HX7TR RFID Ultrasonic Positioning System

Hx7 is a high speed precision positioning device, using ultrasound plus 2.5GHZ local link and Wi-Fi rf. It can be used to form a high resolution positioning network, covering wide area as well as small localized operation. The hx7tr is a transceiver, it serves as both ultrasonic transmitter and receiver simultaneously. Any hx7tr may be mobile or stationary, and the coordinate frame can be dynamic. E.g. quadcopters drones can form coordinate (frame) reference points in mid air, to allow other drones to work together within that spatial zone. The hx7tr comes with a high resolution Gyroscope and Accelerometer, the IMU data is fused into every positioning data block to allow realistic motion logging. Every device in the ratsnest network knows the distance to the next. These distances including IMU orientation data is relayed to the user via standard USART TTL or Wi-Fi. All or selected devices have the ability to be hot spots (access point) or a station on a standard domestic router. I.e. any and every device can join the internet of things IoT.

  ultrasonic 3d positioning

Above: HX7 positioning four point ratsnest illustration

The 4 point hx7tr ratsnest creates 6 scalars which can be turned into vectors. Similarly 5 point ratsnest results in 9 distance scalars. Every Hx7tr device in the hx7 network can be accessed directly using an IP number over the internet.

          APPLICATION Examples             FEATURES
  • Quadcopter Indoor Navigation 
  • 3D Studio and Filming
  • Immersive Virtual Reality
  • Automation and Manufacturing
  • Robotics Guidance and Tracking
  • Speed of sound measurements
  • Echo Ranging Level Detection
  • Dynamic 3d temperature graphs
  •  Range up to 14 Meters
  • High Precision (typically 2mm)
  • Fully wireless
  • Standard USART TTL interface
  • 802.11 Station via router
  • Hot Spot Access point Interface
  • Sampling up to 45s/s
  • Modular

The echo ranging feature

During the measurement cycle the echo from the device's own activity is also logged and recorded. While the system logs ratsnest distances the distance from each device to its nearest object is also measured. This data may be used for collision avoidance and etc.


The hx7tr is a modular device it is created by stacking up modules. The basic unit contains a signal conditioner, processing unit and synchronizing 2.4GHZ rf module. Additional modules are also available such as 802.11 link, Wi-Fi link, hot spot access point IoT. Using extension modules, multi-purpose devices can be constructed for the end application without soldering or electronic skills.

Software Bundle

The hx7 comes with a software bundle written in visual basic 6 and PYTHON, this software provides access to hx7 data via USB serial and IP socket client. It also builds 3d coordinates (x,y,z) from the available ratsnest distances.

Operation and Functions

Each hx7tr device has its own unique identity. When the device receives a string through its TTL interface, it compares characters from the "first in the string" up to & (ampersand) to its unique identity. If there is a match or partial match the device will regard data following the ampersand as commands (it ignores spaces between commands). The device ID may be arbitrarily chosen, i.e. a new ID for the device can be entered at any point. Once it has a new identity it will respond to this new identity.

The evaluation pack comes with a TTL terminal console with a floating command panel written in PYTHON. The source code is simple and open. PYTHON programs run on most major operating systems, and connect to the hx7tr assembly either through wifi (802.11) or a com channel.

Syntax: ID& instruction1 instruction2 instruction3 ... instructionN

hx7 floating instrument panel

The above command if entered using the enter key will call for drone1. If drone1 is in range, unit 1234 will display the distance from it to drone1 with latency depending on range... from about 20mS and up. If the IMU is enabled then the Gyro and Acceleration will also be displayed in the console. For more information about this program.

Command examples and what they do

Given the identity of a device as T1234, the user's TTL string can look like this:

T1234& ip:0x10:0x60  ig:0x0F  ig:0x20

This TTL string will cause device T1234 to put the hexadecimal value 33 into LSM6DS0 control register and read the content of hex locations 0x0F and 0x20

Here is another TTL string

T1234& d2.3 f3.5  ca:1234

if in fact the distance from T1234 to the object is 3.002m the output string returned is

 R1234 X1234 A3002

When the device calls itself it returns an echo. Command d (dead time) and f (flight time) can be used to create a focus envelope around an object of interest. The nearest object somewhere between 2.3 and 3.5 meters away will trigger the echo.

Assuming device Tpete is in range

T1234& d:2.3 f:3.5 mu:1234,pete| a:10 as ms

This statement will cause T1234 to return the distance to the nearest object, and return the distance from device 1234 to device pete, this cycle is repeated every 10x8.2 mS or 12 times per second.

If distance from 1234 to pete is 10.3 meters and the object in previous example is still in place the output string is:

R1234 X1234 A3002

R1234 Xpete A10300

The user can rename every device e.g.:

T1234& me:(x2m,y3m,z4m)|

Then for the pete device the output string will look like the following:

Rpete X(x2m,y3m,z4m) A10300

pete is located on the surface of a sphere with the center at coordinates (2,3,4) With two more coordinates added, pete will have enough information to compute own position within the reference frames of these three points.

All the devices are linked through RF so they can be manipulated remotely. To change the name of the device called pete do as follows:


From here on the device named pete will answer to a call for george 

Note that the first letter in the string can't be changed. It is a part of the system's inner exchange protocol.

Example using the PYTHON console

Hx7tr Specification

Hx7tr WiFi access and IoT

Hx7tr Command Summery

Hx7 evaluation kit


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