What is meant by 'local' in local oscillator?












4












$begingroup$


We know that a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal.




  • But what do we mean by 'local'?

  • How is 'local oscillator' different from normal oscillator?

  • Why a
    normal oscillator like LC-tank circuit or an opamp circuit can't be used in
    heterodyne receiver?






oscillator terminology







share|improve this question











$endgroup$








  • 3




    $begingroup$
    The local oscillator is the one "local to", i.e., part of, your radio--as opposed to the remote oscillator used by the transmitter.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    An oscillator with an LC tank circuit can be a fine local oscillator in a heterodyne receiver. An opamp RC circuit will tend to be way too drifty and noisy, but you could try.
    $endgroup$
    – TimWescott
    11 hours ago










  • $begingroup$
    Heterodyning usually cares about the phase-noise producing adjacent closein energy on either side of the carrier. Leeson's Equation provides a rule-of-thumb model of phasenoise from various sources.
    $endgroup$
    – analogsystemsrf
    1 hour ago
















4












$begingroup$


We know that a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal.




  • But what do we mean by 'local'?

  • How is 'local oscillator' different from normal oscillator?

  • Why a
    normal oscillator like LC-tank circuit or an opamp circuit can't be used in
    heterodyne receiver?






oscillator terminology







share|improve this question











$endgroup$








  • 3




    $begingroup$
    The local oscillator is the one "local to", i.e., part of, your radio--as opposed to the remote oscillator used by the transmitter.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    An oscillator with an LC tank circuit can be a fine local oscillator in a heterodyne receiver. An opamp RC circuit will tend to be way too drifty and noisy, but you could try.
    $endgroup$
    – TimWescott
    11 hours ago










  • $begingroup$
    Heterodyning usually cares about the phase-noise producing adjacent closein energy on either side of the carrier. Leeson's Equation provides a rule-of-thumb model of phasenoise from various sources.
    $endgroup$
    – analogsystemsrf
    1 hour ago














4












4








4





$begingroup$


We know that a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal.




  • But what do we mean by 'local'?

  • How is 'local oscillator' different from normal oscillator?

  • Why a
    normal oscillator like LC-tank circuit or an opamp circuit can't be used in
    heterodyne receiver?






oscillator terminology







share|improve this question











$endgroup$




We know that a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal.




  • But what do we mean by 'local'?

  • How is 'local oscillator' different from normal oscillator?

  • Why a
    normal oscillator like LC-tank circuit or an opamp circuit can't be used in
    heterodyne receiver?






oscillator terminology




oscillator terminology






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 14 hours ago







Shadow

















asked 14 hours ago









ShadowShadow

185312




185312








  • 3




    $begingroup$
    The local oscillator is the one "local to", i.e., part of, your radio--as opposed to the remote oscillator used by the transmitter.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    An oscillator with an LC tank circuit can be a fine local oscillator in a heterodyne receiver. An opamp RC circuit will tend to be way too drifty and noisy, but you could try.
    $endgroup$
    – TimWescott
    11 hours ago










  • $begingroup$
    Heterodyning usually cares about the phase-noise producing adjacent closein energy on either side of the carrier. Leeson's Equation provides a rule-of-thumb model of phasenoise from various sources.
    $endgroup$
    – analogsystemsrf
    1 hour ago














  • 3




    $begingroup$
    The local oscillator is the one "local to", i.e., part of, your radio--as opposed to the remote oscillator used by the transmitter.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    An oscillator with an LC tank circuit can be a fine local oscillator in a heterodyne receiver. An opamp RC circuit will tend to be way too drifty and noisy, but you could try.
    $endgroup$
    – TimWescott
    11 hours ago










  • $begingroup$
    Heterodyning usually cares about the phase-noise producing adjacent closein energy on either side of the carrier. Leeson's Equation provides a rule-of-thumb model of phasenoise from various sources.
    $endgroup$
    – analogsystemsrf
    1 hour ago








3




3




$begingroup$
The local oscillator is the one "local to", i.e., part of, your radio--as opposed to the remote oscillator used by the transmitter.
$endgroup$
– Hearth
14 hours ago




$begingroup$
The local oscillator is the one "local to", i.e., part of, your radio--as opposed to the remote oscillator used by the transmitter.
$endgroup$
– Hearth
14 hours ago












$begingroup$
An oscillator with an LC tank circuit can be a fine local oscillator in a heterodyne receiver. An opamp RC circuit will tend to be way too drifty and noisy, but you could try.
$endgroup$
– TimWescott
11 hours ago




$begingroup$
An oscillator with an LC tank circuit can be a fine local oscillator in a heterodyne receiver. An opamp RC circuit will tend to be way too drifty and noisy, but you could try.
$endgroup$
– TimWescott
11 hours ago












$begingroup$
Heterodyning usually cares about the phase-noise producing adjacent closein energy on either side of the carrier. Leeson's Equation provides a rule-of-thumb model of phasenoise from various sources.
$endgroup$
– analogsystemsrf
1 hour ago




$begingroup$
Heterodyning usually cares about the phase-noise producing adjacent closein energy on either side of the carrier. Leeson's Equation provides a rule-of-thumb model of phasenoise from various sources.
$endgroup$
– analogsystemsrf
1 hour ago










3 Answers
3






active

oldest

votes


















19












$begingroup$

You got that wrong:
The "local" in oscillator doesn't describe the kind of oscillator used. It could just be an LC-tank, it could be a crystal-derived oscillator, it could be something synthesized from a reference clock or something recovered from the data stream received:



The "local" in oscillator refers to the fact that it's what the mixer uses locally to mix down or up, as opposed to the oscillator at the other end of the communication, which simply isn't the same oscillator.






share|improve this answer









$endgroup$









  • 2




    $begingroup$
    You could also contrast it with an external oscillator - like a 10MHz reference input.
    $endgroup$
    – CramerTV
    5 hours ago










  • $begingroup$
    @CramerTV yeah, that will the answer the question - "how is local oscillator different from normal ref. input signal generator?"
    $endgroup$
    – Shadow
    2 hours ago



















7












$begingroup$

Think of frequencies. The local oscillator generates a local frequency, that is only used by your mixer as the intermediate frequency. Whereas the transmitter frequency is not staying on your local board but flying through the air as radio waves. The transmitter and the receiver does not need to use the same intermediate frequency, but could use different local oscillators.






share|improve this answer









$endgroup$





















    3












    $begingroup$

    LO to an RF Engineer means a sine signal "local" or "within the device" used for heterodyning or mixing.






    share|improve this answer









    $endgroup$













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      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      19












      $begingroup$

      You got that wrong:
      The "local" in oscillator doesn't describe the kind of oscillator used. It could just be an LC-tank, it could be a crystal-derived oscillator, it could be something synthesized from a reference clock or something recovered from the data stream received:



      The "local" in oscillator refers to the fact that it's what the mixer uses locally to mix down or up, as opposed to the oscillator at the other end of the communication, which simply isn't the same oscillator.






      share|improve this answer









      $endgroup$









      • 2




        $begingroup$
        You could also contrast it with an external oscillator - like a 10MHz reference input.
        $endgroup$
        – CramerTV
        5 hours ago










      • $begingroup$
        @CramerTV yeah, that will the answer the question - "how is local oscillator different from normal ref. input signal generator?"
        $endgroup$
        – Shadow
        2 hours ago
















      19












      $begingroup$

      You got that wrong:
      The "local" in oscillator doesn't describe the kind of oscillator used. It could just be an LC-tank, it could be a crystal-derived oscillator, it could be something synthesized from a reference clock or something recovered from the data stream received:



      The "local" in oscillator refers to the fact that it's what the mixer uses locally to mix down or up, as opposed to the oscillator at the other end of the communication, which simply isn't the same oscillator.






      share|improve this answer









      $endgroup$









      • 2




        $begingroup$
        You could also contrast it with an external oscillator - like a 10MHz reference input.
        $endgroup$
        – CramerTV
        5 hours ago










      • $begingroup$
        @CramerTV yeah, that will the answer the question - "how is local oscillator different from normal ref. input signal generator?"
        $endgroup$
        – Shadow
        2 hours ago














      19












      19








      19





      $begingroup$

      You got that wrong:
      The "local" in oscillator doesn't describe the kind of oscillator used. It could just be an LC-tank, it could be a crystal-derived oscillator, it could be something synthesized from a reference clock or something recovered from the data stream received:



      The "local" in oscillator refers to the fact that it's what the mixer uses locally to mix down or up, as opposed to the oscillator at the other end of the communication, which simply isn't the same oscillator.






      share|improve this answer









      $endgroup$



      You got that wrong:
      The "local" in oscillator doesn't describe the kind of oscillator used. It could just be an LC-tank, it could be a crystal-derived oscillator, it could be something synthesized from a reference clock or something recovered from the data stream received:



      The "local" in oscillator refers to the fact that it's what the mixer uses locally to mix down or up, as opposed to the oscillator at the other end of the communication, which simply isn't the same oscillator.







      share|improve this answer












      share|improve this answer



      share|improve this answer










      answered 14 hours ago









      Marcus MüllerMarcus Müller

      32.6k35895




      32.6k35895








      • 2




        $begingroup$
        You could also contrast it with an external oscillator - like a 10MHz reference input.
        $endgroup$
        – CramerTV
        5 hours ago










      • $begingroup$
        @CramerTV yeah, that will the answer the question - "how is local oscillator different from normal ref. input signal generator?"
        $endgroup$
        – Shadow
        2 hours ago














      • 2




        $begingroup$
        You could also contrast it with an external oscillator - like a 10MHz reference input.
        $endgroup$
        – CramerTV
        5 hours ago










      • $begingroup$
        @CramerTV yeah, that will the answer the question - "how is local oscillator different from normal ref. input signal generator?"
        $endgroup$
        – Shadow
        2 hours ago








      2




      2




      $begingroup$
      You could also contrast it with an external oscillator - like a 10MHz reference input.
      $endgroup$
      – CramerTV
      5 hours ago




      $begingroup$
      You could also contrast it with an external oscillator - like a 10MHz reference input.
      $endgroup$
      – CramerTV
      5 hours ago












      $begingroup$
      @CramerTV yeah, that will the answer the question - "how is local oscillator different from normal ref. input signal generator?"
      $endgroup$
      – Shadow
      2 hours ago




      $begingroup$
      @CramerTV yeah, that will the answer the question - "how is local oscillator different from normal ref. input signal generator?"
      $endgroup$
      – Shadow
      2 hours ago













      7












      $begingroup$

      Think of frequencies. The local oscillator generates a local frequency, that is only used by your mixer as the intermediate frequency. Whereas the transmitter frequency is not staying on your local board but flying through the air as radio waves. The transmitter and the receiver does not need to use the same intermediate frequency, but could use different local oscillators.






      share|improve this answer









      $endgroup$


















        7












        $begingroup$

        Think of frequencies. The local oscillator generates a local frequency, that is only used by your mixer as the intermediate frequency. Whereas the transmitter frequency is not staying on your local board but flying through the air as radio waves. The transmitter and the receiver does not need to use the same intermediate frequency, but could use different local oscillators.






        share|improve this answer









        $endgroup$
















          7












          7








          7





          $begingroup$

          Think of frequencies. The local oscillator generates a local frequency, that is only used by your mixer as the intermediate frequency. Whereas the transmitter frequency is not staying on your local board but flying through the air as radio waves. The transmitter and the receiver does not need to use the same intermediate frequency, but could use different local oscillators.






          share|improve this answer









          $endgroup$



          Think of frequencies. The local oscillator generates a local frequency, that is only used by your mixer as the intermediate frequency. Whereas the transmitter frequency is not staying on your local board but flying through the air as radio waves. The transmitter and the receiver does not need to use the same intermediate frequency, but could use different local oscillators.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 14 hours ago









          LundinLundin

          3,8411131




          3,8411131























              3












              $begingroup$

              LO to an RF Engineer means a sine signal "local" or "within the device" used for heterodyning or mixing.






              share|improve this answer









              $endgroup$


















                3












                $begingroup$

                LO to an RF Engineer means a sine signal "local" or "within the device" used for heterodyning or mixing.






                share|improve this answer









                $endgroup$
















                  3












                  3








                  3





                  $begingroup$

                  LO to an RF Engineer means a sine signal "local" or "within the device" used for heterodyning or mixing.






                  share|improve this answer









                  $endgroup$



                  LO to an RF Engineer means a sine signal "local" or "within the device" used for heterodyning or mixing.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 14 hours ago









                  Sunnyskyguy EE75Sunnyskyguy EE75

                  64.3k22294




                  64.3k22294






























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