Programmed Test Sources, Inc. is a major manufacturer of fast switching low noise frequency synthesizers designed for stand-alone and OEM uses. Their line of synthesizers is one of the most complete in the industry today. 

Programmed Test Sources, Inc. is a major manufacturer of high performance frequency synthesizers which are designed for stand-alone and OEM uses.

In 1975 they announced their first product, which embodied the goals formulated at the company’s inception: a high quality, fast-switching, low-noise synthesizer of modular construction. This approach would make it possible to adapt the instrument effectively to a broad spectrum of uses and do so at a price not available elsewhere.

Today, they offer one of the most complete lines of synthesizers available in the industry. Their models all use their own direct synthesis systems. Their advantages over competitive designs include excellent specifications for phase-noise, switching speed and spurious outputs along with low complexity.

Synthesizers have become indispensable in many of today’s advanced measurement and production systems, as well as in stand-alone uses. Typical applications range from ATE and NMR medical imaging to satellite earth station oscillators, from magnetic storage media testing to crystal production, from mode-locking of lasers to ECM. Precision timing, radar simulations, Doppler systems, all make use of synthesizers.

Frequency synthesizers are basically variable radio-frequency generators which are very accurately and quickly settable and possess high stability. Within a specified frequency range they can be programmed either manually or remotely to practically any output frequency. This output frequency is as accurate and as stable as a built-in frequency standard, usually a crystal oscillator, or as accurate and stable as an external precision standard which may be connected to the synthesizer in lieu of its own standard. Where very high stabilities are desired, atomic or molecular standards are often used.

Most commercial frequency synthesizers use a decimal read-out or indicator system. The least significant step or digit determines resolution, how closely the synthesizer can be set to any arbitrary frequency. Resolution ranges from megahertzs to microhertzs, depending on use; some synthesizers offer a choice of resolution to match capability (and price) to users’ need. (Although read-out or indication of setting is normally decimal, remote control frequency setting may use other coding.)

The ideal of a pure frequency, a single spectral line, is not attained in practical synthesizers. All produce unwanted frequencies, called spurious outputs, and they also have, like any oscillator, harmonics. While harmonics are at least one octave removed and thus not often troublesome, the suppression of other unwanted frequencies is a major challenge of synthesizer design; units differ widely in this respect, and this is of major impact regarding cost. The same is true of the very close-in noise around the carrier that constitutes unwanted phase-modulation. These perturbations are variously called broadband phase noise, spectral density distribution of phase noise, residual FM, and short term fractional frequency deviation.

Today’s synthesizers use three technologies, singly or in combination, to generate an output frequency from a reference standard: direct analog, indirect, and direct digital.

Direct analog synthesis makes use of a limited number of auxiliary or standard frequencies which are derived from the reference. The output band is covered solely by arithmetic operations on these auxiliary frequencies, using fixed-tuned filters, RF switches, mixers, multipliers and dividers. The "mix-and-divide" direct synthesis approach permits the use of many identical modules, producing arbitrarily fine resolution and low spurious output.

The acceptance of their products has proven the value of their approach. Tens of thousands of PTS synthesizers have been shipped to an international roster of customers. They are proud to have served Analog Devices, Atmel, Boeing, Credence, G.E., Hughes, ITT, JEOL, LTX, Motorola, Philips, Raytheon, Siemens, Teradyne, Toshiba and others. The confidence they have in their products is reflected in their three-year warranty, and by their flat-rate service policy for years four through ten.