A detector that only reacts finds what it is pointed at. Survey work starts the other way round: sweep the band, see what is actually transmitting in this location, then decide which emitters deserve a bearing. This configuration does both, in the order a field team actually works.

The sweep result is what makes the locate result trustworthy. A team that has already recorded the site's permanent transmitters will not spend an afternoon chasing a repeater, and a survey carried out before an event gives the on-duty crew a baseline to compare against.

• Scan the position — record everything transmitting across the three band segments before any drone is in the air.
• Flag the unknowns — anything that is not a fixed site transmitter moves to the watch list.
• Take bearings — direction finding gives each flagged emitter an azimuth, not just a level.
• Confirm identity — DID and RID fields decoded from the link add model and serial information up to 3KM.
• Log and leave — the position is documented, so the next survey pass starts from a known baseline rather than from zero.

• Pre-event spectrum survey — establish the venue baseline days before the crowd arrives.
• New site commissioning — find out what the electromagnetic environment actually contains before setting alarm thresholds.
• Fault investigation — when a detector reports repeatedly at the same level, a sweep shows whether the source is a drone or something bolted to the roof.
• Training and drills — run the sweep-locate cycle in a controlled exercise before it is needed for real.

The DF-04 platform is produced by Chongqing Miao Yi Tang Technology Co., Ltd., a company built with USD 12 million of founding investment in cooperation with the IoT Research and Development Center of the Chinese Academy of Sciences and Sichuan University Zhisheng Software Co., Ltd. (002253). The firm's engineering programme centres on AIoT cloud-plus-edge systems that unify electromagnetic, optoelectronic, visual and positional sensing into one integrated picture for ground and low-altitude security.

Survey support is part of the handover: band segmentation is set to the customer's own spectrum findings rather than to a default plan, and the first sweep is walked through with our engineers either on site or remotely. Consumables, antenna spares and mounting hardware are held in stock so a field position is never idle waiting on a part.

The figures above describe the standard DF-04 receiver; segment plans and survey support scope are agreed at order review.