From time to time here in the forum are messages gets posted about radio communication with quadcopters. So called “radio modems” are used for a “robot to groundstation”-communication. But the more appropriate term would be software defined radio, because it has always to do with ham radio and shortwave communication.

I think, the robotics community has no choice than learn some of the vocabulary used in the amateur radio community, for example JT65 for distance communication and GNU radio for converting audio signals. The main problem seems to be, that it is not possible to utilize a full blown amateur radio station for a small sized quadcopter. A typical shortwave device has a power consumption of 100 Watt and needs lots of space. So my question is, can this be scale down to an USB stick with a simple antenna but provides transmitting facilities to a robot? As far as i know, radio amateurs are often use the RTL2832 chipset which is sold in DVB-T sticks but I'm unsure if it's possible to send a signal with it, or is this more a passive scanner?

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    $\begingroup$ software defined radio (SDR) can be used to receive almost any radio signal .... it is not limited to ham radio and shortwave bands as you suggest ...... it is simply a radio receiver that uses digital signal processing to extract the data from the radio transmission (music, voice, control data) $\endgroup$ – jsotola Nov 7 '18 at 21:58

It is not clear what you are asking.

Software-defined radio (SDR) as a concept essentially means that low-/physical-layer computational tasks like modulation/demodulation, error-correction coding, filtering, etc are being implemented in software and such that the software environment is "opened up" to users. The key thing here really is the run-time environment, not the particular communications technology that happens to be implemented in this environment. In practice, software-defined radio is useful for people doing research in wireless physical layers and/or signal processing, or in situations where (for example because of weight constraints) one only wants to use one piece of communications circuitry but possibly needs to support several communications standards (which is possible, just not at the same time).

The vast majority of all people (and I would include the vast majority of robotics users/researchers here as well) only have "bread-and-butter" requirements in terms of communications and normally have no need to employ SDR, but they will be perfectly fine with commercially available transceivers which don't employ SDR technologies.

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  • $\begingroup$ That most robotics builders are not experts for SDR fits to my observation too. In the past, robotics control was often done with analog modulation and in most cases only in one direction. That means, the operator sends a signal to the robot but the robot can't send status updates back. $\endgroup$ – Manuel Rodriguez Nov 9 '18 at 9:30

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