Hopper

The Hopper app is a specialised transmission tool designed for Frequency Hopping. While the standard Jammer app typically sweeps a broad range of frequencies or stays on one, the Hopper app allows you to transmit on a specific, pre-defined list of channels in a sequence or pattern.

Core Functionality

The Hopper app acts as a list-based transmitter. Instead of manually changing frequencies to jam or test different channels, you load a "hopping list" from your SD card, and the HackRF will cycle through them automatically.

Frequency Lists: It reads .txt files stored in the /HOPPER/ directory on your microSD card.

Transmission Patterns: You can set it to cycle through these frequencies in different orders (e.g., sequential, random, or custom patterns).

Dwell Time: You can control how long the radio stays on each frequency before "hopping" to the next one.

Key Use Cases

Disrupting Frequency Hopping Systems: Some devices (like older wireless security cameras, cheap 2.4 GHz drones, or RC cars) "hop" between channels to avoid interference. By loading their specific channel list into the Hopper app, you can disrupt their connection more effectively than a wide-band jammer.

Testing FHSS Resilience: If you are developing a radio system that uses Frequency Hopping Spread Spectrum (FHSS), you can use the Hopper app to simulate interference on specific channels to see how well your system handles the "noise."

Targeted Multi-Channel Jamming: If you know a target uses three specific frequencies (e.g., three different LoRa channels), you can set the Hopper to only transmit on those three, rather than wasting power jamming the entire 868 MHz band.

How to Use It

Create a List: Create a text file on your PC with one frequency per line (in Hz, e.g., 2412000000).

Change the file extension from .txt to .PHOP and save the file to SD: Place the file in the HOPPER folder on your PortaPack's SD card.

Launch the App: Open Hopper from the Transmit menu.

Select File: Use the file browser within the app to load your list.

Adjust Timing: Set the "Hop Speed" (how fast it switches) and the transmission power (Gain).