I am trying to come up with a system that will allow me to broadcast sensor levels and states and I want operators to be able to pick it up with IPAQ PDAs, problem is, signal strength, format
Any ideas anyone? I would really appreciate your input!
I am thinking a PIC-WEB with a wifi router and wifi enabled pdas… no internet… Will this work ? How far will the wifi travel if I have to implement this in a multi story concrete building ?
THANKS AGAIN FOR ANY INPUT!
WiFi’s biggest problem for wireless sensors is that it is 20MHz wide. Way overkill. This cost greatly in range.
The trend now in wireless sensors is IEEE 802.15.4, without ZigBee or with. Many chip vendors. Many module level vendors - a popular one being DIgi’s XBee. Commonly, sensors talk to a gateway that bridges to RS232 or ethernet or WiFi and on to a LAN/server, not direct to a PDA. The PDA would access the server.
'15.4 modules for 2.4GHz use 2MHz spread spectrum, 250Kbps, work down to -95dBm or so, which is 15-20dB better than WiFi. This translates into much farther range. There are some for 868/900MHz too - more costly, better range due to the lower freq.
Penetrating a few masonry walls is difficult in wireless data systems for unlicensed bands. Doable, but you need an expert and lots of planning.
If you truly want Wifi, I have used/recommend highly the modules from COnnectOne, sold by Mouser or Digikey.
Thank you Stevech for your great reply!
I’ve read a bit about the advantages of ZigBee devices they seem great, but, I still do not solve the information being portable such as with PDA for the operators, the PDA must be able to pick up the signal anywhere in the buidling…
Is there such a thing as a ZigBee module for PDAs or pocket PCs ?
Thanks again!
What about using wi-fi repeaters in every floor of a building ?