astrosatch Chen, which cables are you using? Any recomendations? Specs?
First, a description of USB cables.
The two data lines of 4 pin USB ("USB 2.0") form a differential pair. Differential pair just means that when one wire of the pair goes positive, the other wires goes negative. Just do a Google search to find the advantage of differential pairs instead of single ended -- Bell Labs developed this way back in the 1920s I think, or perhaps earlier. I believe that when Nyquist wrote his 1928 paper (what we today call the "Nyquist Rate"), twisted differential pair was already in use. Your landline telephone cable today uses twisted differential pairs.
USB 2 passes data in both directions on this single pair of data lines (half duplex). Half duplex just means that when one end is talking, the other end can only listen and not talk.
The other two lines in the connector carry +5 V and ground return for the 5V.
With the 9-pin USB ("USB 3"), there are 5 additional wires. 4 of the new wires form two new data pairs, one dedicated to each direction of the data line (so you get full duplex with USB 3.0). You want each of these two additional pairs to be individually shielded so that they are shield from one another and from the rest of the world.
The 5th new pin is a bare ground drain wire and makes contact with the large shield that encloses all wires. Additionally, the better USB cables, like the high quality coax cable that your Internet provider or Cable TV provider uses, will be "double shielded" -- usually with a foil and a braid around the foil. The solid foil is a better shield and the braid has better strength.
As you can tell, the flat ZWO cables have none of these elements.
This is a typical cross section of an acceptable 9 pin USB ("USB 3") cable:
https://m.media-amazon.com/images/I/71hinbsK-rL._AC_SX679_.jpg
Starting from outside, you have a PVC jacket that protects the cable from people, animals and weather. Next is the ground braid. Next comes the ground foil. Notice the ground drain that runs between the foil and the braid.
Inside, the red wire is +5V and the black is the ground return for the 5V. The white and green are the USB 2 data wires. Then, you can see two shielded pairs (and in this diagram, each od the data shields also have their own ground drain. This diagram also includes two fat ground wires.
Good USB 3 cables are fat and heavy, but not all fat and heavy cables are good :-).
They are cheap enough at Amazon, you can sample them and throw away something that does not work. But in general, you want the ads to show that the inside has the proper shields.
If you need to also carry power you would also want a heavy gauge (20 AWG or fatter) power wire. But the ZWO cooled cameras don't need much current as long as you power the cameras with 12V.
Even with good cables, I don't recommend coiling them for more than 1 turn. There are enough selection at Amazon that you can find a length that is not much longer than your needs.
If your power supply is clean of RFI, you can safely cable tie a 12V cable right next to a USB cable (as long as the USB cable is shielded!). I recommend using power supplies that Amateur Radio hobbyists use, since we are very sensitive to RFI. Personally, I use a PowerWerx 30A power supply, which is quite clean. Shop for power supplies at places like Ham Radio Outlet and you are moderately safe.
Most of the rectagular bricks (like what ZWO sells as a 12V power supply) are notoriously RF noisy. Just put an oscilloscope on one if you are unsure.
Personally, I always throw away the flat USB cables that ZWO includes in their boxes.
By the way, here is an old Intel White Paper on the interoperability of USB 3 and WiFi. I don't know if ZWO is aware of this white paper when they designed the motherboard for the third generation ASIAIR:
https://www.usb.org/sites/default/files/327216.pdf
Notice section 4 of the White paper regarding the importance of shielding and placement of connectors.
Chen
