CHAPTER
EIGHTEEN
MULTIPLE DEVICE HARDWARE LEVEL SYNCHRONIZATION
18.1 Purpose
This page describes the modifications required to get multiple HackRF hardware-level synchronisation working. Syn-
chronisation is required for many applications where a single HackRF isn’t sufficient:
• phase correlation
• oversampling using multiple devices
• 40MHz (or more) protocols such as WiFi
The HackRFs will start transmitting USB packets at the same time, which results in an inter-device offset of ~50 samples
at a sample rate of 20MSps. Without this synchronisation, the offset is in the range of thousands to tens of thousands of
samples. This is due to the USB start command being called sequentially for each device, along with USB buffering,
OS-level timing etc.
BE WARNED you will have to open your HackRFs, which is most likely going to destroy the plastic case it comes in.
You will also be electrically connecting them together. If you do this incorrectly, there is a good chance one or all of
the devices will be permanently destroyed.
18.2 Related work
"bardi_" on the #hackrf channel pointed out his paper on synchronising HackRFs. This uses the HackRF CPLD to
synchronise multiple devices.
18.3 Requirements
For this to work you will need:
• at least two devices
• a clock sync cable
• some connecting cables (pin header-type)
• a breadboard
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