Recent content by KerimF

  1. KerimF

    A Simple Reliable Topology to Demodulate an AM DSB-SC Signal

    By the way, do you know a reference that shows how to recover two modulating signals of a DSB-SC one, in case the frequency of the suppressed carrier is also modulated, as on post #1? Thank you. (Please note that I, unlike you, am not allowed to access any AI site).
  2. KerimF

    A Simple Reliable Topology to Demodulate an AM DSB-SC Signal

    Hello again, I like to add that I had the chance to talk about the demodulator above with some professors at faculties of RF communications. Their common reply is that there is no reason to teach it in these days because, in general, DSB-SC is no more used. But, at the same time, they don’t...
  3. KerimF

    A Simple Reliable Topology to Demodulate an AM DSB-SC Signal

    May I add that, obviously, such a demodulator works also for any amplitude modulation index (AM DSB signal), from m=0 (no AF modulating signal) to m=infinity (no carrier). And, being of synchronous type, the transmitted audio bandwidth is limited by the allowed channel bandwidth only (in case of...
  4. KerimF

    A Simple Reliable Topology to Demodulate an AM DSB-SC Signal

    Did you read the comments on the schematic? The simple trick that lets PLL (whose VCO mid-frequency is set at 2*Fc) be locked, despite the polarity reversal of the carrier (Fc), is the frequency doubler (see U2 and U3, XOR gates). Everything else is well-known.
  5. KerimF

    A Simple Reliable Topology to Demodulate an AM DSB-SC Signal

    AF: Audio Frequency MC1496 can generate a DSB-SC signal (say at Fc=1 MHz, modulated by AF_AM). If the frequency of the carrier is first modulated by a sine wave AF_FM (say of 6 Hz or 300 Hz) so that the frequency deviation (delta F) is relatively wide (say +/- 30 KHz), we get an AM-FM signal...
  6. KerimF

    A Simple Reliable Topology to Demodulate an AM DSB-SC Signal

    In the 80's, I used it in my short-range RF voice links (around 3 km, air distance) between my house and workplace. And when a MW receiver was tuned to my channel (say around 1 MHz), the listener would hear sort of noisy interference while a voice signal was transmitted (or nothing during silent...
  7. KerimF

    A Simple Reliable Topology to Demodulate an AM DSB-SC Signal

    Hello, The two well-known topologies for demodulating an AM double sideband suppressed carrier signal (DSB-SC) are of Costas Loop and the Squaring Method. In this thread, I present a third topology which combines those two known topologies, while being simpler and more reliable. It is simple...
  8. KerimF

    Are there still applications for AM DSB-SC system?

    I wonder why you insist asking me to break the rule (even as an order, after you called me a troll)! The schematic is off topic here. It doesn’t answer the thread’s question. It could be the topic of another thread though, for example a thread whose title is like ‘Which is the simplest reliable...
  9. KerimF

    Are there still applications for AM DSB-SC system?

    A new word to learn, thank you. I am looking for the meaning of 'subterfuge'.
  10. KerimF

    Are there still applications for AM DSB-SC system?

    Sorry, I seldom talk to a perfect human (a perfect AI robot?). I liked the description you gave: "ugly bag of water". This is the first time I hear it, thank you. And you followed it by 'an order', as in the army. Yes, it is an amazing situation; ‘an ugly bag of water’ is commanded by a perfect...
  11. KerimF

    Are there still applications for AM DSB-SC system?

    Hi Delta, Yes, I am the one who had the chance to build, in 1979, a simple DSB-SC demodulator. But it is based on PLL, not by inverting the demodulated signal... etc. The one, you mentioned, was patented by someone else and it is not based on PLL. So, it doesn't lock to the frequency of the...
  12. KerimF

    Are there still applications for AM DSB-SC system?

    By the way, a DSB-SC demodulator is said simple if: 1. It hasn’t I-Q signals (in quadrature), as in Costas Loop. 2. And it hasn’t a selective LC filter (a coil), as in the Squaring topology. 3. Also, the values of its resistors and capacitors don’t have to be precise. 4. Its ICs are low-cost...
  13. KerimF

    Are there still applications for AM DSB-SC system?

    Hello, I am new here. So, I apologize in advance if such a topic is not related to this forum. I guess most of you know already that the two main drawbacks in transmitting voice/info by using the RF system of double side band suppressed carrier (DSB-SC) are: [1] Its effective/needed bandwidth...
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