Published: June 2, 2026 by Roombanker Engineering Team
A warehouse in Izmir was burgled last year. The alarm did not trigger. The sensors were working. The hub was online. The security company’s monitoring station showed no fault, no tamper, no alarm. Everything looked normal right up until the morning shift arrived and found the roller shutter peeled open and EUR 18,000 of copper stock gone.
The problem was a EUR 40 RF jammer bought online from a Chinese e-commerce platform, shipped in a plain box marked “car accessory.” It broadcast continuous noise on 868 MHz — the same frequency the alarm system used to communicate between its sensors and the hub. The hub never received a trip signal from the door contacts because the jammer’s signal drowned out the sensor transmissions. And because the system had no active jamming detection, it never reported anything wrong.
This scenario is not hypothetical. Mediterranean security professionals have reported a measurable increase in jammer-assisted burglaries since 2022, particularly in Turkey, Greece, and southern Italy. The devices are cheap, widely available, and require no technical skill to operate. Understanding how jamming works — and how modern alarm systems detect and resist it — is no longer optional for installers who specify wireless security.
What RF Jamming Actually Is
Radio frequency jamming is deliberate interference. An attacker transmits a powerful signal on the same frequency your alarm system uses, drowning out the much weaker signals from your sensors. The effect is like trying to hold a conversation next to a running jet engine — the words (sensor signals) are still being spoken, but nobody can hear them.
How cheap jammers work:
A basic RF jammer costs EUR 20-80 and consists of a voltage-controlled oscillator, an amplifier, and a quarter-wave antenna. It sweeps across a frequency band (typically 700-1000 MHz for Sub-GHz jammers or 2.4-2.5 GHz for WiFi-band jammers) and broadcasts a continuous wave or noise signal at power levels of 1-10 watts. To put that in perspective, a wireless alarm sensor transmits at roughly 0.01 watts (10 mW). The jammer’s signal can be 100 to 1,000 times more powerful.
The attacker turns on the jammer, waits 30-60 seconds to confirm the system is suppressed, then breaks in. The entire process requires zero knowledge of the alarm system — just knowing which frequency band it operates on, which is often printed on the hub label or easily determined from the product documentation.
Why this matters in 2026:
Three factors have made RF jamming a growing concern for Mediterranean security professionals:
1. Jammer availability. A search for “RF jammer” on AliExpress or similar platforms returns hundreds of listings. Most are listed with euphemistic descriptions (“signal blocker for exams,” “privacy protector”), but their purpose is obvious. Customs seizures of RF jammers entering Turkey and Greece increased sharply in 2024-2025 according to regional trade data.
2. Wireless adoption is accelerating. The shift from wired to wireless alarm systems across Mediterranean markets means more installations are potentially vulnerable. Turkey alone added an estimated 180,000 new alarm systems in 2025, the majority wireless.
3. Older systems lack detection. Many wireless alarm systems installed between 2018 and 2022 were designed to communicate reliably but not to detect active interference. They transmit, but they do not listen for jamming.
How Alarm Systems Detect Jamming
Jamming detection is not about preventing interference — it is about recognising when it happens and responding appropriately. Modern alarm systems use several techniques working together.
Signal Supervision
The most basic layer of jamming awareness is supervision. Every Grade 2-compliant wireless alarm system requires the hub to verify communication with each sensor at regular intervals. Under EN 50131-1:2018 clause 8.4.2, the maximum supervision interval is 200 seconds — meaning the hub must hear from every enrolled sensor at least once every 200 seconds.
In typical Roombanker systems, the default supervision interval is much tighter: the hub checks in with each sensor every 12-30 seconds during normal operation. This serves two purposes:
• It detects a failed sensor battery or device fault within seconds.
• It creates a baseline of expected communication timing.
If the hub expects a check-in from a door contact every 15 seconds and nothing arrives for 60 seconds, that is a supervision fault. Under normal conditions, a single missed check-in could be a transient RF obstruction (a truck parked in front of the building, a temporary interference source). Three consecutive missed check-ins trigger a confirmed communication loss.
The limitation of supervision-only detection is timing. A jammer could theoretically suppress signals for 10-15 seconds during a break-in window, and the hub might register a single missed check-in without escalating to an alarm. This is why supervision alone is insufficient — it must be paired with other detection methods.
RSSI Anomaly Detection
Received Signal Strength Indicator (RSSI) is a measure of the RF energy the hub’s radio is receiving on each frequency channel. Under normal operation, a hub sees a predictable background noise level — typically -95 to -105 dBm in a quiet residential environment or -85 to -95 dBm in a city centre where ambient RF noise is higher.
When a jammer activates, the RSSI on the affected channel jumps dramatically — often to -40 to -20 dBm, a signal strength increase of 50-80 dB. This sudden change is highly distinctive. Normal RF noise does not shift by 50 dB in a fraction of a second.
Sophisticated alarm systems monitor RSSI continuously, not just during scheduled supervision windows. If the RSSI on the alarm frequency exceeds a configurable threshold — indicating an active jamming signal — the system triggers a jamming detection event. The key advantage of RSSI monitoring is speed: a jammer is typically detected within 1-2 seconds of activation, far faster than a supervision timeout.
Noise Floor Monitoring
Beyond sudden RSSI spikes, systems can track the noise floor — the baseline RF energy level on each channel — over time. A slowly rising noise floor could indicate a jammer being positioned and tested before an attack. Some modern hubs log noise floor data and flag gradual increases that exceed historical baselines by a configurable margin.
This is particularly relevant for Mediterranean installers working in city centres. The ambient RF environment in a busy Istanbul or Athens neighbourhood is noisier than a suburban villa in Crete. A noise floor anomaly system that learns the local baseline over the first 48 hours after installation can differentiate between normal urban RF pollution and deliberate interference — without generating false alarms.
Frequency Hopping as a Countermeasure
The most effective active defence against jamming is frequency hopping. Instead of communicating on a single fixed channel, a frequency-hopping system switches across multiple channels within its licensed band according to a pseudorandom sequence known to both the hub and the sensors.
A jammer that covers one channel at a time cannot suppress a frequency-hopping system without either predicting the next hop (which requires knowing the sequence algorithm) or broadcasting wideband noise across the entire band. Wideband jamming requires significantly more power — typically 10-50 watts — which means larger, more expensive, and more detectable equipment.
Roombanker’s RBF Protocol uses frequency agility across the 868 MHz band, switching channels dynamically based on both the programmed hopping sequence and real-time channel quality measurements. If a channel shows elevated noise or interference, the system de-prioritises it and moves communication to cleaner channels.
Response to Jamming: What a Grade 2 System Must Do
Detecting a jammer is only half the equation. The system must also respond appropriately. EN 50131-1:2018 specifies what a compliant system must do when communication is lost or interference is detected:
| Requirement | Grade 2 Specification | Practical Implementation |
|---|---|---|
| Supervision interval | Max 200 seconds | Hub checks each sensor every 12-300 seconds |
| Communication loss detection | Confirmed after 3 consecutive missed check-ins | Supervisor fault indicated, event logged |
| Local alarm on jamming | Must trigger audible warning | Internal siren sounds, strobe activates |
| Event logging | Time-stamped, min 500 entries | Jamming start/end times logged |
| ARC notification | Required if ARC-connected | “Jamming detected” signal sent to monitoring station |
For a more detailed breakdown of Grade 2 requirements across the full installation, see our EN 50131 Grade 2 Installation Guide.
In practice, a well-configured system should do three things when jamming is detected:
1. Trigger the local siren immediately. Unlike a burglar alarm, which waits for confirmation (typically two triggered sensors or one sensor triggered twice), a jamming alarm should be immediate. The attacker is actively suppressing your system — there is no time for confirmation logic.
2. Log the event with timestamps. Record when jamming started, when it ended, and which sensors went offline during the event. This data is critical for post-incident analysis and insurance claims.
3. Notify the monitoring station via an alternative path. If the jammer is suppressing the primary RF communication band, the hub should use its cellular (4G/LTE) or Ethernet backup path to send a jamming alert to the ARC. Most Grade 2 hubs include at least one backup communication channel specifically for this purpose.
Sub-GHz vs 2.4 GHz Jamming Resistance
The frequency band your system uses has a direct impact on how vulnerable it is to jamming — and how detectable the jammer is.
2.4 GHz band — crowded and easy to jam.
The 2.4 GHz ISM band is used by WiFi, Bluetooth, Zigbee, and countless other consumer devices. An attacker can buy a 2.4 GHz jammer for under EUR 30 that covers the entire band. Because 2.4 GHz is already saturated with legitimate signals, a jamming signal is harder to distinguish from normal interference. False jamming alarms are more common on 2.4 GHz systems because WiFi traffic spikes, microwave ovens, and other common sources can cause RSSI fluctuations that mimic jamming.
Furthermore, the short wavelength of 2.4 GHz means the jammer does not need high power to be effective. A low-power 2.4 GHz jammer can suppress signals within a 10-15 metre radius, which is often sufficient to cover entry points.
Sub-GHz band — harder to jam, easier to detect.
Sub-GHz frequencies (868 MHz in Europe, 915 MHz in other regions) have two inherent advantages for jamming resistance:
1. Less ambient noise. The 868 MHz band is regulated and primarily used by dedicated devices — alarm systems, utility meters, remote controls. The baseline noise floor is lower and more predictable, making anomalous RSSI spikes easier to identify as jamming rather than normal interference.
2. Jamming requires more power and space. A Sub-GHz jammer operating at range requires a physically larger antenna and more power than a 2.4 GHz equivalent. A wideband Sub-GHz jammer that covers 800-1000 MHz is significantly bulkier, more expensive (EUR 100-300), and draws more current — meaning it cannot run on a small battery pack for extended periods.
For a full technical comparison of how frequency choice affects range, wall penetration, and interference resistance, see our guide: Sub-GHz vs 2.4 GHz for Wireless Alarms. For a deeper look at why signal consistency matters more than peak range in real buildings, see Signal Stability vs Signal Range.
RBF Protocol’s Approach to Jamming Resistance
Roombanker’s RBF Protocol incorporates jamming resistance at the protocol level rather than treating it as an optional add-on feature. Three specific design choices are relevant for installers.
Frequency agility. RBF Protocol does not lock to a single channel. The hub continuously evaluates signal quality across available 868 MHz channels and shifts communication to the channel with the cleanest signal profile. If a jammer activates on one channel, the system shifts to another within the same communication cycle — typically under 100 milliseconds.
Adaptive channel switching. Unlike simple frequency hopping that follows a fixed sequence, RBF monitors real-time channel conditions and makes dynamic switching decisions. A channel with elevated noise is deprioritised until its noise profile returns to baseline. This reduces the window in which a sweeping jammer can lock onto the system’s communication pattern.
Supervision timing flexibility. The hub adjusts supervision intervals based on signal confidence. During normal conditions on a clean channel, check-ins may occur every 30 seconds. If the hub detects an anomalous RSSI reading or a single missed check-in, the supervision interval tightens to 5-10 seconds until confidence is restored. This means the system becomes more vigilant during suspected interference — the opposite of what a jammer attack requires.
For more on how RBF Protocol manages RF communication efficiency — including how these design decisions contribute to 5-6 year sensor battery life — the same architectural choices that reduce power consumption also support faster, more reliable jamming detection. For a beginner-friendly overview of how wireless alarm signals travel from sensor to hub, see How Wireless Alarm Communication Works.
What Installers Should Check
Jamming detection is only effective if the system is properly configured and the installer understands the local RF environment. Here is what to verify during every wireless alarm installation.
Conduct a site survey for RF noise before installing.
Use the hub’s diagnostic mode or a handheld spectrum analyser to measure the noise floor on the alarm frequency band at the proposed hub location. Record the baseline RSSI reading. In city centres, check at different times of day — a location that looks clean at 11 AM may be saturated with noise during evening rush hour when neighbouring businesses activate their own wireless equipment.
A baseline reading of -95 dBm or lower is excellent. Readings above -85 dBm warrant investigation. If the noise floor exceeds -75 dBm at the hub location, consider relocating the hub or choosing a system with frequency agility that can work around the interference.
Test jamming detection during commissioning.
Do not skip this step. Most installers test sensor triggering, tamper switches, and communication to the monitoring station. Few test the system’s response to active jamming.
Use a known-good RF source or a low-power test jammer (available from security test equipment suppliers, typically EUR 150-300) to simulate interference on the system’s operating frequency. Verify that:
• The hub detects the jamming signal within 2-3 seconds.
• The local siren activates immediately.
• The event is logged with a timestamp.
• If connected to an ARC, the jamming notification is received.
Document the jamming test results in the installation record. This protects you and the client if a future incident involves a jamming claim.
Educate the customer.
Explain to the end user what jamming detection means and what they should look for. A customer who hears the siren sound briefly and stops it without investigating may miss a genuine jamming attempt. Provide a simple checklist:
• If the siren sounds and there is no apparent intrusion, do not reset immediately. Check the alarm panel or app for a jamming notification.
• If a jamming event is logged, report it to the monitoring station and consider whether the property is being scouted.
• A single jamming event during the night that resolves itself may indicate a casual attacker. Multiple events over several nights strongly suggest targeted reconnaissance.
Verify backup communication paths.
If the jammer is suppressing the primary RF band, the hub must have a working backup path to send alerts. For every Grade 2 installation, confirm that the 4G/LTE cellular communicator has adequate signal strength at the hub location. A hub that relies solely on RF for all communication — including to the monitoring station — has no way to report a jamming attack. This is one of the most common oversights in wireless alarm installations, and it directly undermines the value of jamming detection.
The Bottom Line
A EUR 40 RF jammer bought online is a burglar’s tool. It is cheap, effective, and increasingly common in Mediterranean markets. The question for every installer and system specifier is not whether jamming is possible — it is whether your installed systems will detect it and respond before the attacker gets inside.
Jamming detection is not a premium feature reserved for high-security installations. For any Grade 2-compliant wireless alarm system, it is a core requirement. The combination of RSSI monitoring, noise floor analysis, supervision timing, and frequency agility creates a detection capability that raises the bar significantly for attackers.
The Izmir warehouse was burgled because the alarm system was deaf to the jammer. Your installations should not share that vulnerability. When you specify a system with proper jamming detection — and, critically, test it during commissioning — you transform a cheap attacker’s tool into a detectable event. The jammer may still activate, but the alarm will sound, the event will be logged, and the response will begin before the first sensor is compromised.
A jammer is a burglar’s tool. For market-specific data on wireless alarm adoption and security threats across Mediterranean and Central European markets, see our Poland Wireless Security Market Report 2026.
Jamming detection is an installer’s insurance. Install accordingly.
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