An internal spurious emission or parasitic oscillation that shows up as a distinct, persistent spike on a spectrum analyzer or a high-pitched squeal in audio equipment. These signals are usually caused by heterodyning, where two internal oscillator frequencies mix and create an unintended byproduct frequency. Technicians track them down to shield the offending traces or adjust clock frequencies to push the interference out of the operational band.
I'm seeing a massive birdie at 455 kilohertz that's completely swamping the IF stage.
If the birdie shifts frequency when you wave your hand near the open chassis, you are likely dealing with an unshielded oscillator radiating into a high-impedance trace.
Also heard as
- spurious emission
- spur
Related terms
Parasitic
An unintended electrical property like capacitance or inductance that exists physically in a circuit.
Superheterodyne
Describing a receiver architecture that converts incoming radio frequencies to a fixed intermediate frequency for easier filtering and amplification.
Hash noise
A harsh, wideband electrical interference that sounds like a buzz or static on an audio output or looks like thick fuzz on a trace.
EMI
An external memory interface connects a microcontroller or processor to off-chip memory.