We have recently switched from a DW1000 to a DW3220 on our PCB. With that, we see a significant decrease in range, from way over 200m to below 80m under LoS conditions.
We have not changed the HF design (apart from removing the balun and re-matching), nor the antenna. Also, we are using the same configuration (channel 5, preamble length, datarate, …) in both cases which rules out a configuration issue.
We use the DW1000 driver/API v5.1.0 and the DW3000 driver/API v4.0.0.
- Are there any known issues in DW3000 driver/API v4.0.0 regarding range?
- Are there any extra steps the DW3220 requires to get optimal receiver sensitivity, that differ from the DW1000?
Have you set the Tx power to give the same power out of the antenna for the two units? I’d expect this to require different gain settings for the two parts.
Thanks for the reply!
Tx power was also my assumption at first, so I cranked it up to recommended maximum for both cases:
0x1F1F1F1F for the DW1000, and 0xFEFEFEFE for the DW3220.
But they may have different maximums.
Without doing a calibrated test to set them both to the same output power it’s hard to know what the actual power levels are.
Since they are using compatible radio settings one test you could do:
Set a DW1000 transmitting at a constant rate.
Have a DW1000 and a DW3000 listen to the messages and count how many the see. Since you know the transmit rate you can easily work out the percentage of messages seen (which should be 100% or very close to it for short ranges).
You can then see how far away you can get before the reception rate drops below a certain point (say 80%). Since they are both listening to the same thing that will give you a good measurement of relative receive sensitivities of the two systems.
You could do something similar to give you an idea of Tx power comparisons. Set a DW1000 to a lowish (say 10dB) output gain. See how far away you can put a second DW1000 and still reliably receive the signal. Now replace the transmitter with a DW3000 but keep the receiver the same. See what gain setting you need to use to get the same reception rate at the same range.
While this won’t give you the required gain settings for regulatory approval and is no substitute for real power testing it should give you a good indication of the difference in gain needed to get the same transmit power.
Andy, you put me onto something here with checking the transmission side. Thank you!
I compared transmission powers using a spectrum analyzer, same Rx antenna, distance and orientation.
I measured the apparent power I see from both devices (Tx power settings as above).
Turns out, the DW3220 creates a signal about 10dB lower in peak than the DW1000 does with maximum TX_POWER register settings.
Will now check my transmitter configuration block is correct. It looks like the procedure for the DW3000 differs from how the DW1000 did it.
Maybe someone from Qorvo could comment:
Could it be that the DW3220 transmits 12dB less maximum power than the DW1000 does, by design?
Obviously it depends on a lot of different factors, your design, antenna, packet settings/sizes etc… but we found that on channel 5 the DW1000 would hit the FCC limits with a transmit gain of around 8-9 dB. So all things being equal a 12 dB drop in power means you’re still able to hit the regulatory limit.
Sure if you can get away with ignoring the limits then the lower power is a pain. But that’s not where the money is, the money is in volume applications and they have to stick to the limits. As such I would imagine that a drop in power isn’t something that Decawave/Qorvo would worry about.
I understand, that would be a valid decision to make given the typical market.
This would also explain why the DW1000 is marketed with an range promise, while there seems to be no such promise for the DW3000 family
(Im not a Qorvo guy) but the range promise can be archived with certain settings. But they are many limits so it is harder to use it. For UWB devices you still need to keep in mind that there is regulations that limit the TX power very low and both devices DW1K and DW3K can archive this limit.
But you are correct the DW1000 maximum power level is higher that DW3K.