Yes. One of the great features of the GB-4000 is that it is capable of doing two kinds of sweep functions.
1) SWEEP: Allows you to run a specified frequency range of your choosing, one frequency at a time. The instrument sweeps from your beginning frequency to your ending frequency.
2) CONVERGENCE SWEEP: Allows you to run two frequencies at a time over a specified frequency range of your choosing. The instrument sweeps from your beginning frequency to the ending frequency and at the same time sweeps from the ending frequency to the beginning frequency. The result is that the two frequencies sweep towards each other, then pass each other, one going up and the other going down and each ending where the other frequency began.