DocID024733 Rev 1

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AN4305

Receiver parameters

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3

Receiver parameters

The family of short range radio devices is divided into three receiver categories, each having

a set of relevant receiver requirements and minimum performance criteria. The set of

receiver requirements depends on the choice of receiver category by the equipment

provider. The SPIRIT1 is a transceiver that meets the requirements of receiver category 2,

which means medium reliable SRD communication media that can cause inconvenience to

persons, which cannot simply be overcome by other means.

The main parameters that have to be measured for the category 2 devices are the

sensitivity, the blocking and the receiver spurious radiation.

3.1

Receiver sensitivity

Receiver sensitivity is the minimum level of the signal at receiver input, produced by a

carrier at the nominal frequency of the receiver, modulated with the normal test signal

modulation, which produces performance of a bit error rate (BER) of 10-2 without correction.

Under normal test conditions, the value of the maximum usable sensitivity for 25 kHz

channel spacing equipment with a 16 kHz bandwidth shall not exceed -107 dBm. If the RX

bandwidth is not 16 kHz, the sensitivity limit is modified according to the following formula:

Equation 1

The measurement is performed using an RF signal source generator centered at the same

receiver frequency as the desired modulation signal. The demodulated data and clock are

taken from the SPIRIT1 receiver and sent to the same generator to do the BER

measurement. The generator signal level is reduced until a BER of 1% is obtained.

To reduce power consumption, an internal SMPS is integrated in the SPIRIT1. Figure 13

demonstrates the ETSI 1% BER sensitivity limit (red line) and the SPIRIT1 sensitivity for the

two investigated data rates with internal SMPS. This application note outlines the expected

performance when using the SPIRIT1 under EN 300 220-1 (v2.3.1, 2012-02) [2.] in the

169.400 - 169.475 MHz band, with channel spacing of 12.5 kHz.

The SPIRIT1 with range extender application is fully compliant with ETSI class 2 receiver

sensitivity requirements, with a large margin.