No problem piglet. I get the ring modulator/double balanced mixer part. (I built an audio DBM once.. silly but fun.) I need read some in Pippards "Physics of Vibration" (He does a nice job discussing para-amps.) And then I'll have more to say/ ask. ... IIRC there is this threshold condition for amplification and I'd like to remember the details.
Georg H. (It's too bad all threads seem to descend into male pissing contests.)
A decent ARM, which typically includes a mediocre ADC, might, with a PWM DAC for the audio, make a usable antenna-to-speaker AM receiver. Could be a student project.
-- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Not so much. See e.g.
About than 10% variation from 1V-30V. 1N4007 is about a factor of 2 in that range.
PIN photodiodes can be in the 7:1 range, but Q is probably going to be disappointing on account of the epi sheet resistance. (The epi has to be thin enough to be optically transparent.) Your basic BPW34 has about
50 ohms' series resistance. (That's for the Infineon ones. The Osrams are much worse.)Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
An arbitrarily strong mixer still needs selectivity to get rid of the image frequency. SSB mixers help, but are a lot more complicated than a tuned RF stage, and rarely have better than 30-40 dB rejection.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Which is why dual or triple conversion is used in some designs, like the Telemetry receivers that we built at Microdyne. The Cable converters we us ed back in the '80s up converted the entire input up to over 1GHZ, then bac k down to Ch3 for the output. It was real fun replacing the transistor in t he up converter. The leads had to be the exact length and bent to match the original pattern. This was long before surface mount, and the Japanese con struction didn't lend itself to being repaired.
Multiple conversions lead to a forest of spurs unless your frequency plan is very clever or the tuning range is small. Since high frequency gain is cheap these days, single-conversion with a very high IF is usually a win.
A few years ago I did a proof-of-concept for a laser microscope based on a 2D acousto-optic scanner. The two scan signals were both an octave wide, 50-100 MHz, and the RX signal came back at
f_RX = 2f_X + 2f_Y.
Mixing that down to a fixed IF of 10.7 MHz was a bit of a puzzle--there were all sorts of spurs crossing the IF. Putting a 1:1 PLL on the LO output fixed it right up.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
The standard topology of LF/MF/HF general conversion receivers has been for decades to use a high first IF e.g. 45 or 75 MHz, Due to the high side LO, the images are up in the VHF range. A steep 40 MHz RF input LPF will easily take out the image frequency.
If the RF amplifier is not sufficiently strong a strong input signal may generate harmonics (mainly 2nd and 3rd), which could mix with the LO and produce the IF. For this reason, some receivers use octave wide fixed band pass filters, to filter out strong low frequency signal harmonics from polluting the higher bands,
The first IF filter is often a crystal filter only 10-30 kHz wide, This can then be mixed down to a low second IF without risk for image responses in the downmix. Alternatively use zero-IF I/Q detection at
1st IF.SDR works also surprisingly well with sampling at say 80 MHz sampling frequency with only 14 bit ADC.
For AM (MW) only SDR receiver, sampling at 4 MHz should be sufficient.
People do. No kidding.
Care to share the math on that one? Or your patent for the "super-bundler antenna"?
[...]-- Regards, Joerg http://www.analogconsultants.com/
If not that, it can be fixed in post.
-- Rick C. +-- Get 1,000 miles of free Supercharging +-- Tesla referral code - https://ts.la/richard11209
A mediocre 10-bit ADC billed as 12-bit. ;)
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Still better than the terrible 1-volt ADCs in the Xilinx FPGAs.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Do tell!
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
I thought Infineon and Osram Opto Semicondustors were both the same ex-Siemens products, at various stages of rebranding. Did you mean Vishay for one of them? I suspect that Vishay may be the ex-Telefunken parts.
They can self-report the chip temperature, which can be fun.
-- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Roight. Osram is the good one, Vishay the bad one.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
That's why many professional receivers have a very high IF, tens of MHz and sometimes above 100MHz, then mix down straight to 455kHz or wherever one can buy the best filters.
Not just that. With car radios every penny counts and I doubt they will contain high-IP3 mixers. Probably not much more than a glorified Gilbert cell in there.
-- Regards, Joerg http://www.analogconsultants.com/
Well, the TMUX1511 is only 40 cents in reels. I use them in switched attenuators, and they're the greatest--2 pF C_off, 5 ohms R_on. Almost like a relay.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
I think your right, but I haven't done an exhaustive research of models coming out in the last year. There are plenty that use a chip. Here's Silabs list of chips and radio type use.
Mikek
$0.40 is a fortune in consumer or automotive electronics. When designing this sort of stuff I have to calculate in fractions of pennies. A good example was a client who wanted me to determine which resistors in an older design of mine could be relaxed to 10%, 20% and untrimmed. The cost difference per resistor was a few tens of milli-cents but their ROI on my consulting fee for that job was in the green within weeks.
Selecting a half-a-buck part would require are really good reason and is typically not in the cards.
-- Regards, Joerg http://www.analogconsultants.com/
Sure, but a CMOS RF chip could have the equivalent built right in. Ed Oxner of Siliconix did excellent work back in the early '80s making incredibly strong mixers out of matched NMOS quads. (The first was the Si8901, but those morons have recycled that part number to refer to something entirely different, so the datasheet is hard to find.)
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
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