Radio Ramblings

I must admit, I’m pretty disappointed with the state of software defined radio in the amateur world. We have great hardware available to us - USRP, FlexRADIO, HPSDR, Softrock and soon hopefully uWSDR - and decent software, but there doesn’t really seem to be any sign of people doing anything new.

GNU Radio should make it very easy to start playing with new modulation schemes and testing out ideas as quickly as we have them. Actually writing something non-trivial in GNU Radio can be a bit daunting though, especially for non Python programmers. Fortunately somebody has written a graphical interface (GNU Radio Companion, or GRC for short) which allows you to drag and drop processing blocks and be up and away with your idea in no time.

To see an example of the power of this, and how it makes designing radio systems easier, install GNURadio and GRC. Load up the

I must admit, I’m pretty disappointed with the state of software defined radio in the amateur world. We have great hardware available to us - USRP, FlexRADIO, HPSDR, Softrock and soon hopefully uWSDR - and decent software, but there doesn’t really seem to be any sign of people doing anything new.

GNU Radio should make it very easy to start playing with new modulation schemes and testing out ideas as quickly as we have them. Actually writing something non-trivial in GNU Radio can be a bit daunting though, especially for non Python programmers. Fortunately somebody has written a graphical interface (GNU Radio Companion, or GRC for short) which allows you to drag and drop processing blocks and be up and away with your idea in no time.

To see an example of the power of this, and how it makes designing radio systems easier, install GNURadio and GRC. Load up the

I must admit, I’m pretty disappointed with the state of software defined radio in the amateur world. We have great hardware available to us - USRP, FlexRADIO, HPSDR, Softrock and soon hopefully uWSDR - and decent software, but there doesn’t really seem to be any sign of people doing anything new.

GNU Radio should make it very easy to start playing with new modulation schemes and testing out ideas as quickly as we have them. Actually writing something non-trivial in GNU Radio can be a bit daunting though, especially for non Python programmers. Fortunately somebody has written a graphical interface (GNU Radio Companion, or GRC for short) which allows you to drag and drop processing blocks and be up and away with your idea in no time.

To see an example of the power of this, and how it makes designing radio systems easier, install GNURadio and GRC. Load up the

I must admit, I’m pretty disappointed with the state of software defined radio in the amateur world. We have great hardware available to us - USRP, FlexRADIO, HPSDR, Softrock and soon hopefully uWSDR - and decent software, but there doesn’t really seem to be any sign of people doing anything new.

GNU Radio should make it very easy to start playing with new modulation schemes and testing out ideas as quickly as we have them. Actually writing something non-trivial in GNU Radio can be a bit daunting though, especially for non Python programmers. Fortunately somebody has written a graphical interface (GNU Radio Companion, or GRC for short) which allows you to drag and drop processing blocks and be up and away with your idea in no time.

To see an example of the power of this, and how it makes designing radio systems easier, install GNURadio and GRC. Load up the

I must admit, I’m pretty disappointed with the state of software defined radio in the amateur world. We have great hardware available to us - USRP, FlexRADIO, HPSDR, Softrock and soon hopefully uWSDR - and decent software, but there doesn’t really seem to be any sign of people doing anything new.

GNU Radio should make it very easy to start playing with new modulation schemes and testing out ideas as quickly as we have them. Actually writing something non-trivial in GNU Radio can be a bit daunting though, especially for non Python programmers. Fortunately somebody has written a graphical interface (GNU Radio Companion, or GRC for short) which allows you to drag and drop processing blocks and be up and away with your idea in no time.

To see an example of the power of this, and how it makes designing radio systems easier, install GNURadio and GRC. Load up the packet_mod_demod.grc.xml file. This has a signal source being GMSK modulated and demodulated, with the input and output displayed on scopes.

In real systems, though, there is a certain level of noise which the receivers have to tolerate. We can see the effects of noise by creating a complex noise source, and then putting in an “add” operator to sum the signal coming from the GMSK encoder and the noise. Create another variable to control the amplitude of the noise, and in seconds you can be raising and lowering the noise floor and seeing the effect which that has on the received signal. I found with GMSK that the signal at the receiving scope was unusable above an SNR of about 0.18. Changing the GMSK coding to BPSK takes a minute, and lets you very quickly see how much more tolerent of noise BPSK is than GMSK