Katashi Hazama

Relation of the Insertion Loss and the Triple Transit Echo in SAW Unidirectional Transducers

The scattering matrix of SAW unidirectional transducers is calculated on the assumption that it is passive, reversible and lossless. Then the insertion loss and the triple transit echo are obtained as a function of the normalized radiation conductance. The propriety of the theoretical results is verified by experiments.

New Color Television Receiver with Saw if Filter and One-Chip PIf IC

For many television engineers, it has long been a dream to develop an all solid-state TV PIF circuit which does not require adjustments on the assembly lines, by replacing a conventional LC filter with a SAW filter. There are several reasons why this dream has not yet been realized — the immature level of technology and insufficient cost effectiveness of SAW devices. But, the most dominant reason was that the TV manufacturers could find no advantages except in cost reduction and labor saving.

Frequency Synthesizing Tuning System with Saw Device

Recently many kinds of TV digital tuning systems have been developed. Especially in the United States the PLL frequency synthesizing method has been widely used. This system has advantages such as 10-key direct addressing, digital channel indication, high stability and accuracy of the local oscillator frequency, and so on. However it has also disadvantages such as harmonic interferences caused by a 1000 MHz ECL prescaler, and radiation from the prescaler which needs a large input level of 0.3 ~ 1 Vp-p.

Automatic Chennel Indicating System with Saw Device

Today television receivers have reached a stage where electronic tuners are widely used in the place of mechanical ones. Basically two types of the digital tuning system are existing. One is voltage synthesizing utilizing a digital to analogue converter (D-A converter) and a semiconductor memory device. The other is frequency synthesizing utilizing a 1 GHz prescaler. We have already successfully developed a tuner addressing system based on the former type.(1) This tuning system is featured with one touch tuning and one touch automatic search preset and contributed to the improvement of easy operation and reliability. However, this tuning system can not indicate channel numbers automatically because it indirectly controls the local oscillator frequency by means of the tuning voltage control.