LimeSDR Hardware Installation
The LimeSDR family of software defined radios are designed to make it as easy as possible to get started in the world of SDR. Before you can begin, though, you'll need to run through some simple steps in order to get your LimeSDR installed and configured correctly.
Unpacking
The LimeSDR family includes the LimeSDR USB and LimeSDR Mini software defined radio devices. Both of these are similar in operation, differing only in their size and base capabilities.
Begin by removing your LimeSDR from its packaging. Note the anti-static bag, used to protect the LimeSDR during transit. The LimeSDR is a sensitive electronic device, and should be handled with appropriate precautions against electrostatic discharge (ESD); be sure to ground yourself, for example by tapping your finger on the exposed metal of a radiator pipe, before removing it from the anti-static bag, and ensure you hold the board by its edges. Also be careful of components, such as the small male pin headers, which protrude above the surface of the LimeSDR board; these can catch on the edge of the bag.
Connecting Antennas
The LimeSDR family of SDR boards have multiple RF ports, to which antennas appropriate to the frequencies in which you will be operating must be connected. Some hardware bundles include antennas; others come without. The port you use depends on whether you will be receiving or transmitting and at what frequency. The following sections describe the ports and their capabilities.
When configuring your software, be sure to select the ports to which you have connected antennas; the LimeSDR does not automatically sense if an antenna is connected to a port or not.
LimeSDR USB RF Ports
| Label | Description |
|---|---|
| RX1_H | Channel 1 RX - frequencies above 1.5GHz |
| RX2_H | Channel 2 RX - frequencies above 1.5GHz |
| RX1_L | Channel 1 RX - frequencies below 1.5GHz |
| RX2_L | Channel 2 RX - frequencies below 1.5GHz |
| RX1_W | Channel 1 RX - wideband |
| RX2_W | Channel 2 RX - wideband |
| TX1_1 | Channel 1 TX - primary (all frequencies) |
| TX2_1 | Channel 2 TX - primary (all frequencies) |
| TX1_2 | Channel 1 TX - secondary (all frequencies) |
| TX2_2 | Channel 2 TX - secondary (all frequencies) |
The LimeSDR USB has U.FL connectors for its RF ports. These can be used with U.FL to SMA 'pigtail' cables to allow for connection to external antennas. Take care when connecting the U.FL end of the pigtail to avoid damage to either connector, and be sure that there is no strain on the cable when the SMA connector is linked to its antenna.
Note that, in all cases, optimal receive performance is obtained by using the *_H and *_L ports within the frequency bands listed. Secondary transmit ports for each channel, where available, can be used with power amplifiers covering different bands or for loopback and other tasks.
LimeSDR USB RF Ports
| Label | Description |
|---|---|
| RX | Channel 1 RX - all frequencies |
| TX | Channel 1 TX - all frequencies |
The LimeSDR Mini has SMA connectors for its ports, requiring no additional conversion for connection to external antennas. Depending on desired positioning, however, SMA extension cables will give you increased flexibility in positioning and alignment.
Case Assembly
If you have purchased the official LimeSDR Acrylic Case for the LimeSDR USB, see the assembly instructions on GitHub. If you have purchased a third-party case, consult the documentation from your case manufacturer for instructions.
If you do not have a case for your LimeSDR, it can be used without one providing you are careful to ensure that it does not come into contact with electrically conductive surfaces - including metal desk coverings - while in use, or the board may suffer a damaging electrical short.
Connecting to a PC
The LimeSDR USB and LimeSDR Mini both connect to a host computer over a USB 3.0 interface, although both are backwards compatible with older USB 2.0 ports at a reduced rate of operation. The LimeSDR Mini includes a male USB plug in its design; simply insert this directly into a free USB 3.0 Type A port on your host computer or via a good-quality USB 3.0 extension lead for more flexible positioning.
The LimeSDR USB comes with a USB 3.0 splitter cable. While the LimeSDR USB draws its power entirely via USB, negating the need for an external power supply, it can require more power than a single uSB port can provide. The splitter cable is wired so that the USB plug with a blue inner, in the middle of the cable, has both power and data connections while the USB plug with a white inner, at the far end of the cable, has only power connections.
Begin by connecting the white, power, USB plug to a free USB 2.0 or 3.0 port on your host computer, then connect the blue, power and data, USB plug to a free USB 3.0 port. The final end of the cable, which is terminated in a USB 3.0 SuperSpeed connector, should finally be inserted into the matching connector on the LimeSDR USB. Note that there is no power switch on the LimeSDR USB; as soon as the cable is connected, the board will become live. Disconnecting the LimeSDR USB should be performed in the opposite order, starting with the USB 3.0 SuperSpeed connector on the LimeSDR USB itself.
If using the LimeSDR USB with a laptop or all-in-one system, the splitter cable may not reach between USB sockets. If so, attach a good-quality USB extension cable - not supplied - to the white, power-only, connector of the splitter to extend its reach.
Next Steps
Windows users will now need to install the LimeSDR driver, following the instructions on the Windows Driver Installation page. All other users should move on to LimeSDR Firmware Management to update their firmware and gateware to the latest releases, without which the LimeSDR may not operate as expected.
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