Doodle Labs Smart Radio User manual

© 2021 Doodle Labs. All rights reserved. September 8, 2021
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Smart Radio Trouble-Shooting
Guide
Smart Radio Trouble-Shooting Guide
Advanced MIMO Mesh Router for Resilient Private Wireless Networks
Introduction
This is a trouble-shooting guide for all Smart Radio models. The Smart Radio runs Doodle Labs
Mesh Rider® OS, a customized version of Openwrt. This guide is organized in the following
sections
•System Overview
•Trouble-shooting radio access
•Trouble-shooting link quality
•UART and USB ports
•Crashes, reboots and others
•Factory Resetting
•Connect with Technical Support
•References
We recommend reading the System Overview section before jumping to any specific section of
the guide.
System Overview
Fig. 1 shows the default network configuration of the Smart Radio. The radios are pre-
configured so that the entire Mesh Rider network acts like one big distributed Ethernet switch.
Therefore, devices plugged into Mesh Rider will automatically be able to communicate with one
another if they are on the same subnet. Accessing the radios themselves requires them to be
on the same subnet as the host machine.

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Fig. 1 Default Network Configuration
Available Interfaces
Table 1 shows the available interfaces for the different radio form factors. ETH1 is configured by
default as a configuration interface which is not remotely accessible, but it can be re-configured
if necessary.
Table 1: Available Interfaces for Smart Radios
Interface
Embedded (-H)
Embedded (-J)
External
Wearable
Helix
Mesh Rider Radio
Yes
Yes
Yes
Yes
Yes
Ethernet (ETH0)
Yes
Yes
Yes
No
No
Ethernet (ETH1)
Yes
Yes
Yes
Yes
Yes
USB Device Port
No
No
No
Yes
Yes
USB Host Port
-U only
Yes
Yes
Yes
Yes
WiFi Radio
No
No
No
Yes
No
UART
-S only
Yesa
Yesa
Yesa
Yesb
aup to 1 Mbps
bup to 115,200 bps

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Mesh Rider Interface
The Mesh Rider interface is the main wireless interface and is available on all Smart Radio
products. Because it uses a proprietary wireless protocol, it is only accessible from other Mesh
Rider devices. The Mesh Rider wireless interface can be configured in Mesh or WDS AP/Client
modes. The WDS AP/Client mode is a star network configuration where all traffic passes
through the AP. Clients may not directly communicate with one another except through the AP.
APs may not directly communicate with one another except over a wired backbone. In Mesh
mode, all devices are equal and communicate with each other or through other devices.
ETH0 Interface
ETH0 is a standard Ethernet interface and is bridged to the Mesh Rider Interface. You may use
the ETH0 interface for communications between different devices in the network and also to
directly access the radio itself (for device configuration for example).
ETH1 Interface
The ETH1 interface is a standard Ethernet interface not bridged to the Mesh Rider interface. It
is normally used for device configuration. It is possible to modify the interface so that it is
bridged to ETH0 if desired. Otherwise, this interface can be treated as redundant and for most
applications it does not need to be used.
USB Device Port
The USB Device port is a Ethernet over USB interface and can be connected to USB host ports
like those found on PCs, or USB OTG ports like those on Smart Devices. It is bridged to the Mesh
Rider interface. USB Devices can only communicate with USB Hosts and not with other USB
Devices.
USB Host Port
The USB Host port is setup as an Ethernet over USB interface and can be connected to USB
device ports or USB OTG ports like those found on Smart Devices. It is bridged to the Mesh
Rider interface. It’s functionality can be extended by installing addition USB drivers on the
Smart Radio, like USB HID drivers. USB Hosts cannot communicate with other USB Hosts, only
with USB Devices.
WiFi Radio
The WiFi radio is bridged to the Mesh Rider Interface and provides standard WiFi connectivity
to devices such as PCs and Smart Devices. The default SSID is DoodleLabsWiFi and the password
is DoodleSmartRadio.
UART
The UART interface is not part of the IP network, however, it can be bridged to the IP network
using software built into the Smart Radio. The UART interface on the Helix Smart Radios
supports up to 115200 bps while other radios support up to 1 Mbps.

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Configuration Recommendations
We suggest that for initial bench evaluations, start with the default configuration (Mesh). Just
power up the radios and they should establish the wireless link
When changing the configuration of your radio, we always recommend starting with the
Simple Configuration menu available in the web GUI by navigating to Network Configuration
→ Simple Configuration. While configuring your device, take regular back-ups of the
configuration so that in the event that you need to factory reset the device, you can always
recover your good configuration.
Accessing the CLI using SSH
You can access the CLI of the Smart Radio using SSH. Windows 10 and many Linux distributions
come with a built-in SSH client. SSH into the radio using
user@host-pc:~$ ssh root@<IP ADDRESS>
You may need to update your ssh known hosts file with
user@host-pc:~$ ssh-keygen -R <IP ADDRESS>
Trouble-Shooting Radio Access
This section deals with problems accessing the radios. As explained in the System Overview
section, in order to access the radios themselves, host machines do need to be on the same
subnet as the Smart Radios.
“I have never been able to access the radios”
If you have never been able to access the radios, then the likely causes are:
1. Most likely there is an IP conflict on your host machine.
2. There may be problem with the physical connection between the host machine and the
Smart Radio.
IP Conflict Issues
1. Turn off any other networking interfaces on your host machine, for example WiFi.
Although this is not strictly necessary, it could be that your other network uses the same
IP subnet as the Smart Radios.

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2. If you are plugged into ETH0, make sure that your host machine has an IP address in the
10.223.0.0/16 subnet. If you are plugged into ETH1, make sure that your host machine
has an IP address in the 192.168.1.0/24 subnet.
a. If you are using a Windows 10 machine, open up a cmd prompt and type
ipconfig to see the IP address of your host machine.
b. In Linux, open up a terminal and type ifconfig to see the IP addres of your host
machine.
3. Disable the firewall on your host machine.
Problems with the Physical Connection
1. If your host machine is a Linux machine, type dmesg | tail after plugging in the
Ethernet port and see if there is a message indicating that an Ethernet device was
plugged in.
2. If your host machine is a Windows 10 machine, check your network adapter settings to
see that an Ethernet adapter is enabled and connected.
“I can no longer access the Smart Radio”
If you previously were able to access the Smart Radio and can no longer do so, first do a sanity
check on the items in the section above. Assuming your IP configuration is fine and the devices
are connected, you can proceed with the recommendations below.
1. Try the 192.168.153.1 fallback IP address.
2. Try IPV6 instead.
3. Factory reset the Smart Radio. This topic is discussed the the section Factory Resetting.
Using the fallback IP address
Make sure to power down any other Smart Radios in the network and only have the local Smart
Radio powered. Change the IP configuration of your host machine and add a new IP address in
the 192.168.153.0/24 subnet. Attempt to access the Smart Radio at 192.1681.53.1.
IPV6 Login
1. First bring down any unnecessary interfaces like WiFi.
2. Power down the other Smart Radios in the network to that you are sure you are
accessing the correct radio.
3. First find out the index number of the interface connected to the Smart Radio. Open up
a cmd prompt and type (ignore the $sign)
$ netsh interface ipv6 show interfaces
Idx Met MTU State Name
--- ---------- ---------- ------------ ---------------------------
1 75 4294967295 connected Loopback Pseudo-Interface 1

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16 35 1500 connected Ethernet
4. In this case, the index is 16. Next, run
$ ping -6 fe80::%16
Pinging fe80::%16 with 32 bytes of data:
Reply from fe80::%16: time=413ms
Reply from fe80::%16: time<1ms
Reply from fe80::%16: time=2ms
Reply from fe80::%16: time=1ms
5. Assuming the ping worked, we can check the ipv6 address of the Smart Radio with
$ netsh interface ipv6 show neighbors
Interface 16: Ethernet
Internet Address Physical Address Type
-------------------------------------------- ----------------- -----------
fe80::230:1aff:fe4e:aabc 00-30-1a-4e-aa-bc Stale
(Router)
a. From here, we can see the ipv6 address (in bold). Note that the corresponding
physical address is starts with 00-30-1a which is true for all Doodle Labs
products. So you can try logging in with
ssh root@fe80::230:1aff:fe4e:aabc%16
6. Once you are logged into the CLI, you can check the ipv4 address of the br-wan
interface
root@smartradio:~# ip a show dev br-wan
6: br-wan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
group default qlen 1000
link/ether 00:30:1a:4e:aa:26 brd ff:ff:ff:ff:ff:ff
inet 10.223.187.38/16 brd 10.223.255.255 scope global br-wan
valid_lft forever preferred_lft forever
inet 192.168.153.1/24 brd 192.168.153.255 scope global br-wan
valid_lft forever preferred_lft forever
inet6 fe80::230:1aff:fe4e:aa26/64 scope link
valid_lft forever preferred_lft forever
Trouble-Shooting Link Quality
This section covers trouble-shooting problems with the link quality. If you are looking for
information on optimizing the link quality, please read the guide, “Optimizing the RF Link”, in
our technical library [1]. This section is broken down into three sub-sections which cover
1. No wireless link

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2. Poor throughput at close range
3. Poor long-range performance
“The radios are not connected to each other at all”
Make sure you can access the radios before trouble-shooting the wireless link. If the radios are
not connected to each other at all, then the most likely causes are:
1. The radios have been configured in different modes
2. The antennas are not connected properly
3. Power supply issues
The radios are configured in different modes
This could happen if you have inadvertently configured one radio in WDS AP/Client mode and
another in Mesh mode or both radios as WDS AP for example. Navigate to the wireless
configuration in the web GUI and check whether the mode is “station”, “master”, or “mesh
point”. Make sure the two radios are in compatible modes. We suggest using the Simple
Configuration menu to configure your radios.
The antennas are not connected properly
Make sure that the connectors on the antennas are compatible with the connectors used on
the cables. RP-SMA (reverse polarity SMA) is not compatible with SMA.
Power Supply Issues
Make sure to follow the power supply recommendations of the particular model which you
have ordered. The power supply must be of the correct voltage and have sufficient current
sourcing capability to power the radio.
“The throughput is poor even at close range”
As the radios are optimized for long range, they do not work well when they are within a close
range of each other. At close range, the radios are likely to saturate the RF front-end, resulting
in poor performance. For bench evaluation, please use RF attenuators supplied in the Eval kit.
You should also reduce the output power of the radios and not use high gain antennas. , It is
further possible to enable Transmit-Power Control (TPC). Note that TPC is only recommended
for point-to-point networks.
If the radios are more than 5-10 meters apart and the throughput is still poor, then it could be
an interference or power supply issue. Please see the advice in the next section.

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“The radios are connected, but the range is poor”
This could be a rather wide topic. The datasheets provide typical performance over distance
assuming a reasonable fade margin (10-15 dB). The fade margin accounts for variations in the
link quality due to things like antenna misalignment or environmental noise. The most common
reasons for poor range are:
1. Not adhering to recommended Fresnel Zone clearance requirements
2. Noise and Interference
3. Power Supply Issues
4. Overheating
5. Poor choice of antennas
6. Antenna cable loss
We will only briefly discuss these topics. Before covering these topics, if your radios are linked,
then you can use the “sysutils checklink” program to perform a quick link check. Setup the two
radios 10m apart from each other and point the antennas straight upwards. Then SSH into one
of the radios and run
root@smartradio:~# sysutils checklink -d 10 -h 10.223.216.116 -g 3
Note that -d 10 means 10m distance, and -g 3means 3-dB total antenna gain (this is the
combined antenna gain for both radios, e.g. 2 dBi on radio 1 and 1 dBi on radio 2). The program
takes about 1 minute to run, and will perform link test between each antenna. At the end of the
test, a log file will be saved at /tmp/results.json. The results report the expected RSSI and
measured RSSI, as well as the link throughtput per antenna. An example is shown below
{
"distance": "10",
"total_antenna_gain": "3",
"frequency_band": "2442",
"expected_RSSI": "-37",
"RSSI1": "-42",
"RSSI2": "-58",
"throughput1": "23987123",
"throughput2": "24518300"
}
The peak single-antenna throughput is approximately 40-45 Mbps per 20-MHz channel
bandwidth per antenna. In the case above, we are getting around 24 Mbps in a 15-MHz
bandwidth due to interference. The expected RSSI was -37 dBm, but the measured RSSI was
significantly lower (-58) on the second antenna because of misalignment.

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Fresnel Zone Clearance
The required Fresnel Zone clearance is the radius around the line-of-sight path which must be
clear of obstancles. The Fresnel Zone clearance is frequency dependent, so we recommend
using an RF calculator to calculate the required clearance for your application. Drone
applications typically do not need to worry about Fresnel Zone clearance, but it is critical for
unmanned ground vehicles (UGV).
Noise and Interference
Background noise and interference has a direct effect on the achievable range. The 2.4-GHz ISM
band may be the most crowded frequency band in the world due to the ubiquity of 2.4-GHz
WiFi. Therefore, the achievable range in urbanized areas is notably poorer for the 2.4-GHz band
than other bands. Aside from the 2.4-GHz band, the 915-MHz band and the 5-GHz bands are
also license-free and may be highly congested depending on where the radios are being
deployed. You can measure the level of the background noise picked up by the radio using the
built-in spectrum analyzer on the wireless configuration page. This is only accessible in the
Advanced Settings. The figure below shows the wireless page with Advanced Settings enabled,
and a Spectrum Scan button available for the radio0 interface. The spectrum scanner is only
available for 10 MHz channel bandwidth or greater.
Fig. 2 –Wireless page with Spectrum Scan available
If you perform a spectrum scan, the radio will scan all channels. We recommend narrowing in
on the desired operating channel to check the noise performance as it will be faster and more
accurate. Note that the thermal noise floor is approximately -116 dBm per FFT bin in a 20-MHz

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bandwidth. The operating range is reduced by 2x for every 6 dB increase in the measured noise
above the thermal nosie floor.
Fig. 3 –Spectrum Scanner results
Power Supply Issues
Please make sure to follow the power supply requirements mentioned in your product’s
datasheet. The Smart Radios have voltage and power requirements. Most AC/DC regulators
specify an output voltage, and the maximum current they can supply. The maximum power
they can supply is simply the voltage multiplied by the current (in amperes). So a 9-V, 2-A
adapter can supply 18-W of power. Additionally, for best performance, power supply lines
should
1. be short to minimize the IR drop
2. be twisted (ground and supply) to minimize their inductance
a. if they cannot be twisted, keep them as close together as possible
3. be routed in a star topology. The power lines should never be daisy-chained
a. the center of the star should be as close to the power supply as possible
Some power supplies are noisier than others. Devices such as powerful motors create supply
noise when they pull current from the source. The Smart Radios have power supply isolation
built in, but their effectiveness depends on how noisy the supply really is. If you are unsure
whether your supply is causing a problem, power the Smart radio from a separate battery.