A slight error above...the AD9833 using a 25MHz crystal (as per photo) is tunable in approximately 0.1Hz steps up to 12.5MHz. Actually 0.0932Hz increments..
The photo is of a general purpose oscillator I recently built for bench-work, it generates sine, square and 5V HC-level TTL signals. The AD9833 can also generate triangle (but not sawtooth) waveforms, but I have no need for them.
It's controlled from a PC via an ASCII serial link (USB to UART) either manually or under automation for frequency response checks for example. The 14-pin chip is a PIC16F688 micro that does the maths and handles the serial link.
This with a bit of 'massaging' could easily handle the FM NBTV subcarrier generation...it wouldn't need the HC540 chip, that's just a buffer for the TTL output.
Steve A.