ZRM Radio Modem

ZRM Radio Modem

  • Modern, low cost, data radio
  • Up to 9k6 bps over* air in 12.5kHz channel (up to 4k8bps in 25kHz for 869MHz band)
  • VHF (Low and High band) & UHF versions available
  • Software selectable RS232, RS485 or RS422 data interface options
  • 9V to 30V dc supply input to support 12Vdc or 24Vdc operation.
  • Low power consumption
  • Forward Error Correction (FEC) selectable at 9k6 bps
  • Supports “Store & Forward” operation
  • Explicitly supports MODBUS protocol in addition to Transparent (any protocol) operation
  • Highly sensitive receiver
  • Easy configuration using supplied software

Available very soon, the ZRM is a high specification, low cost data radio modem which is ideal for stand alone wireless data applications or for integration into OEM products. A discrete component RF stage is used to give better performance than would be possible using the simpler “single chip” solutions found in many other low cost designs.

Low-band VHF (66 to 88MHz), High-band VHF (138MHz - 174MHz), UHF (380MHz - 470MHz) and 869MHz (863MHz - 870MHz) versions of the ZRM will be available for simplex or half-duplex operation.

Applications include security, command & control, data logging, metering, SCADA, radio telemetry, remote switching, differential GPS data transmission, Pan/Tilt/Zoom (PTZ) camera control or any similar applications where serial data needs to be transmitted reliably in situations where a serial cable is not practical.

The ZRM radiomodem has a software selectable RS232, RS485 or RS422 serial interface complete with all standard control lines, although it is also possible to use just the transmit data, receive data and ground lines without handshaking. The speed of the serial interface can be set independently of the chosen over-air data rate.

The over-air data rate can be set to a range of values between 150bps and 9600bps and there is an internal buffer to cope with situations where the interface baud rate is higher than the selected over-air rate.

For 150, 300, 600, 1200 & 2400bps, FSK/FFSK modulation is used with V.23, Bell202 and MPT1327 tone-sets all supported. At 4800bps GMSK is used, while at 9600bps the modulation is 4-level FSK (4FSK). If high speeds are not required, the modem can be programmed to a slower over-air rate to take advantage of the associated improvement in receiver threshold.

Transmit power is adjustable from 100mW to 5W under software control.

The ZRM meets the European ETSI EN300-220 specification and also the tougher EN 300 113 requirements for licensed operation.

Careful attention to spurious response, adjacent channel and blocking performance, makes the product ideal for crowded telemetry radio channels.

The RF and modem parameters of the ZRM are all fully configurable via the dedicated micro USB programming port and it is also possible to change the RF frequency, RF power and read the RSSI level with serial commands sent through the main data interface.

The ZRM radio data modem can operate transparently without packetising the data and without adding any other overheads, thereby maximising data throughput rates. Data is simply sent and received with minimal delay. Alternatively, a simple packetisation option can be enabled for use with old or non tolerant protocols, where the presence of a mute (squelch) tail may cause a problem at the end of a message.

Store and forward repeater operation is possible either using routing tables based on the protocol addresses within the messages to be transmitted or by using our new transparent broadcast repeater mode which does not need to know the serial protocol in use.