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Getting Started

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Alex edited this page Aug 21, 2026 · 1 revision

Getting Started

Choose a package

macOS 13 or newer

Use the Universal DMG unless you need the smaller Apple Silicon (arm64) or Intel (x86_64) ZIP. Drag GP-SDR.app to Applications. Public builds are ad-hoc signed rather than Apple-notarized, so the first launch may require Control-clicking the app and selecting Open.

The native app launches its own local receiver service and prevents idle system sleep while a receiver, Mapper job, or P25 session is active. Display sleep is still allowed.

Windows 10 or 11

Extract the complete x86_64 ZIP and keep its files together. Run GP-SDR.exe -open. A compatible WinUSB driver may still be required for the exact SDR interface; follow the Hardware page rather than replacing drivers on unrelated USB devices.

Debian or Ubuntu

Install the package matching the computer:

sudo apt install ./gp-sdr_1.1.1_amd64.deb
# 64-bit ARM:
sudo apt install ./gp-sdr_1.1.1_arm64.deb
sudo systemctl enable --now gp-sdr

Open http://127.0.0.1:8073/. The service binds to this computer only by default.

First-run checklist

  1. Connect one receiver directly, or through a powered USB hub.
  2. Put a PortaPack in HackRF USB mode.
  3. Open Hardware and press Refresh.
  4. Select Install or How to on anything marked missing.
  5. Open Tuner and select the receiver.
  6. Choose a strong local broadcast FM frequency and WFM mode.
  7. Begin with RF amplifier off, moderate gain, DC removal on, and squelch open.
  8. Press Start and verify a station is intelligible—not merely visible.
  9. Close squelch gradually and adjust gain only as needed.
  10. Save calibration only after comparing against a known frequency.

Demo mode

To inspect the interface without hardware:

gp-sdr -demo -open

Demo data is labeled and is never reported as received RF.

Beginner and Advanced controls

Choose the interface mode under Settings → Controls.

  • Beginner favors automatic sample rates, saved calibration, and a smaller set of controls.
  • Advanced exposes manual RF gain, LNA/VGA, amplifier, antenna power, sample rate, PPM, DC and I/Q correction, and other tuning controls.

Changing modes does not erase saved profiles or calibration.

Safe first test

A strong broadcast FM station is the best initial test because it separates basic hardware/audio problems from trunking or decoder configuration. If it is not intelligible in GP-SDR, fix receiver ownership, antenna, gain, sample rate, squelch, and audio before attempting P25.

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