User's Manual

ACR-201-G Technical Manual

• Make sure that the UTP cable connecting the radio and the host device

meets at least the CAT-3 standard and has a straight-through connection,

not a crossover.

• Make sure that the ACR-201-G is not connected to a hub with multiple

computers/devices plugged in.

• Make sure that the IP address of the host computer/device is properly set

up for the network.

• Make sure that the host computer/device has initiated some packet traffic

since the radio was turned on. (That is the failure of the network

connection is not just determined by trying to access the host from a

remote point in the network.) Reset or re-power the host with the ACR-

201-G turned on may be necessary in order for the ACR-201-G to “learn”

the MAC address of the host computer.

Poor Link Quality

If the “Communication Strength” stays in the Poor range, it could be due to one of

the following reasons:

• Make sure that radio interference is not present in the radio network.

• Make sure that the radio is not surrounded by many strongly reflecting

(metallic) surfaces. With multiple reflecting surfaces between the radio in

question and the target radio, a severe “multi-path” problem may

introduce high bit error rate despite a strong “Signal Strength”.

• Make sure that there is not a condition of severe packet collision caused

by a “hidden node” problem. A “hidden node” problem is the situation

where the RF signal from two or more Station radios cannot reach each

other (but can reach the AP). In such situation, multiple Stations may

attempt to transmit data packet to the AP at the same time and therefore

cause packet collision. To solve this problem, either re-arrange the

Stations in question such that the RF signals are mutually sensible by all

Stations, or turn-on the RTS/CTS protocol by setting the “RTS threshold”

on the “Config” tab to a reasonably small value (500, for example). There

is no guarantee that the packet collision can be entirely eliminated by

invoking RTS/CTS protocol, but the severity can be reduced enough to

see visible improvement of the link quality.

Radio Interference

You may be able to eliminate RF interference by trying the following:

• Find the “channel” used by the source of the interference and coordinate

your network and the interference source to be on channels that are at

least 20MHz, but preferably 30MHz, apart.