Radios for Warehouse and Forklift Teams

A distribution centre looks like an easy radio environment — one large open building. It is one of the harder ones, for reasons that are not visible when the site is toured empty.

A high-bay warehouse is a steel shell filled with regular rows of steel racking, loaded with goods that change weekly. That produces three effects at once.

Reflection. Metal surfaces reflect strongly, creating multipath: the same signal arriving by several routes and interfering with itself. The result is patchy coverage that varies within metres — usable in one aisle position and poor a few steps away.

Blocking. A loaded rack is a wall. Signal travels along aisles far better than across them, so an antenna at one end of a hall illuminates the aisles it faces and shadows the ones it does not.

Change. The stock profile is different in October from June. A coverage design validated once is validated against one loading condition.

UHF is the right band here because a 70 cm wave diffracts through the gaps between racking that a two-metre VHF wave treats as solid. But band choice alone does not solve the geometry — antenna placement does.

Three practices separate warehouse systems that work from ones that are complained about:

Survey loaded. Measure with the building in a realistic state, and ideally at more than one loading. A survey on a quiet Sunday describes a building that does not exist during the season the system matters most.

Illuminate along aisles, not across them. Antenna positions chosen so that signal runs the length of the racking rather than trying to cross it.

Carry margin. 10 to 20 dB of fade margin, because the environment is going to change and nobody will re-survey when it does.

Large centres with several halls, mezzanines, a chilled section and an outdoor yard generally need more than one transmitting position, linked over IP so the whole site behaves as one system.

A forklift cab is a metal frame around an operator whose hands are on controls. A handset in that position performs badly and is used badly.

A vehicle-mounted radio with an external antenna does substantially better, and the reason is the antenna rather than the extra power — a full-size element on the vehicle, clear of the operator's body, in a position that is not inside a steel cage. It also puts a fixed microphone within reach without the driver taking a hand off the controls for longer than a moment.

For teams that do both — driving and picking on foot — the working arrangement is a mobile in the truck and a handset on the person, programmed identically so the transition is invisible. This is set out in portable versus mobile radios.

Warehouse noise — trucks, conveyors, wrapping machines, reversing alarms, ventilation — sits at levels where a radio's own loudspeaker, aimed at a hip, loses.

The consequence is not merely inconvenient. A missed instruction near moving plant is a safety event, and it is routinely reported as a coverage failure, which sends the diagnosis in the wrong direction.

Practical choices: a remote speaker microphone at the shoulder for general work, a headset compatible with hearing protection where noise demands it, and where ambient noise is severe, digital voice earns its cost — DMR's error correction and noise handling keep speech intelligible where analogue audio has already been swallowed.

The default failure is everyone on one channel. In a centre with inbound, picking, dispatch, forklift, maintenance and security teams, that is unusable within a week.

A structure that works:

• Inbound / goods-in, coordinating deliveries and unloading.
• Picking and replenishment, the highest-volume traffic.
• Dispatch and loading, coordinating with the yard.
• Forklift and plant, which needs to be clear for movement instructions.
• Maintenance, which is intermittent and should not sit in operational traffic.
• A site-wide group everyone carries.
• An emergency path, separate and unmissable.

DMR's two timeslots mean this does not require six frequencies; Tier III trunking handles it with a shared channel pool once the site is large enough to justify it.

Warehouses combine moving plant, height and people working alone in aisles at night. The functions that matter:

• Emergency button with automatic user identification and a defined recipient.
• Lone-worker timers for night and weekend shifts.
• Man-down where working at height or alone is routine.
• Position awareness where the site is large enough that "where are you" costs time in an incident.

Configure these fleet-wide rather than per user, and test them on the real system at acceptance. An alarm function nobody has ever triggered is an assumption.

Above a certain size a control position pays for itself: a supervisor seeing the fleet, calling an individual without occupying a group, forming a temporary group for an incident and dissolving it after.

Call recording is worth specifying where incidents need reconstructing — a damaged load, a collision, a dispute over an instruction. It is cheap to include at design and awkward to retrofit.

Survey loaded, and say so in the contract. List coverage areas including mezzanines, chilled sections, the yard and the gatehouse, with a measurable acceptance criterion. Split devices by role, with vehicle installations specified down to the antenna. Match accessories to the noise environment. Agree the channel plan before delivery. And state service terms with a response time, because a distribution centre's tolerance for a two-day wait is nil.