Z-Wave RF PHY Conformance Tests for Device Testing

This article covers RF and PHY conformance tests for Z-Wave device testing. These compliance tests are used for transmitter and receiver measurements of Z-Wave devices.

Z-Wave Device Transmitter Conformance Testing

Z-Wave conformance tests for the transmitter include transmit frequency error, RF data rate, modulation-code rate, transmit RF power, power adjustments, etc. These tests are crucial for Z-Wave device testing.

Transmit Frequency Error

The transmit frequency error is defined as the difference between the measured transmitted center frequency and the ideal center frequency. The frequency error should not exceed $\pm$27 ppm, which includes crystal aging over a 5-year period.

RF Data Rate

The Z-Wave PHY layer should support the following data rates with an accuracy of $\pm$27 ppm:

Modulation Code Rate

Z-Wave supports (FSK, Manchester) for the R1 rate, (FSK, NRZ) for the R2 rate, and (GFSK, NRZ) for the R3 rate. The allowed separation is 40 kHz $\pm$ 10% for R1 and R2 rates, and 58 kHz $\pm$ 10% for the R3 rate.

Transmit RF Power

The transmit RF power is measured at the antenna connector and should meet local regulatory requirements.

Power Adjustments

The device should be able to reduce at least the nominal output power by -20 dB.

Z-Wave Device Receiver Conformance Testing

Z-Wave conformance tests for the receiver include receiver sensitivity, clear channel assessment, receiver spurious measurements, receiver blocking test, maximum input level, Tx-Rx turnaround time, Rx-Tx turnaround time, etc.

Receiver Sensitivity

The test is conducted as per the standard test frame and conditions mentioned in the standard. The receiver sensitivity for different rates should meet the following requirements:

Clear Channel Assessment

The Z-Wave physical layer needs to perform this test to determine if the medium is busy or clear for transmission. The receiver should be able to perform ‘listen before talk’ with a threshold of about -80 dBm.

Receiver Spurious Measurement

The RX spurious limit is -70 dBm at 100 kHz within $\pm$1 MHz from the regional Z-Wave frequency.

Z-Wave Receiver Blocking Test

Blocking is a measure of the receiver’s capability to receive a wanted modulated signal without exceeding a given degradation due to the presence of an unwanted input signal.

• A standard test frame is at the nominal frequency with normal modulation. Its power is adjusted down to the sensitivity level +3 dB.
• The unwanted signal is a CW (carrier wave) at a specific offset frequency. Its power is adjusted up until the receiver gets the FER (frame error rate) that corresponds to the sensitivity level.

Maximum Input Level

A receiver shall function with a maximum input level greater than or equal to 0 dBm (i.e., 1 mW).

Tx-Rx Turnaround Time

It is measured from the trailing edge of the last transmitted symbol until the receiver is ready to begin the reception of the next PHY packet. The limit specified in the standard is about 1 ms.

Rx-Tx Turnaround Time

It is measured at the receiver from the trailing edge of the last symbol of a received packet until the transmitter is ready to begin transmission. The limit specified in the standard is about 1 ms.