M7 GX Technical Manual
30
Raveon Technologies Corp.
Channel-
Lockout”, using the
ATBC 1
command.
ATBC 0
disables BCL, and thus
the modem will transmit whenever it has data to send out.
The factory-default is BCL disabled. Use caution when enabling it, as a CW
interferer, PC with poor shielding, or some other source of RF can stop the modem
from transmitting. The threshold where the M6 senses RF carrier, and determines
that the channel is busy is set by the
ATRA
command. This is factory calibrated to
an equivalent RF level of approximately -110dBm.
7.4. Addressing (Packetized Mode only)
Addressing Basics
One of the more powerful aspects of the
M6
modem is its addressing scheme.
Incorporating addressing in the modem allows multiple radio systems on the same
frequency to co-exist, and not interfere with each other. Also, some user
application cannot tolerate receiving data that was not intended for it, and by
setting the addresses in the modems properly, the system can be configured to
allow reception of only data intended for the recipient.
If addressing is not needed or desired, it can be turned off so that all modems
receive data from all other modems, and all modems can talk to all other modems.
Each
M6
contains a 16 bit address, called its Unit Address, and is represented as a
4 digit hexadecimal number.
M6
address may be any number between 0000 and
FFFF, which is effectively 65,535 different addresses. Every
M6
has a Unit
Address programmed into it, as well as the ID of the unit it will send data to. The
Unit Address is programmed with the
ATMY xxxx
command, and the Unit Address
of the destination modem (the Destination Address) is configured with the
ATDT
xxxx
command.
The defaults UNIT ID in al
M6
modems is 1234, and 1234 is the default for the
destination ID. An Address Mask is used to select which digits of the address will
be used to determine if a particular reception was intended for the M6 modem.
The default Address Mask is FFFF, which means all digits will be used. With these
settings, by default all M6 will talk to and hear all other M6 radio modems.
Hexadecimal Numbers
For those not familiar with hexadecimal numbers, a hexadecimal digit represents a
4-bit binary pattern. There are 16 possible values
(0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,and F). These 16 values represent 4 bits of
information, thus 4 hexadecimal digits can represent 16 bits of information. The
hexadecimal numbers represent 4 bit data in the following way:
Hexadecimal Table
Hex #
Binary
Hex #
Binary
Hex #
Binary
Hex #
Binary
0
0000
5
0100
8
1000
C
1100
1
0001
6
0101
9
1001
D
1101
2
0010
7
0110
A
1010
E
1110
3
0011
8
0111
B
1011
F
1111