I saw an exam question that asked what the advantages of using DSB AM with carrier are. I can't find anything conclusive in my books or by googling.

It seems to me that DSB AM with carrier is less power-efficient (compared to DSB-SC ΑΜ and SSB AM) and that it carries redundant information (compared to SSB AM). The only thing I could interpret as an advantage is perhaps simplicity of demodulation.

So am I missing anything? What are the actual advantages of using DSB AM with carrier?

  • 1
    \$\begingroup\$ Cost of ownership of a million transistor radio receivers using a very simple demodulator is a very big deal. \$\endgroup\$
    – Andy aka
    Jun 11, 2016 at 19:21

1 Answer 1


Simplicity of modulation and demodulation is indeed the chief advantage of DSB-AM -- a DSB-AM signal can use a low level modulator and Class C amps or a high-level final stage modulator with Class C carrier drive, whereas a SSB or DSB-SC signal must be generated low-level with a doubly balanced modulator and amplified linearly, which requires more components and reduces amplifier efficiency.

On the demodulation end, SSB and DSB-SC require either an accurate BFO/carrier inject oscillator or a synchronous demodulator such as a Costas loop, both of which require many more components and are much more expensive than the triviality of a diode demodulator, which only requires a tuned circuit, a sensitive (point-contact "catwhisker" detectors and germanium diodes were used in the bad old days; nowadays, a fast Schottky is the diode of choice) diode, a RC network, and a sensitive earpiece or audio amp.


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