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arxiv: 2606.22751 · v2 · pith:3DEACTSLnew · submitted 2026-06-22 · 📡 eess.SP

Low-Complexity Direct Geolocation of Terrestrial GNSS Jammers from Low Earth Orbit

Giacomo Pojani , Javier Tegedor , Joaquim Fortuny-Guasch This is my paper

Pith reviewed 2026-07-03 23:20 UTC · model grok-4.3

classification 📡 eess.SP
keywords quasi-direct geolocationGNSS jammerslow Earth orbitRF interferencedirect position determinationsatellite geolocationlow complexityopportunistic sensing
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The pith

A quasi-direct geolocation technique performs direct position-domain location of GNSS jammers with far lower complexity than standard DG or DPD methods.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper presents quasi-direct geolocation (QDG) to find emitter positions directly in the position domain while cutting the computational load of full direct geolocation and direct position determination. QDG targets low size-weight-and-power satellites in low Earth orbit so they can monitor GNSS-band interference either by compressing raw samples for ground processing or by running the location calculation on-board. The approach is shown to work by locating a terrestrial jammer from the OPS-SAT PRETTY satellite during Jammertest 2025. A sympathetic reader would care because the method could turn many small satellites into opportunistic sensors for global RFI tracking without requiring high-end processors. The paper notes that the gain in simplicity comes with lower sensitivity and accuracy and applies only to the most common GNSS jammer types.

Core claim

Quasi-direct geolocation carries out passive RF emitter location directly in the position domain, similar to DG and DPD, yet reduces complexity enough for use on SWaP-constrained LEO satellites; the technique supports either downlink of minimal signal descriptors or on-orbit computation and was demonstrated by geolocating a terrestrial GNSS jammer from OPS-SAT PRETTY at Jammertest 2025.

What carries the argument

The quasi-direct geolocation (QDG) technique, which approximates full position-domain processing for jammer signals to cut computational cost while still solving for emitter location.

If this is right

  • Satellites with limited power and processing can still serve as data collectors that compress I/Q samples into minimal descriptors for low-capacity downlinks.
  • The same satellites can run QDG on low-power on-board computers to output jammer locations directly in orbit.
  • Multiple such satellites can feed a multi-constellation RF interference monitoring system without needing high-SWaP payloads.
  • The method covers the jammer classes that dominate current GNSS interference threats.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • QDG outputs could be fused with ground-based sensors to improve overall RFI map coverage and update rates.
  • Adapting the signal model inside QDG might allow the same low-complexity pipeline to handle other narrowband interferers beyond GNSS jammers.
  • On-board QDG results could trigger immediate alerts or beam steering on the same satellite without waiting for a ground station pass.

Load-bearing premise

The emitters must be the most common GNSS jammer types whose signals fit the quasi-direct position-domain processing model.

What would settle it

If applying QDG to the OPS-SAT PRETTY recordings from Jammertest 2025 yields no geolocation near the known terrestrial jammer site, or if the computed location deviates far beyond the reported accuracy, the experimental claim fails.

Figures

Figures reproduced from arXiv: 2606.22751 by Giacomo Pojani, Javier Tegedor, Joaquim Fortuny-Guasch.

Figure 2
Figure 2. Figure 2: Close-up view on the SNR spectrogram above the noise threshold in (11), i.e., 8.4 dB with PFA = 0.001, for the front patch antenna at L5. TABLE I. SIGNAL INFORMATION ALONG QDG PROCESSING CHAIN Data Memory size [MB] Collected I/Q samples (2 x int16) 1080.0 Resampling from 5 Msps to 312.5 ksps Yes No Resampled I/Q samples (2 x int16) 67.50 1080.0 Full STFTs (complex64) 254.80 4303.36 Compressed STFTsa,b (com… view at source ↗
Figure 1
Figure 1. Figure 1: GNSS positions of the satellite every 30 s during the 12-min pass. The SNR (17) of one of the two compressed STFT is plotted in [PITH_FULL_IMAGE:figures/full_fig_p005_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: SNR over a grid of 1000 km with resolution of 5 km (the mirror lower peak on the West is due to the ambiguity of FOAs/PDOAs) [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: SNR over a grid of 50 km with resolution of 250 m (the values range from 5 dB to 45 dB with maximum at the true test jammer position). VI. SUMMARY AND CONCLUSIONS This work proposes and demonstrates the use of QDG for the low-complexity geolocation of GNSS jammers from LEO. The results presented for a single-satellite scenario show that the source of a 50-W CW at L5 can be pinpointed within 0.5 km² by inte… view at source ↗
read the original abstract

This paper introduces a low-complexity technique named quasi-direct geolocation (QDG) to perform passive radio-frequency (RF) geolocation of emitters directly in the position domain, akin to direct geolocation (DG) and direct position determination (DPD). The proposed technique drastically reduces the complexity of DG/DPD and is experimentally demonstrated in geolocating a terrestrial jammer at Jammertest 2025 from a repurposed satellite in low Earth orbit (LEO): OPS-SAT PRETTY. The goal of QDG is to enable satellites to contribute to a multi-constellation system for RF interference (RFI) monitoring as opportunistic spectrum sensors in global navigation satellite systems (GNSS) bands, even if these are constrained by low size, weight, and power (SWaP). They can serve as data collectors and/or edge computers. In the former case, QDG can be used to compress large volumes of I/Q samples into minimal signal information, which can be relayed to ground for post-processing via low-capacity downlinks. In the latter case, QDG can be used to compute the geolocation of RFI sources in orbit on low-power on-board computers (OBC). The drawback of these capabilities is lower sensitivity and accuracy than DG/DPD plus limitations on the types of signal sources that can be geolocated, which, nonetheless, include the most common GNSS jammers.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 0 minor

Summary. The paper introduces quasi-direct geolocation (QDG), a low-complexity technique for passive RF geolocation of emitters directly in the position domain, similar to direct geolocation (DG) and direct position determination (DPD). It claims to drastically reduce DG/DPD complexity while enabling LEO satellites (e.g., repurposed OPS-SAT PRETTY) to geolocate terrestrial GNSS jammers, as demonstrated experimentally at Jammertest 2025. QDG supports RFI monitoring in GNSS bands for SWaP-constrained platforms, either by compressing I/Q data for downlink or performing on-board computation, with acknowledged trade-offs of lower sensitivity/accuracy and applicability limited to common jammer signal types.

Significance. If the experimental results hold with quantitative support, QDG could meaningfully expand opportunistic GNSS-band RFI monitoring by allowing more LEO satellites to participate as low-SWaP sensors or edge processors. The explicit statement of limitations (sensitivity/accuracy trade-off and signal-type restrictions) is a strength that supports practical applicability claims. The work provides a concrete path toward multi-constellation RFI systems without requiring high-performance on-board hardware.

major comments (1)
  1. [Abstract] Abstract: The central claim of experimental demonstration in geolocating a terrestrial jammer from LEO lacks any quantitative results, error bars, baselines, or data exclusion criteria. This omission leaves the performance claims (including the asserted complexity reduction relative to DG/DPD) unsubstantiated at the level needed to evaluate the method's practical utility.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their review and constructive feedback. We address the single major comment below and agree that revisions to the abstract are warranted to strengthen the presentation of our experimental claims.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The central claim of experimental demonstration in geolocating a terrestrial jammer from LEO lacks any quantitative results, error bars, baselines, or data exclusion criteria. This omission leaves the performance claims (including the asserted complexity reduction relative to DG/DPD) unsubstantiated at the level needed to evaluate the method's practical utility.

    Authors: We agree with the referee that the abstract, as currently written, does not include quantitative results and therefore does not fully substantiate the central experimental claim or the complexity-reduction assertion. The body of the manuscript does contain the supporting experimental data (including accuracy metrics, error statistics, and comparisons to conventional methods), but these are not summarized in the abstract. In the revised manuscript we will expand the abstract to include key quantitative findings from the Jammertest 2025 campaign (e.g., reported geolocation errors with uncertainty measures, any applicable baselines or exclusion criteria, and a concise statement of the observed complexity reduction), while preserving the existing acknowledgment of sensitivity/accuracy trade-offs and signal-type limitations. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper introduces QDG as a new low-complexity position-domain geolocation method for common GNSS jammers, explicitly trading off sensitivity/accuracy against full DG/DPD while providing external experimental validation on OPS-SAT PRETTY data collected at Jammertest 2025. The derivation chain consists of algorithmic simplification steps and hardware-constrained implementation choices that are justified by stated limitations and real-world testing rather than by self-definition, fitted inputs renamed as predictions, or load-bearing self-citations. No equations or premises reduce to their own inputs by construction; the central claims remain independently falsifiable via the reported experiments.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Based solely on the abstract, no free parameters, axioms, or invented entities are identifiable; the work introduces a processing technique without explicit new physical entities or fitted constants.

pith-pipeline@v0.9.1-grok · 5787 in / 1114 out tokens · 23364 ms · 2026-07-03T23:20:44.837906+00:00 · methodology

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Reference graph

Works this paper leans on

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