New principles for SDR tools: Seamless merging of scan/hop mode and single-frequency reception

Описание: Browser-based ADALM-Pluto SDR spectrum and waterfall scanner with scan/hop mode and million-times zoom: https://github.com/ur8us/pluto-scanner

Another principle behind Pluto Scanner is the seamless combination of two fundamentally different receiver modes: wide-frequency scan/hop operation and continuous single-frequency reception.

Wide spectrum views cannot always be captured by the SDR hardware in one operation. When the visible frequency range is wider than the instantaneous receiver bandwidth, Pluto Scanner divides it into multiple tuning steps. The receiver moves through these positions, captures spectrum data at each one, and combines the results into a continuous spectrum and waterfall display.

As the user zooms in, fewer tuning steps are required. A wide view may require dozens of separate receiver positions. A narrower view may need only three steps, then two, and eventually just one.

At that point, the program automatically changes to fixed-frequency reception. Instead of hopping between several center frequencies, the receiver remains tuned to one position and continuously captures the entire visible bandwidth.

The important idea is that this change is hidden from the user.

There is no separate scan-mode button, no need to stop the receiver, and no manual change between wideband scanning and narrowband reception. The user simply zooms in or out, while the backend chooses the appropriate acquisition method.

In the demonstration, the initial spectrum covers approximately one gigahertz. To construct this view, the program uses 55 tuning steps, each based on approximately 20 MHz of receiver bandwidth. Only part of every captured bandwidth is used in the final display so that the edges of neighboring FFT segments do not dominate the combined spectrum.

As the view is narrowed, the number of steps decreases from 55 to three, then two. After further zooming, Pluto Scanner enters fixed mode, where the receiver no longer hops through several frequencies and instead receives the selected bandwidth continuously.

Zooming out reverses the process. The program returns from fixed reception to two steps, three steps, and eventually to a much wider scan.

Throughout this transition, the waterfall remains visually continuous. The user should not see an obvious boundary between the two acquisition methods.

This is important because wide scanning and narrow reception solve different problems.

Scan/hop mode is useful for:

Discovering activity across a large frequency range
Locating unknown signals
Monitoring several bands
Finding interference, harmonics, or intermittent transmissions

Single-frequency reception is useful for:

Smooth continuous updates
Narrow-spectrum inspection
Larger FFT sizes and finer frequency resolution
Examining the detailed structure of one signal

Traditional SDR software may expose these as separate modes. Pluto Scanner treats them as different internal techniques serving one continuous spectrum interface.

The user thinks only about the frequency range and zoom level. The backend handles receiver tuning, buffer management, FFT processing, display-row construction, and the transition between scanning and fixed reception.

That is the fourth development principle of Pluto Scanner: scan/hop mode and single-frequency reception merged into one continuous user experience, with the technical transition hidden from the operator.

Chapters

00:00 Combining scan/hop and fixed-frequency reception
00:10 One continuous user interface
00:20 Demonstration of the automatic transition
00:29 Scanning approximately one gigahertz
00:36 Using 55 receiver tuning steps
00:43 Why only part of each bandwidth is displayed
00:56 Zooming from 55 steps to three
01:07 Reducing the scan to two steps
01:21 Automatic transition to fixed mode
01:28 Continuous single-frequency reception
01:40 Zooming further in fixed mode
01:48 Zooming out to two and three steps
02:01 No visible transition on the waterfall

#SDR #SoftwareDefinedRadio #PlutoSDR #ADALMPluto #SpectrumAnalyzer #Waterfall #WidebandScanner #FFT #DSP #RadioScanner #FrequencyScanning #HamRadio #AmateurRadio