse their volts into the wire? If it’s around twice a second I will go and look for one in the same area with an am radio!

Thanks.

Martin

I think electric fences usually 'click' once every couple of seconds.  If you walk up to the fence (but not touch it) you can usually hear the clicking, or at least you can with my wife's horse fence.

Cheers, Geoffrey

Sparky67

Re: Clicking Sound in Headset
« Reply #11 on: December 04, 2021, 06:47:57 pm »
Sorry, I should have said we have flown with an ANR headset one side and PNR the other and have heard the clicks in both. Nothing to stop the ANR adding the noise to the common audio wiring of course. Or vice-versa even. The P3i antenna is a vehicle mobile-radio type mounted on the metal access plate into the rear of the instrument panel area. Something else to bear in mind though.

Last flight was an hour and we *may* have heard one click on approach, difficult to say though as it didn’t repeat. So still trying to work out whether it’s cured. Or not!

Cheers,

Martin

Sparky67

Re: Clicking Sound in Headset
« Reply #12 on: July 15, 2022, 08:23:52 pm »
Just to say the aircraft is currently awaiting a repair to an undercarriage leg and recovering in new fabric, so no updates on this for a while!

Martin

exfirepro

Re: Clicking Sound in Headset
« Reply #13 on: July 16, 2022, 09:01:26 am »
Hi Martin,

Thanks for letting us know.

Best Regards

Peter

Deker

Re: Clicking Sound in Headset
« Reply #14 on: July 16, 2022, 09:46:52 am »
Quick search shows electric fences can be a source of radio and Tv interference:-

"Sparking inside cracked or poor quality insulators causes interference.
Vegetation touching the fence line close to the radio can also cause sparking and therefore interference.
Poor earth.
Bad joints.

To locate sparking caused by leakage, faulty joins, broken wires or faulty insulators, walk the fence line with a transistor radio tuned off station on the AM band on high volume. The clicking will get louder as the fault is approached."

Deker.