Automatic BFO tunning in SSB voice comms

[neazoi]

bfo ssb

hello,
has anyone tried or know where to find a suitable circuit/idea for automatically tunning the BFO of an SSB receiver to the transmiter signal for voice communications?

Has this idea been implemented in any commercial transmitter/receiver system. Do you know any transceiver that uses automatically BFO tunning?

Thanks

 

[vfone]

ssb bfo

I don’t think there is a need for an automatically tuned BFO in a SSB transmitter, whatever method is used (filtering or phasing). All the commercial SSB transceivers that I know use crystal or PLL controlled BFO’s.
Sometimes in the filter method, the BFO frequency is slightly adjusted on the skirt of the SSB filter to adjust the tone bandwidth of the audio modulation.

 

[neazoi]

bfo for ssb

The stability of crystal bfos is not much sufficient I think as the xtal experiences frequency drifting due to thermal or mechanical changes. The use of a pll is ok. Although both of these will work quite right the bfo setting depends on the user experience in tuning ssb signals so there has to be a better way. The thing is to have the operator not worying about tuning the bfo at all, talking just like talking to an AM transceiver.
Is there any commercial/amateur device that could do this?

 

[vfone]

bfo in communication

The stability of a crystal is more than sufficient for a voice SSB communication. Especially if you think that SSB modulators in commercial transceivers use low frequency (few hundreds of kHz, maximum few MHz).
All the modern transceivers use PLL’s controlled by a TCXO, and there is no need to adjust dynamically the frequency of the BFO.

 

[neazoi]

crystal controlled bfo

so there is not such system in commerce for ssb transceivers made by icom, yaesu etc

 

[vfone]

bfo yacht boy

Transceivers made by ICOM, YAESU, Kenwood, do not tune the BFO frequency.

Only cheap radios like Grunding Yacht-Boy, Sony ICF’s, etc., they tune the BFO, because they do not have low frequency steps in the tuning synthesizer. Usually they have a minimum of 1 kHz step frequency resolution, and tuning the ceramic resonator in the BFO they get a “clarifier” in SSB mode. Also tuning the BFO they can get both side-bands.

Commercial and high-end receivers have a frequency tuning resolution down to 1Hz.

 

[neazoi]

bfo for hf transceiver

I got that,
So the need for tuning the bfo is basically because of the lack of accurate pll tuning in cheap receivers, right?

 

[vfone]

how to adjust the bfo of a ssb receiver

Yes