SJUK hears exclusively from Stuart Longley, TETRA device portfolio product leader at Motorola Solutions.
In 1923, the Metropolitan Police began experimenting with radio-equipped vans.
Transmitters of the time required massive antennas to catch a signal.
To communicate while parked, officers had to physically climb onto the roof of the van and hoist a 15-foot telescopic mast.
A short time after this initial experiment with radio, in the early 1930s, the United Kingdom’s first police radios were deployed by Nottingham City Police.
However, they still didn’t use voice. Instead, they relied on Morse Code, which at the time, was easier to send and less prone to radio interference.
Nearly a century has passed since those early days of police radio.
Many technologies have come and gone, including: Bulky TVs, VHS tapes, floppy disks, DVDs, the fax machine.
Yet, the proven simplicity of radio push-to-talk remains the primary communications channel for police departments, fire brigades, ambulance crews and other critical personnel to stay in touch.
What gives these radio networks and their modern descendants, private mobile radio (PMR) systems, their longevity?
PMR does one job.
PMR systems exist to do one thing: reliably deliver signals between those who need critical help and those who can deliver it.
Thanks to advances in technology, today’s critical signals consist of digital voice calls, but their delivery is no less important.
Being able to carry voice calls instead of Morse Code is just one example of PMR technology improving and developing new capabilities, without compromising its core mission.
The electronics revolution in the second half of the twentieth century allowed radio equipment to get smaller, cheaper and more efficient.
Heavy, finicky, vacuum-tube powered equipment was replaced by reliable, solid-state transistor-powered radios that could be installed in every vehicle and eventually carried by every individual officer.
Handheld radios became as much a part of an officer’s equipment as their badge.
The computer revolution of the 1980s and 1990s brought digitalisation.
In the consumer market, the most visible example was the introduction of CDs to replace records and cassette tapes. In public safety communications, going digital meant better voice quality, static-free communications and far more efficient use of radio frequencies.
Thanks to techniques like trunking, which dynamically assigns channels as they are needed, the same set of frequencies could support far more radio users than before.
This is what gave rise to the TETRA (Terrestrial Trunked Radio) standard, released by the European Telecommunications Standards Institute (ETSI) in 1995.
Digitalisation made another major impact on PMR technology: as communications became digital, they turned into data.
Call processing equipment was no longer just about tuners, amplifiers, filters and mixers: it was software.
Today, a lot of PMR infrastructure equipment operates on commercial, off-the-shelf servers.
Critical features such as trunking, encryption, capacity management are all implemented via software.
PMR devices have also changed dramatically thanks to digitalisation.
Far from their analogue technological predecessors, today’s TETRA radios are sophisticated computing hardware, running specialised software.
Not only does the software convert speech to digital signals, it also handles authentication, tracks the user’s location and secures communications with a variety of encryption algorithms.
Cutting-edge audio processing, often created using AI and machine learning, filters out background noise and makes sure users can hear and be heard over deafening crowd noise or loud firefighting equipment, picking up clear audio even in situations where it’s too loud to hear someone shouting.
The rollout of 4G and 5G broadband created yet another opportunity for PMR communications, with today’s TETRA solutions embracing broadband as a complementary technology, able to deliver device-software updates and act as a backup connection for when the device is outside its home radio network.
Software built PMR devices and infrastructure makes the simultaneous use of TETRA and broadband secure, robust and nearly transparent.
And of course, broadband is the right medium for large-scale data communications, such as streaming video.
Whilst we are nearly 100 years removed from Nottingham’s first radio communications, the technology continues to develop,and thanks to its unmatched reliability and decades-long adaptability, PMR remains the gold standard for mission-critical voice.
