Through the measurement of RF transmission characteristics and MUSE VSB-AM transmission experiment on 5 large-scale Cable TV in Japan, we analyzed the characteristics of reflection and the impairment to demodulated signal by reflected signal. We also evaluated the effects of MUSE base band equalizer which employs the equalizing filter with selectable tap length and number of coefficient bits.
Direct carrier PDM (pulse duration modulation) medium wave AM transmitter was developed. The PDM transmitter can be effectively operated without the high power modulation amplifier and LPF circuit on over those currently in use. An operation efficiency of the prototype PDM transmitter has 65% at 60 Watts output conditions, which improves the efficiency compared to the series modulation type solid state AM transmitter.
In this paper we describe the new measurements of field intensity by signal to noise ratio method about the broadcasting satellite (BS-3a,BS-2b). This measurements method can be obtained field intensity by simple and convenient means making use of the C/N value at spectrum analyzer. Experimental values agree well with convert into signal genelator.
A circularly polarized printed antenna composed of strip dipoles and slots (CP-PASS) is realized on a triplate-type substrate at 12 GHz band. Material of the substrate is carefully selected and the trans-mission line loss of 1.4 dB/m is obtained. The strip element is improved so as to be easily coupled to the triplate-type feed line. In the strip element array, a good quality linearly polarized wave with a crosspolar suppression ratio of greater than 30 dB is obtaind over a 6~ bandwidth. A 36 element-set CP-PASS fed by a T-shaped triplate transmission line is fablicated and tested at 12GHz.
The perspective and future trend of the antenna technology for receiving the DBS is de-scribed in this paper. The paper treats the following items: ( l) The chronological table of 12GHz band satellite broadcasting. (2) The change of the improvement of the DBS receiving antenna efficiency. (3) The change of the size of the DBS receiving antennas. (4) The new antenna technology for HDTV, mobile, et al.