Difference between revisions of "EM Field Head Tracking System specifications"
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The EM Field amplifiers are mounted in a 3U 19" rack. Each channel (F, V and H) has a standard amplifier board based on the TDA7294 audio amplifier chip with a maximum output of 100 Watt. Each board is powered by its own toroidal transformer. Each amplifier chip is connected to a 10 x 10 cm heat sink . At the front there are three BNC connectors for the input signal. At the back there are 3 pairs of banana jacks for the output. | The EM Field amplifiers are mounted in a 3U 19" rack. Each channel (F, V and H) has a standard amplifier board based on the TDA7294 audio amplifier chip with a maximum output of 100 Watt. Each board is powered by its own toroidal transformer. Each amplifier chip is connected to a 10 x 10 cm heat sink . At the front there are three BNC connectors for the input signal. At the back there are 3 pairs of banana jacks for the output. | ||
− | *[[:File:TDA7294_datasheet1.png|TDA7294 | + | *[[:File:TDA7294_datasheet1.png|TDA7294 datasheet page 1 (description)]] |
+ | *[[:File:TDA7294_datasheet2.png|TDA7294 datasheet page 2 (schematics)]] | ||
+ | *[[:File:TDA7294_datasheet3.png|TDA7294 datasheet page 3 (absolute ratings]] | ||
+ | *[[:File:TDA7294_datasheet4.png|TDA7294 datasheet page 4 (specifications)]] | ||
===Resonance circuits=== | ===Resonance circuits=== |
Revision as of 13:31, 21 March 2024
Introduction
The EM Field Head Tracking System is used for recording head movements of the subject during a trial. The system consists of the following parts:
- Three oscillators at roughly 45, 55 and 65 kHz or 50, 60, 70 kHz for X, Y and Z direction.
- Three signal amplifiers that amplify the oscillator signals.
- six field coils that make a cube of roughly 3x3x3 meters.
- A small pick-up coil mounted on a glasses frame that is worn by the subject during the experiment.
- Three lock-in amplifiers that split the signal from the pick-up coil in the 3 frequency components and measures their envelope. They output analog signals between -10V and +10V.
- An acquisition device converts the analog output signals from the lock-in amplifiers to digital.
- A RZ6 multi I/O processor that records the acquired data.
- Software that converts the recorded data to head orientations using calibration data.
The following table contains the channel convention with respect of the three directions:
Channel | Frequency | Orientation | Color | Polarity |
---|---|---|---|---|
Channel 1 | 45/50 kHz | Frontal | Red | Front = positive; Back = negative |
Channel 2 | 55/60 kHz | Vertical | Blue | Right = positive; Left = negative |
Channel 3 | 65/70 kHz | Horizontal | Yellow | Up = positive; Down = negative |
Parts
Lock-in amplifiers
Three Femto LIA-BV-150-H Lock-in amplifiers are used in order to separate the Frontal, Horizontal and Vertical signals from the signal that is coming from the pick-up coil. Each Lock-in amplifier has a Sinus Oscillator Module (SOM-1) that is used both as Field Modulation Signal and as Reference Signal. The Lock-in amplifier settings are set at the front of the device (see picture), except for the modulation/reference frequency which is set inside on the SOM-board.
Kenmerk | LIA-BV-150-H |
---|---|
Model | Single Phase |
Werkfrequentie | 50 Hz - 120 kHz |
Tijdconstanten | 300 µs - 1 s (6 of 12 dB/oct.) |
Verstelbaar Signaalfilter | Highpass 2 Hz - 10 kHz, Lowpass 100 Hz - 1 MHz |
Datasheet | 367 kB |
Uitgangen | X = in fase, Y = kwadratuur, R = magnitude, ±10 V volledige schaal, kortsluitbeveiligd, Signaalmonitoruitgang |
Gevoeligheid (Volledige Schaal) | Voltage: 3 µV - 1 V in 1-3-10 stappen |
Spanningsingang | Echte differentiële instrumentatieversterker, ruis 12 nV/√Hz |
Stroomingang | Transimpedantieversterker, versterking 100 kV/A, ruis 0.4 pA/√Hz |
Referentie-ingang | ±100 mV tot ±5 V, schakelbaar naar TTL |
Fase | Aanpasbaar 0° - 360°; resolutie: 8-bit @ f ≤ 60 kHz, 7-bit @ f > 60 kHz, Temperatuur drift <0.01°/K |
Max. Dyn. Reserve | 80 dB |
Digitale Controle | 16 TTL/CMOS ingangen: 8-bit fase, 4-bit tijdconstante, 4-bit gevoeligheid |
Voeding | ±15 V, +120 mA / -60 mA |
Afmetingen | 160 x 100 x 20 mm (L x B x H), gewicht 100 g (0.22 lbs) |
The front panel of each LIA has four dip-switches:
- Mode: 1f means that the fundamental harmonic is measured (2f = second harmonic signal)
- Dyn.Res.: For dynamic reserve the settings Low (L) is preferred because the signal is normally large in comparison with the noise.
- PLL: For the Phase Lock Loop (PLL) the settings Slow (S) is preferred because the frequency is at a fix value. The phase is more stable in this setting.
- Ref.Thr.: Reference Threshold is set to 0V for analog signals (2V is for digital signals).
Oscillators
Amplifiers
The EM Field amplifiers are mounted in a 3U 19" rack. Each channel (F, V and H) has a standard amplifier board based on the TDA7294 audio amplifier chip with a maximum output of 100 Watt. Each board is powered by its own toroidal transformer. Each amplifier chip is connected to a 10 x 10 cm heat sink . At the front there are three BNC connectors for the input signal. At the back there are 3 pairs of banana jacks for the output.
- TDA7294 datasheet page 1 (description)
- TDA7294 datasheet page 2 (schematics)
- TDA7294 datasheet page 3 (absolute ratings
- TDA7294 datasheet page 4 (specifications)
Resonance circuits
%todo
Wall coils
%todo
Pick-up coil
%todo
- Head coil glasses Auditory Sphere Lab
- Head coil glasses Auditory Motion Lab
- Head coil glasses Auditory Perception Lab
- Test coil
Lock-in amplifiers
%todo
ADC's
%todo
recording device
(RZ6 or RA16) %todo