Subcarrier multiplexing (SCM) is an attractive technique to deliver broadband services over optical fibers. The existing SCM systems employ an analogous signal for optical transmission and their performance is limited. Pulse time modulation (PTM) is an intermediate technique which offers high performance at a low cost in optical transmission systems. In this paper we present two popular PTM techniques suitable for SCM systems. Theoretical predictions and practical measurements have been used to evaluate system performance. The technique employed has improved the dynamic range and the optical power budget, compared to conventional systems.