Noise, Sensitivity, and Receiver Design Practical Receiver Questions Informational

What is the required dynamic range for a receiver in a co-located transmitter and receiver scenario?

The required dynamic range for a receiver in a co-located transmitter and receiver scenario must handle both the desired weak signal and the strong interference from the nearby transmitter simultaneously, which demands an extremely large spurious-free dynamic range (SFDR). The co-location challenge: the transmitter and receiver operate on different frequencies but share the same platform (ship, aircraft, vehicle, base station). The transmitter's signal leaks into the receiver through: direct coupling between antennas (determined by the antenna isolation, typically 30-80 dB depending on separation distance, frequency, and antenna placement), out-of-band transmitter noise (the transmitter produces wideband noise that falls in the receiver's passband; this noise raises the receiver's noise floor), and transmitter harmonics and spurious (which may fall directly in the receiver's passband). The dynamic range calculation: the receiver must handle the transmitter leakage signal at the receiver input without generating intermodulation products that fall in the receiver's passband and mask the desired signal. Required SFDR = (P_TX_at_RX_input - MDS) x 2/3. For example: Transmitter power = +50 dBm, antenna isolation = 50 dB, receiver filter rejection at TX frequency = 40 dB. TX signal at receiver input = +50 - 50 - 40 = -40 dBm. Receiver MDS = -110 dBm. Required SFDR = (-40 - (-110)) x 2/3 = 70 x 2/3 = 47 dB. But this is the minimum; in practice, a 10-20 dB margin is added: required SFDR approximately 60-67 dB.

Category: Noise, Sensitivity, and Receiver Design

Updated: April 2026

Product Tie-In: LNAs, Detectors, Filters, ADCs

Co-Located Tx/Rx Dynamic Range

Co-location of transmitter and receiver is one of the most demanding RF system scenarios. Military platforms (warships, tactical vehicles, aircraft) carry dozens of transmitters and receivers operating simultaneously, making co-site interference management a critical design discipline.

Parameter	Superheterodyne	Direct Conversion	Digital IF
Image Rejection	60-90 dB (filter)	30-50 dB (mismatch)	N/A (digital)
DC Offset	No issue	Major issue	No issue
LO Leakage	Low	High	Low
Integration	Difficult	Easy (single chip)	Moderate
Dynamic Range	80-120 dB	60-90 dB	70-100 dB

Noise Sources

When evaluating the required dynamic range for a receiver in a co-located transmitter and receiver scenario?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Performance verification: confirm specifications against the application requirements before finalizing the design
Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades

Cascade Analysis

When evaluating the required dynamic range for a receiver in a co-located transmitter and receiver scenario?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Common Questions

Frequently Asked Questions

What about the transmitter's wideband noise?

Every transmitter produces noise at frequencies outside its operating band. This noise, when received by a co-located receiver, raises the receiver's noise floor. The critical parameter is the transmitter's noise spectral density at the receiver's frequency: N_TX(f_RX) = P_TX + L_noise(f_offset) [dBm/Hz], where L_noise is the transmitter's noise level relative to the carrier at the frequency offset between TX and RX. For a typical PA: L_noise = -140 to -160 dBc/Hz at 50-200 MHz offset. For P_TX = +50 dBm and L_noise = -150 dBc/Hz: N_TX = +50 - 150 = -100 dBm/Hz. After 50 dB antenna isolation: N_TX at RX input = -150 dBm/Hz. The receiver noise floor is approximately -174 + NF = -170 dBm/Hz (for NF=4 dB). So the TX noise adds 20 dB to the receiver noise floor, which is significant.

How do I measure antenna isolation?

Connect a VNA or signal generator to the transmitter antenna port and measure the received signal at the receiver antenna port. The isolation = P_TX - P_RX [dB]. Measure across the full frequency range (both TX and RX bands). The isolation varies with frequency, antenna orientation, and nearby reflectors. For installed antennas: the isolation must be measured on the actual platform (not in an anechoic chamber) because the platform's structure creates reflections and coupling paths that significantly affect the isolation.

What is the frequency deconfliction approach?

Frequency deconfliction ensures that no harmful interference occurs between co-located systems. The approach: inventory all transmitters and receivers on the platform (frequencies, powers, bandwidths, antenna locations), calculate the interference level at each receiver from every transmitter (using the antenna isolation, filter rejection, and transmitter noise characteristics), identify frequency pairs where the interference exceeds the receiver's tolerance, and mitigate (re-allocate frequencies, add filters, increase antenna isolation, or implement time-sharing). For military platforms: this analysis is formalized in the EMIRAL (Electromagnetic Interference Risk Assessment Log).

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