You have the basic carrier frequency.
This is amplitude modulated with 30 Hz (not MHz) to provide one reference.
Then you AM a 9960 Hz subcarrier onto the carrier frequency. This 9960 Hz subcarrier is in turn frequency modulated with a 30 Hz signal to provide a second reference.
The phase difference between these two 30 Hz reference signals is your received radial.
In a Doppler VOR, the phase of the FM signal depends on your bearing to the station while the AM signal is omnidirectional. In a CVOR, the opposite applies with an omnidirectional FM reference and the phase of the AM modulation changing with bearing to the station. The directional signal rotates different ways though, meaning the receiver doesn't know the difference.
The type of VOR may be stated in the ENR section of the AIP, under radio navigation aids. It is in my neck of the woods, but I know it's not universal.
You need pretty sophisticated gear to detect a difference in the signals. Your best indication would be to guesstimate based on how steady the radial received is, but there are both bad DVORs and good CVORs.
Cheers,
Fred