Emona DATEx User Manual

Emona DATEx User Manual

1. Introduction

   • The DATExTM Telecommunications Add-in Module for NI ELVIS DATEx, or Digital Ananlog Telecommunications Experimenter, as its name implies, is used to help students learn about communications and telecommunications principles. The Emona DATEx add-in module is fully integrated with the NI ELVIS platform and NI LabVIEW environment. All DATExTM knobs and switches can be varied either manually or under the control NI LabVIEW VIs.
     • Equipment Required
       • Experiments make use of the Emona DATEx telecommunications trainer kit together with the NI ELVIS platform and NI LabVIEW running on a PC. The functionality and range of the virtual instrumentation available depends on the NI DAQ that is coupled with NI ELVIS platform.
         • IMPORTANT NOTE CONCERNING DAQ SELCTION
           • Ideally the NI-DAQ should have an oscilloscope sample rate of 1MS/s or more, such as the USB-6251 or equivalent. If the NI-DAQ being used has a slower oscilloscope sample rate, then only baseband signals generated by the Emona DATEx add-in module will be viewable.
             • How to handle, install and power up DATExTM
               • When holding DATEx, always hold the circuit board by the edges, as illustrated.
                 • Ensure NI ELVIS Prototype Board Power OFF Before installing the DATEx add-in module in the NI ELVIS PROTOTYPE PCI SLOT, always check the PROTOTYPING BOARD POWER switch is in the OFF position. Hold DATEx by the edges How not to hold DATEx
                   • When installing the DATEx add-in module in the NI ELVIS PROTOTYPE PCI SLOT, always carefully check the alignment is correct before pushing DATEx into position.
                     • After DATEx is correctly positioned, turn the NI ELVIS Prototyping Board Power switch ON.
                       • Ensure NI ELVIS Prototype Board Power is OFF Before removing the DATEx add-in module from the NI ELVIS PROTOTYPE PCI SLOT, always turn the PROTOTYPING BOARD POWER switch OFF.
                         • INSTALLATION AND OPERATION
                           • 1. Installation of NI components
                           • 2. Installation of Emona DATEx components
                           • 3. Setting-up the NI hardware components
                           • 6. DATEx front panel conventions
                           • 7. Power down and unplug DATEx
                           • 5. Operation
                           • 4. Set-up of the Emona DATEx add-in module

2. ADDER

   • The ADDER module is used to sum two signals in real-time.
     • The ETT-202 provides two independent ADDER modules, as pictured above. The first ADDER includes adjustable GAINS. The second ADDER module has fixed GAINS of unity (x1). Care must be taken when adjusting the gains to avoid overloading the following modules. Overloading will not cause any damage but it means non-linear operation, which is to be avoided in analog systems. The ADDER is capable of delivering a signal well in excess of the standard reference level, 4V pk-pk, given a standard level input.

3. AMPLIFIER

   • Another name for the BUFFER is AMPLIFIER. The BUFFER is a variable gain amplifier.
     • The BUFFER may be used to amplify (increase) small signals or attenuate (reduce) large signals. The BUFFER has a gain, (or amplitude), control on the front panel labeled GAIN. Care should be taken to ensure that later modules are not overloaded due to excessive gain. Overload will not cause any damage but it means non-linear operation (distortion), which is to be avoided in analog systems. If overload occurs, turn the gain control counter clockwise

4. ANALOG I/O – NI ELVIS Function

   • Two NI ELVIS analog inputs and two NI ELVIS analog outputs are provided at the front panel of the DATEx add-in module.
     • NI ELVIS analog inputs ACH0 and ADCH1, and analog outputs DAC0 and DAC1 are provided from the NI ELVIS PCI connector. These signals are provided directly, without buffering. These four signals can be accessed through LabVIEW programs such as the NI ELVIS Bode Analyzer and NI ELVIS Arbitrary Function Generator.

5. CHANNEL MODULE

   • A channel is the space (or medium) between the transmitter and the receiver. Two types of channels are provided in the CHANNEL MODULE.
     • Both channel modules take signals which are at the ETT-202’s analog signal levels of 4Vpk-pk. CHANNEL BPF is a bandpass filter used for signals which are modulated at the ETT-202 carrier frequency of 100kHz. The filter is centered at 100kHz with a bandwidth of 20kHz. BASEBAND LPF is a lowpass filter used for data signals which are not modulated. The cut-off frequency of the filter is 2kHz.

6. DIGITAL I/O – NI ELVIS Function

   • Four NI ELVIS digital inputs and four NI ELVIS digital outputs are provided at the front panel of the DATEx add-in module.
     • NI ELVIS digital inputs DI0 to DI3, and digital outputs DO0 to Do3 are provided from the NI ELVIS PCI connector. These signals are provided directly, without buffering. These eight signals can be accessed through LabVIEW programs written for the NI ELVIS platform. Refer to the NI ELVIS User Manual for programming and user information.

7. DUAL ANALOG SWITCH

   • The ANALOG SWITCH is just like a normal switch, but it is controlled by a digital signal instead of being controlled physically.
     • ANALOG SWITCHES Each ANALOG SWITCH may be closed independently by a digital high, or 5V, signal at the respective control input. The switch outputs are combined internally and are presented at the common output socket, as is illustrated on the module’s front panel.

8. FUNCTION GENERATOR – NI ELVIS Function

   • Three signals associated with the NI ELVIS Function Generator are provided at the front panel of the DATEx add-in module.
     • The NI ELVIS Function Generator is a general purpose signal source which is used extensively in experiments with the DATEx add-in module. The NI ELVIS Function Generator can be controlled in MANUAL mode from the front panel of the NI ELVIS platform or on-screen via the NI ELVIS Virtual Instrument front panel. The output frequency of the Function Generator can also be controlled by applying a voltage to the VCO input.

9. HEADPHONE AMPLIFIER

   • The ETT-202 allows students to listen to sounds, their voice and demodulated messages.
     • This module serves as an electro-acoustic interface between the audio signals within the system and the student. The BUFFER may be used to amplify (increase) small signals or attenuate (reduce) large signals. The BUFFER has a gain, (or amplitude), control on the front panel labeled GAIN.

10. LINE CODE ENCODER

    • Line codes are digital data which has been converted to bipolar voltage levels in a specific manner, following the rules of the line code selected.
      • Four line codes are available: NRZ-L : Non Return to Zero – Level; Bi-φ : Bi-phase Line, otherwise know as Manchester; RZ-AMI : Return to Zero – Alternate Mark Invert NZR-M : Non Return to Zero – Mark

11. MASTER SIGNALS

    • Three of the signals have a frequency of 100kHz, which in the context of the ETT-202 is equivalent to radio or wireless frequencies used in telecommunications.
      • 100kHz - CARRIER or WIRELESS signals The ETT-202 models telecommunications systems at frequencies that are lower than real- world telecommunications systems, so that students can easily and safely view the advanced modulation and coding schemes used in modern telecommunications. The “carrier” frequency we have chosen in 100kHz. A 100kHz sinusoidal and a 100kHz cosine signal are provided. A digital-level, 0V to 5V, squarewave signal is also provided to allow more complex experiments to be implemented.

12. MULTIPLIER

    • Two analog input signals X(t) and Y(t) may be multiplied together. The resulting product is scaled by a factor of approximately 1/2 so that, with standard level inputs, later modules are not overloaded.
      • The first MULTIPLIER includes both AC and DC coupled inputs. The other two MULTIPLIER modules have DC coupled inputs, as per their front panel labels. The purpose of the AC coupled inputs is to remove any DC components in the input signal, so that only the AC components of each input signal are multiplied. Note that the output of each MULTIPLIER is input X times input Y times a scale factor “k”, that is, k . X . Y

13. NOISE GENERATOR

    • The NOISE GENERATOR module provides a wide source of electrical noise. Three different amplitudes of noise level are provided.
      • he module requires no input or control signals. The output noise level can be varied in three discrete steps: 0dB, known as the reference level; -6dB, half the reference level; and -20dB, one tenth of the reference level.

14. PCM ENCODER

    • The PCM ("Pulse Code Modulation") ENCODER is the fundamental building block in telecommunications which converts sound, music and speech into digital data. The heart of a PCM ENCODER is known as an analog-to-digital converter.
      • INPUT SIGNALS A minimum of two input signals are required for correct operation: the analog signal to be digitized, INPUT 1, and the sampling "bit" clock, CLK. INPUT 1 (and INPUT 2) will accept any audio frequency analog-level, bipolar signal ranging from DC up to several kilohertz. Note that the INPUTs are not band limited, so that aliasing may be observed if desired.

15. PCM DECODER

    • The PCM ("Pulse Code Modulation") DECODER performs the reverse function of the PCM ENCODER. The PCM DECODER module converts digital data back to sound, music or speech. The heart of a PCM DECODER is known as a digital-to-analog converter.
      • INPUT SIGNALS Three digital-level signals are required for correct operation: PCM DATA, the serial digital data to be converted to an analog signal; CLK, a synchronized and in-phase bit clock, usually taken directly from the PCM ENCODER module's CLK socket; FS, the frame synchronization signal from the PCM ENCODER module. PCM DATA The format of the serial data expected at the PCM DATA input is exactly as generated by the PCM ENCODER module: PCM code words in standard offset binary, with the 8 bits allocated for data. ANALOG OUTPUT The OUTPUT terminal provides a bipolar, standard analog-level signal, decoded from the input digital data at PCM DATA. Note that the signal at the OUTPUT terminal is taken directly from the digital-to-analog converter without reconstruction filtering so that individual steps in the conversion process may be observed if desired. TDM MODE When TDM mode is selected at the PCM ENCODER module, the PCM DECODER module's “TDM” LED will be lit, confirming that the

16. PHASE SHIFTER

    • In telecommunications systems, signals often need to be lined-up or delayed due to the effects of nature or signal processing blocks or circuits. The PHASE SHIFTER is used to help re-align signals as may be required by theory or due the implementation of the task at hand.
      • This variable PHASE SHIFTER is capable of varying the magnitude of the phase shift through 340 degrees in two steps. The 180 degree switch selects the step or region of interest.

17. SEQUENCE GENERATOR

    • In the real world there are essentially two types of message signals which need to be transmitted from one location to another: “analog” and “digital”. Voice, speech and sound are referred to as “analog” messages. Computer data and digitized analog messages are referred to as “digital” messages. (For clarification regarding digitized analog signals, please refer to the PCM ENCODER module).
      • CLK An external clock signal, CLK, must be provided to operate the SEQUENCE GENERATOR. This must be a digital-level signal. CLK only accepts digital-level signals. SYNC The SYNC terminal outputs a digital pulse at the beginning of each X sequence. SYNC is a digital-level signal. X (short) and Y (long) The length of sequence X is 31 bits. The length of sequence Y is 255 bits. X and Y are digital level-signals.

18. SERIAL TO PARALLEL

    • SERIAL TO PARALLEL performs a basic digital logic function, breaking a single serial digital data stream into two parallel streams of data. This module is a fundamental building block used primarily in digital communications experiments.
      • SERIAL input accepts any serial digital data stream such as the X or Y output of the SEQUENCE GENERATOR module A digital-level CLK signal must always be provided. If the SEQUENCE GENERATOR module's X or Y data signals are being used, then the SEQUENCE GENERATOR module's CLK must also be patched to the SERIAL TO PARALLEL module’s CLK input. Outputs X1 and X2 are digital signals at bipolar voltage levels of -2V and +2V.

19. SPEECH

    • The SPEECH module allows speech and audio signals to be converted into an electrical signal.
      • The SPEECH module includes a sensitive microphone which will easily pick-up normal speech and background noise. You do not need to lean towards or speak into the microphone. The microphone will continuously output an electrical of about 0.6Vrms (that is, an effective AC voltage equivalent to 0.6V DC).

20. UTILITIES

    • COMPARATOR The COMPARATOR will square any analog signal and provide a standard digital-level output. The switching threshold level is determined by the voltage level applied to the REF input. NOTE: For correct COMPARATOR operation, the REF input must never be left unconnected. The REF input may be connected to GROUND, VARIABLE DC or any other signal source.

21. TUNEABLE LPF

    • Filters are important building block in electronics and telecommunications. A filter is used to pass some signals and block other signals. A low pass filter passes low frequencies and blocks high frequencies.
      • The TUNEABLE LPF module accepts analog-level signals and outputs analog-level signals. The cutoff frequency is adjustable by the user. The cutoff range is from 300Hz to 16kHz. The amplitude of the output signal can be control via front panel GAIN control. A digital-level squarewave signal is output which has a frequency 100 times higher than the selected cutoff frequency. Measuring the frequency of the digital signal and dividing the frequency by 100 will give the user an instantaneous reading of the TUNEABLE LPF cutoff frequency.

22. VARIABLE DC – NI ELVIS Function

    • Two signals associated with the NI ELVIS Variable Power Supply are provided at the front panel of the DATEx add-in module.
      • The NI ELVIS Variable Power Supply is a general purpose, variable, bipolar output DC source. The NI ELVIS Variable Power Supply can be controlled in MANUAL mode from the front panel of the NI ELVIS platform or on-screen via the NI ELVIS Virtual Instrument front panel.

23. TWIN PULSE GENERATOR

    • A pulse in electronics or telecommunications is a single digital-level signal which may or may not repeat over a particular time frame. Pulses have many uses, such as markers in time, and control signals.
      • A digital-level signal is applied to the CLK input. The TWIN PULSE GENERATOR then sequentially outputs two pulses. Two equal width positive pulses occur as a result of each CLK signal positive edge. Pulse Q1 always occurs before pulse Q2. The width of both pulses is controlled by the front panel WIDTH control. The DELAY control varies the spacing between the two pulses.

24. DATExTM SOFTWARE INSTALLATION & SFP OPERATION

    • Installing NI DAQ and NI ELVIS software
      • Before installing the EMONA DATEx software, ensure that the NI DAQ and NI ELVIS software has been correctly installed as per the accompanying NI DAQ and NI ELVIS user instructions. Using NI MAX (Measurement and Automation Explorer) ensure that the NI DAQ used with NI ELVIS (6251 device) is set to either DEVICE 1 or DEVICE 2. Confirm the correct operation of NI ELVIS before proceeding.
        • Installing the EMONA DATEx software
          • The CD-ROM supplied with the DATEx Kit includes the following items: • DATEx-Main SFP (Soft Front Panel). A large SFP which allows all DATEx switches and knobs to be controlled on-screen. • DATEx-Toolbar SFP. A compact sized SFP which allows all DATEx switches and knobs to be controlled on- screen. • DATEx polymorphic VIs for control of the individual DATEx modules. These VIs can be used by any LabVIEW program to control any of DATEx’s variable parameters. • Example LabVIEW programs which demonstrate LabVIEW control of the DATEx. A selection of simple example programs for using DATEx block functions. The DATEx CD-ROM also includes a soft copy of the Lab Manual, • Emona DATEx Lab Manual Volume One in PDF format
            • Using the DATEx-Main and DATEx-Toolbar SFPs
              • To launch the DATEx SFP go to START > click on DATEx and select either DATEx-Main-SFP or DATEx-Toolbar-SFP. Ensure that the Device selection radio button is set to match the NI DAQ unit device number, either DEV 1 or DEV 2. Use the mouse left button to click and drag the knob or switch to the desired position. TAB can also be used to select knobs and switches. Keyboard arrow keys (left & right) can then be used to change knob positions.
                • Confirming PC-to-DATExTM Communications
                  • To confirm that the on-screen mouse control signals are being passed from the PC through the NI-DAQ to NI ELVIS and the DATEx add-in module, do the following: Toggle any DATEx on-screen switch and look at the 4 LEDs located within the DATEx add-in module. Refer to the diagram to the right. As the switch (or potentiometer) is varied, the communications LEDs should flicker on-and-off. If the LEDs (A, B, D) flicker, then communication signals are being passed from the PC through to the DATEx.

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