A Langmuir probe system has been developed for measurement of electron densities and electron temperatures in the lower ionosphere. While the probe works like the Smith probe, it has various practical advantages. It is an all electron system working on a single floating power supply. This makes the actual system simpler and allows for more thorough prelaunch checkouts while the rocket is on the launch pad. Further, this system can feed an additional guard electrode without the use of any additional electronics. It has greatly helped in reducing the current leakage and the effect of the distributed capacity at the input of the amplifier. Also the sweep used is such that capacitive discharge currents between the sensor and the rest of the system do not appear in that part of the sweep where retarding potential analysis is done for determination of electron temperature. Within this system it is possible to control the sensor voltage with the output of the amplifier and keep it at space potential. In principle this method can be used to determine both the electron density and electron temperature simultaneously and continuously.