Radio frequency receiver circuitry configured for receiving an RF signal and down-converting said RF signal to base band, said receiver circuitry comprising: (a) RF-to-IF conversion circuitry (125; 105) configured for RF-to-IF conversion of said RF signal to an IF signal, said RF-to-IF conversion circuitry (125; 105) comprising mixer circuitry for down-converting said RF signal to a band pass IF signal, local oscillator circuitry configured for injection locking and generating an RF-to-IF mixing signal for input to said mixer circuitry, said mixing signal having a frequency which is a first pre-selected harmonic of a reference frequency, and, tunable IF filter circuitry configured for pre-tuning to said band of said band pass IF signal and, when so tuned, for filtering said band pass IF signal, (b) IF-to-base band conversion circuitry (130; 140) configured for IF-to-base band conversion of said IF signal, said IF-to-base band conversion circuitry (130; 140) comprising sub-sampling and down-conversion circuitry operating at a sampling frequency of a sampling signal input thereto, said sampling frequency being a second pre-selected harmonic of said reference frequency, and, (c) reference frequency source circuitry configured for generating a reference signal of said reference frequency, wherein each of said mixing signal and said sampling signal is derived from said reference signal as a harmonic thereof, further comprising analog to digital circuitry and digital baseband circuitry comprising a microcontroller; and. selectably operable injection locking pre-tuning circuitry configured for pre-tuning said local oscillator circuitry to an injection locking frequency sufficiently within a locking bandwidth of said local oscillator circuitry to enable injection locking by said first pre-selected harmonic of said reference signal, wherein said injection locking pre-tuning circuitry operates said sub-sampling down-conversion circuitry at selectable sampling frequencies determined by said digital baseband circuitry for down-converting said RF signal; and, said digital baseband circuitry comprises an energy detect component configured for determining a measure of energy of said down-converted RF signal; wherein said selectable sampling frequencies are selected for producing those alias bands from which said injection locking frequency is distinguished on the basis of said measure of energy determined by said energy detect component. (a) RF-to-IF conversion circuitry (125; 105) configured for RF-to-IF conversion of said RF signal to an IF signal, said RF-to-IF conversion circuitry (125; 105) comprising mixer circuitry for down-converting said RF signal to a band pass IF signal, local oscillator circuitry configured for injection locking and generating an RF-to-IF mixing signal for input to said mixer circuitry, said mixing signal having a frequency which is a first pre-selected harmonic of a reference frequency, and, tunable IF filter circuitry configured for pre-tuning to said band of said band pass IF signal and, when so tuned, for filtering said band pass IF signal, (b) IF-to-base band conversion circuitry (130; 140) configured for IF-to-base band conversion of said IF signal, said IF-to-base band conversion circuitry (130; 140) comprising sub-sampling and down-conversion circuitry operating at a sampling frequency of a sampling signal input thereto, said sampling frequency being a second pre-selected harmonic of said reference frequency, and, (c) reference frequency source circuitry configured for generating a reference signal of said reference frequency,