OG_MU-4-434_v10e Circuit Design, Inc.
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OPERATION GUIDE
6.6.2 Target station RSSI measurement
In order to perform stable communication, it is necessary to locate the equipment where a sufficiently high signal
level can be obtained.
By issuing the ‘@CR’ command, it is possible to measure the floor noise of the target station and the signal level
from the source station and send the information back.
6.6.3 Packet test
When transmitting data packets with the ‘@CP’ command, the data packet is returned from the target station wtihout
change. Using this, it is possible to measure the packet success rate corresponding to the field status. A data size
between 0 to 255 bytes can be set for each packet with the ‘@CP’ command. In order to locate the equipment in the
optimum place, send packets repeatedly with the ‘@CP’ command and measure the packet success rate. Note,
however, that the packet transmission procedures and the calculation of success rate must be programmed.
6.7 Achieving Data Transmission
The MU-4 can send data of 255 bytes or less at one time. When transmitting data in excess of 255 bytes, you will
need to incorporate a transmission protocol so that, for example, data is split for transmisson.
When transmitting and receiving user data frames, the MU-4 outputs only frames that are received correctly, and
discards those frames that experience errors. There is no response issued for dropped frames.
When transmitting large volumes of data such as files, it is performed using two-way communication such as ARQ
(Automatic Repeat Request), and it is necessary to provide measures against dropped frames caused by wireless
errors. Data frames include frame numbers and the like, and these are used as the criteria for
ARQ.
Source
station
Target
station
Field
noise
Source station signal
This and other
local equipment
@CR: Acquire target station RSSI
RSSI data transmission request
Source station signal level &
field noise level
Command requesting
transmission of RSSI
absolute level data from
the target station
@CR
Data packet transmission(1...255byte)
Source
station
Target
station
Packet test
command
@CP
Return the received data
without change
@CP: Packet test