What should a building owner ask before appointing an in-building radio coverage (BDA/DAS) contractor in Singapore?

Ask for the design basis in writing before you compare prices. That means the acceptance criterion the contractor will be tested against, both the uplink and downlink link budgets, the survey and drawing package you will receive, who handles IMDA licensing and equipment approval, and who maintains and re-tests the system after handover. A contractor who cannot show these before award rarely produces them at handover.

I review a fair number of tenders, and the pattern is consistent: two quotes that look alike on price turn out to cover different systems, because one priced to a coverage target and the other priced to a list of equipment.

What acceptance criteria and test method will the contractor commit to?

This is the question that decides everything else. I have not found a Singapore clause that prescribes a coverage percentage or signal level for a private two-way radio DAS, so the criterion is whatever your tender or contract says. If it says nothing, the contractor chooses, and it will not be the strictest one.

The reference most integrators borrow is US-derived: a signal of at least -95 dBm at the portable, over 90% of a general area and 99% of critical areas, verified on a grid survey. Write your own numbers into the tender and require the method to be stated. Our notes on DAQ 3.0 versus a -95 dBm criterion and on what SCDF and IMDA do and do not require explain why a level alone is not enough.

Will they show both the uplink and downlink budgets?

Ask to see both, line by line. A 4 W portable transmits at 36 dBm; a 40 W repeater at 46 dBm. That 10 dB gap, plus roughly 3 dB of body loss when the radio sits at the hip, means the uplink is frequently the limiting path. A downlink-only budget is incomplete and flatters the design.

Then ask for the fade margin and which path it applies to. My working minimums are 10 dB for a standard commercial building and 15 dB for mission-critical or public-safety use. Any design the contractor describes as passing should state its margin as a number, and a marginal result should be called marginal.

What survey and design package will you receive?

A budget is not a buildable design. Before award, ask what the deliverables are: a site survey including riser access (vertical cable normally runs in the ELV risers), a per-floor antenna placement plan with setting-out distances and the coverage radius each antenna must achieve, and a coupler and tap schedule showing power at each floor feed and each antenna port. Port power should land within about 3 dB across antennas, otherwise some antennas become the weak link.

Ask for an assumptions block as well: what was read off your floor plans, and what was assumed about construction, donor source and portable power. Assumptions buried in prose are the ones that fail at audit.

Who handles IMDA licensing and equipment approval?

A repeater or BDA is a fixed transmitter, so it needs a licence and type-approved equipment. Ask who applies, in whose name the licence is held, and who pays the annual fees. See our note on IMDA licensing and type approval for in-building repeaters and boosters. Confirm current requirements with IMDA directly.

What happens after handover?

Ask for the maintenance scope in writing: annual servicing, battery replacement intervals as stated on the manufacturer's datasheet, spares, fault response times, and who carries out and certifies periodic re-testing. Building changes such as new partitions or facade film can break a system that passed on day one. Our notes on ongoing running costs and re-test frequency cover what to budget.

Key figures

• Signal threshold (common reference): -95 dBm at the portable, US-derived, not a Singapore mandate

• Coverage targets (common reference): 90% general area, 99% critical areas

• Portable vs repeater power: 4 W (36 dBm) vs 40 W (46 dBm), a 10 dB uplink disadvantage

• Fade margin: 10 dB standard commercial, 15 dB mission-critical (engineering defaults)

• Antenna port balance: within about 3 dB

Related questions

Should I appoint the contractor on lowest price? Only after confirming the quotes cover the same acceptance criterion and deliverables. Otherwise the cheapest quote is usually the one with the weakest definition of "covered".

Should the designer and installer be the same company? It can work, but then your acceptance test should be witnessed or independently specified so the party being tested does not set its own pass mark.

When should the contractor survey the building? Before the design is fixed and before award if possible, because riser access, construction and noise floor all change the quantity of antennas and cable.

How Suneast handles this

Suneast designs, supplies, installs and commissions in-building two-way radio systems in Singapore. We issue the survey findings, link budgets (uplink and downlink), antenna placement plan and coupler schedule before installation, test against the criterion written into your contract, and handle IMDA type-approval and licensing for the equipment we install.