The HP 8903A audio analyzer is a complete audio measurement system covering a frequency range of 20 Hz to 100 kHz. It combines a low distortion signal source with a signal analyzer. The analyzer can perform distortion analysis, frequency count, and ac level, dc level, SINAD, and signal-to-noise measurements. The audio analyzer reduces the number of instruments required in many applications involving audio signal characterization.
The 8903A is easy to use. All measurements are selected by one or two keystrokes. For distortion measurements, the audio analyzer automatically tunes to and levels the input signal. Measurement and output ranges are automatically selected for maximum resolution and accuracy. Tuning is independent of the source. Thus, the source can be set to one frequency while the analyzer is measuring the distortion on a signal at another frequency - there is no need to tune the analyzer to the source.
The combined capabilities of the instrument are enhanced by microprocessor control, resulting in more capability than would be available from separate instruments. Virtually all functions are remotely programmable via the HP-IB interface.
Many features of the audio analyzer, such as flexible data entry and display formats, convenient source control, and swept measurement capability, contribute to easy audio testing. For example, distortion can be displayed in percent or in dB. In ac level, you can select from volts, dBV, or watts. Finding the 3 dB points of filters and amplifiers is simplified by using the source increment and decrement keys together with the relative display feature. With low-distortion source and analyzer built in, the 8903A makes stimulus-response measurements. Internal processor control over all functions expands this capability to power swept characterization. When sweeping, the audio analyzer steps its tuning in logarithmic increments.
The 8903A features high accuracy. The instrument can typically measure flatness to 0.5% (0.05 dB) over the range of 20 Hz to 20 kHz and swept distortion of the same range to 0.003% (-90 dB). The 8903A measures the true rms level on all measurements.
The 8903A has several measurements that are specifically designed for transceiver testing. It performs SINAD measurements for FM receivers and signal-to-noise measurements for AM receivers. It has a psophometric filter for testing CEPT recommendations, a reciprocal counter for measuring squelch tones, and a 400 Hz high-pass filter for eliminating squelch tones when measuring transceiver audio distortion. You can combine the 8903A with an 8901A modulation analyzer to make common transmitter tests.
- Source frequency: 20 Hz to 100 kHz
- Frequency resolution: 0.3% increments
- Output level range: 0.6 mV to 6 V
- Source impedance: 600 Ω
- SINAD measurement frequency range: 20 Hz to 100 kHz
- Signal-to-noise measurement frequency range: 50 Hz to 100 kHz
- Distortion measurement frequency range: 20 Hz to 100 kHz
- SINAD and Signal-to-noise measurements display range: 0 to 99.99 dB
- Distortion display range: -99.99 to 0 dB
- SINAD, signal-to-noise, and distortion measurements input voltage range: 50 mV to 300 V
- SINAD resolution: 0.01 dB
- AC level measurement display ranges: 300.0 V, 30.00 V, 3.00 V, 3000 V, 30.00 mV, 3.00 mV, .3000 mV
- DC level measurement display ranges: 300.0 V, 48.00 V, 16.00 V, 4.00 V
- Frequency counter range: 20 Hz to 150 kHz
- Frequency counter resolution: 5 digits
- Rear panel:
- Recorder: 0 to 10 Vdc corresponding to the log of the oscillator frequency; output resistance: 1 kΩ
- Monitor: Output impedance: 600 Ω; in ac level mode, provides scaled output of measured input signal; in SINAD, distortion, and distortion level modes, provides scaled output of input signal with the fundamental removed
- Input impedance: 100 kΩ
- CMRR: 60 dB, 36 dB, 30 dB depending on differential input
- HP-IB interface