PTP 700 Frequency Hopping

By David Aylesworth   March 27, 2024

Dynamic Spectrum Optimization (DSO) is a unique capability offered by Cambium Networks that optimizes link performance by automatically sampling and changing channels to avoid interference without affecting link service. DSO reacts to real-time channel conditions and will not change unless a more suitable channel is detected. Some tactical scenarios call for frequent proactive channel changes to avoid jamming, detection, interception, or geolocation of radio signals. To support these scenarios, Cambium Networks is introducing a Frequency Hopping capability to the PTP 700 product line.

Frequency Hopping (FH) is a tactic used to avoid jamming and interference, and a method of proactively changing channels to avoid detection. Traditional FH is not commonly used in large microwave networks where co-location and reliable communications are a requirement, but it does have its place on the tactical edge, where lowering the probability of interception and detection (LPI/LPD), and mitigating jammers have more value.

Modern wide-band spectrum analyzers used by capable adversaries can monitor and track any fixed or frequency hopping system. FH radios are often locked into smaller frequency ranges of a few hundred megahertz and are operationally confined to low data-rate modulations such as BPSK or QPSK. FH systems can struggle to meet higher standards of spectral efficiency, seeing only 1 or 2 bits/Hz/sec.

Cambium Frequency Hopping is supported on PTP 45700 and PTP 78700 microwave radios, adding FH to the existing Fixed Frequency (FF) and DSO features. All existing PTP 700 series radios except Beam Forming are upgradable to support FH through a license key and the appropriate software version.

Cambium Frequency Hopping intelligently leverages the full suite of DSO tools into traditional blind frequency hopping:

  • Full-time spectrum analysis along with configurable thresholds, channel barring, and wide-band operation, make this feature very compelling when trying to avoid detection and interception.
  • Higher data rates than traditional FH; DSO analyzes the spectrum in real time and holds up to 25 hours of history per channel.
  • The system randomly hops but also avoids high interference channels to keep data rates high.
  • The PTP 700 knows what the spectrum is like and what is changing, and constantly updates the pool of available channels, making it truly a dynamic hopping pattern vs a fixed one.
  • Provides channel changes with adjustable thresholds; The channel change algorithm will actively avoid channels with high levels of interference that exceed the thresholds and those channels barred by the operator, to not interfere with other co-located systems.

Intelligent Frequency Hopping raises the bar and performs better than blind FH systems, which are prone to use congested channels due to their lack of intelligence.

Understandably, implementing any type of frequency hopping will decrease a radio’s maximum performance. When forced to operate in a hostile RF environment, Cambium Networks PTP 700 with Intelligent Frequency Hopping is the clear choice for spectrum agility while maximizing performance.

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This post was updated on April, 10, 2024.

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