CDMA Cellular Modem Reliability

[X49]

We have some remote instruments that are fairly critical to our process and it has been suggested that a CDMA cellular modem be used to send the signals to the plant PLC.

Can anybody comment on the reliability of cellular modem service versus conventional modems with a leased line or dialup line?

Reliabilty is more important than cost.

Thanks

 

[VEBill]

Speaking from experience, due to lack of other options at the time, we used to access the Internet through a CDMA USB modem stick (we later switched to a HSPA network). As with any complex system, it (the cellular and/or data network) was unavailable at various times. It certainly wasn't a problem for household use, but there's no way it would be considered highly reliable. It might be off-line for a couple of hours at a time.

 

[zappedagain]

Anything wireless can be jammed, whether by other CDMA equipment in the area, other RF equipment, or even a microwave oven in the area can degrade WiFi CDMA communications. Thus wires are more reliable than wireless, but still not foolproof.

Z

 

[SteveWag]

In my experience, reliability of leased services goes; most reliable – dial tone dial-up line: cell modem over internet; lowest reliable; dedicated (leased) point-to-point data line. The phone people are very good at maintaining dial service, horrible at diagnosing and repairing dedicated data lines. Cell comms fall in the middle. What is the distance and terrain between your two points? Private radios are very reliable and allow you to control your destiny.
Steve

 

[MacGyverS2000]

Dedicated lines are probably the worst to diagnose because it only affects one customer... if a standard shared line goes down, there's a virtual village of pitchfork-carrying customers at the door wanting blood.

Dan - Owner

http://www.Hi-TecDesigns.com