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  1. #1
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    Disturbance in simple 433MHz ASK receivers?

    We want to switch eight 312W resistor load banks OFF/ON simultaneously by using eight RF receivers and one RF transmitter (because we don’t want wires all over the place). This is for load transient testing for a power supply.
    Can we use eight RF solutions “QAM-RX10-433” receiver modules with one RF solutions “QAM-TX2-433” Transmitter module?

    Since its ASK modulation, we presume that sending an RF signal at 433MHz represents a “one”, and not sending a 433MHz signal is a “zero”. Is this correct?
    ….Woudlnt this be susceptible to disturbance from any 433MHz radio signals that happen to be around in the local neighbourhood?...or is there some kind of coding in the signal so that other 433MHz signals are rejected?

    RF solutions “QAM-TX2-433” Transmitter module?

    RF solutions “QAM-RX10-433” receiver module?

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  2. #2
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    betwixt's Avatar
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    Re: Disturbance in simple 433MHz ASK receivers?

    I would very strongly advise you against this idea. ASK only works reliably when the data it carries is protected and has some kind of error correction or re-send mechanism. What the receiver picks up isn't a '1' or a '0' but a '1' or noise, they are sensitive because they use super-regenerative detectors but the side effect is that in the absence of any input signal they produce random output. When used as intended they transmit a 'long' (eg. several milliseconds) of carrier to allow the receiver to lock and maybe adjust AGC followed by some rapid binary data. The receiver output has to be filtered to minimize anything shorter than a data bit then checked for errors just in case. Using them as simple signal detectors will not work and they will pick up signals up to several hundred KHz away from center frequency.

    If you want a simple wireless remote on/off switch, either use FM modules which are far more immune to interference or use WiFi modules. These days you can buy ESP8266-1 WiFi modules for a fraction of the cost of a 433MHz ASK module and their data path is highly protected. You can even program them (VERY easy!) to switch the load automatically. For example tell it how many seconds on and how many seconds off and then enable or disable it remotely. You decide how it is used and control it according to your program. All you need is a 3.3V supply and at least two modules, one to send and one or more to receive. An ESP8266-1 has two general purpose IO lines. Even ESP32 modules cost less than the ASK modules and you can add Bluetooth to the communication method!

    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.

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