Poor FM REception

[Sabreur]

Ever since I bought my MY13 V70 in 2015 I have been complaing about poor/unlistenable FM Reception. In 2 years just about the only part that has not been replaced is the loudspeaker system and still it is no better. Today, I was told be an exasperated service manager that I would have to pay them £97 for 1 hours investigation before anything else can be done.

As an RF engineer I do have an understanding of the problem but little faith in their ability to progress the issue without some heavyweight RF test eguipment and knowledge. Unfortunately, as I am now retired, I no longer have access to such facilities and their eyes glaze over when I try to explain what needs to be done. Volvo are no help, they just bounce it back to the dealer.

My suspicions are interference emanating from one of the plethora of electronic devices scattered around the vehicle.

Am I the only person with this problem?

As I was less than enthusiastic about throwing away another £97 on another fruitless investigation, they tried to persuade me to spend £295 on a DAB adaptor. However, they could not confirm that this would work properly and not be degraded by the interference degrading the FM receiver.

[Boatie]

I have a MY 12 V70 that's fully loaded with electronic. devices and experience no iterference on it's standard AM/FM radio.

Regarding a DAB tuner I tried one on my radio that a friend had bought on ebay for under £40. Fairly basic it plugged into the 12 v socket and had a trailing wire as an aerial. It worked fine and the only reason I didn't get one was that it was untidy.

[Vainona70]

I have a MY13 V70 with no FM issues. Also, have the £295 pure highway fitted by Volvo giving crystal clear TMS & Planet Rock (signal permitting).

[Clan]

Originally Posted by Sabreur

Ever since I bought my MY13 V70 in 2015 I have been complaing about poor/unlistenable FM Reception. In 2 years just about the only part that has not been replaced is the loudspeaker system and still it is no better. Today, I was told be an exasperated service manager that I would have to pay them £97 for 1 hours investigation before anything else can be done.

As an RF engineer I do have an understanding of the problem but little faith in their ability to progress the issue without some heavyweight RF test eguipment and knowledge. Unfortunately, as I am now retired, I no longer have access to such facilities and their eyes glaze over when I try to explain what needs to be done. Volvo are no help, they just bounce it back to the dealer.

My suspicions are interference emanating from one of the plethora of electronic devices scattered around the vehicle.

Am I the only person with this problem?

As I was less than enthusiastic about throwing away another £97 on another fruitless investigation, they tried to persuade me to spend £295 on a DAB adaptor. However, they could not confirm that this would work properly and not be degraded by the interference degrading the FM receiver.

have you tried looking at the second antenna in the rear bumper ? They are often pulled out when the bumper is removed , check a single wire on the right side in the boot under the tail lamp , in the R/H well ..it goes through into the bumper . also check the rear side window antenna connectors are on properly !

[bobsy852]

My AM Frequency is terrible in my V70 (2008).
It stopped working altogether for a while. Now it's intermitent. Sometimes it works brilliantly, other times it works for a while then the interference starts, and other times it's just static.

Sometimes when I switch the car on, the radio doesn't come on, and when i press the power button you get the radio welcome screen but then the screen goes blank again (switch the car on and off and it comes back)

I don't know if this is similar to the issues you're having?

Some research i've done of volvo forums in the past revealed that a number of people had their radios replaced while under warranty. Obviously the cars are no longer under warranty and radios aren't as easy to change as an old 1990's car, i even think they need programming in by Volvo. I'll keep going with it until it gives up completely I guess

[westie1981]

I had an issue a while back in my XC70 running sensus with very poor reception following the car being washed. Turned out it was down to a receiver in the back window being disloged. Not sure if you have he same aerials but worth a check. There is one on either side of the boot at the top of the near and offside glass.

[SwissXC90]

Originally Posted by Sabreur

Ever since I bought my MY13 V70 in 2015 I have been complaing about poor/unlistenable FM Reception. In 2 years just about the only part that has not been replaced is the loudspeaker system and still it is no better. Today, I was told be an exasperated service manager that I would have to pay them £97 for 1 hours investigation before anything else can be done.

As an RF engineer I do have an understanding of the problem but little faith in their ability to progress the issue without some heavyweight RF test eguipment and knowledge. Unfortunately, as I am now retired, I no longer have access to such facilities and their eyes glaze over when I try to explain what needs to be done. Volvo are no help, they just bounce it back to the dealer.

My suspicions are interference emanating from one of the plethora of electronic devices scattered around the vehicle.

Am I the only person with this problem?

As I was less than enthusiastic about throwing away another £97 on another fruitless investigation, they tried to persuade me to spend £295 on a DAB adaptor. However, they could not confirm that this would work properly and not be degraded by the interference degrading the FM receiver.

Hi, I'm a qualified RF engineer as well.
I have an MY2009 XC90 and am also disappointed with FM performance compare to previous vehicles I have owned. My car is on the P2 platform, yours is P3, so the radios are dissimilar. But the problems and how to solve them are the same.

You don't say what your reception problems are: is it Sensitivity? Selectivity? Intermodulation Distortion? RDS AF switching problems? Harmonic Distortion? Excessive Sibilance?
An RF engineer with experience can distinguish between nearly all of these


As an example, I'll discuss my car, what it suffers, and what I have done so far:

My car suffers excessive sibilance noise (esses) on FM voice, much less noticable on FM music, still slightly present on CD. You really hear it when the DJs speak into their microphone, even the well trained broadcasters.

When I was young I used to align FM tuners in the factory to exacting specifications, back then - in the 80s - FM tuners were simply better because they were carefully made and aligned. Sibilance distortion can occur through bad IF alignment and harmonic distortion.
Later on in my career I worked for the broadcasting company which maintained all the country's FM transmitters.
So I've been at both ends of the FM broadcasting chain.
And I understand the issues

The fact that I also hear some sharp high frequency distortion on CD means that it is also being emphasised by the digital signal processing.

Not much I can do about either issue as I, like you, no longer have access to a test bench with sweep generators and frequency analysers and all the other cool stuff we used.
I know one option is replacement with a new unit, but hey, thats just a bit too pricy for me. And the new unit may be just as bad as the old, indicating more a design issue than an alignment issue

The fact that the garage mechanics don't understand FM reception issues is no surprise. They are trained to believe in the computer reports and to replace suspect electronic modules with new items.
Only the real engineers in the factory totally understand vehicle reception issues and how good, and bad, modern antenna systems and radios can be.

But I digress. Back to my car. Here's some other issues I have noticed:

Weak FM sensitivity
Even though my radio has a diversity antenna system, with antenna amplifiers mounted right at the base of each antenna, I swear the sensitivity is not as good as my previous vehicle. Unfortunately, the city I live in is in a fringe area of my preferred radio station, and thus the signal drops down in many places so low that the AGC winds up and you hear FM noise.


Poor RDS AF Performance
My favourite radio station uses RDS (nearly all do here) and happily broadcasts the PI codes for the whole country. Unfortunately, whilst my radio has a diversity antenna system, it does not appear to have a dual tuner. Maybe it only has one RDS decoder, or a poor RDS design.
Previous vehicles with diversity antennas and dual tuners always checked the AF frequency and then the PI code on the non-active tuner and ensured PI was correct before switching frequencies. On the Volvo radio, it checks the AF list, and then switches to the frequency to check the PI code. Often the PI code received is wrong and then it correctly switches immediately back. BUT during the brief check you get a burst of audio from the other radio station, which is from the neighbouring country and coincidentally on one of the AF lists' frequencies. Really annoying. I wish the radio had a dual tuner or a better algorithm to check the PI codes. Or maybe my country's neighbours could switch off their FM



How to diagnose your radio system
I spent some time on my car to determine, as much as possible, if all components were working correctly
Firstly, you need to turn off RDS (to prevent AF switching and PI scans occurring) and find a weak but audible FM station that you can use as your reference, and measure the signal to noise somehow
The classic way to measure S/N is to inject a tone at the transmitter and use a noise and distortion meter at the receiver.
Of course we cannot do that, unless you have good friends at the local transmitter site....

The second best way is to monitor the tuner's AGC voltage and compare to zero reception, maximum reception (AGC saturation), and ensure you are somewhere within the active AGC curve.
You may think this is not possible, BUT thanks to VIDA you CAN measure the AGC voltage.
On my MY2009 XC90, you can measure signal strength from 0 (min) to 255 (max), and noise level from 0 (min) to 15 (max noise).
You can also manually switch the between the main and sub antennas.
So that's what I used as my reference. You car will be different... as it is a newer generation

The next step is to disconnect the antennas from BOTH antenna amplifiers.
On my XC90, this is easy as they are on the rear side windows: FM1 (main) is RH side, FM2 (sub) is LH side. On some other Volvo models, the sub antenna is inside the rear bumper.

The lead from the connector to the antenna amplifier internals will still act as a small stub antenna, but you should notice a drop in reception level.

Take a notepad, and note the signal strength without antennas
Connect FM1, note the change in signal strength.
Disconnect FM1, connect FM2. Note the signal strength from FM2

Now of course the two antennas in a diversity system will never have identical signal strengths, due to their physical separation, that's the whole point of a diversity system. But you can confirm with the above methods whether the antenna is working or not.

If the antenna was not working due to a corroded / scratched / broken on-glass antenna, then you would have zero to minimum reception on that window

The next step would be to verify the supply voltage and the gain of each antenna amplifier.
Voltage is easy: the antenna amplifiers are fed with DC down the center of the Coax, the DC is 11.5V at 13.5V battery voltage. If the voltmeter confirms power is present, then good.
Check coax cable ground integrity as well with a quick resistance check on the coax shield to vehicle chassis.

Checking the gain of the antenna amplifier is possible two ways:
The classic way through measurement. Unfortunately, as you, I no longer have access to FM test benches and cannot generate or measure FM signal levels. Shame.
The second way is again using an AB comparison of your own vehicles antenna amplifiers
Mark both amplifiers so you know their original locations, then remove them.
Using one antenna only as a reference, and your reference weak radio station, measure the received signal strength as follows:
1. No antenna amp connected to the coax - you should have no signal
2. A jury-rigged antenna made up of 1m of insulated wire (any hookup wire will do) connected by hand to the center pin of the coax. Some reception will be possible, the levels should be lower than normal. Note the signal strength
3. Connect the antenna amplifier 1 without being connected to the antenna, but ensure it is bolted down and grounded. Note the signal strength
4. Connect the antenna. Note the signal strength

Repeat steps 3 and 4 for the other antenna amplifier.
Now you have AB test results between antenna amplifier A and B.
The chances of both failing are very small, but any large difference between the signals strengths from the antenna amplifiers will highlight a poorly performing antenna amplifier.

The amplifiers themselves are a very simple low noise broadband RF amplifiers, designed to cover worldwide FM (70 to 108 MHz) and AM (the good old days of 530 to 1600 kHz) as well as LW in older amplifiers - likely not yours. Only a single transistor mostly, but lots of clever SMD design these days with RF filters optimised for frequency range.
Or maybe they are now sophisticated with remote programmable bandpass filters.... not sure. Open one up and have a look

What else can you do?

You can use a friends car (different make and model) as a reference and park next to him, tune to the same weak station, and compare performance.

Unfortunately sometimes all of the above tests reveal that everything is working properly but the radio still is not as good as other cars. Then it comes down to radio system total design, and that you unfortunately cannot change.
I experienced it once in around 1985 when I was working with the local Ford dealer, trying to diagnose weak radio reception on a new Ford. End result: the new car radio design was simply not as good as the previous model, no improvement possible.

Hope you enjoyed my radio blog!

[SwissXC90]

Originally Posted by westie1981

I had an issue a while back in my XC70 running sensus with very poor reception following the car being washed. Turned out it was down to a receiver in the back window being disloged. Not sure if you have he same aerials but worth a check. There is one on either side of the boot at the top of the near and offside glass.

Those are the on-glass antennas, and the connector connects the antenna to the antenna amplifier.

[SwissXC90]

After spending an hour writing my really long post, I though I should backup what I say with what VIDA says.

So here's the VIDA information about the Radio, know as the IAM, for a 2013 V70. What they call an antenna "booster" is in fact the antenna amplifier:

Function
Audio unit

The integrated audio module (IAM) functions as a stereo system in the vehicle and is connected to other control modules on the MOS T network.

Integrated audio module (IAM) controls settings for:

• Volume
• Bass
• Treble
• Balance
• Fader
• Equalizer

Integrated Audio Module (IAM) has support for reception of digital HD-radio (High performance, High performance multimedia, and Premium sound multimedia). HD-radio is sent digitally on the AM and FM-band, respectively, in the USA. Integrated Audio Module (IAM) will automatically change to reception of digital HD-radio if it is available on the relevant frequency and of the function for HD-radio is selected in the user menu. When Integrated Audio Module (IAM) receives digital HD-radio, a symbol for HD-radio is shown in Infotainment control module (ICM).

The integrated audio module (IAM) lowers the volume from the current source when the control module receives other audio information, such as indication from the parking assistance function or phone call.

If the vehicle is equipped with a navigation system, voice information is played via the existing speakers.

Remote control
The steering wheel remote control (standard/option) is directly connected to the steering wheel switch right (SWSR). The remote control can be used to change volume (increase/decrease) and change the set radio stations. During playback of CD or USB/iPod the buttons are used for track selection. The steering wheel switch right (SWSR) communicates with the infotainment control module (ICM) via the LIN bus. ICM then sends the signals on to the integrated audio module (IAM) via the MOST network.


Design
Control module

Integrated Audio Module (IAM) is installed in the centre console.

The infotainment control module (ICM) display shows the current status of the integrated audio module (IAM).

The Integrated Audio Module (IAM) has integrated amplifier Base 2 x 20 W or Performance 4 x 20 W.
For versions that do not have an integrated amplifier, the Audio module (AUD) is used as an amplifier.

Aerials, integrated audio module (IAM)
V70, XC70, S80

Integrated Audio Module (IAM) is connected to an antenna system for AM and FM. The antenna system consists of an AM-antenna and two FM-antennas (FM1, FM2).
The antennas are located in the rear window. For XC60 (2011-) the AM and FM1 antennas are located in the tailgate's spoiler, the FM2 antenna is located in the right rear window.

AM and FM1 antennas are connected to an AM/FM antenna booster and the FM2 antenna is connected to an FM2 antenna booster. The antenna signals are sent from the antenna boosters to Integrated Audio Module (IAM) via two coaxial cables.

The antenna boosters are supplied with voltage from Integrated Audio Module (IAM).

Integrated Audio Module (IAM) with the option navigation is also connected to GPS-antenna and VICS-antenna (only Japanese market).

Remote control
Remote control via the steering wheel keypad is available as either an option or standard depending on the market. The keypad is on the right side of the steering wheel and is connected to steering wheel switch right (SWSR).

Loudspeakers
The Integrated Audio Module (IAM) for Base has four loudspeakers and Performance has six loudspeakers directly connected to the control module.
In each front door there are two speakers. The 2-way system consists of broad-banded bass/mid-range speakers and separate treble speakers. In both rear doors (Performance only) there is a broad-banded bass/mid-range speaker.
The impedance is 4 Ω for the base/mid range loudspeakers and 15 Ω for the treble speakers.
For versions without an amplifier, the loudspeakers are connected to the Audio module (AUD).


For more information, see Design and Function - Audio Module (AUD).

Microphone
The microphone is directly connected to the Integrated Audio Module (IAM). The microphone transmits analog signals to the Integrated Audio Module (IAM). The microphone has phantom-feed via Integrated Audio Module (IAM).

Telephone calls can be connected via the handsfree. The microphone and speaker are used for calls via the handsfree.

[SwissXC90]

PS the picture in VIDA shows the 2 x antennas: AM/FM1 (main) and FM2 (sub) as being on the left and right hand rear side windows on a V70

You can easily tell the side with AM: it has a longer track on the window for the AM antenna. I think AM, and thus the main antenna, is the left hand side.

The antenna elements that are similar on the left as well as the right hand side are the FM antenna elements.