Radio FM tuner jitter and or distortion

tritonx · 06-03-2010, 08:42 AM

My car is two months old and even with the great service at my dealer, I still have from time to time jitter/distortion on the FM tuner. They have no idea where the problem is, software or electronic. They are waiting for the next update, and "we will see". Here is a video of the problem that first occurred the second day of ownership. I had this happen 3-4 times since, it's not deal breaking but getting very very annoying. It happened again this morning when at left from work, went straight to the dealership where they just told me they will call when they get the new software.

Anyone else have this problem?

Dackelone · 06-03-2010, 03:35 PM

I think that is something in the head unit. Unless you live next to some short wave radio station! lol I would ask for the RSM (regional service manager - he works for BMW NA and not the dealership!) to see what he thinks it might be.

I think right now they are just stalling on you with this software update BS. I think it is a hardware issue. Good Luck.

hlmiii · 06-03-2010, 05:32 PM

This is a tuning problem. There are only two possible causes - the antenna and the head unit.

Antenna - there's a break/faulty portion in the wiring. If so the failure is probably in the antenna input at or near the head unit (BMW tuners have "diversity tuning" which means that there are [at least two, maybe three] antennas on board; a failure of several stations would indicate that it's the antenna system at fault, rather than one of the individual systems).

Head unit - virtually all modern FM tuning circuits involve digital circuitry that works by matching on-board digital chip-generated frequencies with their over-the-air analog station-generated counterparts.

The analog frequencies are the result of calibration and tuning - they are not always exactly correct from the station due to mistakes and inattention. The digital frequencies are the result of the parts in the circuitry - they are not always correct due to varying cumulative tolerance errors.

If there is a mismatch then distortion results. Unlike the older analog tuners digital tuners cannot be "mis"tuned slightly to match the signal (not without circuitry that doesn't exist in automobile audio front ends).

Your distortion sounds as if it is the same across several stations. This would point to a digital tuning chip that is at the edge of or out of spec.

The only fix is replacement of the entire unit. Period. (Tracking down and replacing the chip or associated circuit part[s] is not feasible). It's not a judgment call. It's not tuner software. It's not other hardware. It's not the antenna. It's not the wiring.

In either case - there is N.O. way that this is a BMW software issue. It has nothing to do with radio distortion. Period.

Get with your shop and respectfully tell them what's up. They probably won't understand. Displace patience and persistence. FWIW - get a replacement unit first. It's the only way to work through it as you have to have a known good baseline. Without that it is virtually impossible to track any upstream problem (antenna) in the less likely event that one exists.

(Yes, the above technical explanations are overly-broad and simple. Deal.

)

tritonx · 06-03-2010, 07:05 PM

I totally agree with you hlmiii, I'm a sound engineer, and I've heard the same kind of sounds when computers/hardware isn't sync properly and such. This is a typical digital "bug/jitter", the jitter was the same across all bands. I give them a chance, hopefully it's very infrequent but still unacceptable. I'd be all over them if it happened more frequently, but I'll have to get this fix permanently.

Jaguar66 · 06-03-2010, 09:00 PM

I had this happen in my car about 6 weeks ago. It happened only once, and affected all three systems, AM, FM and my Sirius radio. When playing music through the thumb drive input, no distortion. It happened one afternoon, and did not go away until the car sat overnight. It has yet to return.

tritonx · 06-04-2010, 05:17 AM

Quote:

Originally Posted by RobMason

I had this happen in my car about 6 weeks ago. It happened only once, and affected all three systems, AM, FM and my Sirius radio. When playing music through the thumb drive input, no distortion. It happened one afternoon, and did not go away until the car sat overnight. It has yet to return.

Exact same thing here, it didn't affected the USB playback, haven't tried the CD/Sirius and AM. I guess the USB playback signal might be in some way isolated from the radio tuners signals. Don't wait until warranty is out to have this fixed, it's an annoying problem that can only get worst with time. Especially when you listen mostly to radio.

hlmiii · 06-04-2010, 03:47 PM

Good luck. Please let us know how this turns out.

06-03-2010, 08:42 AM	#1
tritonx Second Lieutenant 8 Rep 247 Posts Drives: '11 128i, '92 325is Join Date: Feb 2010 Location: Quebec, Qc, Canada iTrader: (0) Garage List 2011 128i [0.00] 1992 325is [0.00] 1994 318is [0.00]	Radio FM tuner jitter and or distortion My car is two months old and even with the great service at my dealer, I still have from time to time jitter/distortion on the FM tuner. They have no idea where the problem is, software or electronic. They are waiting for the next update, and "we will see". Here is a video of the problem that first occurred the second day of ownership. I had this happen 3-4 times since, it's not deal breaking but getting very very annoying. It happened again this morning when at left from work, went straight to the dealership where they just told me they will call when they get the new software. Anyone else have this problem?
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06-03-2010, 03:35 PM	#2
Dackelone European Editor 10759 Rep 22,992 Posts Drives: N54 e82 Join Date: Feb 2010 Location: Bayern, Germany iTrader: (1)	I think that is something in the head unit. Unless you live next to some short wave radio station! lol I would ask for the RSM (regional service manager - he works for BMW NA and not the dealership!) to see what he thinks it might be. I think right now they are just stalling on you with this software update BS. I think it is a hardware issue. Good Luck.
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06-03-2010, 05:32 PM	#3
hlmiii Lieutenant 86 Rep 541 Posts Drives: '11 1M '10 M5 '05 M3 '12 CRT Join Date: Nov 2008 Location: Houston iTrader: (1)	This is a tuning problem. There are only two possible causes - the antenna and the head unit. Antenna - there's a break/faulty portion in the wiring. If so the failure is probably in the antenna input at or near the head unit (BMW tuners have "diversity tuning" which means that there are [at least two, maybe three] antennas on board; a failure of several stations would indicate that it's the antenna system at fault, rather than one of the individual systems). Head unit - virtually all modern FM tuning circuits involve digital circuitry that works by matching on-board digital chip-generated frequencies with their over-the-air analog station-generated counterparts. The analog frequencies are the result of calibration and tuning - they are not always exactly correct from the station due to mistakes and inattention. The digital frequencies are the result of the parts in the circuitry - they are not always correct due to varying cumulative tolerance errors. If there is a mismatch then distortion results. Unlike the older analog tuners digital tuners cannot be "mis"tuned slightly to match the signal (not without circuitry that doesn't exist in automobile audio front ends). Your distortion sounds as if it is the same across several stations. This would point to a digital tuning chip that is at the edge of or out of spec. The only fix is replacement of the entire unit. Period. (Tracking down and replacing the chip or associated circuit part[s] is not feasible). It's not a judgment call. It's not tuner software. It's not other hardware. It's not the antenna. It's not the wiring. In either case - there is N.O. way that this is a BMW software issue. It has nothing to do with radio distortion. Period. Get with your shop and respectfully tell them what's up. They probably won't understand. Displace patience and persistence. FWIW - get a replacement unit first. It's the only way to work through it as you have to have a known good baseline. Without that it is virtually impossible to track any upstream problem (antenna) in the less likely event that one exists. (Yes, the above technical explanations are overly-broad and simple. Deal. )
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06-03-2010, 07:05 PM	#4
tritonx Second Lieutenant 8 Rep 247 Posts Drives: '11 128i, '92 325is Join Date: Feb 2010 Location: Quebec, Qc, Canada iTrader: (0) Garage List 2011 128i [0.00] 1992 325is [0.00] 1994 318is [0.00]	I totally agree with you hlmiii, I'm a sound engineer, and I've heard the same kind of sounds when computers/hardware isn't sync properly and such. This is a typical digital "bug/jitter", the jitter was the same across all bands. I give them a chance, hopefully it's very infrequent but still unacceptable. I'd be all over them if it happened more frequently, but I'll have to get this fix permanently.
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06-03-2010, 09:00 PM	#5
Jaguar66 M Power 43 Rep 1,469 Posts Drives: '09 ///M-Sport 135i Join Date: Nov 2007 Location: San Rafael iTrader: (3)	I had this happen in my car about 6 weeks ago. It happened only once, and affected all three systems, AM, FM and my Sirius radio. When playing music through the thumb drive input, no distortion. It happened one afternoon, and did not go away until the car sat overnight. It has yet to return. __________________
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06-04-2010, 03:47 PM	#7
hlmiii Lieutenant 86 Rep 541 Posts Drives: '11 1M '10 M5 '05 M3 '12 CRT Join Date: Nov 2008 Location: Houston iTrader: (1)	Good luck. Please let us know how this turns out.
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