Lab 10.1 — Passive RC filter

Lab 10.1 — Passive RC Filter

Goal

Design a simple passive RC low-pass or high-pass filter and explain how it affects a signal before digitization or SDR capture.

Engineering question

How can a simple resistor-capacitor network limit bandwidth and reduce unwanted components before an SDR receiver?

Low-pass cutoff frequency

f_c = 1 / (2*pi*R*C)

Example calculation

Parameter	Value
R	1 kOhm
C	100 nF
Expected cutoff	approximately 1.59 kHz

Practical steps

1. Choose target cutoff frequency.
2. Select available resistor and capacitor values.
3. Calculate expected cutoff.
4. Draw the circuit.
5. Build or simulate the circuit.
6. Measure or estimate amplitude response.
7. Compare expected and measured cutoff.

Schematic concept

flowchart LR
    VIN[Input] --> R[Resistor]
    R --> VOUT[Output]
    VOUT --> C[Capacitor to ground]
    C --> GND[Ground]

Report checklist

• [ ] State target cutoff frequency.
• [ ] State selected R and C.
• [ ] Calculate expected cutoff.
• [ ] Draw the schematic.
• [ ] Explain whether it is low-pass or high-pass.
• [ ] Explain how it can be used in an SDR bench.

Engineering conclusion template

Generate the reference cutoff and response points before selecting real components:

python blocks/block_10_kicad_and_basic_electronics/python/lab_10_2_rf_passives_design.py

The generated docs/assets/lab102_rf_passives_metrics.json is the ideal calculation baseline. Measured values must be reported separately.

The selected RC filter uses R = ____ and C = ____, giving an expected cutoff of ____ Hz.
The circuit is suitable / not suitable for the SDR bench because ______.