Which one is not a TDMA standard of second generation networks?

GSM
IS-136
AMPS
PDC

The correct answer is C. AMPS.

AMPS (Advanced Mobile Phone System) is a first-generation analog cellular network technology. It was developed in the United States in the 1970s and was the first commercial cellular network system. AMPS was based on frequency-division multiple access (FDMA), which divides the available spectrum into a number of channels, each of which can be used by a single user at a time.

GSM (Global System for Mobile Communications) is a second-generation digital cellular network technology. It was developed in Europe in the 1980s and is now the most widely used cellular network technology in the world. GSM is based on time-division multiple access (TDMA), which divides the available spectrum into a number of time slots, each of which can be used by a different user.

IS-136 (Integrated Services Digital Network – Cellular) is a second-generation digital cellular network technology that was developed in the United States in the 1980s. IS-136 is based on TDMA, like GSM.

PDC (Personal Digital Cellular) is a second-generation digital cellular network technology that was developed in Japan in the 1980s. PDC is based on TDMA, like GSM and IS-136.

Therefore, the only option that is not a TDMA standard of second generation networks is AMPS.