Occasional Insanely Loud White Noise

[RichJordan]

Ok, where do I go from here?

Happened again tonight.

I also had some new behaviour, it would drop the data connection until rebooted. Both iPad and iPhone couldn't connect to it. Happened twice.

Gave up connecting it to my iPad after that and just used the audio alerts.

My PAW is not being the most reliable piece of kit.

[Admin]

Ok, where do I go from here?

Happened again tonight.

I also had some new behaviour, it would drop the data connection until rebooted. Both iPad and iPhone couldn't connect to it. Happened twice.

Gave up connecting it to my iPad after that and just used the audio alerts.

My PAW is not being the most reliable piece of kit.

Hi Rich
I was about to ask about the power, but the fact that you use the charge 2/4 I think that rules that out as an issue. Just to confirm, you are using the power lead provided (required in order to overcome potential voltage drop)

You say

Happened again tonight.

do you mean the audio interference ?
This confuses me, because you go on to say you continued to use the audio, but not the iPad ?

I think we should arrange a Return & Swap to Dave Styles at PilotAwareHardware to investigate.

Thx
Lee

[RichJordan]

Hi,

Yes, the white noise happened again. I pulled the power cable out and once PAW came back, didn't bother reconnecting to the iPad, just used the iPad GPS.

A swap would be great, thanks. I'll go up to the plane at the weekend and grab it. Would you want all the antennas and bits, or just the PAW unit?

[Admin]

Hi,

Yes, the white noise happened again. I pulled the power cable out and once PAW came back, didn't bother reconnecting to the iPad, just used the iPad GPS.

A swap would be great, thanks. I'll go up to the plane at the weekend and grab it. Would you want all the antennas and bits, or just the PAW unit?

Hi Rich,
this is what confused me 
How did you continue to use the audio alerts, if you had pulled the power ?

Gave up connecting it to my iPad after that and just used the audio alerts.

Sorry re-reading your post, I gather you did the following:-
1. you had white noise
2. disconnected power
3. reconnected power
4. did NOT reconnect iPad
no white noise appeared again over the audio (which was still connected)

Thx
Lee

[Moffrestorer]

Hi Lee,

The recent thread regarding Maximum temperature (and issues with PAW) started by Robski mentions high levels of white noise on the audio output when the PAW unit got very hot. Is it possible that the same mechanism is occurring here?

[sdkellner]

Hi Lee,

The recent thread regarding Maximum temperature (and issues with PAW) started by Robski mentions high levels of white noise on the audio output when the PAW unit got very hot. Is it possible that the same mechanism is occurring here?

Interesting.  In case it's helpful to someone, this definitely cannot have been the cause of the white noise issue with my first PAW; it was tucked in a cool spot well out of direct sunlight.  I never saw the core temp rise above the mid-40s, yet still had occasional overwhelming white noise.

Stu

[Ian Melville]

Might have been too cool. Mid -40s is pretty low 😜

[sdkellner]

Might have been too cool. Mid -40s is pretty low 😜

2-hour flight today, decent weather (18C, sunny); core temp on landing 45C.  Open cockpit cooling 

Multiple flights completed with my new PAW now; still yet to hear the white noise.

Stu

[RichJordan]

Hi,

Update on this. Am still using the original PAW unit, have moved it from the tail of the aircraft to under the passenger seat. Tidied the wiring both to and from the USB charger.

Haven't had the GPS or white noise issue yet. (Admitedly I've only flown for 40 minutes in the new configuration).

Fingers crossed.

[exfirepro]

Good news Rich. Keep us posted.

Regards

Peter

[flyingalan]

Just to add to this thread, I am aware of at least 2 more aircraft that have had this problem, one of which I am responsible for. The noise was intermittent lasting for several seconds at a time and could not be suppressed with squelch on the Trig comm. It seemed to be frequency dependent (130.425) as changing to alternative frequency (126.4) did not show the problem. (at least in the short time I listened). Back on the ground, when I changed my power wiring to connect the PAW/Flarm to an alternative circuit breaker instead of the "avionics" circuit breaker (mainly so I could easily turn PAW off in flight), to my surprise the problem seemed to have gone away and the comm was working normally. I flew for around again for some 30 minutes with no sign of the noise. However as I remarked earlier it seemed to be frequency dependent so I cannot  say that is was not on other frequencies! I have not had time to further research the effect but will try to listen on some different channels next time I'm at the airfield.
On the other aircraft reported (which I am not directly involved in) the owner tried moving the power to another CB like mine but this did not seem to cure his problem.
We are wondering if it is coming from the 12-5V regulators we are using and he is now going to try a car style USB PSU to see if it makes a difference. On the bench he reported hearing similar noise on a hand held up to 12 inches away with original PSU, but nothing with a car USB PSU. I'm waiting to hear from him if he has made any further tests.
I will add to this thread if and when we learn more but at the moment we are suspicious that it is the PSU chip radiating.
FYI the PSU we are using is a 3A block regulator from e-bay.(DC/DC Converter Regulator 12V Stepdown to 5V 3A 15W Car Power Supply Module. eBay item number:152563993051)

[Paul_Sengupta]

It's been reported on here before that those CPT voltage converters are notoriously noisy in terms of RF interference.

[exfirepro]

Hi Alan,

I agree with Paul, these things can be very hit or miss, which is why we recommend the Anker USB converters - which have proved more reliable than most. Personally I changed to a Charge 4 some time back, but still get white noise occasionally e.g. couldn't use the Scottish Information frequency on Saturday due to white noise when they weren't transmitting. It wasn't suppressable by turning off PAW and all my other avionics, so remained a mystery. Other radio channels I tried were all crystal clear.

Peter

[flyingalan]

Yes I agree that these things are hit and miss.
I did take a spectrum analyser with pick up loop to it before use and didn't see anything particularly significant in the aeronautical band. However as the interference seems to come and go it may well be load dependent so not easy to see.
Yes the Anker USB units are nice but not really easy for integrating into a single box system.
Having said that I have previously de-gutted a similar unit and re packaged the electronics. Seems like this may be the way to go if my interference returns.
Shame, the format of the CPT units was ideal and easy for integrated packaging.

[Paul_Sengupta]

Somewhere in the far reaches of the forum, someone recommended a similar unit to the CPT one, but which didn't create the RF noise.