OG_MU-4-434_v10e Circuit Design, Inc.
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OPERATION GUIDE
6.5 Creating an Air Monitoring Function
The air monitoring function such as the one in the Evaluation Program obtains the RF input level of the receiver and
monitors the radio wave status of the field.
The MU-4 can get the RSSI level of the designated channel by issuing the RSSI absolute level measurement
command ‘@RA’.
The air monitoring function can be achieved by designating a special ID for obtaining the RSSI level as the
Equipment ID (EI = FFh), and outputting the RSSI level to the graph-making component or similar function while
obtaining the RSSI level of each channel sequentially.
* When the Equipment ID of the MU-4 is EI=FFh, the system is reserved so the MU-4 performs special operations.
When the Destination ID is ID=FFh, data cannot be transmitted, and when the Equipment ID is EI=FFh, even if the
link parameter matches, received data is not output. Instead, the RSSI (radio field intensity) of the current channel
can be read out with the ‘@RA’ command.
The procedure is as follows.
1. Issue the command ‘@EI FF’
This setting is made only once at the beginning.
2. Issue the command ‘@CH xx’
Designate a channel for which to acquire the RSSI level. ‘xx’ is the hexadecimal value that indicates the
channel.
3. Issue the command ‘@RA’
This acquires the RSSI level.
4. The RSSI level acquired is output as graph components or similar data.
5. Repeat steps 2 to 4.
Note: Be sure to confirm the response to the ‘@CH’ command issued first before issuing the ‘@RA’ command.
6.6 Assessing the Field Status for Communication
With applications that use the MU-4, in the development stage or when development is complete and the unit is
actually used, it is necessary to assess the field status of the system at all times for stable communication. In other
words, in the development stage when the MU-4 is mounted on the circuit board, it is necessary to consider the
pattern design and arrangement of components to extract the optimum values for radio performance, and to ensure
stable and reliable communication in operation, it is necessary to measure the state of the radio waves and the
surrounding floor noise and to locate the equipment at the optimal point.
The MU-4 has the following commands to allow convenient assessment of these aspects of communication.
1. @RA : Acquisition of the RSSI absolute level of the source station
2. @CR : Acquisition of the RSSI absolute level of the target station (actual signal level and floor noise level)
3. @CP : Packet test
6.6.1 Source station RSSI measurement
By issuing the @RA command, the RSSI level of the source station can be measured. It is possible to achieve
optimization while measuring the high frequency noise from the unit itself and from peripheral equipment, and the
signal level from the source station. To measure the signal level from the target station, it is possible to issue a
command requesting continuous issue of data ‘@DT 05 @CT xx’ from the source station to the target station.
Command requesting the target
station to issue continuous test data
@DT05@CT03/C
Source
station
Target
station
RSSI absolute level
value acquisition
command
@RA
Field
noise
Continuous
test data
Issue test data
for specified time
This and other
local equipment
@RA: Acquire source station RSSI
