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Test and Measurement Needs for the Shop
Perhaps you need a little more capability though; a more sophisticated analyzer is called for. In that case you could look at Prism Sound's dScope Series III audio analyzers. These are audio test and measurement systems comprising a Windows PC software application coupled with an external audio interface processor for equipment-under-test (EUT) connections. The external interface processor connects to the PC via a standard USB connection making it easy to use with a wide range of PCs, including laptops, and it includes analog and digital outputs and inputs for measurement applications. Additionally, the software also allows the dScope to use installed Windows sound devices such as sound cards generator outputs or analyzer sources. As you would expect, there is a wide choice of standard functions including sine, square, ramp and noise plus complex waveforms (e.g. bursts, pulses, swept sine and twin-/multi-tones). You can also create waveforms via scripting, and you can playback standard WAV files from the outputs of the signal generator, allowing for the most subjective of tests. The dScope Series III provides a continuous-time analyzer (CTA) for continuous display of standard measurements, in addition to fast Fourier transform analyzer (FFTA) for detailed spectral analysis or complex measurements.
The digital age
If you maintain transmitters (of any type) than having an RF spectrum analyzer is practically a necessity. Having HD Radio transmissions makes that even more important. Let's take a look at a couple of options. First, the LPT-3000 from LP Technologies: this analyzer covers the frequency range of 9kHz up to 3GHz, with a 100dB display range on a 6.4" color TFT LCD display. To facilitate testing, you can add the correct 'mask' for measuring IBOC compliance to the display. The unit comes with both USB and LAN (optional) interfaces, and thus can be operated remotely. It has a large internal memory space, and allows you to save screen shots, and to print them out later. Other options include GPIB, a tracking generator, a return-loss bridge, and 300Hz RBW capability.
Agilent has made spectrum analyzers for decades (up until fairly recently under the HP moniker). Its N9340B handheld spectrum analyzer has some great standard features. Its range is 100kHz to 3GHz, with results shown on a 6.5" TFT color LCD, which (according to Agilent) is bright enough to use outdoors. Its internal battery has four hours of run time. It has one-button measurements for channel power and occupied bandwidth; it even has an AM and FM demodulator audio output. I make mention of this particular unit though because of its IBC option, designed to allow the user to make IBOC proof measurements. The N9430B-IBC (as it is known with the option installed) has a dedicated hard-key called MODE which allows the user to rapidly access to its operating modes (depending upon all the options purchased) such as spectrum analyzer, tracking generator, demodulation analysis, and of course IBOC measurements. Also, when entering IBOC measurement mode, you are given the choice between AM and FM, and the instrument automatically activates the appropriate internal hardware and software. It has a feature called Auto Tune embedded in the IBOC measurement mode that automatically sets the reference level and center frequency for you. It also comes pre-loaded with limit masks -- 73.44 for analog AM; 73.317 for analog FM, AM NRSC-5B and FM NRSC-5B.
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