Receiver parameters

AN4103

14/20

Doc ID 023130 Rev 1

Figure 13.

Sensitivity vs. data rate with 1 % BER

3.2

Blocking

Blocking is a measure of the capability of the receiver to receive a desired modulated signal

without exceeding a given degradation due to the presence of an unwanted input signal at

any frequency other than those of the spurious responses or the adjacent channels or

bands.

All the blocking results are measured by positioning the input power 3 dB above the

measured sensitivity limit given in the previous paragraph with a primary signal source

generator. A second generator with an unmodulated signal is used as the interferer,

combined with the primary signal using a power combiner. The second interferer generator

is placed at the desired frequency offset and the power is increased until the BER

degradation of 1% is obtained.

ETSI specifies the blocking limits in absolute value at two points: ± 2 MHz and ±10 MHz.

The limit for class 2 receiver at ±2 MHz is 36 dB, and at ±10 MHz it is 61 dB.

SPIRIT1 is fully compliant with the ETSI class 2 receiver blocking requirements by a large

margin.

In the ETSI EN300 220 [2] standard the adjacent channel selectivity is defined as well as the

measure of the capability of the receiver to operate satisfactorily in the presence of an

unwanted signal, which differs in frequency from the desired signal by an amount equal to

the adjacent channel separation for which the equipment is intended. This parameter has to

be evaluated only for devices that comply with the ETSI class 1 which is not the case for

SPIRIT1.

-125

-120

-115

-110

-105

-100

-95

110

100

Data Rate [kbps]

AM16356v1

SMPS EXT

SMPS INT

ETSI Limits