ANACOM 1/1 Module Setup Procedures

Questions and Answers

What is the primary function of the CERAMIC BANDPASS FILTER block in the procedure?

To amplify the audio signal

To pass the upper sideband while blocking the lower sideband (correct)

To ensure the output signal has constant amplitude

To modulate the audio frequency signal

Which initial condition does NOT need to be satisfied before powering on the ANACOM 1/1 board?

AUDIO INPUT SELECT switch in INT position

OUTPUT AMPLIFIER’s GAIN preset in fully clockwise position

SPEAKER switch in ON position (correct)

MODE switch in SSB position

What happens to the waveform at t.p.20 after passing through the CERAMIC BANDPASS FILTER block?

It shows random fluctuations in amplitude

It changes to a square wave form

It becomes distorted by external noise

It appears as a good, clean sine wave (correct)

What adjustment can be made to vary the modulating frequency of the audio signal?

Turn the AUDIO OSCILLATOR’s FREQUENCY preset Signup and view all the answers

What does the output signal at t.p.20 reveal about the performance of the CERAMIC BANDPASS FILTER?

It confirms the filter is only passing the upper sideband Signup and view all the answers

What initial position should the BALANCE preset be set to before monitoring outputs?

Fully clockwise position Signup and view all the answers

How does changing the modulating frequency affect the amplitude of the signal at the output of the CERAMIC BANDPASS FILTER?

It results in variation of output signal amplitude Signup and view all the answers

What is the purpose of examining the waveforms in the BALANCE MODULATOR & BANDPASS FILTER CIRCUIT 1 block?

To verify that output waveforms match expected patterns Signup and view all the answers

Which preset position should the AUDIO OSCILLATOR’s AMPLITUDE be in for proper conditions on the ANACOM 1/1 board?

Fully clockwise position Signup and view all the answers

What is the required setting for the MODE switch on the ANACOM 1/1 board?

SSB position Signup and view all the answers

What should the OUTPUT AMPLIFIER's GAIN preset be set to on the ANACOM 1/1 board?

Fully counter-clockwise position Signup and view all the answers

When the AMPLITUDE preset is turned fully counter-clockwise, what happens to the monitored output signal from ANACOM 1/1?

The amplitude drops to zero Signup and view all the answers

In order to monitor the I.F. AMPLIFIER 2 output on the ANACOM 1/2 module, what should you adjust?

TUNING dial Signup and view all the answers

What must be ensured about the RX INPUT SELECT switch for proper operation?

It should be in ANT position Signup and view all the answers

What effect does touching ANACOM 1/1’s antenna have on the SSB waveform at t.p. 13?

It decreases the amplitude Signup and view all the answers

What is the correct position for the AGC switch on the ANACOM 1/1 board?

IN position Signup and view all the answers

What is the result of adjusting the CARRIER FREQUENCY preset to 450 kHz?

It allows modulation of the carrier with the audio signal. Signup and view all the answers

What should be monitored at t.p.52 when varying the frequency of the signal generator?

The DC voltage corresponding to frequency changes. Signup and view all the answers

When applying the output from the Foster-Seeley block to the LOW PASS FILTER, what component should be removed?

The high-frequency ripple component. Signup and view all the answers

How is the FM signal modulated in this experiment?

By both the audio input and the noise input. Signup and view all the answers

What is the amplitude of the sinusoidal output used to test the Foster-Seeley detector?

1V (p-p) for the initial input. Signup and view all the answers

What is observed at t.p.14 during the monitoring phase?

The audio modulating signal. Signup and view all the answers

What effect does applying a 2 kHz noise signal have on the FM signal?

It introduces additional amplitude modulation to the FM signal. Signup and view all the answers

What should the curve represent when plotting DC level against frequency after varying the signal generator's frequency?

A curve that resembles the expected output pattern. Signup and view all the answers

What must be adjusted in MODULATOR 2 to achieve equal amplitude of frequency components in the DSK signal?

GAIN control Signup and view all the answers

What frequency corresponds to a data bit value of ‘1’ in the FSK signal?

1.44 MHz Signup and view all the answers

What effect does the higher incoming frequency have on the output voltage of MODICOM 5/2’s FSK DEMODULATOR?

It increases the output voltage Signup and view all the answers

What is the main purpose of the low pass filtering stage in the demodulation process?

To remove unwanted frequency components Signup and view all the answers

What adjustment is necessary for the output pulses of COMPARATOR 1 to match the pulse width of MODICOM 5/1’s NRZ(L) output?

Set the BIAS level Signup and view all the answers

What should happen after turning on MODICOM 3/1’s SYNC CODE GENERATOR?

Ensure synchronization of codes between A/D and D/A converters Signup and view all the answers

When using function generators with MODICOM 3/1, what does the user check at MODICOM 3/2’s analog outputs?

The inputs are successfully reconstructed Signup and view all the answers

What is the end result of frequency modulation by MODICOM 5/1’s NRZ(L) output?

A frequency-modulated carrier signal Signup and view all the answers

What is the effect of increasing the sampling frequency on the ability to reconstruct the original waveform?

It allows for better reconstruction of the original waveform. Signup and view all the answers

How does varying the sampling duty cycle affect the output amplitude of the filter in a practical digital communications system?

The output amplitude remains independent of the duty cycle. Signup and view all the answers

What is the primary purpose of the sample/hold circuit in a digital communications system?

To hold each sampled signal before low-pass filtering. Signup and view all the answers

When comparing the outputs of the Second Order Low Pass Filter and Fourth Order Low Pass Filter, what factor is being analyzed?

The amount of distortion in the waveforms. Signup and view all the answers

At what sampling frequency does the amplitude of the filter output become equal to that of the original analog input?

When the sampling frequency is at least 32 kHz. Signup and view all the answers

What happens to the filter output signal as the sampling frequency is changed using the FREQUENCY SELECTOR switch?

It alters the output waveform significantly. Signup and view all the answers

What is the significance of using a 50% duty cycle in the sampling process?

It provides a balanced sampling and holding time. Signup and view all the answers

What is an expected outcome when displaying the SAMPLE/HOLD OUTPUT on an oscilloscope?

The output will resemble the original sine wave. Signup and view all the answers

Study Notes

ANACOM 1/1 Module Setup and Operation

Connect the ANACOM 1/1 module to the power supply properly.
Set the following initial board conditions:
- AUDIO INPUT SELECT switch to INT
- MODE switch to SSB
- OUTPUT AMPLIFIER’s GAIN preset fully clockwise
- SPEAKER switch in OFF position.
Power on the ANACOM 1/1 board.
Adjust the AUDIO OSCILLATOR block’s AMPLITUDE preset to maximum, and verify output sine wave frequency using an oscilloscope (300Hz to 3.4KHz).
Set the BALANCE preset in BALANCE MODULATOR & BANDPASS FILTER CIRCUIT 1 fully clockwise.
Monitor output from BALANCE MODULATOR & BANDPASS FILTER CIRCUIT 1 and 2 at specified test points.
Observe DSBSC output entering the CERAMIC BANDPASS FILTER, focusing on upper sideband transmission only.

Monitoring and Signal Examination

Verify the output of the CERAMIC BANDPASS FILTER using an oscilloscope; check for clean sine wave.
Note any amplitude variation in filter output due to frequency response changes.
Ensure all other initial conditions are met for further operations, including proper settings for TX OUTPUT SELECT and AUDIO AMPLIFIER’s VOLUME.
Check the Transmitter’s output signal (t.p. 13) for good SSB waveform consistency across AUDIO OSCILLATOR’s FREQUENCY preset adjustments.
Confirm zero amplitude output when the AMPLITUDE preset is fully counter-clockwise.

Transmitter-Receiver Communication

Test SSB signal transmission to ANACOM 1/2 Receiver and verify through antenna loading effects.
On receiver module, adjust settings to maximize I.F. AMPLIFIER 2 block output.

Frequency Modulation and Demodulation with Foster-Seeley Detector

Connect a signal generator (1V p-p, 400 kHz) to the Foster-Seeley Detector block.
Vary signal frequency from 430 kHz to 480 kHz, recording DC voltage at t.p.52 in 5 kHz steps for a frequency-voltage curve.
Adjust CARRIER FREQUENCY preset to 450 kHz, modulate the signal from AUDIO OSCILLATOR, and apply it to the Foster-Seeley block.
Monitor combined signals to identify sine wave and high-frequency ripple components.
Use LOW PASS FILTER/AMPLIFIER to remove ripple and observe the filtered output.

Noise Impact on System

Introduce noise (100 mV p-p, 2 kHz) to observe effects on FM output.
Monitor input audio and LOW PASS FILTER output to evaluate ripple presence.
Use SAMPLE/HOLD OUTPUT linked to FOURTH ORDER LOW PASS FILTER to analyze original waveform reconstruction.

Frequency and Duty Cycle Adjustments

Vary sampling frequency and duty cycle to examine filter output amplitude consistency.
Compare outputs from FIRST and SECOND ORDER LOW PASS FILTERS under varied sampling frequencies for distortion assessment.

MATLAB Simulink Experimentation

Primary objective: Perform frequency modulation signal generation and detection using MATLAB Simulink.
Adjust GAIN control on MODULATOR 2 to balance frequency components of DSK signal.
Analyze the FSK signal and note variations during data changes (0 and 1).
Remove unwanted carrier frequencies using low pass filtering and ensure output signal squaring with the correct pulse width adjustment.

System Functionality Verification

Confirm synchronization across components and functionality of the FSK Transmitter-Receiver system.
Allow testing of analog inputs and real-time reconstruction at modular outputs.

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Description

This quiz tests your knowledge on the proper setup and initial conditions required for operating the ANACOM 1/1 module. Key focus areas include power supply connection, switch positions, and settings adjustments for optimal performance. Assess your understanding of the module's configuration steps.