tv Station power vs time.
mar,2003
The power in the 6 Mhz band of each tv
Station is monitored using the hilltop
monitoring
system.
There are 5 frequency bands of the rfi monitoring system that
contain tv stations: (70, 165, 235, 550, and 725 Mhz). A peak hold
on a band (duration 1 minute) is repeated every 20 minutes.
This gives 74 measurements per band per day. For each tv
station:
- For each measurement the sum of the 6 Mhz tv band is computed.
- The min, max, mean, and median values for the 74 sums of a day
are computed and then plotted.
- Year to date and yearly plots are made.
Some things to be aware of:
- Each hilltop monitoring band has a different tsys and gain.
The plots include these values. At the bottom of each plot are
two dashed lines.
- The black line is the minimum power in the band for the day.
- The red line is the median power in the band for the day.
Use these lines to check whether the power in the band is
changing. They are integrated over 100Khz rather than the 6Mhz of
each tv station.
- When the red and black dashed lines go to zero, there is no
rfi monitoring data.
- Leakage between channels. Tv stations are spaced by 6 Mhz. For
strong tv stations there is leakage between channels in the
spectrum analyzer. If you see adjacent channels moving together
then this is probably the reason. The channel with the higher
power is the channel that is resposible for the power.
- The spectrum analyzer on the hill may be off in frequency by
up to .6 Mhz. This will also mix stations a little.
- When the 430 Mhz transmitter is on, many of the hilltop
monitor bands saturate. When you see many tvStations moving
together, this is probably the reason.
- If a tv station jumps around a lot in the median power plot,
look at the mean or max power plot. The station is probably
turning on for half a day and the median is alternating between
catching the on and off power levels.
Notes:
- 2020: 01mar. K&L switch box fails. After this only 1325 lband filter. So no more tv data.
- 2018: switched station plots to stop at channel 51. above this
was deallocated from tv a few years back.
- 2012:
- 17oct12 off the error. some amps blown out
- restarted with missing amp (fo) and less spectanalyzer
attenuation . So changes in power are from this and not the
signal getting weaker.
Tv
channel
frequencies.
processing: x101/rfi/tv/tvmon.pro
home_~phil