AVT5085 A

A modem for the power grid

The transmission of digital data via the 220 Vac energy network enjoys a large interest of the electronics. The described modem uses a specialized ST7537 system from ST Microelectronics, thanks to which it is reliable, resistant to interference and complies with EMC standards.

Recommendations : we recommend it to designers who intend to send digital data over long distances without installing a cable network designed for this purpose.

Basic parameters of the ST7537 modem:

• half-duplex method of data transmission (transmission can take place in both directions, but not simultaneously, but alternately),
• asynchronous way of data transmission (no separate signal that speeds up the stream of transmitted data),
• FSK modulation applied? the data is coded as two different frequencies for logical zero and one (the bit stream causes switching between these frequencies and this is where the name frequencyshift keying, i.e. frequency shift keying),
• maximum data transfer rate 2400 bd,
• Ease of direct cooperation with the '51 family microcontrollers
• a printed circuit board and documentation in the set
  

Detailed description EP 11/02