EFData SDM-2020 is an early design satellite modulator manufactured by EFData before they merged with Comtech.
For a teleport or VSAT site needing a high data carrier of up to 75Mbps at 8PSK this is an ideal cheap alternative to a much more expensive newer modulator.
The EFData SDM-2020 series was an interesting product because there were two different parts, the SDM-2020M that is the modulator, and the SDM-2020D, which is a demodulator.
Both the modulator and the demodulator are 70 MHz devices.
Taking some lines from the Manufacturer’s data sheet:
The SDM-2020 satellite modulator is a programmable variable-rate, modulator used for digital video and high-speed data applications. The SDM-2020 supports open network modes compliant with the EN XX specifications for Digital Video Broadcasting via Satellite.
DVB or Transparent Data Transmission,
Programmable 1.5 to 100 Mbps
QPSK and 8PSK.