Why “perfect” wireless fails, and how we fix it
Perfect RF Spectrum, Terrible Signal. Here's why it happens, and how we fix it.
A nurse walks past the imaging suite, handset to their ear, updating a colleague about a patient transfer. The call breaks up as they enter the main hallway. Across town, an audio technician in a convention center is troubleshooting a similar issue: crystal clear audio for ten meters, then static, then silence.
On paper, coverage should hold in both environments. The base stations are placed correctly, and the spectrum is reserved and clean. Reality paints a different picture: static, garbled messages, and dropped signals that disrupt critical workflows.
Reserved spectrum can't solve physics
Many wireless devices use Wi-Fi or Bluetooth, so they compete over public airwaves. Pack enough devices into the same building and you get dropped packets, static, and slow connections. This is sometimes called the "noisy-neighbor" problem, where each device is fighting the building's Wi-Fi network and every visitor's phone for the same slice of radio frequency bandwidth.
DECT addresses this "noisy-neighbor" problem by operating on a spectrum reserved for reliable, high quality communication. However, reserved spectrum cannot fix what the building does to a radio signal. Flat, hard, reflective surfaces like steel wall panels or concrete floors bounce radio waves with very little loss. Some of that reflected energy reaches the receiver at almost the same time as the original signal, and some arrives noticeably later, having taken the long way round. The harder and more reflective a building’s surfaces, the worse this problem becomes.
Surprising Science
When a delayed copy arrives close behind the original, it smears into the next bit of data before the receiver has finished reading the first. This phenomenon is called inter-symbol interference, or ISI. The receiver cannot tell where one part of the signal ends and the next begins.
Separately, delayed copies can arrive out of phase with the direct signal and partially cancel it out, a phenomenon called multipath fading. That is what creates this dead spot: not a coverage gap, but a spot where the reflections happen to be working against the signal instead of with it.
Blame the walls, not the clutter
Here is the part that surprises most people: it's the bare, hard surfaces causing this, not clutter. A large, empty room with nothing to absorb or scatter the reflected energy can produce worse RF conditions than a furnished space. In one field test, RTX engineers set up in a completely empty, hard walled convention hall and recorded some of the toughest RF conditions the team has ever measured in 30+ years of DECT tech testing. This terrible signal quality wasn’t because of a crowded hall, but because it was empty.
How SheerWave™ technology fixes it
RTX SheerWave™ is an RF equalizer built into the receiver that constantly estimates how the radio channel is distorting the signal, then adjusts a filter in real time to undo that distortion. This is similar to how noise-cancelling headphones work, but for correcting reflected signals instead of blocking sound. The result is stronger range, better coverage in weak spots, rejection of interference from other DECT systems, and a signal that is easier to decode correctly at higher speeds.
The images below show what that looks like in practice. A clean signal goes out, multipath reflections smear it into something the receiver can barely parse, and SheerWave™ reconstructs the original from what's left.
The radio front-end picks up the signal, the adaptive equalizer filter reconstructs what was actually sent, and a feedback loop keeps re-tuning the filter as the environment changes. Because the correction happens continuously, it also stabilizes the signal-to-noise ratio, keeping it steadier over time instead of dipping and spiking when conditions change.
Proven in the lab and in the field
We put SheerWave™ through a deliberately difficult test scenario: a transmitter walking a fixed path, spinning 360 degrees every five meters. A standard receiver using 8PSK modulation lost 11.2% of packets along the route. We tested again using SheerWave™ technology, and the same receiver lost only 0.8%. Combine this with antenna diversity, and packet loss further approaches zero, even in harsh RF conditions.
Reliability where it matters
SheerWave™ is built into the receiver architecture, so it protects every connection the same way whether that's a voice call in a hospital corridor, an intercom cue backstage at a stadium, a sensor reporting from a warehouse floor, or a microphone feed in a hotel. Each setting has its own stakes when a signal drops: a delayed cue, a blind spot, or missed instructions can bring operations to a halt. SheerWave™ protects against all of these, resulting in fewer missed connections and cleaner communication, no matter the space.
Connect with our Experts
Reach out to our team to see how RTX SheerWave™ technology can strengthen your wireless reliability, and what your next communication system could look like.