Not directly answering your question, but here is a suggestion:
Use a near field probe and spectrum analyzer to sense 499.2 MHz. If you place the near field probe right over the DW1000, you can clearly see the PLL output of 499.2 MHz. The signal might be strong enough for some frequency counters if you don’t have a spectrum analyzer.
The beauty of this method is that it requires no connection to the device under test, and it requires no special software or setup, just that the DW1000 has the PLL operating (IDLE or above mode) which is often the natural case. Observe the 499.2 MHz signal and then adjust XTAL-TRIM until you get it near ideal.
Instead of 499.2 MHz, you can look for 124.8 MHz as well. Usually the 499.2 is easier to see in our experience. If you do enable the GPIO0 clock output, it operates at 62.4 MHz and you can see that as well with a near field probe, but there’s really no point to doing that IMO.
You can also near field the CW signal (say ch 5, 6489.6 MHz) as well. This requires putting the DW1000 into CW mode, of course. Outside of CW mode, there is no viable way to check carrier centering as the UWB signal is way too wide to make any such determination.
The use of a near field probe can help you check the health of the clock system on a DW1000 which is absolutely critical to proper function.
Observing the 38.4 MHz clock tells you if you are getting a good clock input and what is its offset from ideal. This check doesn’t involve any PLLs.
Observing the 124.8 MHz or 499.2 MHz clock shows you the health of the first PLL that most of the DW1000 depends on. By looking at the spectrum, you can see if it is sharp or has side lobes and/or broad width. This indicates a bad input clock (noisy, say), or bad PLL loop filter on CLKTUNE.
Observing the carrier in CW mode (depends on what frequency you select, channel 5 is 6489.6 MHz) tells you about the second PLL health and PLL filter on VCOTUNE.
You can buy near field probes, or you can make one. Take an SMA connector and put a small loop of wire on it. Presto, near field probe. A two turn loop of about 10 mm diameter is just about ideal for 499.2 MHz.
Mike Ciholas, President, Ciholas, Inc
3700 Bell Road, Newburgh, IN 47630 USA
+1 812 962 9408