Jamming Transmitter

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Description

The Jamming Transmitter is a specialized Transmitter component designed to deliberately interfere with communication links by broadcasting RF energy across one or more frequency bands. Unlike standard transmitters that send data packets, the jamming transmitter continuously emits power when active, introducing interference noise into the communication channel of receivers operating within its frequency range. The Telemetry System incorporates this interference power into link budget calculations, degrading the effective signal-to-noise ratio of affected links.

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Example Use Cases

• Electronic Warfare Simulation: Model jamming operations against adversary communication systems.
• Communication Resilience Testing: Evaluate receiver performance under contested RF environments.
• Anti-Jamming Algorithm Development: Test frequency-hopping and spread-spectrum countermeasures.
• Link Margin Analysis: Assess communication system robustness against intentional interference.

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Module Implementation

The jamming transmitter extends the base Transmitter class, overriding key behaviors to support continuous multi-band interference generation rather than packet-based data transmission.

Multi-Band Operation

The jammer can operate across multiple frequency bands simultaneously. Each band is defined as a discrete frequency in Hertz:

$$\mathbf{B}=\{f_1,f_2,\dots ,f_N\}$$

where $N$ is the total number of bands. If no bands are explicitly configured, the jammer defaults to a single band at its configured operating frequency.

When determining which band to use for a particular link, the jammer selects the band closest to the target frequency:

$$f_{\text{selected}}=\underset{f_i\in \mathbf{B}}{\min }\left|f_i-f_{\text{target}}\right|$$

Transmission State

Unlike standard transmitters that transmit only when data is queued, the jamming transmitter continuously transmits whenever jamming is enabled and power is available:

$$\text{IsTransmitting}=\text{CanTransmit}\wedge \text{IsJamming}$$

The IsJamming flag provides user control over when the jammer is active, while CanTransmit is controlled by power availability (see Transmitter Power Model).

Power Consumption

When coupled with a Transmitter Power Model, the jammer’s power consumption scales with the number of active frequency bands. The total RF output power is:

$$P_{\text{total}}=P_{\text{tx}}\cdot N_{\text{bands}}$$

where $P_{\text{tx}}$ is the configured transmitter power per band (default 30 W) and $N_{\text{bands}}$ is the number of bands being jammed. This increased power draw is reflected in the electrical network via the power model’s resistance calculation.

Interference Contribution

The Telemetry System calculates the interference power contributed by each jamming transmitter to affected receiver links. For a receiver operating at frequency $f_r$ with bandwidth $B_r$, the interference from a jammer transmitting at frequency $f_j$ is:

$$P_{\text{interference}}=P_{\text{signal}}\cdot \Gamma (f_r,f_j,B_r)$$

where $P_{\text{signal}}$ is the received signal power from the jammer (calculated using standard link budget equations) and $\Gamma$ is an interference factor based on frequency separation and receiver bandwidth. The total interference power at a receiver is the sum of contributions from all active jammers.

Effect on Link Quality

The interference power degrades the effective signal-to-noise ratio of legitimate communication links:

$${\text{SNR}}_{\text{eff}}=\frac{P_{\text{signal}}}{P_{\text{noise}}+P_{\text{interference}}}$$

This reduced SNR directly impacts:

• Channel Capacity: The theoretical maximum data rate decreases per the Shannon-Hartley theorem
• Bit Error Rate: Higher error probability due to degraded $E_b/N_0$
• Transmission Rate: Effective data throughput is reduced

Frequency Band Matching

The jammer provides methods to determine how many of its bands fall within a receiver’s operational range:

$$N_{\text{matched}}=\sum _{i=1}^{N}1\left[f_{\text{target}}-\frac{B}{2}\le f_i\le f_{\text{target}}+\frac{B}{2}\right]$$

where $1[\cdot ]$ is the indicator function, $f_{\text{target}}$ is the receiver center frequency, and $B$ is the receiver bandwidth. This count determines how many interference sources affect a given link.

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Assumptions/Limitations

• The jammer transmits continuously when active; pulsed or intermittent jamming patterns are not modelled.
• All configured bands transmit at the same power level; per-band power control is not supported.
• Interference is calculated as additive power; phase relationships and coherent interference effects are not modelled.
• The jammer does not transmit data packets; it only contributes interference power to the RF environment.
• Frequency agility and adaptive jamming behaviours must be implemented externally by modifying the bands array.
• The interference factor calculation assumes a simplified spectral overlap model.
• Jamming effectiveness depends on proper configuration of frequency bands to match target communication systems.
• The jammer affects all receivers within range operating near its frequency bands, including friendly systems.