The team spent the week combining the various components of the spectrum analyzer and integrating the hardware and software sub components. The members working in the respective teams  helped in the integration process. The team was also involved in calibrating the components that were integrated and functional, further different parts of the report were assigned to team members based on their responsibilities.

Hardware:

The hardware sub-team was heavily involved with understanding UltiBoard and designing a PCB to hold our switch IC. This involved becoming conversant with the software and understanding industry standards for amount of copper, drill sizes etc. The hardware sub team completed a design for the PCB and combined it with 3 other teams to take advantage of the flat price offered by CCI. However due to the long turn around time, the team agreed to use the back up PCB provided by the teaching staff and soldered and tested the switch IC. A major challenge in this process was to solder the chip with the solder iron in the lab, it required a lot of patience and de-soldering.

The hardware team also realized an issue caused by the 8Mhz crystals. The low center frequency of these crystals meant that 104 MHz and 88 MHz, both within our range, are 8 MHz away from 96 MHz which is also in our range therefore we don’t know which of these frequencies gives us the 8 MHz difference. This was corrected by using crystals with higher center frequency i.e. 18Mhz that made sure that 2 frequencies did not give us the same difference in our range. The new crystals were an efficient fix for what could have been a very difficult issue to debug in LabView.

Software:

The software team continued to better the user interface that was created last week. The markers and traces that were implemented last week were debugged and new controls such as center frequency and span as well as start stop frequency were also implemented. The sub team also debugged and troubleshooted the inputs and outputs from the DAQ and programmed the remaining analog input to control a mux to control the switch. Further, the sub team implemented added functionality that was deemed necessary. The frequency modulation index calculation was implemented via Carson’s rule and testing of the software with input from the hardware was also started. The team has also automated one of the markers to find the peak and display it, the team will continue to make efforts to completely mimic the lab machines but the integration and testing  of the components is more important at this point.

The team has now spent 2 weeks considering the various blocks involved in building the spectrum analyzer. The team mates were assigned different tasks based on their skills.

Hardware:

The goal of the hardware sub-team this week was to finalize the resolution BW filters and the peak detectors as well as determine what amplification is necessary. The resolution BW filters were constructed by using crystal oscillators which were centered at 8 MHz. Two filters needed to be built and so two BWs were decided upon while considering the standard conventions for spectrum analyzers. In order to “flatten” the bandpass region, the gain of the filter was sacrificed. Minor adjusting is still needed however as the BWs are not equal to what was planned.

The design for the peak detectors was finished and circuiting of these designs started this week. Due to faulty breadboards however, the peak detectors were not finished this week.

A test BJT amplifier was constructed to simulate the amplification of signals with very low dBm. The amplifier does not work within the required operating range and thus some adjusting is still needed.

Next week will focus on finishing the peak detectors, video filters and amplifiers as well as adjusting the resolution BW filters. Once this is complete, the hardware components can be integrated and tested as a whole.

Software:

The software sub team worked towards achieving the design specifications. The sub team implemented the user interface for the spectrum analyser after designing the ramp to ouput the right voltage range. The user interface includes traces and markers to help the user to compare different signals and to find the magnitude of signals.

The team used LabView to build a signal diagram to send the ramp input to the VCO and to use the input from the hardware sub team to create x-y plots. Further, the team implemented controls to change sweep time and to switch between traces. Control for the markers was also implemented, this allows the user to measure the magnitude of the signal at different frequencies.

The team had to research ways of displaying multiple graphs on the same plot and to enable/disable each graph separately to allow the user to pause graphs and interpret the data. We used the array builder to combine the signals from two xy graphs and plot them in Lab View.

The majority of the week was spent understanding the individual blocks needed to build the spectrum analyzer as well as familiarizing ourselves with Labview.

VCO

The VCO was first tested by applying a DC voltage to the Vtune pin. The VCO outputted a signal with a constant frequency according to the voltage supplied to Vtune. Therefore, by using the calibration curve, the desired frequencies could be chosen. A ramp generator was then connected to Vtune which effectively swept a range of frequencies based on the offset and amplitude of the ramp.

RF Amplifier

The gain of the RF amplifier was tested by inputting a -40dB signal and measuring the output with a spectrum analyzer. This gain was recorded for future use.

Band-pass filters

The frequency response of the two band-pass filters was tested by utilizing the tracking generator of the spectrum analyzer. The frequency response provided some useful information on the bandwidth and gain of these two filters.

Mixer

The VCO was also tested with the Mixer and a 50 MHz signal. The 10.7 MHz band-pass filter was attached to the output in order to filter out the desired frequency. The Vtune pin of the VCO was then swept until the spectrum analyzer measured a signal from the output of the mixer. The mixer would produce two signals; one at a frequency of the sum of the two inputs and one at a frequency of the difference of the two inputs. Since the band-pass filter was connected to the output of the mixer, one of the two frequencies had to be within the filter’s range. By adjusting the settings of the various inputs, the tuning range of the VCO needed for this project was determined.

Peak detector

The peak detector was designed and built by implementing a high pass filter with a schottky diode. After the circuit was built, it was tested with a 10 MHz signal and the power limits of the peak detector was determined. The transfer function was also found by utilizing the tracking generator of the spectrum analyzer.

LabView Coding

To begin understanding the functionality of LabView, the group members working on software familiarized themselves with the platform by stepping through the starter tutorials online. Next, the team implemented the Ramp voltage output function to be later integrated with the VCO. In the upcoming week, the software functions will be expanded to allow user interface and processing of input signals from the hardware.

The team completed the Orbcomm SCADA project during the weekend of Mar. 1. The remainder of the week was split into completing the report for the first project and getting used to the Spectrum Analyser. We also incorporated Dr. Michelson’s inputs into the presentation slides and report. The team got together to edit and format the report during our scheduled team meetings for rotation 1.

After the briefing for the second project, the team assigned hardware and software roles. This allowed team members to focus their research efforts on specific goals. Our team started work on the first lab tasks, to get familiar with the equipment. We were able to complete all the tasks in one lab session as we were to demo in the second lab session of the week. Team members became conversant with the use of lab view.

The team is looking forward to the reflection activity with Dr. Michelson and look back on the lessons learnt from  the first project and how we can implement what we learnt in the second rotation.

As the demonstration deadline neared, the team worked hard to complete the final components of the project. The majority of this week was spent integrating the hardware and software components of our machine.

Accomplishments:

• Finalized the bash script which sorts emails and replies with tasks for the orbcomm
• Improved the excel file which displays processed data from the orbcomm and presents statistics about wind and weather conditions
• Prepared demonstration files to present the functionality of the system
• Calibrated the temperature, wind-speed, and wind direction sensors
• Soldered, connected, and tested the LED display actuator
• Soldered, connected, and tested the alarm speaker actuator
• Built the housing to hold all circuitry and connected buses for power and digital logic transmitting

Calibration Methods:

Wind Speed

     The team split off into a sub team of 4 to test and calibrate the wind speed sensor. Our method was to mount the sensor to the top of a vehicle and drive down the road on a windless day measuring vehicle speed and sensor voltage. Land speed was measured using the vehicles digital speedometer and voltage was measured using a portable voltmeter. Our sensor was powered using 12volts from a laptop battery and using a logic voltage of 3.5 volts from a pack of AAA batteries. Our Wind speed sensor works by creating a pulse as wind rotates a shaft that is fed into the frequency to voltage converter, which ultimately the Q4000 microprocessor reads using an analog voltage pin. We carried out 6 tests in all from 10km/h to 60 Km/h at 10km/h intervals. The test was a success and a linear frequency to voltage relationship was produced.

     Temperature

     The temperature sensor was calibrated by taking a series of voltage output measurements at various temperatures (measured with a digital thermometer). Using this collection of information, we created a voltage to temperature relation and applied it to the output code to send real temperature data to the satellite.

 Challenges:

•  Calibrating the wind-speed required some creative engineering to make our anemometer mobile, however in the end it was successful.
• The alarm actuation hardware worked in initial testing, however once integrated with the Q4000 modem it ceased being functional. Thus far our team has determined the problem to be a lack of current output from the modem, but we have not been able to find a solution to this issue yet. We’re continuing to test and debug the issue, and are otherwise on schedule to present the project on Tuesday.