Development and humanitarian · Sector explainer

A school, a camp, a river, a clinic.

School connectivity, displacement sites, anticipatory-action hydromet nodes and health-facility monitoring. Five scenes, each a working calculation: what a school link must carry, whether a camp radio link closes, when a river gauge gives enough time to act, what a clinic’s solar and batteries must hold, and what a rapid-deploy kit draws.

Scenarios

4

Live calculations

5

Community fit

Strong

01 · School link

Scenario

Size the link for the lesson, not the brochure.

Satellite or fixed wireless, school Wi-Fi, an open connectivity probe and an optional station. The link is sized from the busiest lesson: students online at once times what each one pulls. Latency has a floor set by physics: the round trip is four times the satellite altitude over the speed of light, about 477 ms through a geostationary satellite at 35,786 km and a few milliseconds through a 550 km low-orbit shell before any processing.

Backhaul

Busy-lesson demand

75.0 Mbit/s

Data per month (20 school days)

2,025 GB

Physical round-trip floor

7.34 ms

Probe on the school side

Speed, latency, uptime

02 · Displacement site

Scenario

A link closes on decibels.

Point-to-multipoint wireless, satellite backhaul, solar and water-point sensors with protection safeguards. A point-to-multipoint link closes when transmit power plus both antenna gains, less free-space loss (20 log d + 20 log f + 32.44, d in km, f in MHz) and 2 dB of cable loss, stays above the receiver’s sensitivity; planners hold about 10 dB of that margin for fading, foliage and alignment. Fresnel zone 1, of radius 8.66 √(d/f) metres at mid-path with f in GHz, must stay clear. Water points are sized to the Sphere minimum of 15 litres per person per day and at most 250 people per tap.

Band

Free-space loss

117.3 dB

Received level

-60.3 dBm

Fade margin

14.7 dB

First Fresnel radius, mid-path

6.2 m

Water per day at 15 L

180 m³

Taps needed at 250 per tap

48

03 · Anticipatory action

Scenario

Act before the peak, on a number agreed in advance.

Stations deployed through UN implementing entities of the systematic-observations financing pathway. An anticipatory-action protocol pre-agrees a trigger and the money behind it. For a small tributary the rational method gives the peak flow, Q = C · i · A / 3.6 (Q in m³/s, i in mm/h, A in km²), to compare with the channel’s bankfull capacity. The lead time is the flood wave’s travel from the upstream gauge, distance over wave celerity, and it has to exceed the time the partners need to act.

Land cover (runoff coefficient)

Peak flow (rational method)

31.1 m³/s

Share of bankfull

124 %

Lead time from the gauge

5.6 h

Trigger

Act now

04 · Health facility

Scenario

Keep the vaccines between 2 and 8 °C.

Power and temperature telemetry for clinics. The array is sized from the daily load over peak sun hours and system efficiency; the battery from the load times the days of autonomy over the usable depth of discharge. The fridge reports every few minutes so an excursion outside 2 to 8 °C is seen while the stock can still be saved.

Array size

2.7 kWp

550 W modules

5

Battery nameplate

22.5 kWh

Cold chain

In range

05 · Rapid-deploy kit

Scenario

Everything that fits in one vehicle.

A first-week kit: a satellite terminal, an access point, a few rugged cases and portable solar. The daily energy is the sum of each draw times its hours; the panel yields its rating times the peak sun hours times about 75 % after heat, dust and conversion losses. What is left over charges the battery; the battery alone carries the kit through the night or a cloudy day.

Continuous draw

105 W

Energy per day

2.52 kWh

Solar yield per day

2.25 kWh

Daily balance

-0.27 kWh

Runtime on battery alone

19.1 h

06 · Proof

Evidence

What agencies and donors check.

Procurement teams ask for registrations, standards and cost evidence before a site is approved. The grid keeps each one as a record beside the deployment it belongs to.

Show the record for

Asked for

UN vendor registration

Record kept

The contracting entity’s registration reference, attached to every quote