Accuracy, Precision and Resolution
Would you be able to tell the difference between accuracy, precision and resolution?
Accuracy refers to how close a frequency or power measurement is true to reality, whereas precision states measurement repeatability within a certain error margin. Check here for more details.
In general terms, accuracy and precision are of the same magnitude in RF Explorer so we may only specify one of them.
Resolution is a function from the selected frequency span. The wider the span the lower the resolution.
RF Explorer specific Frequency Accuracy
| RF Explorer Model | Frequency accuracy | Internal reference device | |
|---|---|---|---|
| Signal Generator RFE6GEN | 0.5ppm | Advanced TCXO | |
| Signal Generator Combo | 0.5ppm | Advanced TCXO | |
| 6G COMBO PLUS | 0.5ppm > 240MHz | Advanced TCXO and 30MHz XTAL | |
| 4G Combo PLUS | 0.5ppm > 240MHz | Advanced TCXO and 30MHz XTAL | |
| WSUB1G PLUS | 10ppm | 30MHz XTAL | |
| ISM Combo PLUS | 10ppm | 30MHz XTAL | |
| 6G Combo | 0.5ppm in 6GHZ 10ppm below 3GHz | Advanced TCXO and 30MHz XTAL | |
| WSUB1G | 10ppm | 30MHz XTAL | |
| 3G Combo | 10ppm | 30MHz XTAL | |
| 2.4G | 10ppm | 26MHz XTAL | |
| ISM Combo | 10ppm | 26MHz and 30MHz XTAL | |
Internal reference device specifications:
| RF Explorer 6G WB PLUS | Standard | RFELIC03 | RFELIC03 + RFELIC05 |
|---|---|---|---|
| Expansion Frequency Range | 15MHZ-6100MHz | 15MHZ-6100MHz | 15MHZ-7500MHz |
| Expansion Frequency Span | up to 960MHz | up to 3000MHz | |
| Mainboard Frequency Range | N/A | ||
| Mainboard Frequency Span | N/A | ||
Crystal tolerance is not the only factor that has influence in the initial accuracy of the unit. PCB parasitic capacitance and manufacturing tolerance plays an important role at these high frequencies. Due to this, you may expect up to +-100ppm initial value tolerance when uncalibrated for a crystal based device.
However, aging and stability is maintained within +-10ppm, in this case the crystal is the dominating factor (the parasitic capacitance is a manufacturing error and is not influenced by age or temperature).
Note
TCXO based devices are inmune to PCB capacitance.
Regardless of accuracy, the most limiting factor is resolution. Understanding it will help to get the best value from your instrument.
There are 112 sweep steps in RF Explorer Spectrum Analyzer screen. Therefore, the maximum resolution you can get is FreqSpan/112.
In other words, for a frequency span of 10Mhz, you get a resolution of 10,000Khz/112=89.3Khz . With this span in the 433Mhz band, it is clear that 89.3Khz is a larger value than 4.3Khz and therefore the accuracy doesn't play as much as an important role as resolution.
If you now reduce the span to 200Khz, then resolution gets as fine as 200Khz/112=1.8Khz . In this case, the resolution is finer than accuracy and then accuracy is the main factor to consider.
Frequency Calibration demonstration video
We keep developing additional firmware features to offer additional calibration capabilities to reach sub-KHz accuracy and better amplitude accuracy in all bands.