A commercial aircraft tracking hardware product.
- LO of the SBS-1 can be seen to the right of the 1088MHz USRP LO peak:
For a good signal:
- Don't use RP-SMA connector. Instead, take signal from signal 2-pin header on decoder board where the signal is fed through (underneath) from the RF board. The ground must be connected to the shield of the unit's antenna connector! It is not sufficient to ground via the RP-SMA connect, screws, or 2-pin header's ground! Failure to do this will result in a messy signal.
- Don't switch on a separate USRP that is not connected to the unit. E.g. taking the above signal to an LFRX is OK, but switching on another USRP will introduce that weird 'hum' into the signal: