Pseudo-Speech and Audio Signals for Analog Radio Testing
The KIKUSUI KSG3600 provides standardized pseudo-speech, pseudo-random noise, and fixed-frequency sine signals for evaluating analog radio and communication circuits.
Its noise source uses a DSP-generated M-sequence pseudo-random bit sequence to produce stable pseudo-white noise. An ITU-T Recommendation G.227 characteristic filter can be switched into the signal path to create a defined pseudo-speech spectrum for communication and radio measurements.
ITU-T G.227
Pseudo-voice characteristic filter
PRBS M-Sequence
DSP-generated pseudo-random noise source
4 Frequencies
900 / 1000 / 1250 / 1500 Hz sine output
600 Ω Balanced
Noise-resistant low-level signal output
The KSG3600 is intended for applications such as occupied-bandwidth and spurious-emission measurements of AM and SSB radios under modulation, as well as speech-leakage measurements in communication circuits and between communication paths.
ITU-T G.227 Pseudo-Voice Filter
A switchable digital characteristic filter complies with ITU-T Recommendation G.227, allowing the pseudo-random noise source to generate a defined pseudo-speech spectrum.
DSP-Based Pseudo-Random Noise
The noise source uses a pseudorandom bit sequence (PRBS) M-sequence generated with DSP for stable and repeatable pseudo-white-noise generation.
Long M-Sequence Period
The x³¹ + x³⁰ + x²⁴ + x¹⁶ + 1 generator polynomial and 500 kHz sampling frequency provide a maximum sequence period of approximately 4294.967 seconds.
Four Sine-Wave Modulation Frequencies
NCO-generated sine signals are available at 900 Hz, 1000 Hz, 1250 Hz, and 1500 Hz for low-frequency modulation and communication-circuit testing.
Built-In Output Attenuator
The output level can be adjusted from -70.0 dBm to +1.0 dBm with 0.1 dB resolution for both normal and low-level signal applications.
600 Ω Balanced Output
A balanced 600 Ω BNC output supports differential connection and improved signal-to-noise performance when working with small test signals.
Defined Pseudo-Voice Spectrum
The G.227-filtered output provides specified spectral tolerance across the audio-frequency range for repeatable pseudo-speech testing.
48 kHz Bandwidth Limiting
The pseudo-random noise path incorporates a fourth-order Butterworth low-pass filter with a 48 kHz cutoff frequency.
AM radio occupied-bandwidth measurement under modulation
SSB radio occupied-bandwidth measurement under modulation
AM radio spurious-emission measurement
SSB radio spurious-emission measurement
Communication-circuit speech-leakage measurement
Speech leakage measurement between communication paths
Analog radio modulation testing
Low-level balanced audio signal testing
KSG3600 Specifications
| Signal Functions | Pseudo-random noise / ITU-T G.227 pseudo voice / Sine wave |
|---|---|
| Noise Generation Method | Pseudorandom bit sequence (PRBS), M-sequence |
| Generator Polynomial | x³¹ + x³⁰ + x²⁴ + x¹⁶ + 1 |
| Sampling Frequency | 500 kHz |
| Maximum PRBS Period | 4294.967 s |
| Bandwidth Limit Filter | 4th-order Butterworth LPF, fc = 48 kHz |
| Pseudo Voice Filter | Complies with ITU-T Recommendation G.227 |
| Pseudo Voice Filter Control | ON / OFF |
| Spectral Tolerance | Within ±1 dB, 100 Hz to 10 kHz; within ±3 dB, 30 Hz to 20 kHz |
| Sine-Wave Frequencies | 900 Hz / 1000 Hz / 1250 Hz / 1500 Hz |
| Sine Generation Method | NCO (Numerically Controlled Oscillator) |
| Output Level Range | -70 dBm (245 μVrms) to +1.0 dBm (869 mVrms), with 600 Ω termination |
| Output Level Resolution | 0.1 dB |
| Output Level Accuracy | Within ±2 dB, -70 dBm to 0 dBm |
| Output Impedance | 600 Ω balanced |
| Output Connector | BNC |
| AC Input | 100 Vac to 240 Vac nominal |
| Allowable AC Input Range | 90 Vac to 250 Vac |
| Power Consumption | 30 VA or less |
| Operating Temperature | 0°C to 40°C |
| Operating Humidity | 0% RH to 80% RH, no condensation |
| Maximum Operating Altitude | 2000 m |
| Dimensions | 280 W × 44 H × 270 D mm nominal |
| Weight | Approx. 3 kg (6.61 lb) |
Pseudo-Voice Signal Architecture
The KSG3600 generates audio-frequency test signals intended to modulate or evaluate analog communication equipment rather than directly generate an RF carrier.
A DSP-based M-sequence source generates stable pseudo-random noise. When the ITU-T G.227 characteristic filter is enabled, the noise spectrum is shaped into a standardized pseudo-speech signal suitable for repeatable communication-system measurements.
500 kHz
PRBS sampling frequency
48 kHz LPF
Pseudo-random noise bandwidth limit
-70 to +1 dBm
Adjustable output-level range
0.1 dB
Output-level adjustment resolution
For discrete modulation testing, the internal NCO can also generate fixed 900 Hz, 1000 Hz, 1250 Hz, or 1500 Hz sine signals. The balanced 600 Ω output is designed for audio and communication-circuit connections and should not be described as an RF output port.
