Assessing Permissive Change Retesting Triggers for Collocated Industrial Transmitters
Collocated industrial transmitters trigger permissive change retesting when radiated intermodulation or combined RF exposure exceeds standalone grant limits.
RF Front-End Mixing
Meaning
Signal processing stage shifts the frequency of an incoming or outgoing radio wave using a non linear element. RF front-end mixing allows the system to translate high frequency antenna signals down to a lower intermediate frequency for easier processing. The process involves a local oscillator and a mixer circuit that produces the sum and difference of the input frequencies.
This stage defines the conversion loss and the noise figure for the entire radio chain.
Frequency Conversion
Translation of information between different bands is the primary function of this circuit block. In a transceiver, rf front-end mixing happens in both the transmit and receive paths. The accuracy of the local oscillator determines the stability of the final output signal.
Signal Chain
Integration of the mixer with filters and amplifiers creates the complete interface between the digital processor and the antenna. Proper impedance matching between these components is necessary to prevent signal reflections. This stage must be shielded to prevent electromagnetic interference from leaking into other parts of the enclosure.
Design Tradeoff
Selection of a mixer architecture involves balancing power consumption against linearity and noise performance. Passive mixers offer high linearity but introduce signal loss that must be compensated for by an amplifier. Active mixers provide gain but usually consume more current from the battery.