Looking for alternate way to hear GPS

[neodoc]

Okay, everyone. Here goes. You may recall I bought a Garmin 2820 back in June for my trip in July, which, BTW, was a disaster because I caught pneumonia, the parents got sick too, and I had to keep the bike in the trailer the whole time because I was too sick to ride. Anyhow, back then I installed the GPS by hardwiring it to the maplight and was overwhelmed by the hardware I bought to integrate the GPS to the current J&M CB2003, so I left well-enough alone and kept my functioning CB/Intercom intact and returned the part I had bought. I even tried to tie into the audio input of the CB which currently uses an AutoCom part that's wired into the rear speakers so I can hear my radio/CD through the headsets, but the noise from the GPS was unbelievable, and I nixxed that idea. J&M says an integrator they sell for the Zumo would work, but may have noise, so why bother. So, my question is as follows: If one can remove the CD changer and plug an iPod in it's place using the bike's head unit, would it be feasible to do the same with the Garmin, which has XM as well as an mp3 player? If so, then what kind of hardware would be required, aside from the audio cable going from the GPS to the back of the radio?

[jamesgoodchild]

If it was me, I'd just pipe the audio into the back of the radio. BMW sells a cord for their cars that plugs into the accessory jack and it has a 3.5mm standard headphone jack to plug your devices into. A quick search should turn this up for you.

[hdfan]

I even tried to tie into the audio input of the CB which currently uses an AutoCom part that's wired into the rear speakers so I can hear my radio/CD through the headsets, but the noise from the GPS was unbelievable, and I nixxed that idea.

Why not connect the GPS to the autocom directly? If you use shielded cables there is no noise. The shielded cable issue may also solve the noise problem you stated above. It also could be that I completely misunderstood the issue. :)

[Texas42]

If you radio has an AUX setting you can use that but you wouldn't be able to hear music from the radio at the same time. You could play the MP3s and XM from the Zumo, but if you switched to the Radio, you wouldn't hear the GPS prompts. This would be the same if you could find an ice>Link device that plugged into the CD Changer.

The noise that you are hearing is a "Ground loop" you can eliminate this by using two ground loop isolators sold at Radio Shack.

You might look over in the Intercom section for better and more complete information.

[rdwalker]

Sorry about your troubles, neodoc.

Garmin GPS should cleanly integrate into the intercom. I have an older version of J&M that has the GPS input - you just connect the audio and voila!

I presume that the 2003 version is similar. Zumo hardware should work, too.

The reason you want to use the integrator is that you want to hear the GPS while other audio sources are active (depending on setup, it will either add to or override your audio).

If you feed GPS into CD changer or into AUX, you will have to keep the radio switched to that source - thus no music.

I'd suggest another attempt at integration.

The reason you had a lot of noise is that the 26xx/27xx/28xx series of Garmin receivers uses differential drivers for speakers, that is, both the positive and negative lead to speaker is active. If you use a standard stereo cable to feed the GPS audio out, you are connecting negative audio to radio ground - causing noise.

The key is either to try the above-mentioned Radio Shack ground-loop interrupters, or to make a connecting cable yourself: the center lead in that cable (coax center) goes from GPS to radio/intercom, but there is no continuity in the shield - it is unterrupted near the GPS (while still grounded at radio for shielding). Works well!

For some ASCII art:


GPS - tip of plug --------------------------------------- intercom tip

GPS ring (shield) ---- X X ------------------------------ intercom ring



Hopefully that helps.

[neodoc]

Thanks to all who have replied thus far. Back when I started, I actually bought a shielded stereo extension cable from Radio Shack (female on one end and 3.5mm male on the other,) cut off the female end and in its place soldered a 2.5mm male plug to fit the GPS audio output. Having done this, I then found the spot on the CB wiring that had the 3.5mm male plug from the AutoCom unit (which itself is soldered to the rear speaker wires,) disconnected this from the female-to-female coupler that is connected to the male coming from the J&M wiring harness (this normally carries the music to the CB and allows me to hear it through the headsets, interrupted only by CB chatter,) and I plugged the wire from the GPS in its place on the coupler. I could hear the GPS, but there was a strange clicking noise and A LOT of hum and noise. I even went as far as turning off the overhead fluorescent light in my garage to see if it was producing the hum, but the noise and hum persisted. My initial goal was to connect the GPS to the CB using a splitter so I could still have the AutoCom part and the GPS sending their signals through the same input on the CB, which in theory should have worked and required only adjustment of the output volume of each so the sound would be good. It obviously was not as simple as that. Although I'm a quick study, I'm a bit over my head on this one and will likely keep it as is for a while until I can either find a detailed set of instructions or a helping hand from someone who's a pro. For now, I guess "Margaret" (my pet name for the GPS's female voice) will be silent.