Quick Answer
Measure the outdoor level at the proposed donor position, then the indoor level in the worst rooms. Record RSRP and SINR, not just bars; the difference between outdoor and indoor levels tells you how much gain the system needs.
What to record
The most useful single number is RSRP at the proposed donor point. Add the band and cell ID so the reading can be tied to a specific network layer. If your app shows SINR, record it as well; a strong but noisy signal can still perform poorly.
- RSRP (dBm): the received power level.
- Band or EARFCN/NR-ARFCN: the frequency layer in use.
- Cell ID / PCI: the serving cell identity.
- SINR (dB): signal quality, if available.
- Operator and SIM: confirm which network the reading belongs to.
Where to measure
Measure outside first. Walk around the building, then test the roof or the highest accessible point. Indoors, test the worst room, the middle of the floor and any basement or stairwell. The difference between the best outdoor reading and the worst indoor reading is your working penetration loss.
| RSRP | Practical meaning |
|---|---|
| -85 dBm or better | Strong outdoor reference |
| -85 to -95 dBm | Usable outdoor signal for many booster systems |
| -95 to -105 dBm | Weak; donor antenna, height and feeder loss become critical |
| Below -105 dBm | Very weak; confirm whether a usable donor exists at all |
Thresholds vary by technology, bandwidth and network load. Use them to organise the site check, not as a guarantee of performance.
How to read the phone
On iPhone, use Field Test Mode where available. On Android, use the network information screen or a measurement app that reports RSRP, band and cell ID. Take several readings at each point and record the typical value, not the single best spike.
Take photos of the proposed antenna position, the cable route and the building facade. Note whether the wall is concrete, brick, metal cladding or Low-E glass. These details often explain a reading that looks inconsistent.
Book a remote diagnosis
Share the site conditions and we will reply with a preliminary assessment and the measurements still needed.
Frequently Asked Questions
Can I use the bars on my phone?
Bars are a vendor-specific indicator, not a calibrated level. Two bars on one phone can mean a different dBm value than two bars on another. Use RSRP in dBm for any equipment recommendation.
Do I need to measure every operator?
If the system must cover multiple operators, yes. Each operator may use different bands and different site locations. A donor antenna position that is good for one network may be poor for another.
How many readings are enough?
For a small site, three to five outdoor points and three indoor points are usually enough for a first assessment. For a multi-floor building, record at least one point per floor plus the roof and the worst area.