Map signal against throughput across your own space

short · 50 min · Objective 5.1

Task

Measure signal strength, noise and actual throughput at several points, and find out whether throughput tracks signal -- because it frequently does not, and that gap is what the signal-to-noise ratio explains.

Steps

  1. Choose five locations and record them in lab/wsig/locations.txt, one per line, with enough detail to return to each.
  2. At each, record signal in dBm, noise floor where the tool reports it, the negotiated data rate and the measured throughput to a host on your own network, in lab/wsig/points.csv with header location,signal_dbm,noise_dbm,snr_db,rate_mbps,throughput_mbs,band.
  3. Compute the signal-to-noise ratio for each point and record whether throughput tracks signal or tracks the ratio, in lab/wsig/tracks.md.
  4. Repeat two locations on the other band where your network offers one, and record the comparison in lab/wsig/bands.csv with header location,band,signal_dbm,throughput_mbs.
  5. Write lab/wsig/deadspot.md naming your worst location, whether the cause is distance, obstruction or interference, and the evidence that distinguishes them.

Verify

grep -c . lab/wsig/locations.txt
awk -F, 'NR>1 && NF>=7 {n++} END {print n" measurement point(s)"}' lab/wsig/points.csv
awk -F, 'NR>1 && $2<0 {n++} END {print n+0" point(s) with a negative dBm figure"}' lab/wsig/points.csv
grep -c . lab/wsig/tracks.md
awk -F, 'NR>1 && NF>=4 {n++} END {print n" band comparison(s)"}' lab/wsig/bands.csv
grep -Eic 'distance|obstruction|interference' lab/wsig/deadspot.md

Five locations with seven fields each, every signal figure negative, a tracking note, band comparisons and a dead-spot diagnosis. A positive signal figure means bars were recorded rather than dBm, which is the mistake this lab exists to replace.

Notes

The interesting result is a location with a strong signal and poor throughput. That is a noise problem, and it is the one that bars can never show.

This is an independent study companion for CompTIA A+ Core 1 220-1201 and is not produced by or endorsed by CompTIA.