Frequently Asked Questions

Each M138 Modem includes a GPS patch antenna, a U.FL to SMA cable, and a Swarm 1/4 wave VHF antenna that is tuned to Swarm’s operating frequencies.

A device’s activation date is the first of the month following when ≥50 messages are sent. For example, if you send the first ≥50 messages on Feb 17th, the activation date will be March 1st and your data plan will annually renew each March 1st. Please see Terms & Conditions for further details.

Data messages will remain on the modem for 48 hours by default after which they will expire if not transmitted. The 48 hour expiry time can be configured as needed by following the instructions in the Product Manual.

The Swarm Modem can queue a maximum of 1000 outgoing messages and 1000 incoming messages. Each type of message is stored in separate files. Customers have the flexibility to break up each larger packet into smaller packets as needed.

Messages that are queued on the Swarm Modem can be read, counted, and deleted using the $MT command. Complete usage instructions can be found in the Product Manual available on the Documentation page.

The Swarm Modem does not manage data “bundling”. Each message is treated as a single packet and is transmitted as such within the system. A designer can choose to bundle messages outside of the Swarm Modem and optimize for package usage if desired.

The Swarm Modem communicates via a standard 3.3V CMOS serial UART interface, or a PC interface with a USB-to-serial converter.

Swarm Modems do not currently support LoRa.

More information regarding power requirements for the Swarm Modem can be found in Section 4.3 of the Product Manual.

The Swarm Modem only communicates via a standard 3.3V CMOS serial UART interface, or a PC interface with a USB-to-serial converter. Please include any necessary signal conversion circuitry if you would like to use another communications protocol in your device.

No, the Swarm Modem does not allow for any user code to be loaded onto it.

GPS cold start (From power off, or more than 4 hours from last fix) takes ~30 seconds depending on your installation location.

GPS hot start takes 5-10 seconds if the last GPS fix was < 4 hours ago, and if the Swarm Modem has been powered on, or in sleep, since then.

After any cold boot (power up, and not from sleep), the Modem will not accept a “$TD” command until time is set by the GPS. Once this happens, then the device is ready to communicate until the next cold boot (Power cycle) even across SLEEP wake-ups. This is because the RTC is set with the GPS time, and the RTC time survives sleep.

Swarm does not support Assisted GPS.

GPS information can be extracted from the embedded GPS module by using the appropriate commands as shown in our Product Manual.

A Swarm Modem will attempt to transmit messages to a satellite after a satellite beacon is received during a satellite pass over Modem’s location. To know when the next satellite pass will be occurring over your device’s location, please use the Swarm Satellite Pass Checker. This video also describes the functionality of the Pass Checker in more detail.

Any Swarm Modem with queued transmission packets will attempt to transmit after receiving a satellite beacon. Satellite beacon packets are shown on the serial output of the Modem in the format $RT RSSI=<rssi_sat>,SNR=<snr>,FDEV=<fdev>,TS=<time>,DI=<sat_id>*xx

Satellite $RT unsolicited messages are printed independently of the background RSSI values as long as the query rate for $RT measurements is not 0.

Each Evaluation Kit includes:

• FeatherS2 – ESP32 board + OLED for quick development, testing, and IoT product creation
• Turn-key with 9W solar panel
• Rechargeable 9000 mAh battery
• IP67 waterproof enclosure
• Aluminum tripod
• Satellite antenna
• GPS antenna
• WiFi, USB-C, and serial inputs

A device’s activation date is the first of the month following when ≥50 messages are sent. For example, if you send the first ≥50 messages on Feb 17th, the activation date will be March 1st and your data plan will annually renew each March 1st. Please see Terms & Conditions for further details.

The Evaluation Kit can be powered with any of the options listed below:

• Lithium Ion 18650 batteries installed in their respective holders behind the PCBA. These batteries can be recharged using the solar panel which is included with your Evaluation Kit.
• An external power supply connected to input terminal J13. The voltage input should be set to a value between 18 and 24 VDC. Please ensure that the power supply is able to provide the necessary current to the Evaluation Kit. This option will also charge the batteries installed in the kit.
• A USB-C cable connected to the USB-C adapter on the Evaluation Kit. This option will also charge the batteries installed in the Kit.

No, there is no change of jumpers required to use any of the options listed above.

The Evaluation Kit is designed for uplink communication only. You can send messages using the Evaluation Kit to the Hive, but not the other way around. Downlink communication is reserved for commercial applications.

Please move jumper J7 (Located next to the stacked Feather/OLED) to the “USB” configuration. You can then connect a USB-C cable to the kit and power it on using the power switch. You will need to use a terminal program such as PuTTY or ZOC connected to the appropriate COM port using the following settings: 115200 baud rate, 8N1, disabled RTS/CTS signal, and flow control OFF.

No, the Evaluation Kit does not support Bluetooth connectivity natively.

Yes, Swarm does support 2-way communication for commercial applications only.

Swarm’s baseline subscription supports 750 data packets a month per device (up to 144 kB per device per month per device).

Swarm provides a maximum of 192 available bytes (out of a 250 byte packet, which includes a wrapper) per data packet.

Users can allocate up to 60 packets (of the monthly 750) per data plan for downlink, with a maximum of 10 downlink messages per day. Please see Terms & Conditions for further details.

Swarm devices are authenticated on the network by the satellites and ground stations. Each device has a unique device ID that is only known by Swarm and the customer.

Yes, Swarm implements end-to-end AES256-GCM encryption for data sent over the Swarm network.

No, the Modem’s device ID cannot be changed, modified, or tampered with in any way. The device ID is set during production by Swarm.

Swarm uses a narrow band carrier (about 40 kHz wide), and a chirped spread spectrum approach. This helps improve Swarm device immunity to noise and common forms of jamming.

Please ensure that the device is powered from a clean power supply with minimal high frequency noise. Having the device placed outdoors with a clear view of the sky away from a city environment will also improve RF performance. The antenna of the device should not be making contact with, or placed near, any other conducting surfaces. The Swarm 1/4 wave antenna should be placed at least 1m above the ground or any solid surfaces. A counterpoise can also be used to improve RF stability.

Swarm currently offers 1/4 wave antennas that have undergone extensive testing. All antennas sent by Swarm are tuned in house. Our team is constantly working on smaller antenna form factors that will operate reliably in most field conditions. All information regarding antennas can be found in the RF Interfaces Section of the Product Manual.

A VHF antenna specifically tuned to Swarm’s commercial frequencies is required to use our systems. A hardware designer can develop their own antenna if they choose to. We include a 1/4 wave antenna with each Swarm Modem.

The Swarm Modem requires its own external GPS and VHF antenna (both are included in the price per unit). Any GPS antenna (active or passive) can be used. We recommend this GPS Antenna.

Ground planes are electrically conductive surfaces that are connected to the ground conductor of the antenna and serve as a reflecting surface for radio waves. Ground planes are required for use with Swarm’s 1/4 wave antenna.

You can use your own ground plane which should be tested before deployment. Another ground plane option is a counterpoise (we use an 18″ long, 18 gauge wire hanging downwards, commonly known as a “Tiger Tail” with amateur radio enthusiasts).

An ideal ground plane for the Swarm ¼ wave antenna would be a flat metal sheet with a minimum radius of 55 cm. To date, Swarm has reliably communicated with its satellites using a ¼ wave antenna mounted on top of a ground plane as small as 30x30x0.3 cm.

The Swarm Modem has a U.FL connector which can be connected to an SMA connector. The 1/4 wave antenna can be threaded onto the SMA connector. There is also a U.FL connector on the Swarm Modem for the GPS antenna.

The 1/4 wave antenna should be mounted at least 1m above the ground, or any solid surfaces.

In electronics and radio communication, a counterpoise is a network of suspended horizontal wires or cables, used as a substitute for an earth connection in a radio antenna system. In the case of the Swarm 1/4 wave antenna, you can use a ~18” long wire connected to the ground element of the antenna and hanging vertically downwards.

Packets sent through the Swarm network have unique device IDs which indicate the device that the packet originated from.

An Organization ID (or OrgID) is a unique number assigned to each Hive Organization. You can find your OrgID by logging into Hive, and then navigating to My Profile.

An Application ID (or AppID) is used to filter user messages. You can assign transmission packets a unique AppID so that the messages can then be filtered when they are retrieved from the Swarm Hive. An example of this would be using AppID 1000 for sensor data, AppID 2000 for location data, and AppID 3000 for status messages. Users have access to AppIDs between 0 and 64999. AppIDs 65000 to 65535 are reserved for internal use only. The default AppID for any message packet is 0. To learn more about how to assign an AppID to a message packet, please refer to the $TD – Transmit Data section of the Product Manual.

You can retrieve data from the Hive by either using the REST API, or by using delivery webhooks. To learn more about how to use the REST API and webhooks, please refer to the API documentation after logging into your Hive account. There is also a Python script example for the REST API that can be downloaded by clicking here.

Swarm stores data in the Hive for 30 days. After 30 days, any data left on the Hive will be deleted. Customers are expected to move their data upon transmission/reception.

Message packets that were received more than 30 days ago are no longer visible in the Hive. If you are using the REST API, or delivery webhooks, then the messages may be marked as acknowledged. Swarm will not automatically acknowledge transmission packets received in the Hive. It is highly recommended to mark message packets as acknowledged once they have been retrieved and logged into your backend application.