Weak FM radio reception in 2010 Prius?

Ohh, hot off the line!

So if yours HU wasn't improved on, makes me wonder about the person that mention their unit got replaced and it worked fine. You would think the replacement would have come from the same factory.?

 

Keep in mind - we are talking about 3 separate HUs - Stock, JBL, and Nav/JBL.

All are different and specific in design (though I'm guessing use the same base - since it seems they all are not too stereo friendly). I can only say the stock unit gets reception that is past poor in quality. It borders on absurd - but since I am swapping it for Nav tonight, I no longer care. I will let others carry the torch...

I do feel bad for Toyota - they're stuck in an endless hard defect loop - so something like this will likely fall into some cracks - as it clearly has - the reception thing has been going since the release ~ 10 months ago... It does make one wonder about 'quality' in general.

Of course, if you (Toyota) admit(s) an issue, or even change it, you show there is an issue. If Toyota changes this/fixes it, they admit an issue, and then you get every PriusChat - then CNN/MSNBC person running for a change - which really means a new HU - which must be a CRAZY cost - likely more than or equal to the brake issue. Service costs to swap a HU must be 1hr...

We no longer live in a world where a TSB went un-noticed...

I'm guessing Toyota is stuck between a "perfect do good" policy - which they have "lived by (and maybe not too well at times)", and a corporate responsibility to shareholders. Getting good tunes from a radio station does not constitute a recall - or even a blip in the big scheme of things...

 

Well...I'm so confused & also embarrassed...A few posts back I indicated that my other three Toyota vehicles with OEM radios did not have this issue;....BUT, yep my gen. II (2005) does the same thing only more faint, & harder to hear...My gen. III is VERY irritating...& here is a new twist...while slowing for an intersection the other day in my gen. III, the "Picket/Fencing" or "Phizzzzt" very definitely matched the vehicle speed or rotational wheel speed or maybe even some other drive/line component rotational speed.......That also agrees with my observation of stopping in a "Right" spot & getting steady interference, THEN moving the car ONLY a foot or so & be in a "Clear" reception zone...FWIW

 

You can't hide forever. It will come back and haunt you. I am surprised Toyota hasn't learned that lesson yet.

I am just waiting paitiently for Toyota to fix this after a while I am thinking of taking action.

It can be a problem especially at night when I turn on my ligts I don't get to hear my radio at all. It was more apparent problem for me one day when there was a huge accidently on the motorway and I needed the radio for update traffic information but I couldn't because it was dark and I had to switch on my headlights.

 

It is an electric issue. I know your pain. I am in worse situation. My radio just won't work when I either turn my headlights on or my map lights. The best is the Map light. The moment I turn it on the DAB radio will just lose signal completely.

 

We ought to be distinguishing between what happens to signals with DAB and with plain-vanilla analog AM and FM. Us retrograde Yanks don't have it as bad as you blokes do. (Canadians, on the other hand . . . . I assume they're as badly affected as Europeans and Antepodeans.)

 

I mentioned DAB because it is gives a clearer picture of the serverity of the problem. I also have the plain vanila analog FM and AM and whnever the DAB gest not signal the analog radio will get a lot of hiss and static. Actually at one point when I turn my lights on it will always lose signal all together even with the Analog radio,

 

Interesting. With the base-model radio, I get what sounds like adjacent channel interference, plus audio distortion on spoken sibilants and other sounds with high frequency components. The automatic level control that adjusts for cabin noise level tends to mask, but not eliminate, those effects when it's full on. I don't get any noise from lights in any mode, and the CD player and Aux inputs are free of noise or distortion. (Zune input to AUX.) Everybody's got problems, but there appear to be levels of severity.

 

Well -just when you thought all the monkeys took their wrenches and went home... I've now played with my new toy (Pioneer Z110BT), and find it also lacking in the signal area (arggg). To date, I probably win on most HUs tested. I'm in a major market - though near the 'hills' in Orange Co (So Cal). All comparisons are to a Lexus GX470, and a Nissan Xterra. Giving each around a 7 on a 10 scale for service - maybe that helps...

A summary:

Car 1 (2010 MFG date around Jun 2009?)
1st HU (stock Prius II - nothing plugged in): bad/awful reception AM/FM - FM is the biggest issue - I'd give the radio a 3 out of 10

2nd HU (random Chinese stock nav looking thing): Better reception - not perfect - similar to existing cars - I'd give the radio a 6 out of 10

3rd HU (random Chinese replacement - they upgraded the software bugs, and I also explained there was a FM reception issue - this must have been also fixed): Really decent reception - not perfect - but I can't get it here. It was better than any of our cars - clearly. I'd give the radio a 8 out of 10

Car 2 (2010 MFG date around March 2010)
4th HU - stock Prius II - nothing plugged in: Same reception as original (from 6 months previous). Bad - I'd give the radio a 3 out of 10

5th HU (Pioneer Z110BT): Better reception to stock - but not crazy better - if the GX470/Xterra were a 7 out of 10, I give the Pioneer 6 out of 10

So I have no idea what all this shows - other than to add a bit of confusion and bewilderment. I do think the Chinese thing was just amazing compared with everything else I've heard for reception.

 

hmm I changed my my map lights hehe hahaha Its LED. BUT saying that it shouldn't have caused my radio/s to shut down!!!

 

It might depend on how the Prius dimming function works. LED brightness is controlled by changing the duty-cycle of the current pulses that power them; incandescents are traditionally dimmed by controlling the dc voltage. It's tricky enough to swap LEDs for incandescents in turn signals. (Pure dc, but the replacement LEDs have to simulate the filament load, so they wind up using as much juice as incandescents.), but the need to dim LEDs has created a whole new makret for IC makers.

Put the old bulbs back and see if the radio works again. If it doesn't, you broke something. With luck,it was only a fuse.

 

I am not sure what kind of FM problem you guys are talking about but it looks like my 2010 Prius P IV receives good FM reception. I picked up 2 weeks ago. It is MFG 3/2010.

I am about 20 mile away from closest FM towers and receive good reception both parked and driving and turning on map lights is also no problem. Except for when I go under power lines, where it gives a hiss. SAT radio is good too. A ttimes there will be weak reception but mostly good and clear.

If you want me try out anything for experiment, like turn of this/that swith etc, I can do post results

 

Don't worry nothing is broken. Radio does work but you just get no signal. Not the same thing.

Of course with the orginal MAP lights on you will have no problem. BUT with all the lights on we know what the problems are.
The problems is that even when you have all OEM lights, when you go pass lamp posts or etc you will get hiss or static sounds from the radio which shouldn't happen.

The lights just boots up the issues by exagerates the signal loss.

 

My understanding is that the Prius may well use pulse width modulation control (PWM) for some of the lights, as this is pretty common now. One potential problem with changing incandescent bulbs for LEDs is that the fast switching edges on the PWM may well propagate down the wires - with the incandescents the filament inductance and change is resistance with temperature may well damp these fast edges effectively.

So, the DAB problem with LEDs may well simply be impulse interference being radiated from wiring, a problem induced primarily by switching from bulbs to LEDs.

The mirror motor problem is down to inadequate filtering of noise from the motors, from the sound of it. This is wholly down to Toyota not adequately dealing with the mirror motor's potential EMI, a problem that I think exists elsewhere in the car's systems, too, and which may well be at the heart of many of the radio problems we're having.

Jeremy

 

Jeremy,

So, after reading over a number of the more recent posts, NOW I understand why so many complaints: They seem all to be associated with DAB!

Well, living in the 'States, I don't have the pleasure of attempting to make a DAB receiver go. So, looking for an overview, I went to the DAB description on Wikipedia.

Ha. And Double Ha. So, there was mention in there about error correction codes. I do know something about those, seeing as I've had to device (in hardware) a few, and have taken enough course work to be dangerous.

I want to hear comments on this, but I have what I think is a pretty good guess about what's going on with you guys and the "I turned on the LED and the durn thing died!"

The Wikipedia page mentioned in passing that different receivers did a better or worse job with the error correction codes.

A very brief tutorial. It's brief because, well, the Prius forums are full of nerd types who probably know more than I do about ECC (Error Correction Codes); I don't know the details of the coding scheme(s) used by DAB; and, just so people can throw brickbats, I only audited the ECC course in grad school, as compared taking it for a grade. (Although, in compensation, I have done extensive VHDL coding on some fairly complex ECC for some even more complex piles of hardware. So I do know my way around the maths, although I'm rusty.)

Say that one is attempting to send a stream of 8-bit data samples. If there's an error, there's an error. Telephone PCM data is like this as are the guts of most retail computer systems.

Now, say you want to detect a bit error. So, you through an additional parity bit in there. So, instead of having 256 possible values showing up in each sample, you now have 512, since one is sending 9 bits (2^9=512) each sample. If any of the "extra" values show up one can say that there's an error and, perhaps, do something about it. The original IBM PC had 9-bit RAM and a bit error caused NMI and would freeze the computer.

However, if you had two bit errors in the same 9-bit field, then you would not detect the error.

So, add more bits. Instead of sending 8 or even 9 bits per sample, maybe one would send 12 bits. That gives 2^12 possible values on each sample, 4096 possibilities.

Now life gets interesting. Imagine a 3-dimensional space with a cloud of individual 4096 bits. One now very carefully selects 256 points within the cloud, equally spaced as far as possible from the other 256 points. Now, put a sphere at each of the 256 points, and expand the diameter of these spheres so they just touch. Bubble city.

Now, suppose that one gets a single bit error. In this case, you'll be within the sphere near one of the 256 possible points. If the distance to the point is "small", then one can say, "I was supposed to be at this point anyway!" and, in real time, "correct" the received 12-bit data to the correct 8-bit data.

With enough bit errors, and, given that there are gaps between the spheres where the points in those gaps are equal distance to the "correct" constellation of 256 correct bits, then one might not be able to say what the correct one of the 256 bit might be - but one does know that there has been an error!

So, and you'll have to take my word on this, it is possible to construct ECC coding schemes for, pretty much, any arbitrary pairs of (correct,detect) numbers, where the "detect" number is equal to or larger than the "correct" number. So one finds ECC(3,5) codes and the like.

Schemes like this are used on hard drives, CD drives (Since day one! Haven't you wondered why tiny scratches on top of micron-sized pits on the bottom of a CD don't cause bit errors? They do, tons. But there are some really robust ECC codes in there.), and higher-end computers everywhere.

Naturally, it gets more complicated than this. Suppose that one really wants to keep the bit rate down? One might, indeed, put in but one ECC bit every 8-bit data sample. But, instead of just using that single bit every byte, one might collect 256 bytes of data and 256 ECC bits along with them - that gives a big enough constellation of data and ECC bits to do some serious ECC. However, by doing things this way, one introduces delay.

It gets stranger. Take that CD I mentioned above. If one has a visible scratch then it's likely that not just one bit, but perhaps 10 bits in a row were lost. It's possible to build ECC codes that handle an entire block of data gone bad as compared to random individual bits gone bad.

So, here's where my ignorance (and rustiness with ECC) kicks in. I personally know that doing ECC correctly may require some serious hardware chops to achieve. Especially if there's a bunch of difference ECC methods in the standard, which looks likely. There are devices like network processors that can do practically anything with programming, but they're expensive, and for good reason. And, additionally, not trivial to program. One would like to have for the retail market something that's dead cheap and settable for the (presumed) different ECCs with as little work as possible.

The Wikipedia article (yes, I know, Wikipedia, but still..) made specific mention that all DAB receivers are not created equal, in particular with ECC. And here you guys are, potentially turning on noise generators that may be wiping out individual bits... Bad ECC, anyone? Especially if a coding error blasts not just one sample, but a bunch? In a radio-quiet environment it sounds fine, but add noise...

One final thing. I have had the pleasure of shepherding some random pieces of electronic widgetry through the EU's idea of proper electromagnetic compatibility (that CE mark is nice to have if one is selling over the other side of the pond). The CE mark testing is pretty stringent. I find it somewhat hard to believe that radiated emissions in the VHF or GHz regions wouldn't be caught during basic testing of the car. Even with PCM, there are some fairly basic (simple) things one can do to kill EMI from this source.

Conducted emissions, though.. I muck with some serious battery voltage type of gear and, unless my mind has gone, we check for conducted emissions from audio to almost daylight. But that is stuff connected to wires that run through buildings. And a car isn't a building. So, I wonder if putting a little EMI filter on the back of the 12V into the radio might do some wonders.

Are all the Prius stock DAB radios in the UK showing this behavior? Or is it just every third one?

 

Just got my 2010 Prius IV w/ Solar Roof in Winter Gray on 4/12/10. It was manufactured on 3/10 and in Japan (if that makes a diff, the dealer made it seem like it did: Japan vs US made Prius). No FM/SAT problems here whatsoever, when it open air. Only problems when I go into structures and I get intermittent dropouts, but when I get to a structure that's not completely "enclosed" - no reception AM/FM/SAT problems. Live in LA County Area. The reception was similar outdoors to my previous car with embedded antenna in rear windshield (08 Audi A4), but doesn't fair as well when not in "structures," which I expected.

Hope that helps.

 

FYI all Prius cars are made in Japan.
Best Regards.
Jim

 

Wow I don't really understand much of that but the stock Radio (analog) also gets affected by the lights, which, doesn't (don't know) have ECC or need ECC. So I am confused there.

But I think I will try some EMI filters on the 12v going into the radio.

 

Well, I have the base (stock) radio, and the problem with mine is, without question, FM multipath distortion. AM is OK, the AUX input is fine, and the anomalies are all exactly consistent with multipath distortion.

Has anyone tried a longer antenna? The stock antenna is a helically-loaded short quarter-wave vertical. I parked next to another 2010 today and noticed their antenna was a good bit longer, and not helically wound. If a different antenna configuration will help, I'll spring for it, although I don't expect to listen to all that much FM.

But, anyway, my radio is definitely suffering from multipath distortion. I had a Nissan Maxima that had two antennas (one in windshield) and a true diversity receiver. I never saw better performance on FM than that, but, alas, pulled it out and put a Sony ES unit in. Don't really listen to that much FM.

 

A long and interesting reply, but the problem extends way beyond DAB. My car doesn't have this very expensive (£470, ~$700) option, yet has truly appalling FM reception, with what is very clearly cross mod/inter mod type interference caused, or at least exacerbated by, variations in vehicle speed/position (picket fencing, odd spots with no reception, variation in background noise level with small changes in vehicle position etc).

As I've mentioned before, it looks very much as if the most likely cause is a combination of poor radio front end design plus a high background electrical noise level from the car systems.

I've arranged to borrow an RF spectrum analyser, with the intention of using it to do a crude assessment of the Prius EM emissions. I have access to a fairly big screened room, and, if the chance arises, I will try and put the car in it and do a wide spectrum measurement to try and see how electrically noisy it really is. Of necessity this will have to be a limited experiment, as I won't be able to deliver power to/from the motors in the chamber.

Jeremy