SiRad Simple

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1 Drivers

EvalKit SiRad Simple wiki.jpg

1.1 Where can I get the driver to connect the SiRad Simple® ?

You need an FTDI cable (delivered with the sensor). You can download the latest FTDI driver (VCP driver) for your FTDI cable from the FTDI Chip Website [1].

1.2 I installed the FTDI driver for the SiRad Simple® but it does not show up.

Please open the Device Manager in Windows and unfold the ‘Ports (COM & LPT)’ section. You should see a couple of ports there. Now unplug and plug your SiRad Simple® sensor. The sensor is installed properly if you can see another port show up, usually named ‘USB Serial Port (COMx)’ or similar. If this is not the case, please check your connection and if the device has power. Remove the FTDI driver and start over with the FTDI driver installation.

1.3 The FTDI driver for the SiRad Simple® does not work properly.

We recommend using a cable with FTDI chipset (delivered with the sensor) instead of cheaper alternatives since a lot of our customers found the cheaper alternatives to be very unstable.

2 WebGUI

2.1 I cannot store presets in the Preset tab.

Please make sure you are not working in the private mode of your browser and you have enabled cookies, since the presets are stored as cookies.

2.2 I cannot see any output in the WebGUI window.

Please first set the SiRad Simple ® up for the USB connection. For that, check if the two dip switches on the SiRad Simple® are set to the off position and if the jumpers are set according to Section 2.1 of the User Guide. If not, unplug the sensor, adjust the settings, and plug it in again. Also check the FTDI cable connection and if your device is powered properly. Then go to the ‘System Configuration’ tab and chose SER1, regardless whether you are using a WiFi or UART onnection. The SER2 option is reserved for our SiRad Easy® Evaluation Kit. You can also toggle the ‘Close’ and ‘Open’ button of the Com2WebSocket tool without closing the WebGUI and see if that helps. Lastly, you can start over, close all WebGUI / Webbrowser and Com2WebSocket windows, disconnect the SiRad Simple® sensor and start over with connecting the sensor, connecting the Com2WebSocket tool and connecting the WebGUI.
running WebGUI

2.3 The spectrum output jumps (partly).

First, if you are not using the WiFi connection, disable the WiFi module by disconnecting the power jumper J2. Sometimes it is necessary to turn the AGC-Mode off in the ‘System Configuration’ tab and manually choose one of the 4 gains using the gain slider. Further, you can try to manually set and increase the base-frequency in 100 MHz steps to see if that stabilizes the output.

2.4 How does the Auto Gain Control (AGC)-Mode work?

The AGC algorithm uses the first two ramps of each measurement to elaborate the highest gain setting without saturating the ADC or the baseband amplifier. In each of the two ramps the controller samples two gain stages while switching on an attenuation network during the first ramp. After that, the controller has 4 gain settings to choose from for the subsequent measurement.

2.5 Can I trigger the SiRad Simple® manually?

Yes. Please read Section of the User Guide about the triggering options.

2.6 Can I use multiple SiRad Simple® sensors in parallel?

Yes. You can synchronize the sensors using the pre-trigger feature. We suggest either driving them in different frequency ranges so they do not interfere, or you trigger them manually to measure alternately. Please read Section of the User Guide about the triggering options.

2.7 The LED goes off when I connect to the WebGUI.

This is because the WebGUI sends a different configuration to the sensor when it is connected. The LED will light again when the proper serial port (SER1 for the SiRad Simple®) is set in the ‘System Configuration’ tab and the LED mode is hanged from off to 1st target rainbow.

2.8 The RF Parameters tab does not show the min / max frequencies properly.

You can try a manual min / max frequency scan by clicking the ‘fscan’ button three times.

2.9 How do I choose a base-frequency?

The base frequency should be at least 100 MHz above the minimum frequency and far away from the maximum frequency. For small bandwidths, you may choose the base frequency 500 MHz or more above the minimum frequency for an improved signal quality. Please be aware, that in most countries the base frequency has to bet set between 122 GHz and 123 GHz for production purposes by law. Please check your local regulations.

2.10 How do I set the maximum bandwidth in the RF Parameters tab?

Click the ‘max BW’ button three times to set the maximum possible bandwidth for the frontend.

2.11 How do I choose a bandwidth?

The smaller the bandwidth, the greater will the range of the sensor become. However, with larger bandwidths the accuracy will decrease. Please be aware, that in most countries the bandwidth is limited to 1 GHz between 122 GHz and 123 GHz for production purposes by law. Please check your local regulations.

2.12 How can I choose the ramp time?

The ramp time can only be set indirectly by adjusting the ADC clock divider and the number of samples, please read section 3.2.5 of the user guide.

2.13 What is the MTI-Mode?

The Moving Target Indicator mode. When activated, the sensor displays the difference between the current measurement and the average of the previous measurements (set by ‘Average n’ slider).

2.14 There are too many targets. The CFAR operator does not work.

You may experience that there are no targets detected by the CFAR operator although there are plenty of targets visible in the FFT output. If there are too many targets adjacent to each other in the field of view, the CFAR operator may treat those targets like noise floor and calculates an envelope around those targets. Increasing the number of guard cells may help in such a scenario.

2.15 How is the distance information calculated?

All calculations are done on the microcontroller on the SiRad Simple® sensor, so that the reported target distance is already in millimeters. The distance formula used is d = nBin * acc, where d is the distance to the target, nBin is the FFT bin of the target, and acc is the accuracy (see Section 3.3.2 of the User Guide for the formula).

2.16 The update rate of the sensor is very low. How can I improve it?

The update rate is dependent on the chosen parameters in the ‘BB Processing’ tab, in particular, on the ramp time, number of samples, number of ramps, and FFT size. Further, the amount of data that has to be transferred is important. You can select the transmitted frames in the ‘System Configuration’ tab. Using only the target list output, the sensor can reach about 50 Hz update rate

3 Sensor Behavior & Range

3.1 How is the resolution defined?

We define the resolution as the ability to separate two targets in range. The resolution is only dependent on the selected bandwidth. With 1 GHz bandwidth the resolution is 15 cm, 6 GHz bandwidth equals 2.5 cm resolution. In practice, target recognition works from twice the resolution.

3.2 How is the accuracy defined?

We define accuracy as the maximum error of the measured distance to a single target. It is dependent on the number of samples, the bandwidth, the downsampling and the FFT size. If the FFT size is twice the number of samples, the accuracy is two times less than the resolution. We can reach about 1 mm accuracy, also see Section 3.3.2 of the User Guide for the formula.

3.3 Is there a minimum range / blind spot when using the SiRad Simple®?

The minimum range depends on the selected bandwidth. 1 GHz bandwidth works from about 30 cm, 6 GHz bandwidth works from about 7 cm. The blind spot is approximately as wide as once or twice the resolution.

3.4 Can something be detected within the minimum range / blind spot?

Going below the bandwidth-dictated minimum range leads to an increased DC-offset in the FFT output. It could be used to detect ‘something is nearby’ but this is very application-specific.

3.5 What is the maximum range of the SiRad Simple®?

The maximum range is dependent on the target. The SiRad Simple® Evaluation Kit reaches about 40 m with strong targets like buildings.

3.6 Can the range of the sensor be increased?

You can increase the range by assembling the lens delivered with the SiRad Simple® Evaluation Kit, however, the opening angle will decrease. Larger detection distances are possible using bigger lenses or well-designed patch array antennas.

3.7 How is the field of view of the SiRad Simple®?

The area covered by the radar over distance is dependent on the field of view of the sensor. Without a lens, the SiRad Simple® sensor has an opening angle of +/-30 degrees (-6dB). With the lens delivered with the sensor, this can be narrowed to about +/- 4 degrees.

3.8 How can I get directional information from the SiRad Simple®?

SiRad Simple® has a single radar transceiver chip, which is not capable of giving directional information directly. It is possible, however, to use more than one SiRad Simple® sensor to get rudimentary directional information.

4 Protocol & RAW data

4.1 Can I use the the SiRad Easy® with own or third-party software?

Yes. Please read the Protocol Description to get an idea how to control the SiRad Easy® with your own software or third-party software. Due to popular demand we have written some scripts for Octave/Matlab.

4.2 Can I activate raw data only or FFT data only output?

Yes. Please read the Protocol Description about how to set up the SiRad Easy® for raw data only or FFT data only output. You may choose between unwindowed raw data and windowed raw data as well as complex FFT data and magnitude / phase data output.

4.3 Can I use the sensor protocol with <any> device?

Yes. The protocol can be used to talk to the SiRad Easy® from any device, it does not need to be a PC.

5 Schematics & Firmware

5.1 Where can I find the schematics for the SiRad Simple®?

You may apply for a non-disclosure agreement (NDA) with Silicon Radar to get the schematics. Please write an eMail to [2].

5.2 Where can I get the source code for the SiRad Simple®?

The firmware on the SiRad Simple® sensor is not freely available but we are working on the SiRad library with a user friendly C programming API that we may provide to our customers. We do, however, provide the source code for the WebGUI and the Com2WebSocket tool.

6 Lenses

6.1 What happens, if you decrease or increase the distance between the board and the lens?

You can manipulate the beam angle by this method - the closer you are mounting the lens the wider the angle.

6.2 What is the lens made out of?

The material is HDPE (high density poly ethylene).

6.3 Where can I get your lens design?

We can send you 3D data of the lens - a NDA has to be signed. Please write an eMail to [3].

7 Application notes

Can you provide us with application notes?

Since the possibilities with miniaturized Radar sensors seem quite endless, we are unable to provide advice on specific applications.

8 MATLAB / Octave

Can you help me to set up the device for the use with MATLAB / Octave?

A description how you can set up and import raw ADC data into MATLAB / Octave can be found here: Octave/Matlab