The RF is IEEE 802.15.4 compliant, there is some crossover between the RF500 frequency and some WiFi
channels but WiFi utilises a completely different modulation scheme. The RF500 modulation scheme is
QPSK with half sine pulse shaping modulation (Quadrature Phase Shift Keying) whereas WiFi uses:
IEEE 802.11b CCK, DQPSK, DBPSK. (Complementary Code Keying, Differential Phase Shift Keying,
Differential Binary Phase Shift Keying).
IEEE 802.11g OFDM, (Orthogonal Frequency-Division Multiplexing).
This means that the signals can occupy the same frequency without interfering with each other. The
bandwidth required by WiFi is in the order of Mega (Million) Bits per second to allow normal data flow, our
systems' bandwidth is only 250 Kilo (Thousand) Bits per second. If it were possible to "hack" the RF link
there is no route to get to the Ethernet port of the RF500.
WiFi Channels: (Europe uses up-to channel 13 this represents the spectrum for the US).
Taken from “OFCOM Higher power limits for license exempt devices” - “Existing wideband data transmission
systems in the 2.4GHz band mostly uses Bluetooth or WiFi. Equipment categorized as wideband data must
comply with EN300328 and is limited to 100mW EIRP.”
Our RF system uses only 1mW ensuring it is not powerful enough to have any significant impact on WiFi.
Connections to Network
Connection to the network is via standard Ethernet connection. However a fixed IP address must be
allocated to the Gateway from IT before it is connected. All web-server interfacing and sending of e-mails is
done over the Ethernet connection or alternately via the Modem connection (if fitted).
Web-server
Comark uses Apache Server to provide the web-server interface. The interface itself has been written by
Comark to provide pages for all data viewing, setup and general management of the Wireless System.
E-mails
The Gateway can be setup to use a mail server on the network to send e-mails. In order to do this the mail
server needs to be setup to accept incoming e-mail from the Gateway IP address and the Gateway itself
needs to be programmed with the IP address or sever name of the mail server.
The system utilises the SMTP protocol to send e-mails, however the RF500 cannot receive e-mails.
Gateway-IT-Note-Issue-10 Page 4 of 9
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