The original 36 channels were 4 kHz. The increase to 48 channels was accomplished by narrowing the bandwidth to 3 kHz. Later, an additional three channels were added by use of C Carrier equipment. Time-assignment speech interpolation (TASI) was implemented on the TAT-1 cable in June 1960 and effectively increased the cable's capacity from 37 (out of 51 available channels) to 72 speech circuits.
The original 36 channels were 4 kHz. The increase to 48 channels was accomplished by narrowing the bandwidth to 3 kHz Later, an additional three channels were added by use of C Carrier equipment. Time-assignment speech interpolation (TASI) was implemented on the TAT-1 cable in June 1960 and effectively increased the cable's capacity from 37 (out of 51 available channels) to 72 speech circuits.