Coverage Verification: How to Prove a Radio System Works Before Sign-Off
A design document is a prediction. Acceptance is a measurement. The gap between them is where disputes live, and it is closed by agreeing the test before installation, not after. What to test, where to test it, and who signs.
| Specification | What it proves.. | Where the pass.. |
|---|---|---|
| Test | What it proves | Where the pass criterion comes from |
| Walk test in the worst structure | Whether handhelds work where people actually stand | The room, stairwell or basement your staff named as worst |
| Drive test on the site perimeter | Whether coverage continues at the edges vehicles use | The route your vehicles take, measured end to end |
| Talk-path load test | Whether the repeater carries the peak number of groups | Peak concurrent groups from your operating procedure |
| Emergency call path | Whether the emergency button reaches the person who must act | Named role and response time in your procedure |
| Audio intelligibility in noise | Whether speech is usable, not merely audible | The noisiest normal working position on site |
| Battery runtime against a shift | Whether a charged radio lasts the shift it is issued for | Shift length plus a margin you define |
| Measured level against the receiver floor | Proves margin, not merely that a voice was audible | Datasheet sensitivity 0.14 uV digital is about -124 dBm; a 10 dB margin lands near -114 dBm |
| Repeat readings at the same spot | Proves the link is stable rather than a lucky sample | Three readings within a few dB; a reading that swings widely means interference or a marginal path |
| Indoor-to-outdoor handover | Whether calls survive walking out of a building | The route people take when they leave in a hurry |
Coverage Verification
The distinction that decides most acceptance arguments is between designed coverage and measured coverage. A design states its assumptions: this many walls, this floor separation, this antenna height, this many concurrent groups. If the assumptions hold, the design is defensible. But the site as built is what the radios actually work in, and only a measurement tells you whether the assumptions were right. That measurement has to be agreed in advance, because after installation both sides have an incentive to define it differently. Write the test plan into the order: which locations, which routes, how many radios talking at once, what counts as a pass, and who is present. A criterion of 'good coverage' is not a criterion; 'audible and intelligible in these four named locations, with two simultaneous groups active' is.
Acceptance Testing
For a remotely supplied system, the split is unavoidable and should be stated plainly. The supplier can design, pre-program and pre-configure, and can support the test remotely by joining a call while your technician walks the route. The supplier cannot walk the site, cannot measure your building, and cannot sign off coverage they have not observed. Put the responsibility where the access is: your team or contractor performs the survey and the acceptance test, records the results per location, and owns the sign-off. What the supplier owes you is a design whose assumptions are written down, a programming file that matches the plan, and a documented response when a location fails. Getting that split into the order at the start is worth more than any warranty clause added afterwards. Put real thresholds in the test plan rather than adjectives. The published digital sensitivity of a current Motorola portable is 0.14 uV at 5% BER, which is about -124 dBm into 50 ohm; a workable acceptance threshold is usually set with margin above that floor, so a 10 dB margin gives a target of roughly -114 dBm at each named location. Because path loss rises with 20*log10(distance), every 6 dB of margin corresponds to half the distance, which is a useful way to read a failing result: a location that misses by 6 dB is not marginal, it is out of reach.
Data Source: Method reflects the scope boundary published on /systems: remote design, programming and support; on-site survey, installation and acceptance by the customer locally. No measured coverage results are claimed. Receiver figures come from the Motorola R7 datasheet (https://www.motorolasolutions.com/content/dam/msi/docs/mototrbo/r7/r7-datasheet-na.pdf): 0.14 uV digital sensitivity at 5% BER. The -124 dBm and -114 dBm values are arithmetic on that sensitivity into 50 ohm, not manufacturer statements.
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