Frequently Asked Questions
:Question: Will there be a 4" or larger version of the tinySA?
:Answer:To reach the largest set of customers it was deliberately decided to first launch the 2.8" version of the tinySA. Next steps will depend on continued sales . A 4" version is expected to fit within the cost and affordable sales price but design has not started. Larger display's are not expected as these will have a substantial cost impact. For the coming months all effort will go to supporting the initial customers and, if required, further maturing the 2.8" version.
:Question: Will there be a 2GHz (or 4GHz) version?
:Answer: This is being studied but there is no plan yet
:Question: Why is a wide scan with a low RWB so slow?
:Answer:There are two factors that make the scan speed decrease. With a large span and a low RBW additional measurement points are inserted to avoid missing signals. Scanning 100MHz with a RBW of 10kHz requires 20000 measurements where using a 600kByte RBW would only use 290 measurements. The RBW filter is implemented in low sample rate DSP and the filter needs time to charge where the charging time is inverse proportional with the RBW. a 3kHz RBW requires more then 7 milliseconds measurement time per measurement point where a 600kHz RBW only requires 0.3 milliseconds.
:Question: Why do the low and high input modes perform so different?
:Answer: The low input mode has an input attenuator to avoid overloading and a good band pass filter to eliminate mirrors. The high input mode is a "for free" feature and we decided to make it available as, even with its limited performance, it could be useful.
:Question: I'm not able to use touch for menu selection and I can not activate the touch calibration
:Answer: Use the jog button to activate the menu and left/right/down of the jog button to select the menu option. If the touch calibration keeps failing loosen the screws of the shell a bit to reduce the pressure of the front of the shell on the touch the screen.
:Question: Can I inspect the SSB modulation of my transmitter?
:Answer: As the minimum RBW is 2.7kHz it is impossible to look at details inside a 2.7kHz wide SSB signal. With careful setup it is just possible to check the alternate side band rejection or see the carrier rejection.
:Question: Am I limited to maximum 290 scan points?
:Answer: In standalone operation the scan can use many measurement points with a large span and low RBW but the display is always using maximum 290 points. When using the tinySA in combination with a PC the amount of points is unlimited. The Windows control program supports scanning with up to 30000 measurement points.
:Question: How are the additional inserted measurements consolidated into one displayed measurement?
:Answer: The displayed measurement is the maximum of all the additional measurements to ensure the level of a signal falling within only one measurement is correctly displayed.
:Question: Why does my signal have some unexpected weird side lobes when I zoom in?
:Answer: The implementation of the [:../resolution:filters] suffers from some spectral leakage due to the chosen DSP implementation.
:Question: Why can't I do a screen capture of the version screen?
:Answer: As long as the tinySA is in a busy wait in the UI there is insufficient memory for the execution of screen captures.
In the normal case you can use the Python3 program nanoVNA.py from Github for a screen capture. If you have Python3 installed, the capture via USB connection is in the terminal:
# the file extension .png is mandatory. $ python3 nanoVNA.py -C filename.png
:Question: In zero span mode there is a weird modulation visible, even when I apply a constant level input signal
:Answer: When the input signal is very close to the zero span center frequency some yet unexplained interference occurs causing +/- 1dB variations in detected level. This can be eliminated by offsetting the zero span center frequency with 1/4 RBW.
:Question: In zero span mode there are weird spikes visible in my AM modulated signal
:Answer: The AGC used to extend the dynamic range of the power detector has difficulty to react to very fast level changes, as a consequence the power detector may show deviations from the actual input signal. To test if this is happening one can disable the AGC in CONFIG/EXPERT CONFIG/MORE/AGC.
:Question: Even without anything connected I still see some signals
:Answer: The shielding of both the high and low input can not prevent strong transmitters from entering. A nearby FM, DAB, TV or mobile phone transmitter can be visible. In high input mode the harmonics of the 30MHz TCXO generating the clock frequencies are visible over the full frequency range at or below -95dBm. The low input is susceptible to the harmonics of the 48MHz MCU clock. When doing a 0-350MHz scan with an RBW of 10kHz these are clearly visible
:Question: Is the design of the tinySA public domain?
:Answer: The tinySA schematic and PCB design are not public domain. The embedded software of the tinySA is FOSS (free and open source software) according to the GPL v3 and can be found at https://github.com/erikkaashoek/tinySA
:Question: Where is the VBW setting?
:Answer: The tinySA does not have a VBW setting for noise reduction, it is advised to use the LEVEL/CALC/AVER function instead.
:Question: My signal was frequency X but the tinySA says it is Y?
:Answer: The total scan range is divided in 290 points with equally spaced frequencies. The tinySA uses these frequencies for the markers, even when using an RBW much smaller then the frequency step between the 290 points.
:Question: I'm trying to measure AM modulation but the measurement seems completely wrong. What can be done?
:Answer: When measuring AM modulation you have to carefully adjust some settings otherwise the measurement will fail. More info available in the page on measuring AM modulation
Question: Self test 3,4, 7 and 10 fail. What can be wrong?
Answer: This is happening when the observed level of the calibration output is wong. Did you connect high and low connectors? Is the used SMA cable OK? Did a power level calibration fail? If so, redo the power level calibration and run the self test again.
Question: The Attenuator self test fails (test 10 and 12 in the latest FW). What can be wrong?
Answer: This could be caused by a faulty attenuator. Here you can find how to check the attenuator
Question: Is there an Android App for the tinySA?
Answer: Not yet, but once there is sufficient free time I will have a look.