Car Adapter - Is It Possible ?

[rustybirman99]

Hi ! Can I use a splitter for the car adapter and plug in two different GPS units at the same time to compare them ? Would the traffic pick up differently (based on the unit) ?
The link below is a sample of what I am asking about. Thanks
Amazon.com: Two-Way 12V DC Car Charger Cigar Cigarette Lighter Double Power Adapter Socket Splitter, Black / DUAL SPLITTER / UNIVERSAL for suitable for cell phone, GPS, iPod, and PDA (ALL Cell Phone Models: Cingular: Electronics

 

[spook45]

As long as the power adapter has enough current to run both units, I would think you will be fine. If the power adapter only puts out 1 amp or less total (500 ma for each power port) you will probably have a problem. Most GPS units require >1 amp to run and charge their internal batteries.

Good luck.

 

[canderson]

The device you showed is a simple pass-through with a diode (for reverse current flow protection), designed for far more current that two GPS units will require, so yes, you can use that without problem.

 

[rustybirman99]

Thanks! I just didn't want to fry either or both GPS units trying this out. (or the car itself!). I wanted to see if traffic and lane assist shows up more often on one than the other.

 

[vlbaindoor]

Thanks! I just didn't want to fry either or both GPS units trying this out. (or the car itself!). I wanted to see if traffic and lane assist shows up more often on one than the other.

I have a strange (probably silly as well) question:

When two GPS units are close by to one another, do they affect each other's performance by any chance?

For example it is said that if lot of old fashioned mechanical clocks are all put close together they end up showing same time as they affect each other in subtle ways - not sure whether you have heard this myth - but coming back to what you are trying to do - don't the presence antennae of each GPS device affect what signal the other device receives and hence affect it?

 

[canderson]

I - don't the presence antennae of each GPS device affect what signal the other device receives and hence affect it?

Any metal of any sort that blocks a direct line signal from a satellite will impede the unit's ability to receive the signal. However, at such short distances, any reflections are irrelevant to the computed position - you'd actually need to be blocking the signal, not reflecting it, before anything showed up in the results.

No GPS will be emitting enough RF energy (from onboard clocks or other oscillators, or the chips that use them) at satellite frequencies to interfere with the other's signal in a side-by-side test - else it wouldn't have FCC or CE markings. That said, they can and do emit enough to be heard over radio receivers at lower frequencies (ahem). Sometimes I wonder if they're really below regulatory limits.

We A/B test GPS handhelds constantly to determine the impact of new GPS chip firmware, antenna systems and chipsets. As long as the two units are set on a horizontal plane (side by side, in effect), there is no problem. If you raised or held one above the other, only then might you be shading a signal that the other might have received better.