reference frequency would be error free. In practice the distribution method would be more complicated than this to overcome some of the practical difficulties in the above technique. For example, when the system is locked each module is required to separate incoming and outgoing signals which have the same frequency but possible much different power levels. This is not easily done and variations on the above method are used so that incoming and outgoing signals are at different frequencies (references 13,14). As a consequence, Figure 4 is not exactly representative. However, it does illustrate the basic methodology and it provides a means of illustrating possible phase insertions that will not be compensated. In addition to the insertion errors of the filters and mixers there can be significant errors due to imperfections in the coaxial cables. Remember that a multitone reference frequency distribution technique is desirable for isolating incoming and outgoing distribution signals at the receive/transmit modules. Since the phase constant of coaxial lines is typically a function of frequency, the compensation of phase errors by this technique is less than ideal and limited by the required bandwidth of the distribution system and coaxial line quality in terms of dispersion. Fortunately, in power transmission systems, very narrow bandwidths are acceptable and as a result cable dispersion is not expected to cause significant errors. Another phenomenon of concern is the required coherence of the reference frequency source. As the output of this source is distributed over the transmitter aperture the locally regenerated
RkJQdWJsaXNoZXIy MTU5NjU0Mg==