The team at CaribouLabs have designed a new software-defined radio that turns any Raspberry Pi into a software-defined radio.
CaribouLite is affordable and open-source hardware. It is designed for makers, hackers and researchers to encourage exploration in the world of radio technology. We anticipate that it will also gain traction in the amateur radio community.
In addition, it will introduce many Raspberry Pi fans to the world of radio and wireless. A great step forward for SDR.
Table of Contents
CaribouLite SDR
Features
The CaribouLite is designed as a HAT (Hardware Attached on Top) for the very popular Raspberry Pi. A HAT is an expansion boards that interfaces to the Raspberry Pi’s 40 GPIO pins. It is used to add functionality to the Pi. For example there are HATs that add DAC functionality and terminal blocks.
In the picture below you can see how the CaribouLite sits beautifully atop the Raspberry Pi Zero.
Soon anyone with a Raspberry Pi Zero will be able to experiment with SDR. In the past we have seen wireless HATs that add 4G LTE capability to the RPi but as far as SDR is concerned this is a first.
Hardware Specifications
The Cariboulite is an RF transceiver – which means it can both transmit and receive RF signals. Let’s take a look at some of the key numbers associated with the hardware design and what they mean
| Specification | Value |
| Frequency range | 30-6000 MHz |
| Bandwidth | 2.5 MHz |
| ADC sampling rate | 4 MSPS |
| Receiver Noise Figure | < 6 dB @ 30-3500 MHz, < 8 dB @ 3500-6000 MHz |
| Max Transmit Power | +4 dBm |
The frequency range is wide with some exceptions. The system doesn’t tune between the frequency ranges of 2398.5-2400 MHz and 2483.5-2485 MHz.
Current State of the Design
The team has evolved their first revision prototype into a rev 2 design with improvements. Here is a list of some of performance enhancements:
- Improved Image rejection filtering improvement to give better out-of-band rejection than the former ones.
- Removal of the FPGA flash. This was unnecessary due to the fact that the Rpi can configure the FPGA.
- Board layout improvements and overlays (silkscreen) beautification (including logo).
- Use of an LDO instead of a switching supply to provide a single system level 3.3V power. The use of a linear regulator helps reduce noise levels.
What differentiates this product from other SDRs out there?
Let’s take a look at what differentiates the CaribouLite from other SDRs like the HackRF and the RTL-SDR. Two very popular SDRs that have seen tremendous sales and each with a large community following.
| Specification | RTL-SDR | HackRF | CaribouLite |
| Device type | Rx only | Tx/Rx | Tx/Rx |
| Frequency range | 0.5-1700 MHz | 10-6000 MHz | 30-6000 MHz |
| Bandwidth | 2.4 MHz | 20 MHz | 2.5 MHz |
Summary
In this post we have provided an overview of the CaribouLite SDR. This is an exciting development in the world of Software-defined radio. The small size of this product and hardware specifications means that it will open up a range of new applications.