XStream
‐
PKG
‐
T™
Telephone
RF
Modem
–
Product
Manual
v5.x00
[2006.02.24]
4.1.
Addressing
Each RF packet contains addressing information that is used to filter incoming RF data. Receiving
modems inspect the Hopping Channel (HP parameter), Vendor Identification Number (ID
parameter) and Destination Address (DT parameter) contained in each RF packet. Data that does
not pass through all three network security layers is discarded.
Figure
4
‐
01.
Filtration
layers
contained
in
the
RF
packet
header
4.1.1.
Address Recognition
Transmissions can be addressed to a specific modem or group of modems using the DT
(Destination Address) and MK (Address Mask) parameters. The transmitting modem dictates
whether the packet is intended for a specific modem (local address) or multiple modems (global
address) by comparing the packet’s DT parameter to its own MK parameter.
Figure
4
‐
02.
Local
Packets
vs.
Global
Packets
(Transmitting
Modem)
TX_DT
=
Transmitter
Destination
Address
TX_MK
=
Transmitter
Address
Mask
Note:
When
TX_DT
=
0xFFFF
(default),
RF
packets
are
global
and
are
received
by
all
modems
within
range.
(Receivers
do
not
send
ACKs.)
A receiving modem will only accept a packet if a packet is addressed to it (either as a global or
local packet). The RX modem makes this determination by inspecting the destination address of
the RF packet and comparing it to its own address and mask. The Destination Address of the TX
modem is logically “ANDed” with the Address Mask of the RX modem.
Figure
4
‐
03.
Address
Recognition
(Receiving
Modem)
TX_DT
=
Transmitter
Destination
Address
RX_DT
=
Receiver
Destination
Address
RX_MY
=
Receiver
Source
Address
NOTE: For more information regarding addressing and masks, refer to Application Note ‘XST-
AN004b’. (Located on the MaxStream CD and on the web: www.maxstream.net)
©
2006
MaxStream,
Inc.,
Confidential
and
Proprietary
27
