Data Dora guidesA field team faces an unresolved physical question: How do 249 mAh and 5 GHz justify this offload? They must answer it before changing carrier on the real device. Predict the direction first.
See the relationship before changing it
Set the input, apply the rule, then read the result with its unit.
The retained audit below checks several chapter fixtures. This added model holds every other chapter fixture fixed, so the numeric fixture does not switch without explanation.
Derive the baseline in four named moves
- 1
Name the input. The chapter baseline for carrier is 5.
- 2
Name the relationship. 249x3.85/1000 = 0.959 Wh 18.7x3.85/1000 = 0.072 Wh saved = 0.887 Wh = 92.5% λ = 3.00x10⁸/(5.00x10⁹) = 6.00 cm; λ/4 = 1.50 cm
- 3
Substitute the chapter fixture. Set carrier to 5. The page ledger gives wavelength as 6.00 cm.
- 4
Read the result. Keep cm beside the value. Use it only inside the technical boundary on this page.
Predict, then change carrier
Try Predict the direction of wavelength. Move one control, calculate, then check your prediction.
Observe Predict a decrease in wavelength as the input increases over this range. Reset to the chapter baseline and compare.
Explain Only carrier moves here. The other chapter fixtures remain fixed.
Source: content/analytics-ml/edge-patterns-cyber-foraging-decisions.qmd — Phoebe's Field Notes: What the 249 mAh Actually Costs, and Why 5 GHz Was the Right Offload Radio. Use the chapter equation and fixed ledger above; only the named input varies.
Check yourself
What should you do before trusting a moved-control result?
What does this small model leave out?
1. Give each number a unit
Milliamp-hours measure charge, not energy. Attach the phone battery voltage before comparing work. Gigahertz measures cycles per second; divide wave speed by that frequency to get wavelength.
2. Name every algebra move
Convert chargeMultiply mAh by volts, then divide by 1,000: E=CV/1000.
SubtractSaved energy is Elocal−Eoffload.
Divide speed by frequencyλ=c/f.
Quarter the waveℓ=λ/4.
3. Reproduce the chapter case
18.7×3.85/1000 = 0.072 Wh
saved = 0.887 Wh = 92.5%
λ = 3.00×10⁸/(5.00×10⁹) = 6.00 cm; λ/4 = 1.50 cm
The transfer check is 3,840 MB ÷ 50 MB/s = 76.8 s.
4. Try the radio frequency
TryMove the carrier while keeping the chapter's charge and transfer case fixed.
ObserveThe energy ledger does not move, but wavelength and antenna scale shrink as frequency rises.
ExplainThe 5 GHz choice supports a compact, wide-channel room link; it does not create the battery saving by itself.
This is a unit ledger, not a complete radio model.
- Battery
- Voltage is held at 3.85 V instead of following discharge
- Radio
- Frequency alone does not determine throughput
- Antenna
- Quarter-wave length is not a finished antenna design
Measure transfer retries, radio power, range, and thermal limits.
5. Keep two decisions separate
Offload only when the local-versus-remote energy and delay ledger wins. Select the radio only when its channel, range, coexistence, and power tests fit the actual room.
6. Record the evidence
Store battery voltage, both charge measurements, payload size, measured throughput, carrier, channel width, range, retries, device identities, and fallback when the surrogate disappears.
7. Check yourself
Why is 249 mAh not yet energy?
What is the 5 GHz wavelength?
Does shorter wavelength prove the link will reach?
The charge, payload, throughput, and 5 GHz case come from the chapter; 3.85 V is a stated typical phone-cell assumption.
- 249 and 18.7 mAh
- Chapter measurements
- 3,840 MB at 50 MB/s
- Chapter transfer case
- 3.85 V
- Teaching assumption
Correct, not complete: this arithmetic does not qualify a surrogate, battery, or Wi-Fi link.