This study investigates a signal difference-based deadband control approach as a solution to reduce data transmission in networked control systems (NCSs). A new modelling method for the NCSs with time-varying delays, time-varying sampling intervals and signal transmission deadbands is presented. The Lyapunov functional with discontinuity is exploited, which takes full advantages of the NCSs' characteristic information including the bounds of network delay (BND), the bounds of sampling interval (BSI) and the bounds of transmission deadband (BTD). In addition, it has been shown that Lyapunov functional decreases at the jump instants. Furthermore, the new stability analysis and stabilisation conditions for the NCSs are proposed, which describes the relationship of BND, BSI, BTD and the system stability. Three examples are used to demonstrate the effectiveness of the proposed methods. The simulation results have shown that the proposed approach could guarantee the system asymptotically stable and effectively reduce the data transmission in network channel.