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Install Garage & Help Desk You've got the radio, now which cable goes where? Got questions about factory installed radios in your car? Ask any installation or help questions here and someone will get to you soon.

 
 
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Old 10-20-2005, 04:01 PM   #1
Jim_Dandy
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Default Question about FM out w/XMs FM Direct. **Answered** Kinda.

Hey everyone. I just got done installing my wife's PNP into her Montero yesterday. It was my first install and it went really well. I also have a Sportster installed by Best Buy in my 99 Cavalier. Once I got everything put together and it all worked a question popped into my mind about the install on my Cav.

With a PNP unit common sense tells me I should have 3 wires coming from the back of my docking station. FM out (for FM modulator), power supply, and antenna coming in. This is how I did the install on the Montero. I am using the same set up for my Cav and only have 2 wires attached to the docking station. A 12V DC and antenna in. I had Best Buy install FM Direct into the Cav about 4-5 months ago and it works a hundred times better than using the FM transmitter. I just can't figure out how the receiver is sending the signal to my radio. Is it just PFM or do some of the FM modulators some how send power in and a signal out of the same DC plug?

I'm not bothered because everything works fine. I just can't figure out how.

Here are my two installs. The Cav by Best Buy and the Montero by me:
http://www.siriusbackstage.com/forum...357&highlight=
http://www.siriusbackstage.com/forum...911&highlight=
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Old 10-20-2005, 04:06 PM   #2
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It sounds like the Montero is a little less sensitive, so it doesn't receive as much interfering crap while tuning in the PNPs built in FM transmitter.
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Old 10-20-2005, 04:28 PM   #3
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I don't use the FM transmitter on either one of them. I've installed SAT-SWB/FM direct/FM modulater relay/whatever you want to call it on both vehicles.
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Old 10-20-2005, 05:03 PM   #4
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Question about FM out w/XMs FM Direct. **Answered** Kinda.
 
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I would check with BB. If they installed the SATSWB you should have a wire plugged into the FM of the cradle.
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Old 10-20-2005, 05:09 PM   #5
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Quote:
Originally Posted by Jim_Dandy
I don't use the FM transmitter on either one of them. I've installed SAT-SWB/FM direct/FM modulater relay/whatever you want to call it on both vehicles.
It may be installed on both vehicles, but if you are only using two wires on one PNP, it can't be hooked up.
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Old 10-21-2005, 04:57 PM   #6
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Okay. Thanks for trying to set me straight but curiosity was killing me so I took dash apart to get a definitive answer. And here it is.

Best Buy used "FM Direct" which is an adaptor for XM. It looks similar to the SirSWB and SatSWB but if you look at the picture below you will see that it is an inline relay from the FM antenna to the FM port in the back of the stereo AS WELL AS a relay of some type for the sat. antenna. It receives the antenna wire and sends out an antenna wire to the sat receiver.

I don't quite understand how but it works just as good as the regular setup in my Montero so I'm just going to leave it as is.


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Old 10-21-2005, 07:23 PM   #7
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ohhhh, you beat me to the punch, i should have posted last night. BTW thanks for the pics of your install.

that's what i was going to post last night, they must have used the XM FM direct adapter, as the Sirius FM switching box requires the use of the internal fm transmitter from the Sirius cradle FM OUT port to exit and go back into the switching box, for an actual hardwired signal carrier, as it's simply a relay that waits for an audio signal to be detected before switching over.

the newer design XM FM box is the only one that does not require the use of the audio out port on the cradle, because it isn't a hardwired signal, or a fm modulator, the way their older model was:



this is how i understand the XM FM box to function: it is not a modulator, like their older design, or a truly hardwired FM connection, like the SAT-SWB, it simply grabs the wireless fm signal being broadcast from the PNP receiver out of the air, and carries it along the Sat wire back into the box where it is then actually feed into the FM antenna out jack which is plugged directly into your car radio. it uses the Sat antenna input coax as an antenna to carry that FM signal back to the box where it is soldered directly into the FM RADIO output jack.

i have never opened one up before, but i'm curious to see the internal layout.

unless someone else here has a completely different understanding of its functionality...
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Complete OEM XM Honda Tuner Locations with embedded links to HON-SC1 installations per vehicle model- PDF format:
http://www.keepandshare.com/doc/view.php?id=482275&da=y

OEM XM Acura Tuner Locations with embedded links to HON-SC1 installations:
http://www.keepandshare.com/doc/view.php?id=522731&da=y

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Old 10-22-2005, 05:07 PM   #8
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FWIW the SAT-SWB (and other similar units no doubt) are so sensative they
may "work" without being physically connected to the FM out of the base unit at all. You will most likey get better sound if you actually hook it up right.
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Old 10-22-2005, 08:12 PM   #9
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that's what i was saying, the XM FM box isn't hardwired into the FM antenna port of the XM receivers, they don't have them, aside from the XR9, they have audio out ports instead, nor is it plugged into his Sirius PNP, it isn't designed to.

as you said, it has a very sensitive reception and picks the nearby wireless fm signal coming from the PNP and transmits that along the Sat coax wire acting as an antenna to then be wired directly into the FM RADIO lead of the box, which in turn is plugged into your radio, giving the PNP fm station the strongest amplitude.
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Complete OEM XM Honda Tuner Locations with embedded links to HON-SC1 installations per vehicle model- PDF format:
http://www.keepandshare.com/doc/view.php?id=482275&da=y

OEM XM Acura Tuner Locations with embedded links to HON-SC1 installations:
http://www.keepandshare.com/doc/view.php?id=522731&da=y

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