Products

		Frost Alarm/Weather Station/Irrigation Monitorin: Solar powered wireless frost alarms, complete weather stations and irrigation monitors.
		Outdoor Temperature Logger: Recently released temperature logger built into a temperature shield with various logging options.
		Sewer Flow Monitor: Using specialy designed Pelican cases combined with a SPE to monitor loggers, flow meters, ultrasonice sensors and float switches for a variety of applications.
		Serial Port Extender: Used to set up a virtual connection between a remote device (with a serial port) and a central computer. Remote equipment can then be controlled from anywhere in the world, and treated as if it were connected directly to the central computer. Harvest Electronics can customise this product (hardware and software) to suit your application.
		Industrial Telemetry Unit: A version of the SPE with extensive I/O and logging capabilities.
		Rail Crossing Monitor: Custom GPRS telemetry device that monitors various functions at a rail level crossings throughout New Zealand.
		Portable Intruder Alarms: The Harvest Portable Intruder Alarm system incorporates a passive infared sensor, GSM GPRS cellphone and six AA batteries to form a reliable portable alarm system.
		GPRS Modems: Motorola G24 modules, and Siemens MC35 and MC35i terminals. These modules can do GPRS data, circuit-switched data (CSD), text messaging (SMS), and more. They are suitable for various applications with PPP and IP support.
		Motorola M930 Handset: Motorola M930 is an ergonomically designed fixed mobile car phone, uniquely designed for the vehicle environment.

More About GPRS

The General Packet Radio Service (GPRS) is a packet data extension to the GSM cellular network. Unlike circuit-switched data, GPRS does not assign a fixed bandwidth per call and charge per minute, but instead uses packet switching and charges for the data volume.

GPRS comes into its own when you need to make many calls or stay online, or when you have small amounts of data to send. With a circuit-switched call you might pay for 60KB of data when you only send 500 bytes, whereas with GPRS you'll pay only for what you send. (60KB is based on a 1-minute minimum charge at 9600bps. Note that some charging plans include a minimum data volume charge that must be considered.)

In order to use GPRS, your equipment must support Internet Protocol (IP), Point to Point Protocol (PPP) and the associated protocols. This is not a problem if you are using a PC, but most industrial and telemetry equipment can only deal with RS-232. Our SPE adds a microcontroller to allow RS-232 equipment to talk to a GPRS modem. The SPE deals with all the necessary protocols and packetisation, so your equipment only has to deal with the data.