31. After vacuum tube oscillators were invented in 1913 by Alexander Meissner the heterodyne receiver replaced the tikker. 32. The analogous diversity reception for optical heterodyne has been demonstrated with arrays of photon-counting detectors. 33. Other more complex laws may be needed if the network contains nonlinear or heterodyning systems can be approximated. 34. Heterodyne detectors are the most commonly used, and most self-build detectors are of this type.35. Calls missed by the heterodyne function, if present, can be seen and measured on the analysis. 36. Retuning with an FD detector is not required although this is done with a dual type with heterodyne . 37. Another reason for heterodyne processing is that for fixed fractional bandwidth, the instantaneous bandwidth increases linearly in frequency. 38. The direct-conversion ( heterodyne ) detector was invented to make continuous wave radio-frequency signals audible. 39. Failure of the BFO to match the original carrier frequency when receiving such a signal will cause a heterodyne . 40. Continuous wave ( CW ) doppler radar detectors are basically heterodyne detection devices that compare transmitted and reflected beams.