DOI:10.1049/ree.1969.0058

出版商:IERE    

年代:1969

数据来源: IET

摘要:

Future engineering objectives for each of the parts of the transmission chain are forecast. they include smaller cameras with higher sensitivity (possibly using solid-state sensors), flying-spot film scanners operating on both the 625/50 and 525/60 standards, automated signal switching systems, improved recording systems using high-density magnetic and laser techniques, the use of p.c.m. for television links (which may employ optical fibres), and solid-state receiver displays.

DOI:10.1049/ree.1969.0059

出版商:IERE    

年代:1969

数据来源: IET

摘要:

The main features of domestic monochrome and colour receivers are surveyed, particularly with respect to the larger screen size. Circuit technology has reached the stage at which integrated circuits are starting to challenge the transistor while in certain applications the valve still has a major advantage, mainly due to the scanning power required by the picture tube.

DOI:10.1049/ree.1969.0060

出版商:IERE    

年代:1969

数据来源: IET

摘要:

The familiar logic building blocks of AND, OR, NAND, and NOR functions are practical realizations of well-known basic boolean algebraic connectives, and as such enable any two-state logic system to be constructed. however, a more powerful basic logic building block than boolean gates is the ‘threshold gate’. such a gate has binary inputs A, B, C,…, with ‘weights’ a, b, c,…associated with these respective inputs, and a binary output z. the output from such a gate is:Z = 1 if 〈a.A + b.B + c. C +…〉≥some value t1Z = 0 if 〈a.A + b.B + c.C +…≤ some value t2where normal arithmetic rules are involved in the above summations.such gates can be used to realize all the normal basic binary logic functions, and in addition can realize more complex switching functions which would otherwise require the use of several normal logic gates. thus the number of gates in a switching system may be drastically reduced by using threshold gates in place of the normal types.

DOI:10.1049/ree.1969.0062

出版商:IERE    

年代:1969

数据来源: IET

摘要:

Diodes possessing very accurate square-lawI/Vcharacteristics have recently been developed. An analytical technique is set out in this paper for the evaluation of cross-modulation and intermodulation distortions in a tuned frequency-converter using such diodes. The theory is used to predict the distortions obtained under practical conditions and it is shown that, where limited local-oscillator power is available, such a converter potentially generates less non-linear distortion than circuits employing conventional diodes as resistive switches.

DOI:10.1049/ree.1969.0063

出版商:IERE    

年代:1969

数据来源: IET

摘要:

The noise temperature of a low-noise microwave amplifier can be measured by connecting the amplifier input in turn to thermal noise sources at different physical temperatures. The conventional technique is limited by the necessity for a very stable amplifier and system gain during the measurements. The paper describes a manually-balanced radiometer circuit designed to overcome this limitation, and intended to measure amplifier noise temperatures in the range below 500°K. Examples of experimental measurements on a maser and on uncooled and cooled parametric amplifiers are discussed.

DOI:10.1049/ree.1969.0064

出版商:IERE    

年代:1969

数据来源: IET

摘要:

A three-channel pulse generator is described which uses r.t.l. integrated circuits as the sole active devices. Each output pulse has a width variable from 100 ns to 1 μs and may be delayed by up to 2 μs with respect to either a fixed synchronization pulse or an external trigger. The circuit as a whole demonstrates the flexibility of some digital integrated circuits in non-digital applications.

DOI:10.1049/ree.1969.0065

出版商:IERE    

年代:1969

数据来源: IET

摘要:

The buffer unit forming the interface comprises two distinct sets of logic circuits: computer interrupt equipment and peripheral control unit. Information transfers across the interface are over a bidirectional bussed highway up to 25 bits wide. Eight unidirectional lines control computer to peripheral connexions. Transfer times range from 1 to 5 μs

DOI:10.1049/ree.1969.0066

出版商:IERE    

年代:1969

数据来源: IET