GSM-900MHz interference in Centurion?

[Roadrunner]

Nokia 6710 Navigator GSM-buzz in earpiece

I have just come across the weirdest issue I have ever had with a cellphone:

About 80% of my calls are plagued with some sort of interference which makes it difficult for me to hear the person I am speaking to and vice versa.

It happens at random times in random places, which eliminates the possibility if it being localized interference only at my house. I have found that if I lock the phone to the 3G network only, this does not happen at all. I can however not leave the phone connected to the 3G network, because the coverage is quite poor in this area. I also confirmed that this interference happens on both Vodacom and MTN's networks.

I handed the phone (Nokia 6710 Navigator) in this morning at the Autopage shop in the Centurion Mall to be repaired, and the staff there were just as baffled as I was. Strangely enough another phone, a HTC HD2, was just handed in this morning before I got there with exactly the same problem.

The problem that I can see now coming from a mile away, is that the technicians are going to test the phone and find nothing wrong with it, because it doesn't happen with every call, which means I will get it back and the interference will still continue.

Anyone have a possible explanation for this or experiencing the same issue in the Centurion/Midrand area?

I have uploaded a recording of a call to my voicemail where you can clearly hear what it sounds like:

http://drop.io/h5yq3r8/asset/jan26-21-58-121-amr

 

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That's definitely not RF interference in the 900 MHz band, which would cause a high error rate on the channel and the characteristic breaking up / dropping of GSM calls. It sounds like some local electromagnetic interference into the audio circuits of the phone (perhaps from the RF circuits inside the phone) - just like you would get if you held the phone close to a radio or TV. My guess is that it is the phone itself. Are you using a hands-free kit? Then its probably just the wire getting too close to the antenna, or a poor quality hands-free kit. A source of interference like this across the whole of Centurion seems unlikely, or you'd all be glowing in the dark.

 

[mh348]

Had a similar problem last week. A few of my friends also on MTN were complaining about it. All of use using different phones.

 

[Roadrunner]

That's definitely not RF interference in the 900 MHz band, which would cause a high error rate on the channel and the characteristic breaking up / dropping of GSM calls. It sounds like some local electromagnetic interference into the audio circuits of the phone (perhaps from the RF circuits inside the phone) - just like you would get if you held the phone close to a radio or TV. My guess is that it is the phone itself. Are you using a hands-free kit? Then its probably just the wire getting too close to the antenna, or a poor quality hands-free kit. A source of interference like this across the whole of Centurion seems unlikely, or you'd all be glowing in the dark.

That may be, but then if it is something that is faulty with the phone - it must surely happen with every call? Also, if another person with a completely different brand and model of phone is also experiencing this it indicates that it is not an isolated problem with my phone only.

I am not using a headset or any other Bluetooth device anywhere close to the phone.

 

[ajax]

I have just come across the weirdest issue I have ever had with a cellphone:

About 80% of my calls are plagued with some sort of interference which makes it difficult for me to hear the person I am speaking to and vice versa.

It happens at random times in random places, which eliminates the possibility if it being localized interference only at my house. I have found that if I lock the phone to the 3G network only, this does not happen at all. I can however not leave the phone connected to the 3G network, because the coverage is quite poor in this area. I also confirmed that this interference happens on both Vodacom and MTN's networks.

I handed the phone (Nokia 6710 Navigator) in this morning at the Autopage shop in the Centurion Mall to be repaired, and the staff there were just as baffled as I was. Strangely enough another phone, a HTC HD2, was just handed in this morning before I got there with exactly the same problem.

The problem that I can see now coming from a mile away, is that the technicians are going to test the phone and find nothing wrong with it, because it doesn't happen with every call, which means I will get it back and the interference will still continue.

Anyone have a possible explanation for this or experiencing the same issue in the Centurion/Midrand area?

I have uploaded a recording of a call to my voicemail where you can clearly hear what it sounds like:

http://drop.io/h5yq3r8/asset/jan26-21-58-121-amr

Aah, I get that with my old Nokia 6210 (the ones released around 2001). The problem is that the speaker/amplifier is not shielded properly from the rf circuit transmitting. You will find if you are in an area with good signal strength, the "interference" will only occur for the 1st few seconds and then fade away. This is because the phone gradually reduces its output power from 2 W down to around 20 milliWatt.

When you put the phone in 3G only, you are using a different frequency. There either the shielding properties of the phone is better, or the electromagnetic susceptibility of the speaker section is lower. The problem is also much less pronounced for the GSM1800 band.

It plainly just is a badly designed phone.

 

[Roadrunner]

Aah, I get that with my old Nokia 6210 (the ones released around 2001). The problem is that the speaker/amplifier is not shielded properly from the rf circuit transmitting. You will find if you are in an area with good signal strength, the "interference" will only occur for the 1st few seconds and then fade away. This is because the phone gradually reduces its output power from 2 W down to around 20 milliWatt.

When you put the phone in 3G only, you are using a different frequency. There either the shielding properties of the phone is better, or the electromagnetic susceptibility of the speaker section is lower. The problem is also much less pronounced for the GSM1800 band.

It plainly just is a badly designed phone.

Aha, so the first thing I thought of turns out to be correct. I dismissed the idea later however, because I thought if it was lack of proper shielding, I should have been getting that interference on every call.

 

[Roadrunner]

Aah, I get that with my old Nokia 6210 (the ones released around 2001). The problem is that the speaker/amplifier is not shielded properly from the rf circuit transmitting. You will find if you are in an area with good signal strength, the "interference" will only occur for the 1st few seconds and then fade away. This is because the phone gradually reduces its output power from 2 W down to around 20 milliWatt.

When you put the phone in 3G only, you are using a different frequency. There either the shielding properties of the phone is better, or the electromagnetic susceptibility of the speaker section is lower. The problem is also much less pronounced for the GSM1800 band.

It plainly just is a badly designed phone.

Just one thing, I am sure there must be more people that have this phone, so shouldn't they all be experiencing this problem seeing as they use identical parts?

Google searches do not indicate that there are.

 

[ajax]

Just one thing, I am sure there must be more people that have this phone, so shouldn't they all be experiencing this problem seeing as they use identical parts?

Google searches do not indicate that there are.

It could just be bad Quality Assurance during the manufacturing process causing some phones to have this problem.

EDIT:
If the repair shop still has your phone, tell them to make calls in a place where they get maybe 3 bars of signal on GSM 900.
Not sure if that will you get you anywhere as the repair shop probably won't know which parts to replace, if any, and you won't know if you are on GSM 900 or GSM 1800 when making a call. For that you will need a detailed map of the towers in the area.

 

[Roadrunner]

It could just be bad Quality Assurance during the manufacturing process causing some phones to have this problem.

EDIT:
If the repair shop still has your phone, tell them to make calls in a place where they get maybe 3 bars of signal on GSM 900.
Not sure if that will you get you anywhere as the repair shop probably won't know which parts to replace, if any, and you won't know if you are on GSM 900 or GSM 1800 when making a call. For that you will need a detailed map of the towers in the area.

Thanks Ajax, will do that.

I am also still curious to find out if it was just a coincidence that a HTC HD2 was handed in the same day with the same problem.

 

[Roadrunner]

Just got the phone back now, and guess what? EXACTLY what I predicted in the original post came true.

Tested the phone inside the shop, and it sounded fine, but as soon as I got outside in the parking lot and tested it again, the buzzing sound was audible again.

 

[Roadrunner]

Just handed the phone in with Nokia at Vodaworld.

Let's hope they have better luck with it.

 

[Roadrunner]

Got the phone back today from Nokia. They exchanged the earpiece and main flex assy.

Made three calls in the Vodaworld parking lot to confirm issue is was sorted out and did not pick up any sign of a hum.

Tried again in Midrand and in Centurion areas and sure enough, humming was back.

Taking it back now on Monday for the third 'repair'.

My advice is don't get this phone, and save yourself a big headache.

 

[Roadrunner]

Just got the phone swopped out yesterday after it has been with Reconnect Mobile (Nokia) in Vodaworld for six weeks. The GSM-buzz issue is gone, but now I have the infamous zoom bar issue which affected about 90% of all the units:

http://discussions.europe.nokia.com...e;jsessionid=442FF5A4BA607FBBAF87DADDF30ECB78

As I did not want to take it back AGAIN, I searched for a possible solution and found one. You install a keymapper application which remaps the zoom bar to keys which don't exist, and that disables it.

Of course, you cannot use the zoom bar now, but other keys can perform the same function so it is not really needed.

Don't understand why Nokia is still selling this model in SA, as they stopped doing so in several other countries because of all these problems.

The only explanation that I can come up with, is that they think we are too dumb to figure this out for ourselves and they are using SA's sales to make up some of the losses they made overseas with this phone.

 

[Tacet]

The only explanation that I can come up with, is that they think we are too dumb to figure this out for ourselves and they are using SA's sales to make up some of the losses they made overseas with this phone.

Or they wanted a drop-off point for all those units they couldn't sell anymore.