Newer SSB quality

[scanmanmi]

Please comment on this video. Does this apply to amateur equipment as well? When did this start? Are there certain mfg that do this? https://www.youtube.com/watch?v=feW4gtMiLbM

 

[zz0468]

Please comment on this video. Does this apply to amateur equipment as well? When did this start? Are there certain mfg that do this? https://www.youtube.com/watch?v=feW4gtMiLbM

First off, I believe the guy is basically correct, in that the quality of the crystal filter will affect received signal quality. I also expect that he's correct in saying people today are more cost conscious and less interested in quality.

I don't think that the problem has spread to ham radio, however, as evidenced by the proliferation of high end gear like the Elecraft K3, and other high end radios. One thing you'll see when researching ham HF gear, there is a lot of talk and attention paid to the crystal filters. Many radios have factory provision for upgraded filters, even on high end radios.

Getting back to cb radios, I think he's right on the money, but left an important detail out. A lot of signal noise is also due to low quality synthesizers.

Any of the old radios that sound so good were rock bound, not synthesized. Between that and the filters, I'm not surprised that the radios tend to sound noisy. Quiet radios are expensive.

 

[AK9R]

Given that many of the newer amateur radio HF transceivers use digital signal processing, the crystal filter "problem" may be a thing of the past in that market. In a DSP radio, the IF bandwidth is determined by algorithms in the DSP, not by a crystal filter.

 

[WA8ZTZ]

Quiet radios are expensive.

^^^ this

 

[WA8ZTZ]

Given that many of the newer amateur radio HF transceivers use digital signal processing, the crystal filter "problem" may be a thing of the past in that market.

^^^ and this

 

[prcguy]

Well, sort of. Most "DSP" and "SDR" HF radios are still superhet types using a traditional IF with a crystal, ceramic or mechanical IF filter and these radios rely on the IF filter for the bottom line receiver performance. The DSP IF will allow adjustment narrower than the fixed filter but at a lesser spec for high signal level handing.

Some models from Elecraft (KX2 and KX3), Flex and now Icom (IC-7300) are direct conversion without any fixed IF filter but these radios have carefully designed front ends with band pass filtering and high performance, high level IQ mixers and A/D converters to survive crowded bands and field day.
prcguy

Given that many of the newer amateur radio HF transceivers use digital signal processing, the crystal filter "problem" may be a thing of the past in that market. In a DSP radio, the IF bandwidth is determined by algorithms in the DSP, not by a crystal filter.

 

[AK9R]

If a radio is a direct sampling SDR, then does it need mixers?

 

[majoco]

The main purpose of SSB communication is to get the message across by the most efficient method. In fact it has more to do with the qualities of the transmitter and its bandwidth rather than anything in the receiver. If the transmitted frequencies range from f(suppressed) plus 300Hz to 2700Hz (which is a bit less than the old telephones) and there is only signal when required and the receiver operator gets the message correctly then all is achieved. RF power is saved by not having a useless carrier and a duplicate of the sideband and supplied power is also saved by having a smaller and cheaper transmitter, albeit a little more complicated. The atmospheric noise is reduced by having a narrower bandwidth than AM in the receiver, hopefully to match the 300 to 2700Hz of the transmitter. If the received signal sounds like Donald Duck then you haven't tuned to the signal properly - but as someone has said, you have poor quality crystal filter - or DSP system. More modern crystal filter that are computer designed are much flatter with steeper sides that the old hand-calculated variety, especially noticeable where one filter is used for USB and LSB.