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Intercept audio signal from XM radio to do a "nav cut" from your phone

2684 Views 11 Replies 5 Participants Last post by  AZKlaus
I brought this up in an other thread but realized maybe it should be its own discussion as there could be other implications.

With our radios XM comes in from a separate module that is controlled via class 2 serial data and then receive an audio input via 3 wires, radio left, radio right, and common (i'm assuming these are line level). Why is this interesting? A lot of us like to listen to the music on our phones but we also like to listen to XM. And myself personally I use my phone a lot for navigation. The problem is (and this really comes into play for another setup where we can display and control our phones on our touchscreens via a mimicsX2) that if you are listening to XM and have your phone audio plugged in you'll miss your nav directions.

Phones are very good about not broadcasting "dead signals", in otherwords the headphone jacks only send a signal when your phone is generating audio, a lot of this has to do with bluetooth power management but it comes into play on the hardwired headset as well.

This all leads into using an automatic A/B line level switch. What this would do is allow you to listen to XM radio normally as we would convert the outbound pins from the XM controller into RCA, plug them into the input A (constant) and have the RCA output connected into the wires running into the headunit. You would then have your phone connected with a mini to RCA adapter to the B (sensing) input and then when you play either music, navigation, or whatever you would it would sense the signal and switch to the B input.


Clip 3 wires coming out of XM module- BN/WH (L Audio +) D-GN/WH (R Audio +) and YE/WH (common) (see wiring diagram below)

Connect these to the wires coming out of the module:
Each blue wire gets a plus, the white wires connect to the common.
Connect the two RCAs into the A Input of this:
Connect a stereo RCA to (trs) headphone adapter to your phone and then to the B input of the switch. We'd have to play with the sensitivity to see what works best but the delay should be very low so nav instruction start immediately
Take a second set of the 2 channel speaker adapter and connect the RCA side to the output of the switch and the wires to the wiring going back into the headunit same as the input (blues to +, whites to common)

Theoretically you would now have factory style nav interrupt (maybe a call interrupt too?) that you can use with XM radio.

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I don't even know whats going on here anymore....
Haha I'll break it down :)

This will let you have a signal sensing Aux input over your XM channel. When you have your phone plugged into this while you listen to XM if your Navigation starts talking or you get some other notification it will cut the XM (like the factory radio does) and play what is coming out of your phone then automatically switch back to XM. This has many standalone benefit especially for those who do not currently have aux in.

People who would use this:
If your factory nav is broken and you want to use your phone nav anyway because the factory nav is terrible compared to google, waze, etc- but you like to jam out to XM and when you do you miss your phone's nav directions because you can't here it over your STP on Lithium
If you have RSE and want a second aux- that way people in the back seat can watch a DVD and you can still have your phone plugged in and listen to your own jams up front
If you are using a MimicsX2 unit to actually view and control your phone on the screen and want to be able to listen to your XM Radio while you do it but still have your nav that you have on the screen function like a factory radio where it cuts the music when turn by turn directions are given.

And I'm sure there's other reasons :)

I told you I'm going to bring some technical stuff to this forum man :)
Very cool!! Does it have the ability to mute my wife?!?

.......That seems to be the biggest factor in my missing some important info I'll never hear again...LOL
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