SI2107-X-FM SILABS [Silicon Laboratories], SI2107-X-FM Datasheet - Page 33

• Manufacturer Part Number: SI2107-X-FM
• Description: SATELLITE RECEIVER FOR DVB-S/DSS WITH QUICKLOCK AND QUICKSCAN
• Manufacturer: SILABS [Silicon Laboratories]

The default values for the minimum and maximum
symbol rates are zero. Enter minimum and maximum
symbol rates.
Recommended values are SRMIN = 1 MBaud and
SRMAX = 45 MBaud for discovery of all possible DVB-
S channels.
2. Program the following registers with the following
Important: It is highly recommended that the registers
in Step 2 be programmed with default values provided
by Silicon Laboratories. Refer to “AN298: Si2107/08/09/
10
Software”, for the recommended values. The values are
documented in the QuickScan section of the application
note. Silicon Laboratories has tested QuickScan under
real world conditions in a number of countries and the
recommended values provide the best performance.
3. Clear the following Host Control Register bits.
a. Default values
parameters.
a. LSA Control Register 1. The length of the time
b. Tilt Correction Threshold Register. A correction can be
c.
d. 1 dB Bandwidth Threshold Register. This sets the
e. 2 dB Bandwidth Threshold Register. This sets the
f.
g. Inband Power Threshold Register. This sets the
a. SR_CTRL_HOST
b. ADCSR_CTRL_HOST
c.
d. FTF_CTRL_HOST
Application
Reference Noise Level Margin Threshold Register.
3 dB Bandwidth Threshold Register. This sets the
CTF_CTRL_HOST
averaging window is set by setting AVG_WIN. The
averaging removes uncorrelated noise from the
spectrum.
applied to the spectrum to compensate for "tilts" in the
spectrum due to frequency dependent attenuation
such as poor cables for example.
This sets the power level threshold for the detection of
channels.
tolerance level for determination of the 1 dB
bandwidth for a detected channel.
tolerance level for determination of the 2 dB
bandwidth for a detected channel.
tolerance level for determination of the 3 dB
bandwidth for a detected channel.
threshold for determining the drop in power in a
detected channel to determine the channel bandwidth.
i. SRMIN = 0 MBaud
ii. SRMAX = 0 MBaud
iii. BS_FMIN = 825 MHz
iv. BS_MAX= 2087 MHz
Programming
Interface
Preliminary Rev. 0.81
Example
Important: These bits should be returned to their
default settings (allowing host control) if the user wants
to tune to individual channels following blindscan for
single channel acquisition.
4. Set BS_START in the Blind Scan Control Register. This
5. Wait for either BSDA (or interrupt BSDA_I) or BSDO (or
6. Take the following actions depending on which condition is
RF(MHz) = BS_CTF x 10 + {BS_FTF(decimal) + CFER
(decimal)} x BS_ADCSR
Symbol Rate (MBaud) = SREST x BS_FS / 2^23
7. Repeat Steps 1 through 6 with the change in values for the
8. End of blindscan operation. The final set of estimates for
initiates the blindscan process.
interrupt BSDO_I) to be set.
present:
a. When BSDA (or BSDA_I) is set: the device has found
b. When BSDO (or BSDO_I) is set: the blindscan
following parameters if the Symbol Rate search range is
below 12.5 MBaud.
a. Set SRMIN to 12.5 MBaud.
b. Keep SRMAX the same value from the first pass.
c.
d. Set 2 dB Bandwidth Threshold Register to the second
RF center frequencies and associated symbol rates can
be used by the host to lock to the detected channels to
obtain channel information such as Channel ID for
example. Also at this point channels falsely identified
during blindscan can be rejected upon failure to lock.
Set Inband Power Threshold Register to the second
a potential DVB-S or DSS (depending on the part's
operating mode) channel. The host can read out:
operation is complete within the RF and symbol rate
search ranges. The device automatically clears
BS_START.
recommended default value.
recommended default value.
i. BS_CTF, BS_FTF, CFER, and BS_ADCSR
ii. SREST to determine the channel's symbol
iii. Upon reading these registers, the host
to determine the channel's RF frequency
from the following formula:
format of <15,14> and CFER with a fixed
format of <16,15> are 2's complement
numbers which need to be converted into
decimal numbers first.
Where BS_FS = BS_ADCSR x 1 MHz
Note: The registers BS_FTF with a fixed
rate estimate from the following formula:
should clear the BSDA & BSDA_I bits. Go
back to Step 6.
Si2107/08/09/10
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