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AM/FM radio performance

Discussion in 'Gen 4 Prius Audio and Electronics' started by dangrass, Jul 23, 2016.

  1. dangrass

    dangrass Junior Member

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    I'm finding that my 2016 Gen 4 has pretty bad AM/FM performance. Stations seems to drop and be replaced by other stations in the SF Bay Area. Seems that the antenna design leaves much to be desired.

    My VW Jetta Sportwagen TDi has a similar shark fin antenna for GPS/XM, but uses the rear side windows behind the rear passenger windows) as carriers for printed AM/FM antennas....and it works well.

    Does anyone know how if there are separate printed antennas on the 2016 Prius or is whatever there is in the shark fin?
     
  2. PriUncut

    PriUncut Active Member

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    What you describe can often be caused by summer-time inversion layers. At least in Southern California, this is fact of life with FM signals. As heat layers stack up, FM signals can travel much further than normal. Distant signals can suddenly become strong, over taking local signals (or cause interference to adjacent channels).

    A few weeks ago, I was in San Diego listening to a local station (stopped at a traffic light). All the sudden another FM station, over took the local one. In and out (for a couple of seconds), the completely over taking it. I tracked down the station that was "skipping" in... it was from Coalinga, CA (north of Fresno)! This is FM (not AM).

    Now another problem I've noticed with the Prius (and probably all modern cars) is with the FM radio. HD radio basically sucks. Because it will drop out and revert back to a lower bit rate. If you have a mountain (or hill) between you and the transmitter site, you can notice the high end go away first. Then it drops back to analog and the radio will blend back into mono (as a means of dealing with FM multi-path interference/distortion).

    I have a broadcasting background. The Prius is my first new car with HD radio. Those are some of my observations (so far) after 2 months of ownership.

    If you want to geek out more on summer-time inversion layers, read on:

    Tropospheric propagated signals travel in the part of the atmosphere adjacent to the surface and extending to some 25,000 feet (7,620 m). Such signals are thus directly affected by weather conditions extending over some hundreds of miles. During very settled, warm anticyclonic weather (i.e., high pressure), usually weak signals from distant transmitters improve in strength. Another symptom during such conditions may be interference to the local transmitter resulting in co-channel interference, usually horizontal lines or an extra floating picture with analog broadcasts and break-up with digital broadcasts.
     
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  3. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    HD radio leaves a lot to be desired.
     
    #3 krmcg, Jul 23, 2016
    Last edited: Jul 23, 2016
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  4. fuzzy1

    fuzzy1 Senior Member

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    What makes you suspect it is an antenna issue?

    If dropped and replaced signals are on the same frequency, that is seems mostly likely to be a local signal strength issue in the air, before even reaching the antenna. If both stations are heard simultaneously, garbled together, then it would be a combination of signal strength and radio performance issues (good radios can reject the weaker signal, but none can handle matched signals). If the dropped and replaced signals are on different but close frequencies, then it is more likely a radio performance issue.
     
    #4 fuzzy1, Jul 23, 2016
    Last edited: Jul 23, 2016
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  5. dangrass

    dangrass Junior Member

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    All this is true, but under the same conditions the radio in my VW doesn't have this problem. I believe that the radio antenna on the Prius is printed on the hatch glass, unlike the VW where there are 2 distinct and different antennas printed on either rear side glass. I suspect that part of the problem with the Prius arrangement is that they are attempting to use the same antenna for 560-1,600 khz as they are for 88-108 mhz, which simply isn't going to work very well. The other problem probably has to do with the horizontal polarization of the rear hatch glass versus the vertical polarization of the VW antennas.

    All in all it seems that if they wanted to have decent broadcast radio performance they would have made a greater effort to cause this to happen. I guess we're all supposed to be past that and more interested in using the cell phone system as our connection with the outside world. But then I miss the clutch and shift lever too.....
     
  6. PriUncut

    PriUncut Active Member

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    Then that would be a "diversity antenna" design... which is far superior.

    Funny, I've studied that pattern on the rear window, trying to determine what part was the antenna and what is the window defroster. I've not found definitive information on that.

    In another thread, I was trying to get info on the radio antenna and if the shark fin on the roof is just the satellite or GPS antenna?

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