I recently got a Delphi Roady XM radio. While waiting to install it on my boat, I've been using it in my truck where I also sometimes use my Garmin SPIII GPS. The first time I used them together, as soon as I turned on the XM, the SPIII lost satellite reception. It took me a little while to figure out that the XM was responsible. Here's the setup: XM and GPS plugged into separate 12 volt outlets (my truck has about 12) GPS mounted on dashboard XM antenna sitting on dashboard Extra XM antenna cable coiled up It appears that the GPS signal is impacted dramatically by the location of the XM antenna cable. Moving it a few inches can mean the difference between no fix and a normal fix, or sometimes between 19 foot accuracy and 200 foot accuracy. Anyone else had GPS troubles since they installed XM? I wondering how to minimize the impact when I install it. Harry Bethesda, MD Hunter 456 - "Czech Mate" harry@greenspun.com
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Interference...
I have GPS and XM radio (Delphi) on board and have not had any problems (mind you the GPS antenna is on the stern rail and the XM is about 20 ft away). I don't think the problem is in the dc connections. I believe XM and GPS both work around the same frequency. It sounds as if the XM is radiating rf energy that is zonking the GPS. The question is: is the energy coming from the antenna, or the Roady unit itself? You say that moving the antenna makes a difference. Try moving the various things around (even leaving the antenna alone and rerouting the cable) and determine how far apart they have to be before the GPS starts to work again. Try leaving the antenna on the dash and moving the Roady away from the GPS, then if that doesn't work, try moving the XM antenna outside. My son gave me a marine XM antenna (Terk XM-5) for Xmas, and I was about to mount on the stern rail right next to the GPS antenna. Now I'll make sure I try it before doing a permanent installation - just in case any rf is being radiated by the antenna
Derek
I have GPS and XM radio (Delphi) on board and have not had any problems (mind you the GPS antenna is on the stern rail and the XM is about 20 ft away). I don't think the problem is in the dc connections. I believe XM and GPS both work around the same frequency. It sounds as if the XM is radiating rf energy that is zonking the GPS. The question is: is the energy coming from the antenna, or the Roady unit itself? You say that moving the antenna makes a difference. Try moving the various things around (even leaving the antenna alone and rerouting the cable) and determine how far apart they have to be before the GPS starts to work again. Try leaving the antenna on the dash and moving the Roady away from the GPS, then if that doesn't work, try moving the XM antenna outside. My son gave me a marine XM antenna (Terk XM-5) for Xmas, and I was about to mount on the stern rail right next to the GPS antenna. Now I'll make sure I try it before doing a permanent installation - just in case any rf is being radiated by the antenna
Derek
receiving antennas very often transmit
Without delving deep into radio theory, antennas for most receivers very often transmit one of the mixed frequencies used to tune the receiver frequency. The signal strength is quite low but may be significant enough to overload another nearby receiver. If repositioning doesn't work, there are ways to deal with it. Check to see if a helical resonator is available to be inserted into the antenna line of the xm radio. It would pass its reception frequencies but block the fundamental (offending) mixing frequency that is being radiated.
Without delving deep into radio theory, antennas for most receivers very often transmit one of the mixed frequencies used to tune the receiver frequency. The signal strength is quite low but may be significant enough to overload another nearby receiver. If repositioning doesn't work, there are ways to deal with it. Check to see if a helical resonator is available to be inserted into the antenna line of the xm radio. It would pass its reception frequencies but block the fundamental (offending) mixing frequency that is being radiated.
Another possible cure....
...would be to install a ferrite choke core over the lead from the XM antenna. These chokes act somewhat like an 'electronic sponge' and soak up extraneous RF energy that is likely eminating from the antenna lead. Radio Shack has 2 different models that may help, part #273-104 and #273-105. Might be worth a try. Jeff
...would be to install a ferrite choke core over the lead from the XM antenna. These chokes act somewhat like an 'electronic sponge' and soak up extraneous RF energy that is likely eminating from the antenna lead. Radio Shack has 2 different models that may help, part #273-104 and #273-105. Might be worth a try. Jeff
Sirius and GPS
I have never had problems. My Sirius antenna and GPS antenna are about 15 feet apart. Also have a powered TV antenna at the mast head and don't think that it interferes (but I don't watch TV while sailing). Bill
I have never had problems. My Sirius antenna and GPS antenna are about 15 feet apart. Also have a powered TV antenna at the mast head and don't think that it interferes (but I don't watch TV while sailing)
. BillTry www.xmfan.com
Try www.xmfan.com, this problem has been addressed. Lots of XM info on this site.
Try www.xmfan.com, this problem has been addressed. Lots of XM info on this site.
Update: Delphi responds
I posted the same question on a motorcycling bboard I follow and was informed that there was a problem with shielding in the Roady and Delphi was dealing with it. I wrote Delphi last night and got this quick response: Dear Mr. Greenspun: Thank you for your inquiry. This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. Delphi has taken it upon themselves to exceed these government regulations and have improved our product to better suit these types of uses. We are waiting for the new Delphi XM Roady stock to arrive in our warehouse. Once we have them in, we will contact you on how to exchange your current Roady device with the new stock. We should be replying to you within the next couple of weeks. Thank you for visiting www.delphi.com. Sincerely, Yvonne Bonnici Delphi Corporation yvonne.bonnici@delphi.com =======================================================
I posted the same question on a motorcycling bboard I follow and was informed that there was a problem with shielding in the Roady and Delphi was dealing with it. I wrote Delphi last night and got this quick response: Dear Mr. Greenspun: Thank you for your inquiry. This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. Delphi has taken it upon themselves to exceed these government regulations and have improved our product to better suit these types of uses. We are waiting for the new Delphi XM Roady stock to arrive in our warehouse. Once we have them in, we will contact you on how to exchange your current Roady device with the new stock. We should be replying to you within the next couple of weeks. Thank you for visiting www.delphi.com. Sincerely, Yvonne Bonnici Delphi Corporation yvonne.bonnici@delphi.com =======================================================
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