MDEV-868-PRC datasheet(10/55 Pages) LINX

10 / 55 page

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Theory of Operation

The HumPRCTM Series transceiver is a low-cost, high-performance

synthesized FSK transceiver. Figure 19 shows the module’s block diagram.

The HumPRCTM Series transceiver operates in the 863 to 870MHz

frequency band. The transmitter output power is programmable, though

the maximum power is automatically limited on the higher channels to

comply with ETSI regulations. The range varies depending on the antenna

implementation and the local RF environment. When operating near the

maximum range, there can be higher packet loss when transmitting on the

higher channels due to output power limiting, although it is anticipated that

most customers won’t notice any difference since the transceiver utilizes 70

channels for transmissions.

The RF carrier is generated directly by a frequency synthesizer that includes

an on-chip VCO. The received RF signal is amplified by a low noise

amplifier (LNA) and down-converted to I/Q quadrature signals. The I/Q

signals are digitized by ADCs.

A low-power onboard communications processor performs the radio

control and management functions including Automatic Gain Control

(AGC), filtering, demodulation and packet synchronization. A control

processor performs the higher level functions and controls the serial and

hardware interfaces.

A crystal oscillator generates the reference frequency for the synthesizer

and clocks for the ADCs and the processor.

Figure 19: HumPRCTM Series Transceiver RF Section Block Diagram

LNA

FREQ

SYNTH

ADC

MODULATOR

ANTENNA

PROCESSOR

GPIO /

INTERFACE

Module Description

The HumPRCTM Series remote control transceiver module is a completely

integrated RF transceiver and processor that is designed to send the

logic state of its inputs to a remote unit and replicate the logic states of

the remote unit’s inputs. This allows for the easy creation of basic remote

control systems.

The module operates through a series of dedicated I/O lines, resulting in

a hardware design that does not need any software development. The

module does have a serial interface that allows for some configuration in

applications that need specific control. This interface is likely not needed for

basic remote control applications.

Since this module can act as both transmitter and receiver, terminology and

descriptions are important. This guide uses the term Initiating Unit (IU) to

describe a module that is transmitting commands. Responding Unit (RU) is

used to describe a module that is receiving commands.

The module has 8 status lines numbered S0 through S7. These can be set

as inputs for buttons or contacts or as outputs to drive application circuitry.

When S0 is taken high on the IU, S0 goes high on the RU, and so forth. A

line that is an input on one side needs to be set as an output on the other

side.

The HumPRCTM Series adds a remote control application layer to the

protocol stack used by the HumPROTM Series data modem. This enables

the simple creation of remote control systems that benefit from the robust

feature set of the protocol stack, such as a fast locking Listen Before Talk

and Adaptive Frequency Agility (LBT+AFA) algorithm, AES128 encryption,

32-bit addressing, assured delivery and a simple Join Process for

associating multiple modules with each other.

As a result, much of the HumPRCTM Series terminology is the same as the

HumPROTM Series. Likewise, most of the software registers are the same,

though some do not apply to the remote control application.

A result of this common protocol stack is that HumPRCTM Series

transmissions can be received by another HumPRCTM Series module for

simple remote control applications or by a HumPROTM Series module for

applications that want to combine data transmissions (such as sensor

values) with remote control functionality.

MDEV-868-PRC Datasheet(PDF) 10 Page - Linx Technologies

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