I'm trying to get started with this radio. Here's a picture of the device:
I wanted to use Matlab to communicate with the radio, so I followed Mathworks' guided-host radio hardware setup instructions found here:
Then I ran Mathworks' test script which is intended to send and receive a test tone. The script is here:
However, I did not attach a loopback cable between the TX1A and RX1A ports as instructed nor did I attach an antenna to those ports. Even so, after running the script I saw the following result:
Which is exactly what the test script's website says I should see, but for the fact that I didn't have a loopback cable or antennae attached when I ran the script. In an attempt to troubleshoot the problem, I changed the test tone to 50 kHz and reran the script. I got the following result:
Which is exactly what I would expect to see (a peak at 50 kHz) if I actually had a loopback cable attached. Next i tried putting 50 ohm terminators on the TX1A and RX1A ports and reran the script with a test tone of 25 kHz. I got the following result:
The noise floor is slightly higher, but the peak at 25 kHz is still clearly visible. Next, I commented out the line that tells the transmitter to start transmitting. I got the result you would expect, which is that the 25 kHz peak vanished. (Don't have a screenshot of this one, sorry.)
Am I misunderstanding the hardware or the software somehow, such that a loopback cable is actually not needed? If this behavior is unexpected, what further steps can I take to track down the problem and restore the expected behavior?
This is expected since the receiver is very sensitive and the signal doesn't have to travel very far. Adding cables will provide better SNR.
Thank you, Travis. I'll try adding in a loopback cable and see if the SNR improves.