Part II: Settings and Measurements
12-4 Bidirectional Test System Parameters and Range Setup
12-4.1 Downstream Communication Signal Parameters
1.
Down Freq = the DS communication signal frequency from the DS1615. The comms carrier bandwidth is
less than 300 kHz.
Note
: Take special care to avoid inserting these comms channels on an occupied
spectrum where active signal is present.
Input range value = 42~120MHz (
Note
: This is an intrusive carrier signal. Take special care to ensure the
spectrum space is empty and available). The comms signal frequency must be identical to the "Down
Link Freq" set in the DS2831.
2.
Down Amp = the DS output communication signal (comms) amplitude from the DS1615. The amplitude
of the signal should be about the estimated downstream distance (in dB of loss) from the HE. (As a
general safe practices, always start the comms signal level as low as possible and work your way up to
the point of “sync”, so not to introduce unnecessary additional RF power and potentially overdrive your
lasers and introduce non-linear distortions on your network, ensuring high enough levels to maintain a
reliable communication between the HE and field location. (2-3dB additional headroom is acceptable)
Input range = 25~50dBmV.
3.
Sync Code: This is reserved for system extension function and normally does not need to be modified, it
is recommended to use the default value.
12-4.2 Upstream Communication Signal Parameters
1.
Pilot Frequency: this signal frequency is required for a valid DS2831 registration with the HE equipment.,
Do not
insert the pilot frequency channel where active signals may be present (e.g. DOCSIS channels).
Valid range = 5~65MHz. The value must be the same as the "Pilot Freq" in the DS2831 parameter setting.
2.
Pilot Amplitude: The DS1610-D will validate the DS2831 registration amplitude. The value should be less
than the pilot amplitude transmitted from DS2831 so that the DS1610-1D can correctly accept the
DS2831 registration request. The pilot signal amplitude received by the DS1610-1D should be equal to
the pilot signal amplitude from the DS2831 minus (-) the estimated attenuation from the DS2831 (field
location) to the DS1610-1D (HE or Hub).
Note
: The pilot amplitude should be greater than the combined noise and interference signal in the
network at any given US port of the DS1610-1D to avoid that the DS1610-1D mistakes random noise as a
registering request from the DS2831. It is recommended to choose the port with the worse signal quality
as the standard when setting up. However, Special care should be given to insure the pilot carrier level
is not “too high” on clean looking nodes so as to avoid unnecessary RF energy contributions on the
return path.
3.
Up Freq = the frequency used by the DS2831 for communication. This narrow FSK modulated signal uses
a bandwidth of less than 200 kHz.
Do not
insert these comms channels on an occupied spectrum where
active signal is present.
Input value range = 42 ~ 120 MHz. The value must be identical with "Up Link Freq" in the DS2831
parameter setting.
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