The Hewlet Packard Spectrum Analyzer shown above is the type that the customer required. Many of the wireless microphones that Bexel rents are frequency agile. This means that the transmitter can be switched to more than one carrier frequency. The details of wireless and Radio-Frequency operation is outside the scope of this article, however, some discussion is required to explain the use of the device.

Unlike acoustic energy, Radio Frequency energy is NOT dependent on air for the transfer, or propagation of the energy over distances. Likewise, an audio spectrum analyzer uses a microphone to "sense" the measured signal, while the RF-Spectrum Analyzer uses an antenna that is appropriate to the "range" of frequencies to be measured. At an event or show that has a lot of frequencies in both the VHF and UHF ranges, the analyzer gives a "picture" or display of all the RF carriers that are active. More important, however, as the analyzer is presenting "Actual Utilization of Available Spectrum", it indicates which frequencies are NOT in use. These available areas are where the customer can set the switches on the agile transmitters. Without the analyzer, it is anyone's guess which frequencies are available.

In addition, it is important to understand that a single frequency has artifacts called Harmonics. These harmonics manifest themselves as additional RF energy at unique mathematically determined frequencies. These harmonics can be on another receiver's frequency, causing interference.

To conclude, when a customer asks for a "spectrum analyzer", ask if it is for audio or RF purposes.

NOTE:

Some synonyms for the audio analyzer are:

(1) RTA (what it does)

(2) IVIE (brand name)

(3) SPL meter (alternate use)

Some synonyms for the RF Spectrum analyzer are:

(1) Service Monitor (a device that includes a spectrum analyzer in addition to other tools)

(2) IFR (brand name)