Hey guys, I am having some issues and hoping that someone with more experience can help to enlighten me.

I just installed an indoor carpet track in my shop with a MyLaps RC4 decoder. The coaxial run is approximately 30 ft long (copper shielded wire). The detection loop is 1 ft x 5 ft.

The noise level on the coaxial by itself is around 9 to 10. The noise level on the whole system with the detection loop connected is around 70 during the day and as it gets later in the evening sky rockets to about 150.

I have mounted the detection loop on a piece of cardboard and moved it around the room and up and down with no real difference in the noise floor.

During the day, the noise is not a big deal because the signal from the cars is close to 100 points over the noise. But by 7 to 8pm, I'm concerned that the signal to noise ratio will not be great enough to ensure accurate readings 100% of the time.

Is there any way to shield the loop, or anything else to minimize the noise introduced to the system?

Thanks a bunch for your help!

Shannon

Try making a new loop from 22awg wire or something similar. Keep the spacing at around 1ft as you had previously. If that doesn't change anything, look for any machinery or CFL lights in your shop that could be inducing noise in the environment. Try turning off lights or machines/tools. Also, do you have any neighbors that operate Ham radio gear, large antennas outside their house?

Our decoder sits around 17-20 with the loop and coax connected when we run at an indoor gym.

Thanks for the tip.

Do you put a resistor in the middle of the loop, or is it just a single strand looped?

Thanks again,
Shannon

Should have a 470 ohm .5 watt resistor (Radio Shack)! I use 18 gauge speaker wire with no problems. There is always an increase in noise at night

We have a 470ohm resistor in ours, but the club an hour away from us runs just wire, no resistor. They both work with no issues.

Do you have MYLAPS black box (impedance matching device) at the end of coaxial cable? Without black box you can't get low noise and good signal.

The other issue I have seen is to keep the coaxial cable away from all other electrical cords. I have also seen if there is access coaxial cord, and it is spooled up in a circle and near any electrical cords, it makes it even worse. If there is access cord, keep it in the middle, of the run, away from all other electrical cords. Look at the schematics of the building, see if there are any conduits running under the floor with electrical lines in them. That will cause issues too.

"Do you have MYLAPS black box (impedance matching device) at the end of coaxial cable? Without black box you can't get low noise and good signal."

The trials I have run have been interesting.

I have the "official my laps" detection loop that you show a picture of. I made another detection loop with the excess wire I cut off of that without a resistor and it made no difference at all in the sensitivity or the noise level.

I tried 18 gauge wire and it was almost identical to the mylaps as well without the resistor.

I then tried a solid core wire rather than stranded which was somewhere around 18 to 16 gauge in size and the noise wasn't any higher, but it picked up the signal of the cars going across it better.

So, at least in my installation, the resistor made no difference at all in the performance of the noise or the signal from the cars.

Shannon

One thing to try to reduce the noise is to isolate the computers PSU, especially if you are using a laptop, the crappy power packs that come with laptops today are quite useless at filtering noise on the incomer which can then play havoc with all sorts of timing gear, we installed a ups for using our MyLaps loop running from a small genny, then we had similar issues running from mains power with our miniZ loop, noise on the ground plane. Any crappy UPS or Line Filter will ake a world of difference.