VLF equipments ESH 2 TEST RECEIVER from Rhode and Schwarz, for use as Field-strength Meter 9 kHz to 29,9999 MHz / -30 to +137dBuV SPM-60 receiver from Wandel and Goltermann, Selective Level Meter 200 Hz to 18.6 MHz USB soundcard 192 kHz 24 bits Spectrum analyser MT8820A The model 2230 A is a Programmable Frequency and Level Generator. Frequency range: 50 Hz to 1 MHz Resolution: 1 Hz resolution The output frequency can be controlled according to four operating modes: digital setting by six lever / indicator switches, remote programming in parallel BCD code or through the IEEE bus, analog setting by two verniers with graduated scale, frequency sweep by external signal. Four output signals are simultaneously available: Main output with push-button selectable impedance: 75 ohms coaxial, 150 ohms balanced, 600 ohms balanced or low-impedance balanced (key 0 ohm) Auxiliary output with Z < 1 ohms impedance Square-wave output with 5 V or 10 V amplitude Tracking output delivering a signal with 4 MHz offset with respect to the dialed or programmed frequency his device outputs low-jitter reference clock frequency-locked to GPS signal. Long term stability of output signal is defined by high accuracy of GPS Caesium references and approaches 1×10-12. Short term signal quality is defined by internal TCXO clock source providing high-quality, low phase noise clock signal with sub-picosecond RMS jitter. Digital PLL allows main output reference frequency to have almost any value between 400Hz and 810MHz. Output signal is a square wave at 3.3V CMOS levels with 50 Ohms characteristic impedance. Output drive level can be adjusted.