ITS Propagation Data Measurements - Phase 1 Data
FTP
ftp://flattop.its.bldrdoc.gov/propdata/phase_1/
access raw Phase 1 propagation measurements from FTP directories.
PHASE_1 data are spot measurements using frequencies that emphasize
the VHF band (30-300MHz) and environments that emphasize irregular terrain.
One feature is that many of the paths appear in threes
with the receiving antenna at the "principal" location or at an
"alternate vertical" or an "alternate horizontal" location. The
principal location is assigned from a map, and should be fairly
random. The alternate locations simulated "siting improvement".
For the alternate vertical location, the receiving vehicle was
driven slowly over available roads within a 100-meter radius of
the principal location while observing vertically polarized
100-MHz test signals with the 3-meter antenna height. The new
location is that at which the received power is a maximum. The
alternate horizontal location is determined in the same way,
except that horizontally polarized signals are used.
For each of the three measurement sets there are three data files:
- xxpars.txt - provides values for the pertinent parameters of the measurement system.
- xxpath.txt - gives coordinates of both terminals together with computed distance between them.
- xxdata.txt - provides the corresponding measured values.
- They are given as the observed "attenuation relative to
free space" (also called the "excess path loss"). If a space is
blank (or .0000) there was no corresponding measurement--often because of
equipment failure. If the signal was below system sensitivity
there is a different indication. The maximum attenuation that
would have been observable (less 5 dB to make a conservative
estimate) is computed, and then the value used is that computed
attenuation plus the number 500. For example, the value 560
means that the corresponding attenuation was unobservable but was
evidently greater than 60 dB.
The three data sets correspond to three different terrain
types: the plains, and then the mountains of central Colorado,
and the hills of northeast Ohio. The basic measurements are
nominally at 20, 50, and 100 MHz, and the last frequency at both
vertical and horizontal polarization. There are additional
measurements according to the data set involved.
In Colorado (for both the plains and mountains data sets)
there are two additional measurement sets. The first used a
second transmitter at 100 MHz. This was a commercial FM
broadcast station having the call letters KLIR and located about
40 km southeast of the basic transmitting site in a fairly flat
region. The second set of additional measurements concerned the
cross-polarized signals at 100 MHz. The vertically polarized
transmissions were received on the horizontally polarized antenna
and the horizontally polarized transmissions on the vertically
polarized receiving antenna. The results are recorded in the
files ..XDATA. Note that the original data analysis, as repeated
in the reference reports, used the wrong receiving antenna gains.
In the present files there has been an attempt to correct the
data. This correction, however, has introduced a further
variability of about 3 or 4 dB.
In Ohio, there were six transmitting sites--a "central" site
and five "peripheral" sites. The latter were evenly spaced on
the circle 50-km from the central site. Receiving sites were all
within this same circle. In the present files, the central site
has been called T0 and the peripheral sites T1,...,T5.
The following data exists:
- Johnson, M. E., M. J. Miles, P. L. McQuate, and A. P. Barsis (1967),
- Tabulations of VHF propagation data obtained over irregular terrain at 20, 50, and 100 MHz,
- ESSA Tech. Report IER 38-ITSA 38.
- Johnson, M. E., M. J. Miles, P. L. McQuate, and A. P. Barsis (1967),
- Tabulations of VHF propagation data obtained over irregular terrain at 20, 50, and 100 MHz,
- Part II: Colorado Mountain data, IER 38-ITSA 38-2.
- Johnson, M. E., M. J. Miles, P. L. McQuate, and A. P. Barsis (1967),
- Tabulations of VHF propagation data obtained over irregular terrain at 20, 50, and 100 MHz,
- Part III: Ohio data, ESSA Tech Report IER 38-ITSA 38-3.