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Radio Comm Guide

This document serves as a beginner's guide to radio communication and Software Defined Radio (SDR), covering key concepts such as the electromagnetic spectrum, frequency bands, and modulation techniques. It explains the flexibility of SDR, highlights various SDR devices, and discusses the fundamental role of antennas in communication. Additionally, it outlines practical applications of SDR and provides key formulas related to radio communication.

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samarth2004.isro
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5 views2 pages

Radio Comm Guide

This document serves as a beginner's guide to radio communication and Software Defined Radio (SDR), covering key concepts such as the electromagnetic spectrum, frequency bands, and modulation techniques. It explains the flexibility of SDR, highlights various SDR devices, and discusses the fundamental role of antennas in communication. Additionally, it outlines practical applications of SDR and provides key formulas related to radio communication.

Uploaded by

samarth2004.isro
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Beginner’s Guide to Radio Communication and

SDR

1. Introduction to Radio Communication


Radio communication is the transmission and reception of information using electromagnetic
waves. These waves travel at the speed of light and can cover short or long distances depending
on their frequency.

Key concepts:
• Electromagnetic spectrum: Ranges from low-frequency (kHz) radio waves to GHz
microwaves.
• Frequency bands: HF (3–30 MHz), VHF (30–300 MHz), UHF (300–3000 MHz), SHF
(3–30 GHz).
• Modulation: Techniques such as AM (Amplitude Modulation), FM (Frequency
Modulation), and digital modulation are used to encode information onto carrier
waves.

2. Software Defined Radio (SDR)


SDR is a modern approach where traditional radio functions (filters, modulators, demodulators) are
implemented in software rather than hardware. This makes SDRs flexible and capable of handling
multiple communication standards with the same hardware.

Examples of SDR devices:


• RTL-SDR: Cheap, covers ~24 MHz to 1.7 GHz.
• HackRF One: Mid-range, covers 1 MHz to 6 GHz.
• LimeSDR: Covers 100 kHz to 3.8 GHz, supports full-duplex.
• USRP: High-end research-grade SDR.

3. Antennas in Communication
Antennas convert electrical signals into electromagnetic waves and vice versa. The dipole antenna
is the most fundamental and widely used antenna.

Dipole Antenna:
• Consists of two conductive elements, each ~λ/4 long.
• Total length ≈ λ/2, where λ = c/f.
• Radiation pattern: Donut-shaped, maximum broadside, nulls along axis.

4. Practical SDR Applications


With SDR, you can experiment with many real-world signals:
• Receiving FM broadcast stations.
• Receiving ADS-B aircraft signals (at 1090 MHz).
• Listening to amateur radio bands (with proper license).
• Decoding weather satellite signals.

5. Key Formulas in Radio Communication


Wavelength – Frequency relation:
λ = c / f, where c ≈ 3 × 10^8 m/s.

Dipole length approximation:


L (meters) ≈ 143 / f(MHz).

Friis transmission equation:


Pr = Pt Gt Gr (λ / (4πR))^2, where Pt = transmit power, Gt = transmit gain, Gr = receive
gain, R = distance.

6. References and Resources


• RTL-SDR Blog: https://www.rtl-sdr.com
• ARRL Handbook for Radio Communications.
• Online communities: Reddit r/RTLSDR, HackRF groups.

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