Aclara Power-Line Systems Inc. Y72553-1 Manual Do Utilizador

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Chapter 2 • Functional Description

RF operation block diagram

During the installation and configuration process, the HHTR-3 and EMTR-3 use 

one or more of 51 channels spaced 322 kHz apart in the 902-928 MHz band to 

intercommunicate with each other. Control commands and data are input to the 

HHTR-3 via the keypad by the installation operator and passed to the EMTR-3 

over the RF link. The EMTR-3 acknowledges transmissions from the HHTR-3 and 

can read back internally stored data for confirmation of receipt. EMTR-3 

transmission occurs only when data is sent or requested by the HHTR-3. 

Frequency channel selection is controlled by the HHTR software and is not 

operator selectable. Both the HHTR-3 and EMTR-3 operate as intentional radiators 

under Section 15.249 of FCC regulations, with transmitted field strengths limited 

to less than 94 dBuV/meter. These units use frequency shift-keyed digital data at 

9600 bps to communicate, and no subcarriers are used. The occupied bandwidth of 

the EMTR-3 or HHTR-3 transmissions is 200 kHz. Both the HHTR-3 and the 

EMTR-3 devices have permanently atttached integral antennas and use single 

integrated circuit RF transceivers.

 

HHTR Data

RF = PIC 18 LF242

902 -

 

928  MHz

UI = PIC 18 LF6720

8  MHz

7.

 

2V NiMH 1600 mAH

Regulated to  5V and  3.3V

EMTR-3 Data

Orion Data

916 .45  MHz

Data Rate  = 100  kbps

2-level FSK  +/- 50  Khz

(3 of 6)

 

 

PC

Data Transfer 

from

 

/

 

to

HHTR

 

 

 

 

 

    

Wire Interface to 

 

Water/Gas Meter

 

Encoder

 

 

 

   

 

 

1-

 

way RF Link

 

902-

 

928 MHz

 

Bi-

 

Directional

 

RF Link

RS-

 

232

Multi-port EMA provides 1 Electrical port 

and 7 RF ports for gas/water.

EMA unregulated voltage is 6V to 13V. 

EMA regulated voltage is 5V. 

Regulated from EMA to EMTR-3 is 3.3V.

PIC18F 4525 

8MHz 

DRAFT