1.Will this TWR be extendable to a full system?

Yes, at the time you decide to go to full TDoA version, you just re-flesh Tag and Anchor memory with new firmware, which we provide you. In order to extend to TDoA version, you need to buy TDoA software licence. Ask us for a quotation.

2.How to scale RTLS TWR system, what are the limitations?

Yes, you can add up to 10 Anchors and 20 tags. Easy tag and anchor configuration is described in the datasheet. In order to have new anchors visible in the Sensmap, you need to add the anchors manually in RTLS menu in the Node setup.

Follow the steps in Tag set-up according to the datasheet.

Follow the steps in Anchor set-up according to the datasheet.

3.Do the anchors in TWR communicate wirelessly?

Yes, all anchors measure distances from tags and wirelessly transmit data to the master anchor that composes UPD packet and sends it through the ethernet to RTLS server.

4.Is it possible to set configuration over the air?

No. RTLS TWR kit provides only Terminal configuration. Wireless configuration and management is native part of RTLS TDOA system, please upgrade to if necessary.  

5.Why I cannot use database and see history within RPI2 RTLS Software?

Raspberry PI 2 does not include Real Time Clock, thus there is no time reference to timestamp positioning data. Second reason is that operating system and storage place are located on SD card, which has very limited write cycles. To overcome this limitation please ask for RTLS software distributed as virtual image.

6.What is the highest refresh rate?

TWR technique requires three messages to be transferred between tag and each anchor in order to get location, more info can be found here. Furthermore, the system is designed in a way where each Tag has pre-fixed time-slot required for a communication to avoid collisions. Therefore, the maximum refresh rate is  depended on total number of Tags and Anchors within the system RTLS TWR system. The refresh rate is also dependent on radio mode selected, where each mode requires different occupancy over the channel.

Implicitly the RTLS TWR Kit is preset for 5 Anchors and 5 Tags which gives the highest refresh rate  2.5Hz (391ms).

For example, 1 Tag and 5 Anchors gives maximum refresh rate 35Hz (28ms) for RF Mode 1, while 10 Tags and 5 Anchors gives refresh rate 4.4Hz (227ms).

Spreadsheet for refresh rate calculation and battery lifetime is available on email request.

If particular application requires high refresh rates for multiple tags, RTLS TDOA system is preferred.

7.Configuration Parameters Explanation

The RTLS TWR Kit provides several configuration parameters for both Tag and Anchor, please see the picture below:

rtls_twr_kit_config_params

The channel access is based on time division multiple access in other words each tag has dedicated time-slot for its communication. The time-slot scheme is prefixed. Each time-slot is given by the device address number. All parameters above marked with green color must be set equally on all tags an anchors within the system. While address must be unique per device. 

Tag address must be set consecutively 0x1001, 0x1002, 0x1003, 0x1004, 0x1005 .
Anchor address must be set consecutively  0x0001, 0x0002, 0x0003, 0x0004, 0x0005 .

The system is designed for the lowest energy consumption and for the highest refresh rate, therefore there is no communication overhead for solving collisions or in appropriate config settings.  

TDMA Scheme:

 

 

rtls_tdma_operation

 

 

8.RF Modes Explanation

There are three RF modes available. The lower RF mode number the better signal robustness and range, but the longer transmission time. The better signal robustness might help in scenarios where line of sight between anchor and tag cannot be achieved or devices are on a border of their communication range.

RF0 (Data rate 110K) – the most robust, the longest transmission time, 14ms/ranging

RF1 (Data rate 850K) – the less robust, the faster transmission time, 2.5ms/ranging

RF2 (Data rate 6M8) – experimental – do not use

In order to change RF mode over the devices please continue here. Please keep in mind that the same RF mode must be set on all tags and anchors within the system.

9.How parameters affect accuracy?

The key thing for the accuracy is a correct placement of tag and anchor. Please follow the description here.

Furthermore the signal robustness might be increased with selecting lower RF mode number.

Other parameters such as power level (higher) or channel (lower) can increase a range.

10.What is maximum number of devices within system?

Maximum number of Tags is limited to 100, while number of Anchors to 10. More devices are supported within RTLS TDOA system.

11.How to reset software to initial settings?

In case of Raspberry Pi please follow this section. For a virtual image RTLS Software, please remove the current image, download and add a new virtual image. 

12.Is it possible to connect into linux machine where RTLS Software is running?

Yes. There are several options:

For a file transfer WINSCP client is recommended, user/password sensmap/sensmap .

For a command line please use Putty, user/password sensmap/sensmap. 

For a database access please use http://10.0.0.1/phpmyadmin .

 

13.What is the communication range of your UWB devices?

We use integrated chip antennas in our devices. The reliable distance using maximal transmission power reaches around 60 meters, however it strictly depends on the data rate configured.

The maximal range between Tag and Anchor can be up to 50m.

The distance between Anchor and a Master Anchor shall not exceed 30m, in case we need ranging and a precision. In general the communication range can be up to 100m base on Tx power, but we loose the accuracy.

14.Is the mentioned MySQL database available on the Raspberry Pi, or only the mentioned http-interface?

For performance reason, rPi supports only real-time locationing, storing data to MySQL database is not supported. If you need history, you can get VirtualBox image of RTLS TWR Software with MySQL database preinstalled.

15.Do we need to have preinstalled software running in order to get locations?

In case you get our RTLS kit, you always have Rapsbery Pi with running RTLS server. You can get a position data only in Real-time. In case you want to save location data, you need to install a VirtualBox to your PC. For a licence fee we provide an extended version of RTLS server which allows you saving the data.

16.Can we integrate the VMware rtls server / sensmap server with our own database / servers?

Yes, go through the API documentation to see more details about server interfacing:  HTTP API link HERE.

17.Does your software run on the server inside the building or is it in cloud?

It is way how the RTLS kit is designed. The RTLS server runs at Rapsbery Pi or at your PC by using VirtualBox with history. The server is accesible via HTTP interface.

18.What is the size and weight of the tags?

We provide two versions of the tags, both compared in a comparison table.

19.Do you provide a tag multicharger?

Li-Ion tags are charged through the mini USB connector, therefore the multicharger does not present a significant issue.

 

20.Why Tags stops update positions if I left it alone for a while?

This is because of internal motion detection feature. It can be disabled via terminal, please follow follow this section.

21.What is the energy consumption of Tags?

The energy consumption is parametry affected by the requirement on refresh time of position estimation, communication distance, number of monitored Tags and dimensions of area, where RTLS system operates. Therefore it is suitable to know these parameters in advance in order to estimate the energy profile of Tags. The Tags are equipped by the 600 mA Lion battery.

For an example with a refresh rate of 2 seconds, the battery life reaches about 35 days.

However, if your application requires to reach battery life of month we can offer it as well since the Tags for final application can be equipped with more capacitive battery. Actually, since we provide full customization service of all the hardware and software, you can send us in future requirements for final customization.

TDoA version is significantly reducing the energy consumption.

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