Weak FM radio reception in 2010 Prius?

Many of us (including myself) have done just that.

To prove my point to my dealer, I connected my cheapo Best Buy portable HD radio (in regular FM mode), which by the way uses the headphone cable as the antenna, to the Aux input of the head unit (NAV in my case). Crystal clear on multiple stations. Then I changed to the NAV's FM on the same station. Lots of static. We then got into two other new Priuses on the lot, and they both had the same static problem - so the dealer wasn't willing to do anything about it, since they all seemed the same.

I think those on this forum who have good performance are either just lucky to have a unit that happens to perform a bit better, or are perhaps closer to the transmitter towers than they realize. It seems clear that this is a very common problem with the 2010 head unit(s), due to a design flaw. Toyota should address it. This is basic FM receiver design.

 

Ya same here, my radio signal and receiving is also great. Can receive strong radio stations from my area (williamsport) in the Poncono region (about 100+ miles away ~ 1 hour 30 min away) crystal clear. Now the satellite radio receiving.... that definitely could be better. Love when I go in between two mountains and loose signal... Oh well, can't ask for the best of everything. Just mostly everything.

 

Everybody with FM radio problems, please contact Toyota customer service - the more the better. Also for Toyota, because then they have enough data points to have the problem fixed. A "single" case reported is not very helpful - especially with radio problems where it can be elusive to understand where the problem/design flaw lies.

 

I, too, must be one of the lucky ones (nice for a change, actually). I'm actually getting BETTER FM reception of a distant station (I'm in Washington DC and there is a station in Baltimore -- approximately 60 miles away -- that I like to listen to) than I did with my Gen II Prius.

 

I had the issue with hiss,static, and poor reception - fixed it with a new HU (which of course you don''t want to do). Keep up the good fight

BTW - you are not comparing apples to apples. A HD radio gets a *HD* signal - which is digital, and hence should have *no* hiss (other than what the station digitized).

 

Any chance is it something obvious like the wrong spark-plugs?

 

Hm, I think I posted that my FM reception was okay right after I bought my car. But I've been listening to FM more lately and my reception for a local station was horrible the other day. I'm in Los Angeles so I should get great reception.

This and the fact that the stereo will start playing an mp3 that I never selected just because I'm scrolling through the library makes me feel that they need to fix this unit. I will be officially complaining about it.

 

As I stated in my post, I was using the portable radio in regular analog FM stereo (non-HD ) mode - not digital. And it was much cleaner than the Prius head unit.

 

OK. It's like this. I happen to have access to some decent spectrum analyzers from work and, since they're not currently in use, could borrow one for a good cause.

Now, my understanding from reading these posts is that there's an amplifier underneath that antenna in the rear, probably because the thing is too short to pick up a good signal. So, in my mind at least, there's some possibility that some of these amps might not be doing a good job.

Proving it is what one could do with a spectrum analyzer, easily. Now, my Prius III doesn't seem to have any problems with radio reception. I'm willing to volunteer this car, that appears to work, in a comparison study with a car that isn't working so well. The idea here is that somebody with a "weak radio reception Prius" would meet me in somewhere with a power outlet handy. We'd then disassemble both dashes to the point where the coax into the back of the radios could be pulled from the back of the radio. A coax with a female RCA jack could then be connected to each coax in turn.

If, for example, my Pruis's antenna/amp shows some radio station at -20 dBm, but the Prius Under Test is sitting at -30 dBm, possibly with noise, on the same station, then we have Identified A Problem. If they're both the same, then, assuming that my Pruis sounds clean but the PUT is noisy, then we've likely Identified A Problem.

Of course, this means that whoever would do this with me either knows how to get the dash apart, or can bring a buddy that does, seeing as I haven't done this kind of thing yet. And it would be useful if the other person was in the NY/NJ area since I don't think I'm quite ready to drive, say, to California for the fun.

Comments? Takers?

KBeck.

 

Somebody PLEASE, take this person up on this offer. I have been on this aspect many posts ago, in this very thread. If kbek can tell how much RF his system produces, how many dBm of signal level, and can then measure a defective antenna amp assembly. If there is a significant difference in level noted, then the amp is susect.
You can also measure the output of antenna and amp and see if possibly it is too hot and you are actualy overloading the receivers front end, which would also sound just like not enough signal...if that might be the case, it can always be padded down!
RF is strange, but fun!!!

So, somebody close to this gent, hook up and lets see if there is a difference!!
Kbeck, if I could hop a ride on a C-130, car and all, I would take you up on the offer... but then I also have an '08, but also have enough sigal that I can run it through a splitter and feed the FM unit and also a another radio. Indicatig that there is more than enough signal to split, and..both radios receive perfetly. Take some screen pics of the analyser and post them, I would like to know what levels you determine the system puts out!!

 

Has anyone tried some type of in-line amp that would boost the signal? I know the risk with these is that they can magnify bad signals but it might be worth a try.

 

Ahem. It's been awhile since my grad/undergrad school days, but low-noise broadband preamplifiers live and die by proper biasing. They typically don't have much gain; just a few dB or so. However, they set the noise floor for the rest of the receiver system. If any of the first few transistors in line, or their biasing, is snackered, then one might get some feed-through, but the system noise figure will be rotten.

Any amplifier put in line after such a snackered amp will amplify both the noise and the signal. In the first case the signal would likely be 'way down, because that first amp is probably attenuating, not amplifying. In the second case noise from the transistor which, in the FM band and up, is the actual limiting factor in how weak a signal a receiver can pick up, would probably be pretty close to the level of the attenuated signal. Hence, you'd be sitting there amplifying both signal and noise, together, and, of course, any amp would add it's own noise, too. (2nd law of thermodynamics, anyone?)

Result: I betcha not much improvement.

This is why a decent spectrum analyzer is so much fun to play with. You can actually see the signal to noise ratio. And, if it's horrible on one car and not another you've got a pretty good indication What's Gone Wrong.

There's other things that can go wrong, too. There's this general idea of "3rd order intercept". It's a measure of the quality of a receiver and the first stage of amplification has a lot to do with it. Think of it this way: Any given linear amplifier, given an input signal, puts out an output signal, noise, and, because no linear amplifier is perfect, some distortion terms. The biggest one of these tends to be the third harmonic of the input signal.

As one raises the level of the input signal, the output signal goes up more-or-less linearly. However, the third harmonic goes up faster; Eventually, they're equal. A good receiver has a 3rd-order intercept around +3 dBm (that's around 2 milliwatts input power). Bad ones have 3rd-order intercepts around -10 dBm. What this means is that when one is traveling down your local intermod alley, big powerful signals that get into your antenna and don't get filtered out can make all the other signals into your receiver go bad, simultaneously.

(This is typically why that pre-amp up on the antenna should have very little gain: There wouldn't be much in the way of frequency-rejecting filters on its front end (that's in the actual radio receiver), so it sees everything. Which means a lot of input power. Which also means significant output power, and you sure don't want to approach the limits of what those input trannies can do.)

One solution is that some better amps can detect when this is happening and (ha!) switch a straight attenuator into the antenna line. The idea is that this mucks with weak signals, but you usually can still receive the weak signals, where you wouldn't get them at all if you continue to hang out near the big transmitter. Of course, if you're in the boonies, then there's no strong transmitters around and the attenuator goes away.. But, what the heck, the Prius probably doesn't use an amp quite that fancy anyway.

KBeck.
WA1MEE

 

Probably buried early in this thread - I bought an amp - and it worked - it amplified the sound - noise and all...

When I swapped out the HU (for a random Chinese thing), the result was great reception (better than our Lexus).

For the record, the first Chinese HU had the same if not worse reception to stock. It was sent back, and "fixed". The result was a HU (using stock Prius antenna and wiring) that got better reception than both my old Nissan Xterra, and our Lexus GX470...

 

New owner here. I've just slogged through all 16 pages of posts and I'm ready to pipe in with my own two cents.

What I'm hearing sounds like multipath to me. Discriminator can't decide what phase to lock to, and the problem seems to go away in open country, even when far from weak stations.

I have an experiment in mind . . .

Don (NR7X)

 

. . . Didn't work.

What I figured was that the dinky OEM antenna was too small. (Amplifiers didn't work because they amplify noise along with the signal. SNR stays the same.)

Initially,I was going to get a metric screw at the hardware store, hacskaw off the head and jam a "replacement" telescopic whip (which I'd adjust for a quarter wavelength in the middle of the FM band), butcher the end of the whip, cram that over the headless nut, and see what happened.

Then, I found the Metra RM01B on the Web. It's a center-loaded whip, a good deal longer than the toyota OEM antenna, that's designed for replacement use on cars. It even comes with an assortment of screw-in studs, including one that matches the toyota threads. An altogether tidier solution. They had them at Kragen.

Experimental results: no discernable difference. Back to the drawing board.

I am keeping it on the car as its first farkle. Looks geekily cool.

 

+1 for the effort, fellow HAM!!
Nice antanna however, I would prefer the thin steel to the thick stock antenna.
I want to see the Spectrum Analyser pics if they happen!!!

 

Count me in also....I have both a gen. II (05) & gen. III 2010....Gen. II no problem...Gen. III FM not so great, & don't even THINK about using AM!...

 

And this is why I'm confused. OK, I live in New Jersey. It's part of a major metropolitan area. Sure, I guess if I stuck up a 40' whip and touched the bottom I could be fried by all the EM energy collected by the thing.

But: I get AM for all the stations in the area, just fine. The FM comes in, just fine. Heck, I was running back and forth between here and Boston yesterday, and was clearly picking up a station in Springfield, MA when I was 3/4 of the way down I-91 on my way down to I-95 (a goodly distance) with no problems.

I think we're looking at bad hardware, here, and a relatively large number of failures. It's just not something that a dealership is equipped to test. Old-timey TV repair shops, yes, but not any of those install-a-radio-in-a-minute shops. One actually has to have real test equipment.

I was serious about testing my car vs. some other car with the problem. I don't know if it's a bad radio, bad amp, or whatever, but it's not like this kind of stuff is rocket science.

KBeck.

 

Thanks KBeck...FWIW, My AM reception is useless, all stations are weak with static across the entire band....With my FM "Reception", the stations are "Strong" but with a constant "Phzzzzit, phzzzzit", as though static takes/over for a mil-sec....This is only when the car is in motion; when stopped everything seems fine (I know NOTHING about RF tech., Can you tell?)

 

Please contact Toyota customer service and your dealer and complain - the radio is defective - you have the same problem as me.