HP a-140 free download

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January 1980 A Cardiff Publication FREQUENCY MHz ( 5532.[][]QQQ] AM FM RF www.HPARCHIVE.com Signal Generator Specifications Part I To an engineer or technician faced with the requirement for an RF signal generator, a proliferation of instruments is available. The challenge is to purchase the signal generator which has the specified capacity to fulfill all of the applications requirements. To aid the user in this task a review of the important signal generator specifications and how they affect various applications is presented here. By Rob Oeflein Marketing Engineer Hewlett-Packard T o be classified as a signal generator an instru- ment must have three basic characteristics: 1. Calibrated and variable frequency over a broad standard signal generator characteristics which are required to perform them. range. 2. Calibrated and variable output level over a wide dynamic range. Types of Signal Generators 3. One or more forms of calibrated modulation. Most oscillators only cover a single octave, but It is important to notice that not all frequency sources many applications require greater than one octave or synthesizers are signal generators. Sweepers, of frequency coverage. Three techniques are com- test oscillators, and traditional frequency synthe- monly used to obtain wide frequency coverage in sizers cannot be classified as signal generators RF signal generators - reactance band-switching, because they usually lack a calibrated output or high frequency tuned resonators with dividers or some form of calibrated modulation. heterodyne circuits, and synthesis. The wide variety of applications addressed by The reactance band-switched signal generator signal generators and some of the critical specifica- was the earliest design. Most of the older tube-type tions associated with each are listed in Figure 1. generators used switched inductors with variable The primary application in today's market, however, capacitors and many updated solid-state signal gen- is that for which the signal generator was originally erators sH11 employ this technique. designed - receiver testing. Most signal generators The advent of broadband output power amplifiers can be easily classified, therefore, according to their and solid-state high frequency oscillators led to the capacity to perform in-channel (sensitivity, audio development of signal generators that use a single bandwidth, squelch threshold) or out-of-channel