substituting old IF cans

See the Sid Darlington paper. 300Hz to 3kHz is less than three octaves. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Something like figure 8 here:

That qualifier is just meant to exclude approaches such as the Weaver architecture where you can shift the problem of, "how well can you generate a

90 degree phase shift?" over to "well, if you can build a really good low-pass filter instead, you don't necessiary need to be able to generate that great of a 90 degree phase shift anymore..."

Cool, please let us know what you find!

I think that particular Atmel chip came out of Norway, so it's good your design had better performance. :-)

---Joel

It's a cheat because it doesn't actually generate the SSB equivalent of the input signal, but rather of the input signal with a nasty all-pass phase smear on it. (Check out the step response of one of those filters.) It works fine for voice, but not for much else.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

For AM SSB, isn't _voice_ what it's all about? ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed

It's such a small world anymore, who knows? My co-designers were an Atmel team in Germany. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed

I got an email from Linkedin today. When I checked it out, your name & photo came up as someone I might know. :)

--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.

Rockwell / Collins filters were probably the commonest, IIRC. Max-Gain systems has a bunch of them, as surplus parts.

Take a look in the current "Experimental Methods in RF Design" book. There's quite a bit of discussion of these sorts of phase-shift filters, for use in phasing-based transceivers. This approach has become more popular of late, with the resurgence in interest in direct-conversion ("zero IF") designs.

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!

"Experimental Methods in RF Design" discusses these issues in quite a bit of detail. There are a number of different filter methodologies which (when carefully implemented) can produce very good results, and some of these have (as you point out) been used for decades.

If I recall correctly (I was just perusing that chapter a week or so ago) it's possible to make such a filter using 3 op-amp stages per side, and 1%-selected components, which can be used in a very high-performance SSB receiver or exciter with excellent results. With a bit of trimming (one pot for phase adjust, one for amplitude adjust) I think I recall that one might be able to get 55-60 dB of opposite-sideband carrier rejection across the 300-3000 Hz audio range. The phasing cancellation becomes good enough that there isn't a practical need to get better... beyond that point, spurs in the undesired sideband are dominated by IMD products elsewhere in the signal chain.

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!

I think pilots would fight that tooth and nail, because AM just plain works. In Europe they did that with emergency services, replacing their traditional FM gear. From what I've heard that has resulted in some problems.

Of course, consumers just get it over the head. Like with DTV where every other movie pixelates out and sometimes we can't watch the news anymore.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

range

interference.

In Darlington's time, sure.

I've used baseband phase-type SSB mixers in instruments, though, and it usually matters there. In optical stuff you don't usually care too much about the sideband rejection as long as it's more than 20 dB or so, because you're usually just trying to get rid of the image noise before it gets folded over onto your signal. You need a couple of linear phase all-passes to do a good job of that. It's a good application for the Swiss Army switched cap filters like the late lamented LMF100.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

You need to move closer to the Xmit antenna. ;-)

Cheers! Rich

ISTR 2Q30 or 3Q4 or so, but it was many many moons ago...

Thanks! Rich

The signal is way strong but ATSC stinks under multipath conditions, which are rather extreme here. But the fact is, NTSC was better because it always worked.

Then some stations did the unbelievable, gave up their precious VHF channels for UHF. I will never understand that. This was like trading your plate of filet mignon against one with macaroni and cheese, but paying the same price.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

I still have several MF10's in my parts bin ;-)...

...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed

< >

--
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml   email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com

I just checked, and you can still get LMF100s and MF10s. They cost three or four bucks apiece, though.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

I've seen your there as well. LinkedIn seems pretty good at digging up connections -- I probably at least recognize 3 or 4 people of every ten it thinks I might know, even if in many cases I only know them very superficially.

Now where's that button to add you to my connections... :-)

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Thanks Don, that reference list is nice. I've built phase sequence filters, as someone pointed out it's important to match the caps with the same nominal value rather than hit some specific capacitance value. One of the first times I really appreciated spice. No way was I going to try writing down all those mesh equations and solve it.

George H.

Wasn't that some imperial edict handed down from "on high"?

Thanks, Rich