Frequently Asked Questions

 

Yes, the DW1000 meets RoHS 6 requirements as laid down by the 2011/65/EU RoHS2 Directive.

 

Minimising the carrier frequency offset between different DW1000 devices improves receiver sensitivity.

The DW1000 allows trimming to reduce crystal initial frequency error.

For more details see the section on Crystal Oscillator in the DW1000 datasheet and for registers to use

see chapter 8.1 IC Calibration – Crystal Oscillator Trim in the IC user manual.

DW1000 datasheet and DW1000 user manual can be downloaded from

http://www.decawave.com/support

 

In Software when using DWM1000, DW1000, the output power configuration and control can be altered by using register map register file 0x1E

The use of this register is in great detail explained in the IC user manual and Application note APS023 Transmit Power Calibration & Management

Both are available on http://www.decawave.com/support.

 

For every received frame the DW1000 receiver provides a set of frame-related diagnostic information.

For more information on these diagnostics and other transmit / receive error information see the DW1000 Software API Guide and the DW1000 IC user manual Chapter 4, which describes diagnostic registers.

Both are available on http://www.decawave.com/support.

 

As we are a semiconductor company, we have various partners who may be able to help you. 

Please contact our partners directly or via the Partners page on our website at http://www.decawave.com/partners.

If you have further questions or are not able to find what you’re looking for please contact us at info@decawave.com.

 

To understand the hardware we advise you to study the following documents:

  •  DW1000/DWM1000 datasheet. The Datasheets explain various aspects of the DW1000/DWM1000 like connectivity,​ application Information, capabilities of the DW1000/DWM1000 and much more.
  •  EVB1000 Schematic, it also includes the BOM.
  • DW1000 user manual,

 

DW1000/DWM1000 datasheet and schematic are available from http://decawave.com/support

  •  APS013 DW1000 and two way ranging. This application note explains the implementation ofan example two way ranging application.
  •  APU001 DSC configuration Mode1-16. This application note gives directives on DW1000 depending on the use case.
  •  The DW1000 user manual. A 250+ page compressive document, but start with chapter 2. Overview of the DW1000 and the chapter 12 APPENDIX 3: Two-Way Ranging.
  • In addition we advise you to read the source code guides and/or APIs for the sample programs. This API contains various basic procedures for send and to receive messages.

Software API and sample code is available from http://decawave.com/support/software

 

Yes, the DWM1000 meets RoHS 6 requirements as laid down by the 2011/65/EU RoHS2 Directive.

 

As there is no microprocessor on the DWM1000 module it cannot be certified as delivered by Decawave because its mode of operation is not defined. The mode of operation is decided only when a customer connects a microprocessor and programs the module as part of their end application.

 

As part of the DWM1000 production the crystal has been trimmed and its trim value is stored in the OTP. TX power and RX sensitivity are tested but not calibrated. Further information can be found in chapter 8 DW1000 Calibration of the DW1000 user manual

The DW1000 user manual is available from http://www.decawave.com/support.

 

The EVB1000 does not support the reprogramming of the on board STM32F microcontroller via USB. The EVB1000 has a 20-pin JTAG header which should be used to do this.

 

 

The EVB1000 has no physical UART interface. EVB1000 outputs the results of two-way ranging over the USB port and also to the LCD display. The on board STM32F microcontroller does have an UART peripheral. To enable UART functionality on the EVB1000, both software and hardware changes are required to use this peripheral and output data on it. Please contact DecaWave for details of how to do this.

Moreover the DW1000 SPI interface is accessible through the J6 connector. For further information see EVK1000 user manual for use of the external SPI. Also on board USBtoSPI application can be used to read/write data to DW1000. Please see the DecaRanging Source Code Guide on using USB VC protocol to write and read DW1000 SPI data.

 

EVK1000 boards are calibrated for the default use cases of channel 2 and 5 to have output powers of just below  -41.3 dBm/MHz at the SMA connection point.

For more details see the EVK1000 user manual, available from http://www.decawave.com/support

 

The TREK1000 default configuration as supplied from Decawave supports 8 tags and up to 4 anchors. If support of additional tags is necessary, you should refer to the document “TREK1000 Expansion Options Instructions” available on http://www.decawave.com/support

One can also develop their own tags using our DW1000 IC or DWM1000 module. To assist customers with PCB layout of a DW1000 based product, three files in DXF format are available from Decawave. See APH006 PCB Layout available on http://www.decawave.com/support.

Yes, it is possible to use a 4th anchor.

However, there is only one use case for the 4th anchor, and that is when one wants to locate the tag above the plane of the anchors. If the tag is always below the plane of anchors then the 4th anchor is not supposed to be used. It will not result in any improvement in the location estimation.

For further details see the section 8.2.1 adding a 4th anchor in the TREK1000 user manual.

 

Antenna delay does vary with temperature. Consult the DW1000 user manual where the following is quoted: -

For enhanced ranging accuracy the ranging software can adjust the antenna delay to compensate for  changes in temperature. Typically the reported range will vary by 2.15 mm / ⁰C and by 5.35 cm / VBATT.

The DW1000 user manual is available on http://www.decawave.com/support.

 

The antenna supplied with the EVK1000 and the Partron chip antenna supplied with the DWM1000 are both omnidirectional antennas. The gain of both antennas is frequency dependent with the gain of the EVK1000 antenna higher than the Partron antenna.

The Partron antenna used in the DWM1000 is commercially available under the Abracon brand name as the ACA-107- T. The datasheet for the antenna is available from www.Abracon.com Information on the DWM1000 antenna radiation pattern data as measured by Decawave can be found in the DWM1000 datasheet available on http://www.decawave.com/support#term4

 

Antenna delay is a generic team used to refer to: 

  • the delay between the time a signal arrives at the receiving antenna and the time the arriving message is time-stamped inside the DW1000
  • the delay between the time an outgoing message is time-stamped inside the DW1000 and the time the signal leaves the antenna

Antenna delay will vary slightly between different units of the same design. Depending on the accuracy you require you may decide that you do not need to calibrate out this inter-unit difference. Further information on antenna calibration can be found in Application Notes APS014 "Antenna Delay Calibration of DW1000-based Products and Systems" and APS012 "DW1000 Production Tests".

 

 

In Decawave’s demonstration application the tags and anchors use Two-Way ranging protocol to exchange messages and calculate range/distance between them. To calculate a single range a minimum of 3 messages are needed (if tag needs to be told of the range result, then either this information can be sent via next Response message or an additional 4 th message can be used (e.g. ToF report)).

DW1000 supports various data rates and preamble combinations. Depending on the preamble length and data rate used, a single message can vary between 190 µs (6.81 Mbps, 27 bytes, 128 preamble) to 3.4 ms (110 kbps, 27 bytes, 1024 preamble). This means that time to calculate a single range can vary from couple of milliseconds to tens of milliseconds.

In TDoA systems the blink frame (with preamble length of 64-symbols) and 12 octets of message payload, is around 110 µs this means that RTLS system can support 1700 blinks per second for 1 device or 170 blinks per second for 10 devices etc.

For more information see the DW1000 IC user manual Chapter 9 Node density and air utilisation, available from http://www.decawave.com/support#term4

 

This depends on the RTLS scheme employed, the tag blink rate, the message duration per tag and a number of other factors: -

  •  Data rate;
  •  Number of data bytes;
  •  Preamble length;

For further information one should read the DW1000 IC user manual Chapter 9 Node density and air utilisation. TREK1000 Expansion Options Instructions available as parts of the TREK1000 ARM version 2.10 package available from http://www.decawave.com/support/software

 

It may not be necessary to take any avoiding action depending on the tag density and the tag update rate. If these are sufficiently low then the probability of collisions will be very low and ALOHA-type access rules can be employed.

If tag density is high and high update rates are required then you can avoid collisions between ranging exchanges by dividing time into slots (using TDMA) for each tag's activities. One of the anchors can act as a “controller” node monitoring on-air activity and assigning “allowed” transmission periods to each tag.

 

There are various factors which influence the power consumption of the DW1000 during transmission and reception such as preamble length, data rate, number of data bytes and so on.

Detailed information on power consumption in the various different DW1000 states is available in our DW1000 datasheet and application notes APS001 DW1000 Power Consumption and APH005 DW1000 Power Source Selection. Datasheet and application notes are available on http://www.decawave.com/support

 The human body introduces approximately 30 dB of insertion loss so the transmitted signal from the tag will be heavily attenuated. Depending on the proximity of the tag antenna to the body the level of attenuation may be such that: - 

 

  • no signal at all is received at the intended receiver or the direct path signal is heavily attenuated and only a reflected signal is received at the intended receiver thereby giving an incorrect distance measurement
  • the direct path signal is heavily attenuated but is still received correctly at the intended receiver in which case the distance measurement will be correct.

 Most monopole antennas are designed to operate in free space i.e. not in proximity to the body. Proximity to the body reduces antenna efficiency and fidelity factor. This could distort the UWB pulse and thereby give an incorrect range measurement. The solution here is to design an antenna which takes the body proximity in account. Consult Decawave for more information on this area For more information on non-line- of-sight propagation see the three application notes: APS006 part 1, APS006 part 2 and APS011 Sources of error in TWR available on http://www.decawave.com/support

 

RSSI values can be calculated. See chapter 4.7 assessing the quality of reception and the RX timestamp in the DW1000 User manual (Received Power Level). The DW1000 User manual is available from http://www.decawave.com/support

 

Yes, we provide an abstracted view of the DW1000 register set to the software programmer. This API includes a set of examples demonstrating how to use the API to perform some of the most commonly required operations.

This API and the software source code can be downloaded from: http://www.decawave.com/support/software

 

In order to maximise range DW1000 transmit power spectral density (PSD) should be set to the maximum allowable for the geographic region. For most regions this is -41.3 dBm/MHz. The DW1000 provides the facility to adjust the spectral bandwidth and transmit power in coarse and fine steps.

See for further details APS023 Transmit Power Calibration & Management available from our website: http://www.decawave.com/support

 

For software developers and firmware engineers to debug their software we have an application note. This application note describes step by step debugging of the applications and drivers which control the DW1000.

See APS022 Debugging DW1000 based products systems on our website: http://www.decawave.com/support

 

The DW1000 chip provides a complete PHY layer but does not implement a full MAC, although it does provide some MAC features such as address filtering. In the context of RTLS tags you should carefully consider the necessity for a MAC scheme because these generally require each node to listen for synchronizing broadcasts of some kind. This increases power consumption and reduces battery life.

For more information see the DW1000 IC user manual Chapter 5 “Media Access Control (MAC) Hardware Features” which is available from http://www.decawave.com/support#term5

 

Processor requirements are highly dependent on the end application. 

For a Two-Way ranging (TWR) mobile tag a microprocessor with at least 16k of flash and 4k of RAM should be used to run Decawave’s TWR demo application.

For TDoA based mobile tag application, a smaller microprocessor e.g. with 4-8k of flash and 1-2k RAM may be used.

If you want to minimize system power consumption we recommend using a microprocessor with a fast start-up time and an SPI interface capable of the maximum 20 MHz rate supported by the DW1000.

 

The example EVK and TREK application software source code is built on the ARM Cortex M3 based microcontroller (STM32F105RCT6) which is a 32-bit, little-endian processor. Areas to be considered when using an 8-bit microcontroller are described in Application Note: “APS019 Driving DW1000 from 8-bit MCU v1.0” available on http://www.decawave.com/support#term5.

 

As the package is an industry standard 48 pin QFN 6 x 6 mm with 0.4 mm pitch and exposed ground paddle, we refer customers to JEDEC specification J-STD- 020.1 (March 2008).

This specification is available from the following link: http://www.jedec.org/standards-documents/ PCB land-pattern libraries are available for 3 common CAD packages on the Decawave website.

 

To assist customers with PCB layout of a DW1000 based product, files in DXF format are available on www.decwave.com. These DXF files can be imported into most PCB layout EDA tools and used as an overlay to replicate the DW1000 section of Decawave’s EVB1000 evaluation boards.

Please refer to application note “APH006 PCB Layout” available on http://www.decawave.com/support#term5

 

Decawave and the IEEE 802.15.4a standard specify +/-20ppm crystals. Other crystals meeting this specification should also work provided the guidelines in the DW1000 datasheet are followed. Alternate crystals should of course be tested before committing to a design.

 

We have an application note which explains the different design considerations to take care of, to maximise communications range.

See APS017 max range in DW1000 systems available from our website: http://www.decawave.com/support