2.3.2 Intermodulation products The intermodulation phenomena involve the mixing of two or more signals at different frequencies, in a non-linear circuit, which results in the generation of a signal at a different frequency. In general: where: : frequency of the intermodulation product f0 : frequencies of interfering signals f1, f2, f3 : positive integers. m, n, p In this Recommendation, only one form of intermodulation is considered, that due to the dominant effect, i.e. the 2-signal, 3rd order mix, given by: When within the bandwidth of the wanted channel(s), the nuisance field (NF) should be determined f0 using the following parameters. When applying the procedure of § 3, FI is replaced by: where and are the field strengths (dB(V/m)) of the interfering signals at frequencies and E1 E2 f1 f2. However, may be an improvement in the calculated nuisance field which results from the response of the receiver front end at frequencies and/or f1 f2. The protection ratio (PR) required for analogue speech systems (12.5-25 kHz channel bandwidth) associated with intermodulation products is: dB for base stations –70 dB for mobile stations. –65 Similar considerations may apply for digital systems. 2.3.3 Spurious responses Spurious responses to unwanted signals can be expected to occur in receivers at frequencies related to the receiver local oscillator and intermediate frequencies. The frequencies at which spurious responses can occur should be calculated using the following expressions: and where: : frequency at which a spurious response may occur fsp : frequency of the local oscillator applied to the first mixer of the receiver flo : switching range of the receiver (i.e. the maximum frequency range over which the receiver can operate without sr being reprogrammed or realigned) : integer greater than or to 2 n : intermediate frequencies of the receiver. if1, if2  ifn The protection ratio which applies when the vision or sound carrier of a TV signal or the carrier of a sound broadcasting signal occurs at these frequencies is dB. Under these circumstances, the power of the relevant carrier –67 should be used when calculating the field strength of the unwanted signal. Similar considerations may apply to digital systems.
2.3.2 Intermodulation products The intermodulation phenomena involve the mixing of two or more signals at different frequencies, in a non-linear circuit, which results in the generation of a signal at a different frequency. In general: where: f0 : frequency of the intermodulation product f1, f2, f3 : frequencies of interfering signals m, n, p : positive integers. In this Recommendation, only one form of intermodulation is considered, that due to the dominant effect, i.e. the 2-signal, 3rd order mix, given by: When f0 within the bandwidth of the wanted channel(s), the nuisance field (NF) should be determined using the following parameters. When applying the procedure of § 3, FI is replaced by: where E1 and E2 are the field strengths (dB(V/m)) of the interfering signals at frequencies f1 and f2. However, may be an improvement in the calculated nuisance field which results from the response of the receiver front end at frequencies f1 and/or f2. The protection ratio (PR) required for analogue speech systems (12.5-25 kHz channel bandwidth) associated with intermodulation products is: –70 dB for base stations –65 dB for mobile stations. Similar considerations may apply for digital systems. 2.3.3 Spurious responses Spurious responses to unwanted signals can be expected to occur in receivers at frequencies related to the receiver local oscillator and intermediate frequencies. The frequencies at which spurious responses can occur should be calculated using the following expressions: and where: fsp : frequency at which a spurious response may occur flo : frequency of the local oscillator applied to the first mixer of the receiver sr : switching range of the receiver (i.e. the maximum frequency range over which the receiver can operate without being reprogrammed or realigned) n : integer greater than or to 2 if1, if2  ifn : intermediate frequencies of the receiver. The protection ratio which applies when the vision or sound carrier of a TV signal or the carrier of a sound broadcasting signal occurs at these frequencies is –67 dB. Under these circumstances, the power of the relevant carrier should be used when calculating the field strength of the unwanted signal. Similar considerations may apply to digital systems.