| 摘要 |
A bi-directional, digital data transmission system is disclosed for transmitting an interrogation signal in a first direction from an interrogation unit to a data gathering transponder unit, and a data return signal in a second direction from the meter or data gathering transponder unit to the interrogation unit. This system comprises a single transformer having a primary winding coupled to the interrogation unit and a secondary winding coupled to the transponder unit. The interrogation unit generates an interrogation signal comprised of a first train of regularly occurring digital clock pulses and transmission interval pulses, each transmission interval pulse defining a transmission interval for the transmission of the data return signal. The transmission interval is set to be of a sufficient length to permit the transformer to desaturate to a level to permit efficient transmission of the data return signal to the interrogation unit. The transponder unit includes a data transmitting circuit responsive to the transmission interval pulses appearing at the secondary winding for generating and applying, during the transmission intervals, digital signals indicative of the gathered data to the secondary winding to be transmitted via the transformer to the interrogation unit. |
