Claro cell phone problems in Utuado
The engineer for claro phone
company contacted AO on 06may14 reporting a problem that they were
having with 5 cell phone tower sites in Utuado. The problem
started around 21apr14. He wondered if we had seen anything
different in that frequency range starting on 21apr14. The
problem was with the uplink bands:
This is the same engineer who helped us when we
were searching for the 430 Mhz problem a few weeks back (it
ended up having nothing to do with Claro).
- 835-845 Mhz
- 846.5 - 849 Mhz
I looked at the rfi hilltop monitoring system to
see if anything unusual appeared around 21 apr 14.
System description of the hilltop monitor system:
The two dynamic spectra show power vs time for 15apr14 ->07may14
- a disc cone antenna going 10 Mhz to 1.5 ghz, and a high
frequency antenna 1 to 10 Ghz.
- connected to a filter bank with amplifiers
- and then to a hp spectrum analyzer.
- The system cycles through 20 bands covering 10Mhz to 10 Ghz
- At each band , the filters, amps are set up , and then a 1
minute peak hold is done on the band
- This data is then read back into the computer.
- It takes 20 minutes to cycle through the 20 bands, so each
band is sampled once every 20 minutes
- The 810 to 1100 Mhz band covered the Claro uplink bands. It is
sampled with a 100Khz resolution bandwidth.
- The horizontal axis is frequency 810 to 1100 Mhz
- the vertical axis is day of month for april14
- numbers > 30 are just the beginning of may..eg 35 =
- White is stronger, dark is weaker power. (it is an image of
data on a db scale).
- High sensitivity img
- This shows the noise floor. The strong signals have
- low sensitivity img
- the image is scaled to show the stronger signals.
The second set of plots shows
the total power in each of the 2 uplink bands vs time (.ps)
- The top plots shows the power averaged 835-845 Mhz vs time
- The bottom plot shows the power averaged 846.4-849 Mhz
- You can see the daily usage of the cell phone towers.
- high during the day, low at night
- Nothing different is occurring around 21apr14.
- the images show that there are no strong out of band emissions
that started around 21apr14
- the total power vs time for the two bands also look unchanged
pre 21apr14 pos 12apr14
- the problem was reported for some towers in utuado.
The signals that we see here are probably coming from towers
closer to AO.