ETTC'2003 - SEE

ETCC'2003 European Test and Telemetry Conference
Data can be accessed over ftp. The outlook of data concentrator is on figure 4. Data
concentrator can collect meters simultaneously over RF communication and over low voltage
network 230V (Distribution Line Communication – DLC). The interior of external RF module is
on figure 5.
When meters are difficult to be connected (because of different reasons), a hand terminal unit,
equipped with RF module, is used in walk-by method (figure 6). The computer base for HTU is
Compaq’s Ipaq PDA which is inserted in a custom made case, consisting of RF part with
external antenna, NiMH charger and NiMH accumulators. Connection between Ipaq PDA and
RF part is running over RS232 interface. A special program package is running on Ipaq,
collected data are stored on a Flash memory card and transferred later in database either by
public communication or manually.
figure 6 HTU RF, based on Ipaq PDA
3. Basic characteristics of used RF communication
In all devices RADIAN 433 protocol is used. The protocol itself is the output of RADIAN user
group (see www.radianprotocol.com), currently in 433MHz band, in 868MHz is part of TC294
WG5 work. Used frequency bands are license free, but can be adapted to national or even
customer’s needs. Some basic specification from the protocol:
Nominal Frequency
The nominal operating frequency 433.82 MHz
Frequency accuracy and stability of the transmitter
Frequency stability is ±4 kHz.
Temperature range
-20stC to 70stC (with temperature compensation –40stC to +85stC)
Power and sensitivity
The values for power and sensitivity shall follow at least the existing national and international
standards for RF equipment operating in this ISM band [ETSI 300 220]. Furthermore, to ensure
compatibility, the following minimum requirements apply:
Power (ERP) : 0 dBm < Pout < 10 dBm (however, higher output up to 300mW can be
achieved). The output power is programable
Sensitivity : better than –110 dBm, (with Rs=50 ohm for a BER of 1% for a PRS of 1023 bits).
Unwanted RF radiation
The communication module is complying with the international standards for the unwanted RF
radiation for the ISM frequency band used [ETSI 300 220].
Modulation method
Modulation: two-level FSK with BT=(0.5-1)..
Signaling rate
The medium signaling rate: 2380 baud
Symbol Period: 420 usec