QM35825 Practical RTLS Range Guidance for Tracker Anchor/Tag Deployment

Wireless Connectivity Ultra-Wideband
1

Good day,

We are evaluating an RTLS setup using uTracker boards based on the Qorvo QM35825 UWB chipset.

Our current test setup uses two uTracker boards:

  • One board configured as Anchor / Controller
  • One board configured as Tag / Controlee
  • FiRa TWR ranging is used between the two devices
  • Final target system: one moving tag communicating with multiple fixed anchors
  • Deployment environment: indoor, mostly line-of-sight, with expected wall/ceiling multipath
  • The QM35825 and antenna/RF path are integrated into the device PCB/enclosure, so practical range may depend on antenna placement, surrounding electronics, enclosure material, and mounting orientation

We would like your guidance on the expected practical installation range for this hardware.

Our questions are:

  1. For a QM35825-based anchor/tag RTLS setup, what practical line-of-sight ranging distance should we normally expect indoors?
  2. Is 20-30 m spacing between anchors/tags a reasonable initial deployment target for an indoor/tunnel-like environment, assuming good antenna placement and line-of-sight?
  3. How much can practical range be reduced when the QM35825 antenna is integrated inside a custom device/PCB/enclosure compared with an ideal reference board or external antenna setup?
  4. Are there recommended guidelines for antenna placement, PCB layout, enclosure material, mounting height, or orientation to maintain reliable ranging around 20-30 m?

We are not asking for a guaranteed range specification. We want to understand whether 20-30 m is a reasonable deployment assumption for QM35825-based RTLS, and what design/test conditions should be satisfied to achieve reliable performance.

Best regards,
Azimbek

2

Hi @Azimbek,

Can you clarify what are the uTracker boards that you are referring to? Do you have a link for these?

20 - 30m seems reasonable. Which channel are you looking to use?

3

Hi @akash,

The uTracker board is our custom PCB with a soldered-down UWB (Qorvo QM35825) module integrated on the board. The UWB module is not used as a separate plug-in device; it is part of the board-level design. It is not a commercial board, so we do not have a public link yet. Our current default is channel 9. The firmware also supports channel 5.

Thank you,
Azimbek

4

Hi @Azimbek,

Understood, thanks for sharing. Ultimately, the best answer to your questions is to just test it as there are many factors including antenna, enclosure, etc. that can impact your range performance. We have a few app notes that would be good references for this topic on our page here: Application Notes - Qorvo

  • APH5801 - QM3582x Hardware Design Guide
  • APS017 - Maximizing Range in DW1000-Based Systems (principles can apply to QM35 designs as well)
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5

I would be surprised if it can’t do 30 meters generally. The QM35825 incorporates an LNA (low noise amplifier) to increase receive sensitivity which helps improve range.

Also, it matters some what jurisdiction you operate in. In Europe, specifically, they allow a +10 dB power increase for indoor operation. The QM35825 includes a PA (power amplifier) which provides the ability to reach those new power levels. This does come at increased power consumption, and so far, I think it only applies to CE (Europe) devices, but is a nice regulatory change for some use cases.

I would be surprised if you can’t achieve 30 meter radio range with the QM35825 module using normal transmit power levels, and 50 meters if you get the +10 dB Europe power increase.

Disclaimer: this is based on our work with the QM33110W with LNA QM14068, which gets 70 meters on channel 9 (but with our own antenna design), so we expect the QM35825 to be reasonably similar given the QM35825 derives in large part from the QM33xxx series. We have not actually use the QM35825, though we have used the DK and designs in progress as we speak.

A properly designed enclosure will have relatively little impact on performance.

Plastic is a dielectric, so when it gets near the antenna, it will detune it somewhat, so best practice is to keep some clearance from the plastic housing to the antenna. Typically, 10 mm is enough, and we violate that often in our designs with minimal impact.

Any metal near the antenna is a problem, so keep that away. Even a small screw can have a meaningful impact on the antenna pattern.

The module datasheet will usually give keep out zones and clearances.

As far as I know, there is no official QM35825 module from Qorvo. Which module are you using and what does the datasheet say?

I think you will be okay if your device is reasonably designed.

Mike Ciholas, President, Ciholas, Inc
3700 Bell Road, Newburgh, IN 47630 USA
mikec@ciholas.com

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