GP-SDR

Receivers0connected

Signals0discovered

Events0logged

Session—idle

Receiver controls

Ready

No signal

Receiver

Receiver Mode Bandwidth · kHz

RF

LNA · dB VGA · dB PPM RF amp Antenna power

Signal

DC removal Q balance IQ phase · ° Swap I/Q Audio level auto Squelch · dB Open squelch Auto calibration

RF amp and antenna power default off. Antenna power is only for compatible powered accessories.

Spectrum

Waiting for receiver

Noise Activity

Waterfall

Live RF activity

−110−20 dBFS

———

Latest

Most recent transmission

No activity yet

Channel mixer

Audio controls do not affect logging

Start a channel profile

Band monitor

One wide capture · independent channel audio

Idle

BandReceiver

Listen modeCarrier · all codes

Sample rate Receiver gain · dB HackRF LNA · dB HackRF VGA · dB Squelch · dB Auto gain HackRF RF amp DC removal

Privacy codes are squelch tones, not encryption. Carrier mode hears every transmission, including radios with no code. GP‑SDR identifies CTCSS on active audio and leaves the code blank when there is not enough evidence.

Channels0monitored

Active now0receiving

Last tone—CTCSS detected

Capture—shared bandwidth

Channels

Active channels rise to the top

Choose a band and start monitoring

Live receivers

Independent spectrum and waterfall for every SDR currently producing IQ

Waiting

Start a receiver or Mapper job to watch it here.

Spectrum controls

Standalone swept spectrum analyzer

Idle

The display continuously sweeps and retains the strongest observed level at each frequency until stopped or cleared. Use a smaller range or coarser resolution for faster updates.

Receivers0

Spectrum bins0

Captured slices0

Full sweeps0

Spectrum

No sweep data

Hover over spectrum

Start a sweep to build a live spectrum across the selected range.

Analog FPV receiver

Continuous low-latency video · HackRF or PlutoSDR

Idle

Analog NTSC/PAL only. A receiver is usable whenever it can tune the selected frequency and sustain the selected capture width. The RTL-SDR cannot cover 5.8 GHz. Keep RF amplification conservative because overload destroys picture sync.

Live video

Waiting for decoded frames

Decoded analog FPV video

Choose a channel and start the receiver.

Receiver

Sample rateGain · dBLNA · dBVGA · dB

Signal

Squelch · dBNoise reductionPPMQ balanceIQ phase · °

Choose a receiver and frequency.

Spectrum

No IQ data

Hover for frequency—

Waterfall

Newest samples appear at the top

−110−20 dBFS

———

Transmit & test lab

Known-signal fixtures and guarded SDR playback

Receive-only

Source Transmitter Frequency · MHz Mode Duration · seconds TX gain · dB Audio WAV Dry run (generate IQ, no RF) I am using a dummy load and understand this transmits RF

Choose a PCM WAV file or generate a known test fixture. Dry run is selected by default.

Open Explore to load local observations.

Frequency × hour

Recorded events by hour of day · UTC · top 60 groups · click a cell to inspect

Dark cells mean no recorded events, not proven silence. Quiet-check history and total monitoring time are unavailable. Counts favor longer-observed frequencies.

Activity timeline

Recorded events per day · UTC

Collection map

Offline coordinate map · circles: receiver observations · diamonds: reference area centers

No map tiles or coordinates are sent to a third party. Reference areas are not transmitter sites. Click a circle to inspect its data.

Frequency groups

Same frequency, separate receive areas

Bookmarked

Save	Frequency	Area	Events	Recorded time	Mode	Decoded / transcript

Select a frequency or map point

Review recorded evidence and geographically applicable reference candidates here.

Discovered signals

Repeated activity is grouped by frequency

Frequency	Identity	Type	Hits	Last seen

Job setup

Independent tasks per receiver

Idle

Job name Receiver

Use all connected receivers

Workflow

Map Discovery Identify

Range preset Start · MHz End · MHz Step · kHz Time per channel

Receiver tuning Auto gain · safe sample rate · simultaneous channels

Capture width Channels at onceActual count is limited by capture width, spacing, and usable receiver bandwidth. Receiver gain Sensitivity HackRF amp Receiver gain · dB HackRF LNA · dB HackRF VGA · dB Signal above noise · dB

Identify filters

Compute & schedule Optional capture now · analyze later · timed phases

Capture qualityOriginal CS8 IQ uses 7.2 GB/hour per MS/s: 144 GB/hour at 20 MS/s or about 442 GB/hour at 61.44 MS/s. Scanning and processing leave gaps. Analysis timing Timed Discovery → Identify

No deferred compute queuedRuns decoders, transcription, and the enabled local model without opening an SDR.

Modulation Decoder

Location Optional tagging

Include location Precision Location name Latitude Longitude

Map repeatedly sweeps the range, identifies activity, runs available local decoders and transcription, then retains only useful IQ evidence.

Receiver monitor

Continuous · loops until stopped

Current frequency—Waiting to start

Active jobs00 receivers assigned

Total checks00 completed passes

Hits0No activity yet

Successfully identified0Authoritative matches

Analyzed frequencies0Candidates · not verified

Elapsed——

Next pass ETA—No active pass

Create or start a Mapper job.

Receiver captures

Every active Mapper receiver is shown at the same time

Waiting

Start a Mapper job to watch its receivers.

Stored capture analysis

Decoder, transcription, local model, and retention processing without an SDR

Files queued0No work queued

Frequency groups0Grouped by receive area

Completed00 failed

Elapsed—ETA —

Current frequency—Waiting for work

StageIdle—

No frequency groups are active.

Live analysis log

Newest entries appear at the bottom

Start analysis to process stored captures.

All recordings at the same frequency and nearby location are evaluated together. Captures from distinct receive areas remain separate. Rejected IQ is deleted only after analysis completes successfully under the selected retention policy.

Combined results

No detected activity

Repeated only

Frequency	Identity	Type	Hits	Source	Last seen

Google SheetOptional Additions Queue uploadOff

Fully identified requires nearby reference data or valid decoded frames.

Channels & profiles

Portable channel banks, scan ranges, and receiver roles.

Receivers

Multiple radios can run concurrently with independent roles.

Receiver & antenna lab

Compare observed RF response across both receivers

Idle

This is an ambient comparison, not a laboratory sensitivity measurement.

Remote RTL-SDR

Connect to an rtl_tcp server on your network

Decoders

Optional tools appear only when actually available.

Integrations

Optional receiver, decoding, transcription, and reference components.

Hardware references

Bench documentation included with GP-SDR

Repeater schematic ↗Solder map ↗

Data & reference sources

Channel databases and automatic range updates.

Range updates

Sync built-in scan ranges from Google Sheets.

Not configured

Paste a shared sheet link to begin.

Sheet columns

Profile, Name, Start MHz, End MHz, Step kHz, Mode, Dwell ms, Enabled

Local database

Recursively import CSV, TSV, and GP-SDR JSON files.

Not configured

No folder selected.

Choose a folder containing supported channel files.

RadioReference download steps

Open a county, state, or system page while signed in.
Open Downloads and save its CSV into a folder organized by state or county.
Choose the top-level folder here. Rescan after adding files.

RadioReference does not document a single whole-US archive. GP-SDR does not scrape or mirror its database.

RadioReference

Location-based channels and P25 systems.

Not configured

Premium account and approved app key required.

Request application key ↗

Local intelligence

On-device signal correlation and confirmed learning.

Local signal intelligence

Use Ollama on this Mac or a private-network computer. IQ and audio never leave GP-SDR.

Off

Models to compareCommand-click to select multiple models. Large models may take several minutes.Export confirmed training set ↗

No benchmark run yet.

The model receives metadata only; raw IQ and audio remain in GP-SDR.

How it works

GP-SDR first detects and classifies the waveform, runs the selected protocol decoder, and optionally transcribes decoded voice. The local model then summarizes that evidence. Decoder frames remain authoritative and uncertain signals remain Unknown.

Display

Spectrum, waterfall, and rendering controls.

Display

Spectrum refreshApplies to every spectrum and waterfall. Faster refresh increases browser and server load but does not change SDR sample rate. Waterfall quality Spectrum detail Trace smoothing20% Spectrum peak hold Channel markers Display floor Display ceiling

Changes apply immediately and are saved on this device.

System

Web access, application information, and storage limits.

App & web access

Address: —
Access: LAN · token protected
Version: —
Architecture: Universal-ready

Core scanning and logs stay on this computer. The web app uses the private network link above.

Software update

Install verified releases without replacing your data.

Not checked

Check when GP-SDR opens

The native Mac app can download, verify, install, and restart GP-SDR. Settings, Mapper results, recordings, and profiles stay in Application Support.

Release notes

Expert transmit mode

Skip the repeated transmit acknowledgement on this Mac.

Off

This convenience mode remembers your acknowledgement locally. It does not bypass local-only access, hardware/range validation, the emergency stop, firmware-health blocks, or the 60-second transmission ceiling.

Storage

Total used: —
Recordings: —
IQ evidence: —
Journal + profiles: —
Original IQ archive: —
IQ analyzing: —
IQ retained: —
IQ rejected: —

Calculating local storage…

Results are separate. Media cleanup removes eligible IQ data and recordings only. Mapper results, event history, transcripts, decoded metadata, profiles, calibration, and channel data remain until you explicitly clear their corresponding data. Original archives and pending IQ retain their existing protection rules.

Acknowledgements

GP-SDR includes SDRTrunk and JMBE Creator, and integrates with SoapySDR, whisper.cpp, HackRF, and RTL-SDR. Each remains under its own license. Complete credits and source details are in THIRD_PARTY.md.