REVIEW: Police Test DJI Drone Loudspeaker

• Devon & Cornwall Police test the CZZN MP130 loudspeaker with the DJI M300 RTK drone: Watch the videos and read the review;

• Police say the loud hailer provides the capability to communicate with a person on the ground in a way 'not previously possible' with the M300 RTK;

• Tests show the speaker's audio was clear in a real-world environment up to 300m distance;

• Pre-record messages or record live messages for dynamic incident response;

• Use alongside other payloads, such as H20T camera, to enhance mission versatility and effectiveness;

• Loudspeaker particularly useful during a missing persons search or communicating with crowds at a large-scale event. 

"This is Devon and Cornwall Police. We can see you. Help is on the way."

Loud, clear and crisp - this message is relayed by the Force's drone team using the CZZN MP130 loudspeaker.

Okay, this is a test situation, but it proves the capabilities of this third-party payload for the DJI M300 RTK drone, and its benefits during live operations.

Crucially, the broadcast from the hailer can be transmitted from distance - perfectly audible at 300m to maintain a safe distance from the subject. 

PC Chris Linzey, of the Alliance Firearms & Drone Team, says: "The loud hailer attachment for the DJI M300 RTK provides the capability to communicate with a person on the ground in a way not previously possible."  

Following the trial, heliguy™ caught up with PC Linzey to get his feedback on the loudspeaker, also compatible with the DJI M200 Series V2 and V1.

Drone Loudspeaker - Audio

The loudspeaker is designed to convey public safety messages or provide a key communication channel to nearby individuals during critical, lifesaving emergency operations. 

According to the spec sheet, the max volume exceeds 130dB, the effective broadcast range is 300-500 metres, and the max broadcast range is around 1,000 metres.

So how does this translate in practice? According to PC Linzey, rather well.

He says: "The hailer was tested at 200ft AGL and 150m horizontally. It was then tested to 400ft AGL and 300m horizontally. On both occasions, the volume was set to high.

"The sound was as clear to me at 300m as it was at 150m."

PC Linzey says for the best audio; the speaker should be directed towards the subject when broadcasting.

"While still audible when pointed away, it is significantly more effective when directed towards the subject," he adds. 

Drone Loudspeaker - Broadcast Modes

The loudspeaker has a suite of play modes to enable mission versatility and ensure it can be used during live incidents and pre-planned operations.  

Broadcast modes include text-to-speech, scanning QR code to transmit text, voice broadcast and audio file playback.

PC Linzey says: "At this stage, spontaneous incidents are where we would envisage the most use, but the equipment does create opportunities for pre-planned operations where a police commander could carefully construct a selection of messages in advance of the operation.

"At the necessary time, and at the touch of a button, the most appropriate public safety message or direction could be transmitted.

"Of course, for more dynamic and spontaneous incidents, there is still the ability for the operator to record a live message via the controller and replay it immediately through the drone."

For this live mode, PC Linzey says that, as long as the operator speaks loudly into the microphone via the smart controller, the broadcasts will be effective.

"During the testing, such recordings were made and played, and found to be perfectly audible at 300m," he concludes. 

Drone Loudspeaker - Connectivity

The loudspeaker is compatible with the DJI M300 RTK and M200 Series via DJI Skyport. It can be controlled via CZZN software or DJI Pilot software. 

PC Linzey says: "The hailer connects easily to any of the gimbal ports. The included app, once installed, provides a user-friendly interface with which to operate it.

"The microSD card is housed on the hailer which provides sufficient storage space for large audio files and ensures fast file loading times."

As this image shows, the loudspeaker can be used in conjunction with other payloads, such as the H20T. This set up - giving operators thermal, zoom, wide-angle and laser rangefinder capabilities, as well as the loudspeaker - enables mission effectiveness and versatility. 

The loud hailer can be controlled from up to 10km away to benefit long-distance operations. This is especially useful, considering the M300 RTK's increased endurance.

And the design of the speaker - weighing 545g - ensures that it doesn't overly impact the flight time. 

"The hailer is made of a lightweight plastic so adds very little to the overall take-off mass of the drone," says PC Linzey.

However, he does admit that the loudspeaker will incur some air resistance when the drone is traversing. 

Drone Loudspeaker - How It Helps Public Safety Operations

Having tested the loudspeaker, PC Linzey believes it will be of major benefit to real-world operations - particularly effective for missing person searches, in rural areas like Dartmoor and also for rescue situations such as along Devon and Cornwall’s coastline.

He says: "Devon and Cornwall Police undertakes a significant number of deployments involving vulnerable and missing person searches.

“The speaker will allow us to communicate with persons we locate with the drone to provide reassurance and/or instructions whilst suitable ground units are directed to their location to help.

"Unfortunately, it’s not uncommon for a person to be lost and/or injured and be unable to provide their location, despite being able to communicate in some way. 

"It is also often the case that a vulnerable person suffering a mental health crisis will be contactable by mobile phone but may be unwilling, or unable, to provide police with their location.

"During these conversations, the police operator will be asking questions and listening for clues as to the person’s possible location. The ability to transmit sound at a high volume, will, in the right circumstances, provide an opportunity to narrow down the search area.

"When the operator hears the sound in the background of the call, the area in which the person is located will be narrowed down substantially.

"Further use cases include the ability to broadcast messages to a large group of people at public events. This is particularly useful in public order/public safety environments where the elevated position of the drone, coupled with the high volume of the hailer, could overcome crowd noise."

Drone Loudspeaker - Verdict 

Overall, Devon and Cornwall Police says it is impressed with the loud hailer and can see it benefiting operations. They are now considering adding it to their payload inventory.

PC Linzey concludes: "This payload assists workflows in a number of ways.

"It solves the current inability to communicate with persons on the ground. Without the hailer, we’re only able to monitor via video link. With the hailer attached we can conduct clear one-way audio communication which, in turn, could return visual communication clues back from the subject(s)."

About Devon and Cornwall Police's Drone Team

Devon and Cornwall Police's drone team began in 2015. At this point, the Force was the first emergency service organisation in the UK to establish a dedicated drone unit.

Utilising a range of DJI aircraft, including the Mavic 2 Enterprise Advanced, the Force has 35 drones and the same number of trained pilots.

Recently, the team utilised police drones to support the security policing of this year's G7 summit in Cornwall.