Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
  • H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
  • H03J1/02—Indicating arrangements
  • H03J1/04—Indicating arrangements with optical indicating means
  • H03J1/045—Indication of the tuning band, the bandwidth, tone control, the channel number, the frequency, or the like
  • H03J1/047—Indication of the tuning band, the bandwidth, tone control, the channel number, the frequency, or the like using electronic means, e.g. LED's
  • H03J1/048—Indication of the tuning band, the bandwidth, tone control, the channel number, the frequency, or the like using electronic means, e.g. LED's with digital indication
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
  • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
  • H03J7/02—Automatic frequency control
  • H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
  • H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
  • H03J1/0008—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor
  • H03J1/0041—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor for frequency synthesis with counters or frequency dividers
  • H03J1/005—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor for frequency synthesis with counters or frequency dividers in a loop
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
  • H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
  • H03J1/06—Driving or adjusting arrangements; combined with other driving or adjusting arrangements, e.g. of gain control
  • H03J1/14—Special arrangements for fine and coarse tuning
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
  • H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
  • H03J5/02—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with variable tuning element having a number of predetermined settings and adjustable to a desired one of these settings
  • H03J5/0245—Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, in which no corresponding analogue value either exists or is preset, i.e. the tuning information is only available in a digital form
  • H03J5/0272—Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, in which no corresponding analogue value either exists or is preset, i.e. the tuning information is only available in a digital form the digital values being used to preset a counter or a frequency divider in a phase locked loop, e.g. frequency synthesizer

Definitions

• the RF signals are transmitted by the satellite in the Ku band, and are converted by the block converter to the L band.
• the frequency range of the RF signals transmitted by the satellite is somewhat smaller (e.g., between 12.2 and 12.7 GHz) than that for the analog satellite television system, and the frequency range of RF signals produced by the block converter is accordingly somewhat smaller (e.g., between 950 and 1450 MHz).
• FIG. 2 is a block diagram of a digital demodulator for use in the satellite receiver shown in Figure 1 and useful in understanding the recovery of digital data from the tuning system shown in Figure 1;
• Figure 3 is a simplified block diagram of a digital satellite television receiver shown in Figure 1 and useful in understanding the operation of the tuning system;
• FIG 4 is a picture representation of the operation of the tuning system shown in Figure 1; and Figure 5 is a flow chart of the tuning routine for searching an offset signal by the tuning system shown in Figure 3 in accordance with an aspect of the present invention.
• the frequency of LO 911 is controlled by phase locked loop (PLL) arrangement 919 comprising PLL integrated circuit (IC) 921, external frequency reference crystal 923 and external filter network 925.
• PLL phase locked loop
• the frequency of the LO signal is controlled by PLL 919 in accordance with instructions generated by microprocessor 19.
• Slicer 1111-2 takes the derotated constellation and outputs decisions based on the quadrant of the input. Each I, Q 10 pair out of slicer 1111-2 is the estimate of which symbol was transmitted.
• Phase detector 1111-3 takes the input and output of slicer 1111-2 and generates a phase error signal for each symbol. This phase error signal is applied to loop filter 1111-5. Loop filter 111-5 controls numerically controlled oscillator (NCO) 1111-1 and provides an estimate of the offset frequency. This estimate is also available to microprocessor 19 as a control signal .
• NCO numerically controlled oscillator
• a frequency error for example, due to a LNB derived frequency offset of the selected RF signal, causes a so-called
• phase detector 1111-3 measures the position of the demodulated data relative to the ideal position in the data constellation. To correct for data rotation and tilt, the frequency, and thus the phase, of NCO
• the search may start from the middle point and proceed in a positive direction while in another system, it may 14 start searching in the opposite direction (i.e. in a negative direction). In either system, when no lock point is found (i.e., no offset signal in found) in one direction, the search continues again from the middle point and proceeds in the opposite direction.
• a system in accordance with aspects of the present invention starts searching at an end point of a band of frequencies in which the offset signal may be found. For example, if the search starts at the top most frequency of the band, the starting point of the CTL search is always above the frequency of the offset signal. Therefore, the system always tries to pull in a negative frequency offset.
• the arithmetic computation approach employed in the digital demodulation system appears to accelerate the entire process of pulling in negative frequency offsets because computation (such as two's complement arithmetic) may produce an arithmetic bias that biases the operation of CTL 1111 in favor of the search for the negative offset signal.
• the arithmetic bias may aid in preventing CTL 1111 from being erroneously stabilized at a false lock point. That is, the arithmetic bias appears to contribute to destabilizing CTL 1111 at a false lock point.
• the tuning system does not waste time, at a false lock point, on determining whether or not it has acquired the real offset signal. Therefore, the entire search process will be accelerated.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
• Channel Selection Circuits, Automatic Tuning Circuits (AREA)
• Superheterodyne Receivers (AREA)
• Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
• Position Fixing By Use Of Radio Waves (AREA)
• Circuits Of Receivers In General (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22169161

Family Applications (1)

Country Status (10)

Cited By (2)

Families Citing this family (12)

Citations (2)

Family Cites Families (9)

• 1999
  • 1999-04-16 BR BRPI9909676-5A patent/BRPI9909676B1/pt not_active IP Right Cessation
  • 1999-04-16 AU AU38617/99A patent/AU770301B2/en not_active Expired
  • 1999-04-16 CN CNB998051349A patent/CN1148871C/zh not_active Expired - Lifetime
  • 1999-04-16 EP EP99921391A patent/EP1072091B1/en not_active Expired - Lifetime
  • 1999-04-16 JP JP2000545246A patent/JP4338895B2/ja not_active Expired - Lifetime
  • 1999-04-16 US US09/673,041 patent/US6678012B1/en not_active Expired - Lifetime
  • 1999-04-16 KR KR1020007010591A patent/KR100610564B1/ko not_active Expired - Lifetime
  • 1999-04-16 WO PCT/US1999/008367 patent/WO1999054998A1/en not_active Ceased
  • 1999-04-16 DE DE69909994T patent/DE69909994T2/de not_active Expired - Lifetime
  • 1999-04-16 MX MXPA00010064A patent/MXPA00010064A/es unknown

Patent Citations (2)

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